MG-Cars.com
MG TD TF 1500 To hot for the hot tub BBS discussion at MG-Cars.net
MG-Cars.net
Welcome to our resource for MG Car Information.
Recommendations
Parts
MG parts spares and accessories are available for MG T Series (TA, MG TB, MG TC, MG TD, MG TF), Magnette, MGA, Twin cam, MGB, MGBGT, MGC, MGC GT, MG Midget, Sprite and other MG models from British car spares company LBCarCo.
|
|
MG TD TF 1500 - To hot for the hot tub
| Wife and daughter left for the evening so headed up to the store in the TF for some brewskies. After a conversation with the owner that "no it's not a kit car buddy it's the real deal" I took it out on the interstate with the intention of getting a reading off the mile posts for the speedometer gear correction adaptor (5 speed). Watching the gauges closely I became concerned that the temp gauge kept climbing till it leveled out at 110c. The oil pressure maintained 55lbs but I forgot all about the mile markers and pulled off at the nearest exit and headed for home. Checked the temp with my wife's (don't tell her) meat thermometer and the gauge is accurate. Ive been taking 5 to 6 mile jaunts with a reading of 85c. I was running with the traffic (75 mph) at 3700 rpm and the air temp was about 90f. New Moss water pump, thermostat, correct belt and the engine and block are not an issue. The engine is running rich because of the repo helings filters. Timing is dead on but have thought about giving it some advance because of the altitude (4300 ft). Anybody have any thoughts? LaVerne; parinoid in Colorado |
| LED DOWNEY |
| LaVerne, You running points or a pertronix ignightor? Check here: http://www.ttalk.info/ Under "Pertronix Igniter" in tech section. "advance for 30 degrees at 3000 rpm" works well for me! Also check the Jet-Hot info on that site under "picture this". I still think this is the best $100 I ever spent on mine! No ...I don't work for "Jet-Hot" but have done it on several cars now and most pleased with results. Cheers, David 55 TF1500 #7427 |
| David Sheward |
| LaVerne, David has great advice. I only want to add you might want to check the openings in your radiator grill slats. They should be quite open, like a half inch visible between each. dave |
| Dave Braun |
| Thermostat??? Odd to have a sudden change from your last drive. Matthew |
| Matthew Magilton |
| Took the air filters off and took her out for about 8 miles this morning. Gauge settled right in at a little above 85c. Outside temp about 75f. The slats are 1/2" plus apart, the pertronix is still in the box and had the exhaust manifold ceramic coated (not hot jet). Will give it a try again this evening with out the filters. Was going to try and find some K & N's to fit in them any way. Supposed to be well above 100f again today. LaVerne |
| LaVerne |
| Interesting to see what its like without the air filters on the 100 + day. I had the same problem and the only thing I could do to fix it was to recore with a triple core. Now even when its 105+ I am running at 75C. |
| Chris Couper |
| Took it out again. 100f air temp. 9 mile drive with no filters and temps holding now about 95c. I think I'm inclined to check the compression for a head leak but don't see any other signs in the oil or water. Think I'll take her out again and see what see does after I lean it a little more. LaVerne |
| LED DOWNEY |
| After another 12 mile run its back at 100c. Chris can you tell me more about the radiator redo? This temp has to come down. Oil cooler is a likely addition also. LaVerne |
| LED DOWNEY |
| Curious if anybody had a number plate under the bumper and removed it and after noticed any reduction in engine temp. Thats one option I'm looking at right now , plus might form an air scoop under the front valance to push some more air through the engine compartment. I have a new Thermostat in but I'm wondering if the old flap type really make any differnce on the TF system. LaVerne |
| LaVerne |
| LaVerne, On my TD (not the same as a TF, it is non-pressurized) my below bumper license plate never made a difference. dave |
| Dave Braun |
| Well the next attempt is going to happen here in a few minutes. I believe I probably way over the 50 50 mixture on the antifreeze after the freeze plug change so i'l try and get that sorted and then will have a go with the waterwetter treatment and head out on the highway again. If no noticble difference the off with the plate. And so on, and so on. 103f right now. As Eddie Murphy in his best James Brown charachter said "Too hot for the hot tub Yaoooww!!! LaVerne |
| LED DOWNEY |
| Sad to report that the waterwetter treatment has shown no measurable improvement. Neither did removing the plate. I have noticed that the temp will hold down in the 95c range if I keep the rpm's below 3000. Also the temp will hold at 95c or drop back down from 105c range to 95c at idle. Previous over heating problems for me have been at slow traffic or idle speeds. Here it appears to be the opposite. I think the next move will be to try and advance the timing about 5 degrees and see what gives. After that I'm at a loss. LaVerne |
