N47 Head Removal Problem

[LeonV]

6 minutes ago, gwri8 said:

Question:  Is it wise to use Anti-seize on the head bolts and exhaust studs?  I'm wondering if it holds up under high heat.  I would like to avoid snapped bolts in the future.

Yes on the exhaust studs, NO on the head bolts.

The FSM specifies fresh motor oil on the head bolt threads before install to control bolt friction during torquing.

[rcb280z]

2 minutes ago, LeonV said:

Yes on the exhaust studs, NO on the head bolts.

The FSM specifies fresh motor oil on the head bolt threads before install to control bolt friction during torquing.

Tom Monroe say's the same for the head bolts-oil them.

[siteunseen]

I was pleased with these stainless steel manifold studs from zcardepot.com, no more rusty studs. 

https://zcardepot.com/stainless-steel-bolt-kits/engine-kits/intake-and-exhaust-manifold-stainless-steel-stud-kit.html

[gundee]

21 hours ago, rcb280z said:

Tom Monroe say's the same for the head bolts-oil them.

Yes, I asked the vintage race engine builder that has done some work for me.

When I asked what he does he said 30wt oil, set down and let drain for 20 minutes. Then install and torque.

[gwri8]

Update:  Got the head back, It was warped and had a couple of bent valves in #3 and 4.  All the exhaust valves had to be reground also. Now shaved with a couple of new valves. As I was adjusting the valves before I put it on, I noticed something odd. Two adjustments were waaaay off (new valves) and another would not adjust at all….. So I call the machinist and asked if he had kept everything in order during disassembly/reassembly.   He said no .  He looked at me like I had slapped him in the face with a fish when I brought it back.  My fault for not making that point clear when I dropped it off.  The result is, he moved the lash pads around and shortened the new valves. At least hey adjust normally now.

So I get the head torqued back on and buttoned everything down. All is looking good at this point. I took the time with the head in the shop to refresh the engine and bay a little.  Cleaned the plugs and replaced the Cold start and Thermotime connecters. In addition, I replaced the '77 fuel rail with one from a '78 or '79 (not sure) from unknown heritage (used) to reduce the amount of fuel line hoses. I made sure it was not blocked using carb cleaner and an air tank.   Which leads me to new issues.  When It started the engine it was running really rough at low idle. I tried to adjust the timing via distributer but it had no effect.  Then I noticed my fuel pressure gauge was at 50 psi.  It was 30 psi with the old rail/FPR.  I pulled the #'s 3 and 6 plug and they were both black.  I needed to walk away for a little while.

So my my thinking is, Is there that much difference between a 77 and 78 FPR?  Maybe It's bad.  Maybe I reconnected something wrong?  Opinions welcome….

New fuel rail pic.

Edited October 24, 2016 by gwri8

[SteveJ]

Are you sure the return line didn't get kinked/blocked off somehow? The FPR should be the same for the 77 & 78.

[Diseazd]

You said your machinist shortened a couple valves. Hate to throw up another point of concern, but if you shorten valves in a Datsun engine (with cupped lash pads), the lash pad can actually hang over enough to contact the valve keepers.....not good. If you have the flat bottomed lash pads, this isn't as likely a problem......Sounds to me like your machinist doesn't know Datsun engines very well....IMO..

[EuroDat]

Hi Greg, Im with Diseazd. Are you sure he used the "correct" L28 valves?

The  early N42 and N47 heads had 2mm shorter valves. If you use the valves for a P79 of P90 they will be too long and need grinding. That will only be the start of your problem if he did that.

That was the trick with using a P90 on a NA engine. Grind 2mm of the head, shim cam towers and valve springs 2mm and install N47 valves (2mm longer) to correct all the geomentry.

[Diseazd]

That's correct, the early valves are 2mm longer, so if you have an early head N42/N47, this shouldn't be the problem (valve too long). However in Datsun engines, if you grind the top of the valve, the keeper groove moves closer to the "cupped" lash pads possibly causing the lash pad to contact the keepers and eventually dropping the valve. Valve height should probably be fixed with new seats (old seats ground too deep).....not by cutting the top of the valve stem. With all the problems you've had with this head, you might consider dumping it and while you're at it dumping your machinist. Call someone Datsun savvy (Eiji at Datsun Spirit) or someone else reputable and have them build you a new head.....one that you have confidence in......just my humble opinion. BTW....the engine is beautiful....looks like you've done your part

 

 

[Zed Head]

As noted, the FPR's all regulate to the same pressure.  The ports are different, but otherwise they're the same.

Considering the work done, and the fact that three valves were out of their adjustment range, a check of the wipe patterns would be a good idea, wouldn't it?  The FPR problem might be saving your engine.  Don't run it until you give it a good inspection.