az240z Posted April 17, 2016 Share Posted April 17, 2016 I'm wondering which head would be best for my car. I have a 1973 240z that I bought last year, that was supposed to have an early Rebello engine. Unfortunately there is no documentation on it and Rebello doesn't keep records for early 1990 builds. 2 months ago the head went bad with a burnt valve. I replaced the E88 head with a P90a that had been rebuilt, just to drive the car, and took the E88 to a machine shop to get it rebuilt. I now have the head and realize that its a standard head with no porting, or polishing. The shop replaced the springs, did a 3 way valve job, lightly shaved the head to eliminate some very minor unevenness. The question is should I re install it or leave the p90 on? I have someone who may buy the car but wanted the E88 back on, assuming that it was a built head by Rebello. He now knows that that isn't the case. I have a n L28 block, rebuilt, with flat top pistons that the P90a was on. Are there any performance gains between the 2 heads assuming everything else are equal.. By the way when changing the heads, I didn't have a micrometer to measure the bore, so used a paper to get the bore size and than miked it at work. It measured at 89mm. Quote Link to comment Share on other sites More sharing options...
NewZed Posted April 17, 2016 Share Posted April 17, 2016 You should get more information. Does the E88 have stock size valves? In stock form the P90 would have bigger valves. Does the 89mm bore contain flat-tops or dished? What is the stroke of the "Rebello" engine? Maybe it's an early stroker. Does the P90A have hydraulic pivots or solid? That's a consideration. Take cylinder pressure measurements to get an idea of CR. You miked a sketch on a piece of paper? I would have used a ruler. Quote Link to comment Share on other sites More sharing options...
az240z Posted April 17, 2016 Author Share Posted April 17, 2016 Good questions with no answers. Will look into it.. Quote Link to comment Share on other sites More sharing options...
az240z Posted April 17, 2016 Author Share Posted April 17, 2016 It was an early Rebello build 3.1 build.. Quote Link to comment Share on other sites More sharing options...
Tony D Posted April 17, 2016 Share Posted April 17, 2016 It's an L-Engine with an 89mm bore. That's all you know, and that's all anybody can know. Quote Link to comment Share on other sites More sharing options...
az240z Posted April 18, 2016 Author Share Posted April 18, 2016 It's an L-Engine with an 89mm bore. That's all you know, and that's all anybody can know. That's correct... Quote Link to comment Share on other sites More sharing options...
supernova_6969 Posted April 30, 2016 Share Posted April 30, 2016 (edited) ok. I can't say if this is true, but this page (http://www.zhome.com/ZCMnL/tech/head.htm) says that there are various e88 heads and that some of them sucked.... I found other places that say that the intake valve are slightly bigger on the p90a. from what I remember, the p90a hall have hydraulic lifters. in terms of maintenance, that's pretty cool (no valve lash adjustments. ever). on the other hand, the p90a head has a significantly lower compression ratio that the early heads.. that would definately play when considering both current power and future mods.... there is tons of onfi online.. you might even be able to find flow bench results if you dig deep. if you have specialty shops around, id' give them a call to, just for fun. oh, and if you're selling the car, just offer the head with it for an extra, don't bother unless you're really into giving yourself trouble for fun. oh. I just found this page. pretty comprehensive http://www.viczcar.com/forum/topic/4286-overview-of-l6-engine-heads/ Edited April 30, 2016 by supernova_6969 Quote Link to comment Share on other sites More sharing options...
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