| LED DOWNEY |
| LaVerne, I gather you know for absolute sure that the two(2)3/16ths holes located in the blocks 'swollen' gallery and behind the two(2) 35mm core plugs are perfectly clear of debris.TF's in particular will overheat at high speed if these openings are choked up. I have also seen the Water Pump impellor on new Water Pumps being moved('pressed')away from the pump body when the pulley is put back onto the pump.Many of the new pumps impellors are only press fit onto the shaft.This unwanted gap allows water to 'duck'from where we really want it to travel for efficient cooling. Take out the Thermostat and check it's operation? Finally,TF's like new,clear Radiator cores as Chris.C.eluded to. Cheers Rob. Grantham. |
| R GRANTHAM |
| La Verne, Try setting timming advance for 30 degrees at 3000 rpm. Also ...does the passagner "floor" feel very warm when your temp is "up"? If "yes" on the floor, (that's where exhaust is on the TF) your not getting the hot fumes "out" of the compartment fast enough. Ours used to bake my wife before I did "jet-Hot" treatment on the manifold. (the big advantage with JH is they treat the "inside" of the manifold making it slippery). Quicker you get hot fumes out of your engine, lower the operating temp will be! Although I am still running the stock 4 blade fan, I have heard many have changed over to MGB 6 blade plastic fan. While on that subject...any chance your fan is on backwards? If it is, could be trying to "push" air through the radiator instead of "pulling" air from the front! This might explain why you are staying cooler at slow speed! Cheers, David 55 TF1500 #7427 |
| David Sheward |
| I agree with David Sheward on all but one point. A backwards fan will still push air in the proper direction, just not as efficiently, and the fan doesn't help cooling at motoring speeds, which is where the problems seem to lay. When I cleaned out my block on the TD, I did have to clean out the 3/16 hole which was originally there, and then I added the one behind the other core plug. I don't know if the factory eventually added that hole to the later XPAG and XPEG engines, but my understanding is that the cooling is improved by drilling out those holes. dave |
| Dave Braun |
| Did a little timing advance and took it for a short spin but not long enough to observe the temp. Down on power so back to original setting. Did a compression check. All cylinders in the 120 to 125 lb area. Somewhat suprised at the readings but considering the head wasn't shaved and was slightlty over 3" thick I suppose thats tollerable. Should workout if a certain someone comes thru on the new supercharger. I can't say one way or the other on the freeze plug holes as the block was tanked and plugged at the machine shop. The front plug does show the slightest sign of seepage so I'll probably remove it and have a look sometime soon. The floorboard test won't work for me as I installed some heat shield material under the floorboards on both sides. The fan blades are on correctly. I'm leaning two directions. Because of the rise in temp over 3000 rpm leads me to believe I'm not getting enough advance. Think I'll see if I can get an idea whats going on with a timming light. Might pull the thermostat next and take a run without it for comparison. LaVerne |
| LED DOWNEY |
| From my experience in dealing with general motor reconditioners,not one of them was aware of the two(2)holes located in the blocks side gallery.Even after a thorough 'pickling' in their block cleaning baths,the stubborn,hardened built up scale will remain.Because they see that the side gallery is clear at this point,on go the new core plugs blissfully thinking all will be well.If the holes are blocked,the occlusion takes on the characteristic look of the original casting and is very difficult to detect from a quick visual check.TF's should have two(2) holes whereas most of the TD's I have seen have only one. Rob. Grantham. |
| ROB. GRANTHAM |
| I'm baffled beyond belief. Timing moving up and down with engine speed as it should. Removed the thermostat and took her back out. Ran it hard and the temp held at about 100c. About 95f air temp. Pull back in the driveway and let it idle back down. It will hold 85c at idle forever. Brought the thermostat along with the old flap type in and put it in a pan water with the temp gauge and heated them up. The new one opens at 75c as advertised and the old flap at 180f. Spark plugs are showing normal heat range indicating its not weak at speed which could cause the high temp. So I am now at a loss as to what the cause might be. Also checked the water pump to make sure the key was in place and spinning the pump along with the pully. Something is causing the motor to heat up at higher RPM's. Any more ideas?? By the way my nice red engine is now partially a crap shade brownish red from the antifreeze spill. I guess we all know why. I'm thinking I'm going to have to pull the head and have a look at the head gasket next. This is gonna suck. LaVerne |
