280zwitha383 Posted June 6, 2007 Share Posted June 6, 2007 So the guys that put the head and cam on my '81 (before I bought it)apparently put on a p90a head that doesn't seem to be milled (even thuogh they claimed it was from the guy they bought it from) and an E-30 cam which is a turbo cam?! The cam is not shimmed. I tried to mic the head at work to see if it was under spec but I can't really do it well with the head on the engine, it looked to be normal which I think is right around 4.5". The engine has always run iffy under 2k but surprisingly good after that. I thought originally that the E-30 cam was some sort of rare cam off of a L24 like the E-31. However, after seeing this: http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=130118883503&sspagename=ADME:B:AAQ:US:1 I emailed him and he said it was the stock turbo cam.... So now what? I wouldn't mind buying a mild cam for it but not for a while. I do have the cam off of the original engine from the '81. I bought two cars and took the current engine out of another car and I have the original P79? sitting in the garage. I'm getting 20mpg with it to work and back and really it doesn't run bad at all. I'm just thinking with the low compression that it possibly has and a turbo cam, what could this thing really be capable of. It's wishful thinking but does anyone have an aftermarket cam they're willing to part with. I guess I could take the head off and have it milled also if it's not. What kind of costs are involved in that? I assume you should dissasemble the head beforehand. Quote Link to comment Share on other sites More sharing options...
ZSPEED77 Posted June 7, 2007 Share Posted June 7, 2007 There is very little difference between a turbo cam and non-turbo. Even then it depends on which cams are being compared. They have different specs thru the years. Low compression could be a result of mismatched head and piston. Are you running flatops or dished? The p79 and p90 yield normal compression with flat tops. You put them on a motor with dished pistons and you get turbo engine compression which is lower. A bad valve adjustment also yields low compression. If you advance your cam a couple of notches you could gain even more compression. Quote Link to comment Share on other sites More sharing options...
280zwitha383 Posted June 8, 2007 Author Share Posted June 8, 2007 I assume they're flat tops because the original engine (short block) was out of an '82. I would have never thought of it having normal compression since they're flat tops.... Good to hear about the cam also. hmmm Thanks for the input. I guess if it runs well enough then I'll just leave it alone. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted June 8, 2007 Share Posted June 8, 2007 My understanding was that the turbo cam was advanced 4 degrees from where the NA cam is. You should check that out cause that's an old memory, but that's what I seem to remember. If that is the case you'd want to retard the cam timing because that would give you more top end. The turbo engines seem to peter out at about 5500 rpm. If yours is the same, check and see if you can move it to another mark on the cam gear to retard the timing and get some more top end. Quote Link to comment Share on other sites More sharing options...
280zwitha383 Posted June 8, 2007 Author Share Posted June 8, 2007 I forget which way is which. If the slot is underneath the indicator that would be retarded right? If so, that's what it was before I changed it. Quote Link to comment Share on other sites More sharing options...
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