Hotrodpez Posted September 15, 2008 Share Posted September 15, 2008 I think I've decided on the direction I want to go. Well, before I spend time and money only to find out I overlooked something, I would appreciate it if you guys could look this over and see how it sounds. F54 block with P79 flat-top pistons (rebuilt a few thousand miles ago, ran until head gasket blew, then pulled) N42 head (was on another running car, and looks to be in good shape other than being dirty) This should get me around 10:1 CR, right? Stock Nissan head-gasket. Arizona Z Car 4bbl intake manifold with Holley 390CFM carb Arizona Z Car 6 into 1 header with 2.5" exhaust Newish clutch (only has 800 miles on it before I pulled motor) And my last two questions... 1. Without actually disassembling it, is there any way to tell if a differential is limited slip or not? 2. I have a 5-speed trans I'd like to drop in instead of the 4 speed. However the rear bearing was dented when the trans was removed from the donor car (it fell off the jack). Is it worth it / possible to fix the rear bearing, or should I just keep the 4-speed? Quote Link to comment Share on other sites More sharing options...
JSM Posted September 15, 2008 Share Posted September 15, 2008 Sounds fine I guess, but what are you trying to acheive? Nothing against Arizona Z cars, but why not SU's? On the LSD, if you jack the car up both tires spin the same direction. If you see it in the car it has the finned cover. If not take the cover off to verify. Make sure it is out of gear and no e-brake is on. Quote Link to comment Share on other sites More sharing options...
Hotrodpez Posted September 16, 2008 Author Share Posted September 16, 2008 Here are a few pics of the donor motors. The dirty one is the one that the N42 came off of. The clean(ish) one was rebuilt a few thousand miles ago, but the head gasket blew (probably because the PO drove it like his @$$ was on fire) and thats when I came to own it. Now about the cam gears... I've never see one with more than 4 holes. That one was on the rebuilt P78 head. Is this stock for that head? Quote Link to comment Share on other sites More sharing options...
Hotrodpez Posted September 16, 2008 Author Share Posted September 16, 2008 Well, I've read alot of good things about the AZC manifold. I like the idea of an electric choke, and I am familiar with the Holley 4bbls. The SUs I have are in desperate need of a rebuild, and I just dont feel like messing with them. Quote Link to comment Share on other sites More sharing options...
Hotrodpez Posted September 16, 2008 Author Share Posted September 16, 2008 And I guess if you want a ballpark HP estimate that I'm hoping for, I'd say around 180. With decent low end torque, and easy streetability. Realistic?? Quote Link to comment Share on other sites More sharing options...
Zmanco Posted September 16, 2008 Share Posted September 16, 2008 An N42 head with flat top pistons will likely have detonation on pump gas. When I first put that combination (N42 head and flat top pistons) together BRAAP warned me that it was likely to have detonation and that the benefit of the higher compression would be more than offset by the loss due to retarding the timing. Even with bigger cam I had to retard timing to around 20 degrees. I could feel the torque fall off as the engine RPMs pulled through the band where I had the timing pulled back. Is there something wrong with the P79 head that causes you to want to switch to the N42? Otherwise, why not put it back together with a Felpro gasket (1 mm)? That will yield a CR of 8.7 and you can run with full advance. Quote Link to comment Share on other sites More sharing options...
Hotrodpez Posted September 16, 2008 Author Share Posted September 16, 2008 No, the p79 head is fine. I had heard that N42 head with flat tops was a good combo, but if what you say is true, then I'd rather not do that... Quote Link to comment Share on other sites More sharing options...
blue72 Posted September 16, 2008 Share Posted September 16, 2008 I think the argument goes that the AZC manifold is good, but other designs aren't nearly as well thought out, or people don't understand their Holley carbs. The cam gear is just an aftermarket piece, nothing special. It was probably replaced during the rebuild. You might want to check the head with a quality straightedge to make sure it isn't warped. Personally, I'd stick with the P-79 after reading through all of the cylinder head discussions on these boards. If you wanted more compression it could be shaved, the cam towers shimmed, and different valves installed. That way you keep all of the "quench" capability which is supposed to help ward off detonation. I'm also partial to the SU carbs, but that decision is up to you. By all calculations my F54/P79/SU combo should be making 250 or so HP, but I have quite a bit of head work, a hotter cam, and my SU carbs were overbored and worked over by Rebello. A plain jane F54/P79 SU carbed rebuild would probably be in the 170-180 range. Also, what do you mean by rear bearing on the transmission? Are you talking about the tailshaft area where the bearing and seal are that the driveshaft fit into? Was the seal area dented, or just the sheet metal dust cover? Quote Link to comment Share on other sites More sharing options...
Hotrodpez Posted September 16, 2008 Author Share Posted September 16, 2008 Thanks for the input. Unfortunately, it is the bearing / seal, as well as the dust cover. If it was just the dust cover I'd just pry it round again. Quote Link to comment Share on other sites More sharing options...
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