| LED DOWNEY |
| LaVerne, Have you tried giving John Twist a call about this one? He does a daily "call in" for questions at his shop in ADA. Just one more thing I can think of to check...have you done a visual inspection of the springs and counter weights under the points in the dizzy? I recall when I first had purchased my TF having some "timming issues" that I traced to one of the springs in the dizzy being broken/rusted. This caused mine to sometimes "sputter" at higher RPM though...and this does not seem to be an issue here. Cheers, David 55 TF1500 #7427 |
| David Sheward |
| LaVerne: This may or may not have a bearing on your problem but how are your hoses and pressure cap? Is it possible that under high RPM's the hose(s) might collapse thus restricting flow and causing an overheat? I know on one of my other cars I had cooling issues when the upper hose was collapsing at highway speeds. The dealer figured it out and replaced the aftermarket hose with a new one. Never had a cooling problem again after that. Cheers, Jim |
| Jim Rice |
| How long is it since the tanks have been off the radiator and it has been rodded out? All kinds of junk can block the radiator tubes. Would be a shame to be doing all of this fiddling if the basics are not right. If you have in/t done, try a stocking in the top tank for a while any you'll be surprised how much junk you pick up. Regards, Richard. |
| R Payne |
| The engine runs smooth thru all rpm and the timing light shows that there is no bouncing around, seemingly eleminating the distributor as the cause. The radiator was tanked 3 years ago but sat dry in the shop until last month when I finnaly got the engine in. The hoses are new and the upper one is not the bellowed varity but a stiff section and it's not collapsing. The cap a new correct 4lb. Belt is new, cogged and tension is good. I think I'd actually prefer to pull the head verses pulling the radiator. Funny, but I thought with this kind of heat I would have had some vapor lock at some point but that hasn't happened yet. Wish I'd have some vision that would point out some little quick fix but that hasn't happened yet. LaVerne |
| LED DOWNEY |
| LaVerne, "Wish I'd have some vision that would point out some little quick fix but that hasn't happened yet." I think I speak for the group here when I say we are all hoping for the same! I'm stumped. Do try John Twist with this one, he loves a challange! (You out there ready this John?) Cheers, David 55 TF1500 #7427 |
| David Sheward |
| With your radiator, did you seal the openings when it was in storage? We get mud wasps and other creepy crawlies that love to build their nests in places like that. Regards, Richard. |
| R Payne |
| I like Richard's idea. Before pulling the head I would remove the hoses and flush the block and everything like crazy. Also, maybe pull the water pump (I know, not fun on the TF) and look at it to make sure the implellor is attatched, etc., but you would think that would effect more at idle. Re-tourque the head also before pulling.Is your engine really new? If so it is no doubt tight and will run a little hot. If you are running it at 3700 at 70 mph, you are really stressing it. Did you try dropping down a gear and see if that cooled it? I am surprised it wasn't boiling like crazy if it was really 110C. As far as the tiny hole behind the plugs, see the archives. This somehow mysteriously helps some cars, even though it has nothing to do with coolant flow or cooling. The water pump pumps cool water through the raised passage on the side of the block, up and into the head, and out the front of the head. The block has no active coolant flow whatsoever. See the factory manual "Cooling system: thermosyphon, pump- assisted". The water in the block jackets surrounding the cylinders simply circulates by hot water rising. That way the temperature stays more consistent- active cool coolant flowing through the hot head, passive circulation through the cooler block. George |
| George Butz |
