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MG MGB Technical - 18V camshaft opinions...

I will be rebuilding my '74 roadster's 18V engine shortly, and am considering a cam upgrade. I basically have it narrowed down to either the Piper 270 or 285. I have done fairly extensive research, including buying the Peter Burgess book on power tuning the MGB engine. I was wondering if any of you with aftermarket cams could comment on how successfull you feel the upgrade was. I fully understand the mechanics of the differences between the two cams I have mentioned, but that's a far cry from driving it to see if the loss of bottom end power is too great... Anyone have thoughts to share?

Much appreciated, Dave
Dave Whitehead

Depends on th type of driving you do - if it is a lot of city, stop start driving then the 270 is better than the 285. If it is mostly open road driving then I would go for the 285.
Chris Betson

I would go with the BP 270 unless you are doing other performance mods to the engine- raised compression, overbore, headwork, and your car is not a dailey driver. The BP 285 works very well with mods but as Chris implies it can be a pain in city driving. Usually if you are uncertain which of 2 cams to use you will be more satisfied with the less radical one. I have a BP 270 in one of my cars and am very pleased with it.
Terry

My machine shop stated that all piper cams are reground not new. Does anyone have any information on this statement. I thought they were new. Thanks
JEFF BECKER

They are available both as regrinds and as grinds on new blanks. Brit-Tek (800-255-5883) usually has both types available. I prefer the new.
Terry

Dave

Interestingly I have tried both these cams successively in the same engine, and both are quite satisfactory BUT using a data logger there was virtually no difference in acceleration between them - altho having said that, I have not used a 43D distributor with them

Compared with a standard cam they produce a slight loss of low speed torque but a noticeable increase in both revability and performance from 4500 rpm onwards - 6250 rpm is no problem at all

Curiously, my car has been very unresponsive to tuning - there has been very little gain from 285, HS6s, and Burgess fast road head over my original set up of DIY 3 angle seat head, 270 cam and HS4s

Frankly, I would go for the 270

FWIW

Christopher Storey
CHRIS

Dave-
The Piper BP 285 gives a somewhat lumpy idle and mediocre power output below 3,000 rpm, but really comes alive above that, charging to the redline. This makes it a bit of a pain to drive around town with, but makes for better acceleration out on the open highway, so long as you don't mind risking your license if you get carried away. Being what was once called a "3/4 Race Cam", it will demand that you pay attention to your carburetion and ignition settings. Stock aircleaners will only strangle it, so expect to lay out the money for a larger set of K&N airfilters. If you give it a pair of 1 3/4" SU carburetors to inhale through it will really reach its true potential, but expect all aspects of performance below 3,000 rpm to suffer. The Piper BP 270 has much more low-rpm torque and a smooth idle, but not as much high-rpm power. If you give it a pair of 1 3/4" SU carburetors to inhale through it will lose more at low rpm than it will gain at high rpm, so don't bother. Overall, the Piper BP 270 is the best choice for all-around performance. It is much more tolerant of slightly out-of-tune carburetion and ignition. I've got one in my engine and am quite happy with it.
Steve S.

This thread was discussed between 11/03/2003 and 14/03/2003

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