Diseazd

I just got my E31 head back from the machine shop. I had them install new bronze valve guides, new hardened valve seats, stock L24 intake swirl valves and L28 (larger) exhaust swirl valves with the corresponding larger hardened seats. My question is, the stem height on the exhaust valves are higher than the intakes. I'm installing an Isky Stage II cam, and to get proper rocker geometry, I need a .190 lash pad to center the intakes on the new rockers and a .160 lash pad to do the same on the exhaust. Is it OK to have the two valve stem heights different since I can get geometry right, or do I need to go back to the machine shop and have them adjust the valve stem height so that they are the same? If I need to go back to the machine shop, how do they make the adjustment? Thanks Guy

I learn something new (usually from a screw up) every time I build an engine!

Call Les at Clasic Datsun.....He sells spray cans that are dead on. www.classicdatsun.com

I find it's easier to install the chain and sprocket if you haven't installed the chain tensioner at all. After installing chain and torqueing the chain sprocket, then compress the tensioner boot and install the two bolts and torque the chain tensioner. IMO .........either method will work. Guy

Once again....finally some color! <a href="http://www.flickr.com/photos/14049800@N00/4878481153/" title="IMG_1221 by RVAE34, on Flickr"><img src="http://farm5.static.flickr.com/4118/4878481153_6392020c26_b.jpg" width="1024" height="683" alt="IMG_1221" /></a> <a href="http://www.flickr.com/photos/14049800@N00/4879087924/" title="IMG_1217 by RVAE34, on Flickr"><img src="http://farm5.static.flickr.com/4099/4879087924_5b15874860_b.jpg" width="1024" height="683" alt="IMG_1217" /></a>

Dana.....I'm sure John would enjoy riding in the right seat of what you work in also. Now that's really flying!!!

Steve....I noticed that you said you had L28 valves in the L24 head and you bored it out .040 over with a Stage II cam. Did you use the larger intake and exhaust valves or just exhaust valves? Did you notch the block before installing the head, or did you just bore it out and bolt it up. The reason I'm asking is because I'm in the process of building 2 L24's bored .040 over with E31 heads and L28 intake and exhaust valves. Did you have any valve clearance problems with the larger valves? Thanks Guy

Check post number 30 on this thread (gives my dyno result with SU's and SM needles).The L28 with Stage III Isky and .080 inch shaved head never missed a beat . The A/F was darned near perfect throughout the RPM range. Guy http://www.classiczcars.com/forums/showthread.php?t=31001

No problem OZ......you're human afterall! The harmonic is clockwise and the distributor is counterclockwise....makes you think doesn't it? Kind of like the the pin height on the L28 piston.....right? Cheers!

Mine always seem to run best at 15 degrees plus or so, but mine all run Isky cams and european distributors. Back in the 70's, we always advanced the timing until it starting knocking and then backed it off a tad. Set it at idle by ear at the smoothest idle....lock it down then check it with a light. Every car combo runs different. Glad you got her running right. Now reset your points and you're good to go! Good Luck. Guy

John.....You are correct....the mark furtherest to the left on the balancer is TDC (when looking from the front of the engine). The two adjustments are the 10 mm bolt that allows you to retard and advance the base plate on the distributor, and also if you look under the condensor on the back of the distributor, there's a bolt that allows adjustment of the base plate itself. Make sure when you are on exact tdc compression and that your distributor drive shaft is installed exactly as illustrated in the FSM. If not, remove the oil pump and do it again. Look at the last picture on the post below. Make sure your distributor drive looks like that at tdc compression stroke. Guy http://www.geocities.com/inlinestroker/index.htm

Doradox is right.....remove the number 1 plug....put the car on a level surface and put it in 4th gear...let down the handbrake. Have someone push the car with your finger over the number one plug hole. When you feel the compression pushing against your finger, you know you're on the compression stroke. Now bring the car slightly forward until the far left timing mark on the balancer is matched to the pointer (early Z) or 0 for later Z's. You should now be on tdc compression stroke. Now remove the distributor cap....if the rotor is pointing toward the radiator, you're good. If it's pointing towards the rear of the car, you are 180 degrees out. The only way it will run that way is if the PO moved all the wires 180 degrees before you got the car and if you installed the distributor drive 180 out. My guess is you were'nt on tdc compression stroke before. While you are on tdc compression, check to make sure your distributor drive is in the proper location 11:25 o'clock with the notch in the right direction. Remember, you have 2 adjustments on the distributor to adjust advance-retard, so you've got some wiggle room with your timing light. Hope this helps. Guy

I'm not totally sure, but I don't think the chambers are deep enough to take .080" off of the N42. The P79 and P90 have deep chambers.We shave those heads .080, use the longer early L28 valves and shim up the towers and springs .080" to keep geometry and cam sprocket height correct, but I don't think you can do that with the earlier heads. Maybe someone else can chime in on that subject. Guy (Don't forget to buy Isky's lash pads for the Stage II cam to keep rocker geometry right)

You can buy 'em new from Nissan.

Let me know if Richmond is on your list. Would love to talk cars with you. Guy

Thanks for that info John......I was afraid that I was going to drive the woodruff key through the oil slinger if it wasn't aligned properly. The early 280 dampers are honed out 1/4" by the factory so you can feel the woodruff key lock into the damper. I usually put a mark on the center of the the keyway for installation, but if you misalign the damper, it can gouge the damper or worse.

I bought 2 of the SFI-spec racing dampers from MSA. The fit was poor....I had to take the pulley to a machine shop to modify both the keyway and the bore. It was so tight when I tried to install it out of the box that you would have needed a sledge hammer to install it!!! I ended up putting them on the shelf and buying 2 stock two groove dampers. If you or anyone else wants the racing dampers, PM me and you can have them both for $100.00 plus shipping. The early 280z stock dampers are the best (for either the 240 or the 280) because there is a 1/4" honed area in the bore that allows you to slide into the woodruff key and then tighten it up. Experience is good!!!

The front pages of the the Black Dragon catalog (8-9) has the vin numbers for each year......000013-021000 is a 1970.

http://www.classiczcars.com/forums/showthread.php?t=31001&page=2 If you look at post 29 of this thread you'll see that the fuel air ratio of the SM's was almost perfect! The dyno operator commented that it looked like a fuel injected engine. Guy

Marty.....I e-mailed the Z Doc in Roanoke......He said the factory says .020, but he has shaved up to .040 to .050 with no serious problems (whatever that means). Guy

Marty.....We used to shave our E 31 heads .015" with no mods and no problem. The "How to Modify" book says you can shave up to .050" off any of the L series heads with stock pistons, but must then modify the chain guides and possibly the tensioner to take up the slack in the chain. Cam tower shims would make the guide and tensioner mods unnecessary.

Thanks Greg.....enjoyed talking to you and your crew at Road Atlanta. How did you do? I had to leave Friday for my Dad's birthday so couldn't watch the race. Please let us know when you're going to run again at VIR. Guy

I hear you Jon.....If they wear out too fast I'll replace with 205-55-16, then reset camber. What's a good number for street application? Lee..... you're right....I do love the way it bites into the turns.

I appreciate everyone's ideas. I think I'll see how these tires wear........then make a decision. Thanks Guy

I've installed Ground Control coilovers on my 72 Z. I set up the car as low as possible for street use. My question is........With the 225-50-16 tires on 16" Panasports, we had to dial in almost negative 3 degrees camber to prevent rubbing on the rear fender lips. I don't want to roll the fenders. Is 3 degrees too much for street use or is that OK? I can go to a smaller tire (205-55-16), but really like the 225-50-16's. Thanks Guy