| Led: Sorry I was away. I feel your frustration. I did everything you have (you can try one of the water treatments like redline). The only way I finally fixed it was to recore. I think I might have been able to just hot tank and rod the core but there was a leak in it that I had since the last job, so I just opted to spend the $100 and have a new triple core put in. I am somewhat convinced that the new gasolines have a heating effect on our engines but don't have the emperical evidence to prove it. If you go the recore route make sure the guy knows T'series radiators and remounts both of the etched plates appropriately. I would send you off to my guy but he retired recently. Perhaps someone else can give you a another option. TD raditors are small enough to ship around if you cannot find a local. Just make sure you double box it and have them return using your packing. |
| Chris Couper |
| I've spent the morning looking it over again and scratching my head. Took the distributor plate off and had a look around. All clean and cams moving back and forth freely. Springs look good. Decided now was a good time to put the Pertronix in. Set the static timing about 2 degrees advanced and will take her out for a warm up after lunch and double check the tappet settings. Crane card recomends .020 exhaust and .018 intake. No bugs in the shop other than an occasional spider. Tried the redline treatment. Really have no idea how fast I was traveling as I still need to get the speedometer corrected or travel along side some one at fixed speeds. The engine now has about 150 miles or so on it. Fully redone including the high dollar crank. I'm inclined to believe at this point that I'm getting some cylinder blow into the water but have no real evidence such as water in the oil or oil in the coolant. Just my guess at this point. Easier to pull the head than the radiator or pump, so I think thats next. LaVerne |
| LED DOWNEY |
| LaVerne- Two things- I find your compression readings a bit low, though I'm not all that up on stock(?)T series numbers, are you checking correctly with throttles wide open? I would check cam timing. Late cam timing causes low compression readings in a good engine, somewhat low vacuum readings, overheating under load, general loss of performance and fuel mileage, and excessive oil consumption (this especially in worn engines). I have found improvement in all these when replacing timing chains in engines that really needed a rebuild. An engine with late cam timing (within reason!) will run perfectly, frequently with no complaints, but if it is then set up right, everything gets better. We once had a Healey with a sheared crank key that was 50-60 degrees late - started and ran perfectly but had no power. A Spitfire I did recently was assembled at the factory with cam about 10 deg late, plus about 4deg chain wear, ran fine and nobody noticed anything wrong. But when it had to come apart I found the error (and replaced the chain, nothing else was changed except bearings) and it picked up by guess about 8-10hp and mileage went from C27 to C 31, and it ran cooler. Given the number of old or repro parts involved, I trust no marks, and doublecheck final settings everytime. Second, and I have posted this numerous times on various boards, but nobody listens, is restricted exhaust. The OE systems on these cars are borderline, and anything that further restricts is trouble. The big ones are bad repro mufflers with built in restrictions (start cutting mufflers apart and you will see), failure of internal baffles causing partial blockage, shifting of fiberglass and other packings, and mouse nests. I have had this trouble on a number of cars. My XK120 didn't need a speedo over 50, because you could pretty well read speed by the temperature gauge; the DPO had cobbled up a system that fed two 1 3/4 pipes into a single 1 1/2 muffler. A correct system fixed that. My Mazda recently felt like it hit a wall on hard acceleration, then blew the muffler into pieces and took off like a rocket; an internal baffle had failed, letting fiberglass block the outlet. In that case it wasn't a mystery, but a partial blockage could drive you nuts. The old (OE?)muffler had a restriction from 1 3/4 down to 1 1/2, which I didn't care for; the replacement went down to less than 1 1/4 internally, which pisseth me off. A customer MGB quit due to carb float failure, took the carbs off, ordered parts, went back two weeks later, refit carbs and it wouldn't run - no compression. Turned out mice had filled the inlet manifold and a couple of cylinders with dog food. Had to remove the head to get it out; on starting it was sluggish until I held it wide open for a bit - it blew several pounds of dogfood out the exhaust - about 25 feet of driveway covered. You may be able to get an indication of blocked exhaust with a vacuum gauge, but with a partial borderline restriction this won't do; the only sure way is to fit a pressure gauge to a tapping in the front pipe and read backpressure at speed. Easier and more fun to take the muffler off and go for a ride! (put a piece of straight pipe on - exhaust temps can be well over 1000F under load - don't want to cook things!) Check these two items, I see no good reason for pulling the head at this point. FRM |
