madkaw

What i am saying is that the oval shaped fire rings are big enough for the larger exhaust or intake valves to be intsalled. Most HG's have the oval shape already. It seemed the OP was concerned with getting a perfectly round fire ring on the HG . Well that might not work for anything other than stock. The only way to be sure is to lay the HG on the head to make sure it doesn't impede into the combustion chamber. If you have your "how to modify" book, look in there. The oval fire ring allows for some nice unshrouding which is strongly recommended on the L24. Cliff-you shouldn't use a 280 Hg

Revisting the oval/round fire ring aspect. The perfect round fire ring type HG should be avoided for the fact that most head rebuilts include installing larger valves that WON'T likely clear that type gasket, or clear your cylinder bore for that matter. Any unshrouding work would also make that HG useless.

Here's my collection. top to bottom: Old felpro(I believe) Nismo New Felpro(universal 1970-1980 Victor reinz 1983 stock HG All Hg have oval FIRE RING except new Felpro and 83 stock Nissan

I have HG's of every variety now for some reason and I will take some pics when I get a chance. The latest Felpro HG has turned into a universal gasket which covers 70-80 models. The Nismo was very specific to the e30 block with the HG being cut out around unused water passages. The Felpro has a decent reputation amongst the Z owners I have read. I have two of the Victor Reinz HG's and I wouldn't put them on-they look cheap to me. Oval bore holes? Hmmm. That's weird. You might think the combustion chamber was oval or something

Felpro or Nismo from Nissan?

Well everyone has pretty much told you that the stock ECU will probably not handle this combo-but-good luck trying it. By the way ,that combo yields 8.63:1 , so a mild shave probably won't be 10:1 Maybe you should find a local Z club and buy someones gas and dinner for a ride in a stock Z and make your decision then.

It should. Shaft sits in oil pump, pump connects to timing cover. Gear should be closest to the pump. Look at your FSM for timing. #1 cylinder TDC compression stroke Insert so dizzy tang is sitting 11:25 clock

TUNE TUNE TUNE. Without an aftermarket ECU, you just need to optimize your stock tune. I've driven a very nice 77 all stock and it ran good. Very torquey! Everything was in good repair and the tune was spot on. Gearing is also a good way to quicken things up too. Or just say hell with EFI and go whatever engine combo and slap on some nice SU's or triples better yet.

460 is the limit for stock springs and valve seals from what I have read.

You know you won't be able to just throw that cam in that head without lot's of other work. Need to upgrade springs and valve seals. Valve lash pads will not be correct so your valve geometry will need to adjusted. I would strongly recommend degreeing that cam and than check piston/valve clearance. Exhaust liners will be the least of your concern. Tuning and proper valve geometry will give you best gains. Why not try a smaller cam? That 90/47 combo should be stout and with good octane fuel and good tune should run great.

Hate to see this kind of carnage-sorry about your luck.

I think you are 'hoping' that the ECU handles these changes and adds HP, it might just turn out to be a headache. If you are familiar with tuning you might consider Mega Squirt or another to maximize your upgrades. Not too much that I have read that has gone your route with stock ECU and brags success, but maybe you can be one of the first. It is 40 year old tech!! Assuming header bolt on means HP is probably wrong. I would actually think that sticking with stock exhaust would keep the stock ECU closer to a proper tune. I think your formula p90/flat-top= (+HP), but you won't be able to tune it to it's optimum which will cause frustration. There is a member here that is creating a plug in ECU for your year, but it hasn't materialized yet. I have documented a MS install here and on Hybridz.

I think your plan falls short with the stock ecu. As stated above, changing to 14mm injectors and having an engine that will run differently than the stock might not bode well with stock tuning . Not sure about the thicker gasket idea? Going with the P90 for better quench area and than defeating that with a thicker gasket? Consider an aftermarket ECU and tune away!!!! Headers for the wife? I would opt for a performance exhaust from the manifold back and keep it quieter to keep her quieter-. Seriously though, for your plans the header might be waste. Good luck

Umm, Datsun rods are forged ;-)

Wasting money buying aftermarket rods unless you are building a RACE motor. Find another used set and have your machinist work them-DONE! With the money you spend on rods you might get forged pistons-now we're talking

I would rearrange the furniture or have a garage sale, or throw away some sh!t and find a way to store the motor, but wouldn't run it NA. You will be disappointed to say the least and in reality it will take a LOT longer than you think get turbo charge that motor or do anything else to the motor to keep you happy. 45$ buys you a cheapy engine stand and you can roll it around out of the way. That L24/31 combo will run circles around that 54/90 combo NA.

yes-it's as big I care to go on a street motor ----right now!

That's the cam I have now-but I'm going to sell it and move up a notch to the cam Guy is using -Isky grind

That cam is serious-are you that serious-really? You would about have to build the motor around that profile-HA

Horizontal-up or down play-seems contradictory. Are you separating U joint from other issues? My shaft had issue at the rear of the trans. I could grab the DS at the yoke(while installed) and move it up and down using moderate to hard force. The movement was enough to be audible. When I had my t-5 rebuilt here recently, the builder said the tailshaft bushing was elongated and he replaced it. What I experienced in the car was vibration at higher speeds-maybe this was the issue? i don't know since the car is apart now. There really shouldn't be any movement that can be produced by hand in the driveline.

Sounds just like my 2.4- Looks likes a blast Jon, and a family project too-even better

Check with who's making what as far as piston kits. Sealed power has limited sizes now, so stick with a popular oversize like 1mm-not .030 Engines are pretty well balanced, but make sure the flywheel is balanced, might consider lightening it, and get damper rebuilt or get a new one. I have good luck with my Schneider cam, but Isky has history with racing Datsuns. Just have your original cam reground for 125$ by Isky or Sunbelt and save some $$ and have the proper metallurgy to match your stock rockers. The more money you put in the head will outweigh anything else you do to the motor. Consider using an engine builder familiar with these engines. Check your rockers, since finding good ones or reputable rebuilt ones are hard to find. Consider newer, better ignition system.

Isn't all this advice based on the hope that the pulley and pointer are in proper condition? More than likely it is. Finding TDC in the above suggestions should all be done in the same direction of rotation. The only true way to find TDC is with a degree wheel and a piston stop-but that's for true cam timing adjustments! This way you can go back and forth and take the difference and eliminate the chain slack aspect.

Well slow down dude! So it is a tooth off? It takes some luck and a couple of tries to get it right. Timing lights are good for troubleshooting. These cars are also prone to detonation so it's nice to know when you are close to those limits. The ole "advance till it pings and then back off a couple of degrees", works on most cars, but an unexperienced ear might not pick up detonation before it's too late. My argument for accurate or at least verifiable timing.

The latest timing figures seem right and the plugs look good, so if it runs good I wouldn't sweat it. Are you sure the dizzy/oil pump shaft is clocked correctly? Might be off a tooth.