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MG MGA - Vacuum tube

I am getting an MGB 18V rebuilt. I have/had a rubber vacuum advance tube and now rebuilt 1500 carbs (H4s?). My engine builder said the vacuum tube connector (what ever it's called, "vacuum line union") on the SU was buggered so he installed one "in the middle of the intake manifold" I haven't seen it yet (it's 75 miles away). He says it should work better.... I don't remember why. I was thinking that the tube located there would pick-up the fuel charge that would be sucked into the distributer advance mechanism. Anything to be concerned about?
Steve Meline

Your engine is under vaccum so it is sucking in air not pushing air out. Your line there should be fine. I presume the line will be no bigger than the copper tube that was stock. My only concern is if the line is too big, it might create it to advance the timing too soon. What problems did you encounter with your rebuilt engine that Sid did to cause it to have to be rebuilt again.
JEFF BECKER

Thanks Jeff, makes sense to me. Others concur?

I had only about 13,000 miles on the engine, There was some kind of lubrication failure with scored mains and premature cam wear. You may remember, on anther front, I was dealing with incessant pre-ignition knock. With the head removed we found wet pistons tops and glazed cylinder walls suggesting that the rings never sealed allowing oil into the cylinders. This may have caused knock from dieseling. Lots of speculation without much evidence to explain this combination very well.
Steve
Steve Meline

Your troubles sound like the other posts regarding the new specifications for todays oil. Rapid cam wear, on a new engine due to less zinc additives in the oil. Before staring your new engine, you should check this topic out. There is a great deal of concern regarding this matter. I am worried as my new 1500 engine has 600 miles of Castrol oil on it. I hope I have done no damage but I have now switched to Diesel oil with STP additive. Gordon
Gordon Harrison

Thanks Gordon,

Thankfully I read those posts, and with great interest. I think that info is vital to all. If anyone hasn't seen it they should review the related "New Oils..." thread running on the T Series TD TF board. Before the car was started I sent it to my mechanic and had him change the oil to, as I recall, Valvoline VR1. Hope your new engine is unharmed.


I suspect that factor contributed to the cam wear but I'm not certain it would explain the bearing wear. Steve
Steve Meline

This thread was discussed between 13/01/2007 and 15/01/2007

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