| FR Millmore |
| I to was a little disturbed by the readings. I expected something close to the 140 area. But owing to the fact that I removed a small amount of material when I polished the head and the fact that the head hasn't been shaved to death I would suspect that I'm barley making 8 to 1. Should be a good match come supercharger time. The exhaust is new front to rear stainless. Set the gears and chain per the manual. Did not degree the stock replacement Crane cam. Power dosen't seem to bad but certainly not up to my modfied B. Got any sugesstions on where one might find a place for a vaucum fitting without drilling a new port? I suppose the muffler could be a culprit and it would be an easier check than the head. Really Hadn't give'n the exhaust a thought since it's brand new. |
| LED DOWNEY |
| LaVerne, you may want to check the compression with your gauge and methods on another T-series engine. It will verify if your gauge is giving consistent readings which are also accurate. Or borrow a gauge from another source, and recheck. They have been known to read off, that's one reason everyone stresses consistent readings from cylinder (10% variance max.) Also, Tom Maine from our club found he needed a copper head gasket with his supercharger. Fletcher, your anecdotes and knowlege never cease to amaze me. I always enjoy your posts. warmly, dave |
| Dave Braun |
| LaVerne- The little material you removed is no doubt offset by any skimming done in the head's life. With such a mild cam, I also would expect 140 or better, IF the throttles are open and the starter/battery is good. Sounds like the only likely exhaust problem is mousie related - hopefully they are supplying a decent muffler. Don't have a T to hand, but isn't it these that have a mysterious bolt screwed into the bottom of the inlet manifold balance passage? That would be a good place for vacuum reading. But I am more inclined to go with a cam timing check. The shop manual gives "intake opening - .009 piston traverse"; since the valve opening is at 5BTDC, I take this to mean that the piston is .009 from (before) the top of its travel, when the IN valve clearance hits zero. Need to get a dial indicator mounted down the plug hole to check that, so To check cam otherwise, and Assuming that there is an accurate tdc mark: This cam has symmetrical timing, ie intake opens 5BTDC and Ex closes 5ATDC. Set the valve clearances accurately on #4 cylinder to something like .035, turn the engine until #1 is just before firing point. The valves on #4 should be just before "rocking" - EX will be almost closed and Intake will be about to open, but EX will still have no clearance and IN will have lots. A bit more turning will cause EX to become loose and IN will still be loose, if not, you need to increase the .035 figure until both valves have SOME clearance at this point. As you carefully turn the engine in very small increments, Keep measuring the clearance on both valves until they are EQUAL. When you measure exactly equal clearances in this position, the CAM is where it should be at TDC - see if the crank marks agree. IF not the position of the CRANK at the equal clearance position will show you how far out the cam timing is. The gross form of this test is to just turn the engine until valves on either 1 or 4 are visually just rocking and see if the TDC marks line up, I do this as a routine part of tune up, but it takes a practiced eye. FRM |
| FR Millmore |
| "Didn't degree the cam..." Hmmm. It sure would be easy to be off one tooth. Which "stock" Crane cam do you have? The fat lobed from Moss, or the Abingdon stock by Crane small lobed cam? I recall the valve timing is different on each of these. You will have to use the spec card for whichever one you have for detailed timing. FR's method of valves rocking on 1 or 4 at TDC should tell the tale (exhaust closing/intake opening). The "T" marks and colored links on replacement chains seem to be random, and you have to count pins, etc. Definitely do this before pulling the head. George |
| George Butz |
| Cam is the Moss variety with the oversized lobes. Card shows two sets of cam timing. One shows intake open at 11 degrees btdc with a 242 duration and the other the intake open at 15 degrees atdc and a duration of 190 dgrees. As this was the standard grind am I to assume that I should use the figures for the 190 degree duration. I understand before top dead center and after top dead center but need some enlightment as to abdc and bbdc. Will try and check the cam timing tonight. I have no reason to doubt the gauge but could slap it on the B for kicks just to see what its reading after a full rebuild 12 years ago. You are correct about the bolt plug on the manifold. Marked the chain myself. LaVerne |
