Leon

I'm not going to dwell on P/H clearance too much, unless Braap or 1 fast z feel like retracting their claims. If it was safe from the factory, I assume it'll be safe with .004" taken off the block deck. Guess we'll find out, eh? Got the .263" lash pads that were supposed to be correct for my cam, but of course they are not. I'll be scrambling to determine correct lash pad thickness tomorrow, as I need shorter ones. My guess is .240" should be just right, but I'll probably just bite the bullet and cut up some feeler gauges to be sure. I'll also be looking for a local shop with a surface grinder but will probably have to resort to turning them on a lathe...

Jim, you're right that .022" is very tight. I should've said that I'm aiming for .022-.025", so .022" would be the minimum. I got the numbers from the guys that have built way more engines than I have: http://forums.hybridz.org/topic/58127-best-way-to-achieve-piston-to-head-clearance/ I'm anticipating being OK with the OEM gasket but I'll let you guys know how the numbers pan out. I definitely have confidence in getting the car to idle smoothly, THAT I do have experience in! I'm looking forward to JCCS, but first will be the wedding on the 31st and a trip to Hawaii afterwards...

It's relative motion, whether the sleeve moves or the bushing moves there's always going to be movement between the two. What you don't want is axial preload on the bushings, for reasons that were already mentioned.

I just hope it runs at all! Good point on the piston rocking, although I'd hope that the piston doesn't rock enough to make .010" worth of difference! Thanks for the tip on the copper gaskets. If I were proactive enough, I'd order one right now just in case. However, $125 for something that I might not use is a little hard to swallow. With that said, I'd probably opt for a .043" gasket as that would give me a very nice .022" piston-head clearance which is just about what I'm shooting for with the Nissan gasket. Are you guys using a copper gasket, Jim? Yes, I considered the elasticity of the putty as well, hence my thoughts of trusting the numbers from the dial indicator. Those should be dead-on. The putty will not be used for piston-head clearance checks.

Here's my reasoning: if stock deck height is .021-.025" above the block as Braap said and I run a Nissan gasket, why would this be a dangerous scenario? I would of course like to err on the side of caution so I guess we'll see what the numbers are.

I highly doubt that made sense to anyone... Again, read the exhaust sticky. This is a technical site so please leave the conjecture to yourself.

Making some progress... I banged in the core plugs, a much bigger pain-in-the-ass than I expected. Busted out some turbo head bolts that I got for Christmas or a birthday present years ago and did some clearance checking. I used an indicator and a bracket attached to the head to get some relative measurements regarding gasket compression and piston-to-head clearance. The head was torqued down with a previously compressed Felpro gasket that Jim sent me. The indicator was then zeroed and all bolts loosened. The number on the indicator then represented how much the gasket was compressed. The indicator showed .021". I measured the uncompressed gasket thickness as 1.5mm/.059", meaning compressed gasket thickness is .038" or .97mm. I also double-checked myself with the indicator by reinstalling the head but without the gasket. The indicator read .0385", so within .0005" of the calculated value. I then triple-checked that using clay aka Silly Putty. Before the head was torqued down with the Felpro gasket, I placed the clay in one of the cylinders. The engine was rotated once with the clay inside. I measured the clay by slicing it in two with a fine blade and using the depth gauge of my caliper. The readings I got were .7-.8mm, or .027-.031", which should directly represent the actual piston-to-head clearance. That's way off from my other measurements and calcs, which I trust more. I'll probably use the clay for piston-to-valve checks but I'll rely on the indicator for piston-to-head numbers. Using the .038" compressed gasket thickness, I get piston-to-head clearance of .017". Yes, that is pretty dang close but I'll be using a Nissan HG in the final iteration so I'm hoping for another .004-.008" from that. I will, however, use the indicator to measure compressed thickness upon final assembly to be sure. In other news, I got a few parts the other day. My order of Nissan head dowels, wire-netting (PCV vent), and radiator hoses came in. Here's the wire netting compared to some old stuff I harvested from one of my other blocks. Obviously it's new and clean but I also like how the wire is soldered to the netting instead of just being wrapped around it. I've got some lash pads on order, should've bought those a while ago. Progress is being made and if I don't have the engine in the car this coming weekend then I've screwed something up. As far as I can think of, the only thing that isn't figured out is the fuel routing in the engine bay and the exact plans on the exhaust.

That may just be the most awesome V8 swap ever...

Read up on how exhaust systems work before posting nonsense please: Exhaust Tube Sizing

Your "mechanic" is guessing... With all that said, do you prefer to spend $75-100 on a leak down test, or thousands on a rebuild, or hundreds on a used engine which will then require lots of TIME to pull the old one out and install the used one? That will cost a lot of money if you're not doing the pulling and installing yourself. DO THE VALVE LASH ADJUSTMENT FIRST! Then check compression again, and perform a leak-down test if compression isn't satisfactory. Gollum does well to point out that the oil burning could easily be caused by worn valve stem seals.

Like I said, do a valve lash check first, before doing ANYTHING else. Maladjusted valves can cause low compression. If it turns out to be a valve sealing issue (determined with a leak down test) then a head rebuild is in order. I have a receipt somewhere but from memory, my head rebuild was ~$250-300. However, this is only for parts and machine work as I'm putting the head together myself.

Have you done a valve adjustment? I have trouble believing that one ring has gone bad while the others are fine. A rebuild is unwarranted until it's actually determined that it's necessary. If the valves are ok, I'd do a leakdown test before proceeding. I don't understand how all these "mechanics" diagnose these things without at least checking leakdown, unless you're leaving out information...

Ok, let's just discard physics all together then... Thanks for saving me the explanation, Nigel. Well said.

Sounds like a nice setup! I've used the dyno a few times and there are plenty of people here that have as well. It's a very valuable tuning tool, if used correctly.

Comp header with twin pipes all the way back.

Damn Clive, looking good!

Yeah, the machinist said he took off .004" from the block deck. I calculated that I need the head gasket to compress to about 1.1mm. I have an OEM Nissan HG on hand which I hope should make everything a-ok. With that said, I'll be doing a similar check as Lazeum did by putting a dial indicator on the block and seeing the height difference of the head with and without a HG. This will allow me to calculate true compressed gasket thickness. As a double-check, I've got silly putty on hand to check head-piston as well as valve-piston clearances. Thanks Jim, I've been reading through a ton of Braaps old posts! Speaking of which, I should've listened when he said to buy extra valve stem seals, because sure enough I cobbled some up...

I enjoyed the short-story...

Wow, helluva project! Nice work so far, you don't see a lot of race-prepped ZXs around here.

Let's go with "the bee's knees" then.

I've started this morning with measuring deck height. I'm at .021" (piston above deck). Looks like this is the same number you had, Matt. I'll be reading through your thread again. EDIT: removed units from deck height measurement to avoid confusion.

Well at least it stands up to WOT in 5th, that's the important bit. Maybe the bounciness is due to throttle modulation (touchy throttle)? My combo on this engine will be a 10lb Fidanza with the stock clutch. I'll do as you have and test the limits of the stocker before dropping dough on a fancy setup. Besides, I don't imagine my engine being as high performing as yours (no port work and ZX distributor for now).

Download the FSM from xenonS130.com. Take a look at the BE section.

Oh man, that would be hilarious! Quick, somebody put this man in a skimpy swimsuit and do the first middle-aged-man bikini ride-along. It'll be a hit!