| LED DOWNEY |
| I understand the bolt plug on the manifold has a balancer attached to it, which can be heck to get back in place and balanced if disturbed. Just a thought. dave |
| Dave Braun |
| LaVerne- It is manifestly impossible for the cam to have two different timing figures, unless the clearances are changed, in which case the card should tell you what the clearance is, and when you use it. Neither figures match the shop manual figure of 5BTDC/45ABDC = 230 duration for inlet opening. "BDC" means "bottom dead center", exactly analogous to T(op)DC. I suspect that the 11TDC etc figures are for running clearance, and the cam has a bit more duration than normal. The 15ATDC numbers are probably with clearances significantly above running, and these are setting clearances, but they have to tell you what the clearance is and where to measure some event with these settings. It could be intake max opening, intake closing, some overlap event, etc. Suggest strongly that you post everything on the timing card for us, verbatim. If the requisite info is not on the cam card, a call to the doofuses who made it is in order. NOTE!!! Just found another listing in the (same) manual, showing timing of 11BTDC/57ABDC Inlet = 248duration and 52BBDC/24ATDC Ex = 256 duration for earlier TD. This is NOT a symmetrical cam, and the overlap point will NOT be at TDC. The described procedure will NOT work, and it is unclear which cam the .009 "piston traverse" figure refers to! My procedure will show that the timing is late which will not necessarily be true with this cam. You can still do a rough approximation by checking the point at which either #1 or #4 inlet just closes up its normal clearance to zero - it should be at whatever the stated IN opening occurs, ie, 11 deg BTDC. Calculate the distance 11deg is on the circumference of your pulley, it'll be about 1/2-5/8" - look at the B pulley to get a reasonable idea. If the timing is significantly late, the clearance won't close up until TDC or after. FRM |
| FR Millmore |
| FRM, Perhaps I don't understand the card. So here go's. part no: 340-0002 Mechanical blueprinted grind number 553-0S engine ident. 1940-1954 mg tc-td-tf4 cylinder 1250cc Valve setting:intake .018 exhaust .20 hot lift: intake@cam 238 @valve 357 rocker ratio exhaust@cam 238 @valve 357 1.5 cam timing opens closes advertised dur @ .014 intake 11* BTDC 51* ABDC 242* tappet lift exhaust 51* BBDC 11*ATDC 242* Spring requirements recomended RPMRange none given min 1000 max 4500 float 5500 cam timing opens closes max lift dur @.050 Intake (15*) ATDC 25*ABDC 110ATDC 190* Tappet exhaust 25* BBDC (15*)BTDC 110BTDC 190* Oversized lobes are to reducse wear Etc. Using the quick method reveals that the Intake and exhaust are both fully closed at TDC as indicated by the pully timing mark. Whats your diagnosis Doctor (other than patient is an idiot)?? LaVerne |
| LED DOWNEY |
| If your compressions are pretty even, there is no water in your oil, no oil in your water and no bubbles in your radiator then it is unlikely to be a head gasket problem. You could double check though, by letting the engine get up to the high temperature, letting it idle and earthing each spark plug in turn. The revs should drop the same amount for each cylinder. Regards, Richard |
| R Payne |
| LaVerne- OK, now we're gettin' nowhere! Be aware that some of these measurements are fudged; it is a way of advertising more than you get, and relying on theory rather than reality. "Valve setting:intake .018 exhaust .20 hot lift: intake@cam 238 @valve 357 rocker ratio exhaust@cam 238 @valve 357 1.5" " Since the cam lift is identical on IN&EX, the lift at the valve cannot be identical with different clearances, They are cheating on the clearances, though possibly with good functional reasons & results. Set the clearances equal for checking; I suggest .019 as that was the factory number for the early cam. The valve lifts given are calculated based on the theoretical rocker ratio, which is neither exact or constant through the travel. "cam timing opens closes advertised dur @ .014 intake 11* BTDC 51* ABDC 242* tappet lift exhaust 51* BBDC 11*ATDC 242*" " This would appear to indicate that this .014 is measured at the cam, which would give .021 at the valve (just closing up the clearance) with the theoretical 1.5 rocker ratio, or, it is very close to being a "seat to seat" number. Close! "cam timing opens closes max lift dur @.050 Intake (15*) ATDC 25*ABDC 110ATDC 190* Tappet exhaust 25* BBDC (15*)BTDC 110BTDC 190*" This is (maybe) one fairly standard way to measure real effective cam timing; The timing and duration are measured after the tappet has risen .050 from the base circle = no clearance involved. It is more usual to spec effective duration at .050 valve opening, which would involve clearances & rocker ratios. The only unambiguous info here is that max intake lift is at 110ATDC, and max EX at 110 BTDC, as these are idependent of clearance. Trouble is, you need a degree wheel set up to use the info, although you could calculate what 110 is and mark the pulley, then check max lift points. What we have learned is that this IS a symmetrical cam, but not either of the cams in my copy of the manual. Use the method I first suggested, after settimg the valves on #4 to an equal large (.035)checking figure. The rough test will also be off if the clearances on IN & EX are not equal. The patient (car)has a slight fever, and the intern - you - is learning fast, don't feel bad. I've been studying it all for years, still get confused, mostly by crappy info provided. A call to Crane should satisfy all questions, but only if you get an actual knowlegeable person - not likely. I frequently wind up measuring every available event to arrive at the real facts. FRM |
| FR Millmore |
| I am confused professer. Do I understand that the card indicates that the intake valve should be opening at 11* BTDC ? If so then a rough visual indicates that event is happening at TDC and hence retarded valve timing , Yes ? No ?. If yes then the 64 dollar question would be why would the cam not be drilled ,tapped and marked for these events to happen using the standard gear , chain installation method to give the desired cam timing ? LaVerne |
| LaVerne |
| When my XPEG engine was rebuilt, Bob Wagner timed the new (hotter) Crane cam, it was not as specified but was offset by a number of degrees. He was able to correct it with an offset cam woodruff key. The engine was then set up on the dynomometer and tuned and timed exactly. At external temp of 100 deg. F running at 65 MPH, water temp is 85 deg C, on the button. This would not be the case if he had not retimed the cam. So carefully check the cam timing, at least one Crane cam was offset from the factory. Bob used a degree wheel and dial indicators on the valves for precision. |
| Don Harmer |
| You guys are far better mechanics than I am with much more experance ...(I would not trust my skills to take on this job!) Just one little thing I would say ...last year when I had the TF re-built my mechanic told me one thing that was holding up the process was he had aquired several cams (From the usual sources) that he did not fell comfortable with installing due to not being "in spec". He finally did get one in from a UK supplier, but still sent that one out to have some "work done" on it. I know I am being very vauge here, due to my lack of knowledge of such things...but could this be yet another case of re-pro parts that are just not "quite right"? The chap that did my engine had a lot of experance with XPAG/XPEG engines and seems to have done an excellent job. Just a thought.... Cheers, David 55 TF1500 #7427 |
| David Sheward |
| Hint! Stick with stock engine specs. Our 1954 TF, abeit an original car. It has never had the block or the radiator cleaned in its 52 year history. It runs all day at 3500 prm in the latest Michigan heat wave of 90's plus and the temp gauge neve goes above 85 deg. We run on regular gas, with carbs a little rich, and timing set by the "knock up the hill method". Never had an overheat problem. |
| Colin Stafford |
| LaVerne, Don has the answer pretty well in hand, but I'll amplify one thing. The circle for the gear is pretty big, and a few degrees is easy to see at the outer edge. The circle for the cam and crank shafts, and the mating hole in the gears, where the key goes, is pretty small, and it is more difficult to discern a degree. It wouldn't take much for the keyway in the gears to be slightly machined off, and the keyways in the shafts to be slightly machined off, before you started to have some real errors introduced into your timing, hence needing an offset key for one of the shafts. One would hope the errors would cancel out, but they may not. An offset key is just that, a woodruf key which has an offset so the gear can be rotated slightly relative to the shaft, and still locked in place. It is installed typically on the crank shaft, to get the valve timing to agree with the piston travel. dave |
| Dave Braun |
| LaVerne- "Do I understand that the card indicates that the intake valve should be opening at 11* BTDC ?" Hope so, since that's the facts! " If so then a rough visual indicates that event is happening at TDC and hence retarded valve timing , Yes ? No ?." YES, but do the check as I first gave it to find out how far out it really is. That's what we're trying to find! "If yes then the 64 dollar question would be why would the cam not be drilled ,tapped and marked for these events to happen using the standard gear , chain installation method to give the desired cam timing ?" There are a LOT of places for errors to creep in, Dave B pretty well covers it. Dave S gives you another point - cams are notoriously variable, and always have been. The processes used are demanding and checking is very time consuming. The cam manufacturer can't fix errors from the crank builder, or the sprocket makers, and so forth - it all adds up. Production marks will usually give you an engine that runs "OK", because if it didn't run it went back under warranty. All this is why cams should be degreed in, especially if any parts are non-OEM, as practically everything is on your engine now. David Vizard, who has checked thousands of cams, says that he has found them with timing errors of 16deg in the cam itself, and found that certain factory cams have never achieved their advertised characteristics. When you get real picky, you wind up measuring every event on every lobe - sounds like what Dave S's man was doing. DO the check as I first described it - it is no harder than adjusting the valves and only takes a half hour or so. If the cam is retarded, you probably have found your problem, and no amount of doing anything else will fix it. And I now realize that this is a brand new engine - don't run it at constant speeds or throttle openings until it has maybe 500 miles, back roads good, interstate bad! FRM My original suggestion to check cam timing was to cover all possible errors in parts and assembly, since it checks the end result of all that; if it's wrong then you go back and find the error(s). Anybody with a lot of experience with many cars of the same kind will tell you that some examples are pigs and others are rockets - I think that cam timing is one of the major factors in this. Colin's suggestion to stick with stock specs is indicative that HIS car came out well in HIS eyes, but doesn't mean that any other "stock" configuration will; in fact, it is entirely possible that his car is off in a favorable direction, leading it to be better than usual! FRM |
| FR Millmore |
| My machinist insisted in degreeing my cam, as he said so many are off to some degree (no pun intended). He was surprised that with new sprockets, chain, and Abingdon Spares/Crane cam it was absolutely perfect, as that seems to be the exception rather than the rule.George |
| George Butz |
| One thing that I missed ? is that his car only has 150 miles on it since a rebuild? Its not unusual for cars to run hot for the first 1000 miles or so until everything smooths and polishes out no? For example the rings have to seat (may affect compression ratings?). |
| Chris Couper |
| Sounds like the engine is going to have to come back out. DAMN! Will verify that the piston is actually at TDC with the timing mark before that happens. Never really gave a thought to having to degree the cam as I expected it to go staight in out of the box ( original type). So the lesson learned here is trust nothing. I understand the retarded valve timing will give the heat build up thats happening here. I'm no super mechanic. I've only built about 6 in my lifetime. Not one did I degree the cam on and all ran very well without any problems until now. Would you say that I was just lucky and it finnally ran out. I always assumed that degreeing the cam was for the serious high horsey power boys. Thanks to all who gave advice and to those who pointed out the error of my process. Think I'm going to give it a chance to sit under the cover a while as I've been consumed for several months with getting on the road and could probably use a break before disassembly (again). Embarrased in Colorado LaVerne |
| LaVerne |
| LaVerne- Don't be embarrassed, and DON'T pull the engine until you do the cam timing check properly! You WILL be deservedly embarrassed if you pull it and find that the cam timing IS right! Chris is exactly correct in saying that this could be a matter of too hard running on a new engine, that's why I said "And I now realize that this is a brand new engine - don't run it at constant speeds or throttle openings until it has maybe 500 miles, back roads good, interstate bad!" You know the engine is new, but we didn't get that info until about 20 posts in. Excessive blowby from unseated rings can easily cause low compression and high temperatures, and create havoc inside as well. You need to load the rings by accelerating at 1/2 to 3/4 throttle, and then sucking oil up past them by coming off throttle briefly. This keeps them lubricated so they don't score. Backroad driving is perfect for this - NO CONSTANT THROTTLE operation for more than 30 sec in the first 200miles, or 1 minute in the first 500 miles! FRM |
| FR Millmore |
This thread was discussed between 27/07/2006 and 31/07/2006
MG TD TF 1500 index
This thread is from the archive. The Live MG TD TF 1500 BBS is active now.