L76 valve lash

[George J.]

Re: L76 valve lash

I'll take most everyone's word that doing it cold or at least not running is the way to go and skip the "valuable learning experience."
Thanks again

Bill,
It really is one lesson you don't need to experience to understand. ; ) Good luck.
A couple of tips:
It is easier to mark the 90 degree points on the balancer when the car is up on a lift for an oil change. I did it at the shop I use for that, right before I was going to adjust the lifters.
Make sure you have a fairly long, but not too long torque wrench or breaker bar to turn the engine. I used the bolt on the front of the balancer.
Take the spark plugs out before you start to make turning the engine easier.
Take the cap off of your distributor to make sure you're at no. 1 tdc.
Be ready when you first start it to have the engine sing. It felt like an electric motor compared to before adjustment. Good luck.

George

[Duke W.]

Re: L76 valve lash

Also, if the last adjustment was to OE spec on the 30-30 or LT-1 cams, you will have to go through the idle speed/mixture adjustment procedure, and you may have to increase the idle speed; 900 is about as low as you can go and FI may require 100-200 more.

Idle quality will be a little worse and low end torque a little less, but the top end will be stronger and there will be little, if any valve train noise.

Duke

[Michael H.]

Re: L76 valve lash

Also, if the last adjustment was to OE spec on the 30-30 or LT-1 cams, you will have to go through the idle speed/mixture adjustment procedure, and you may have to increase the idle speed; 900 is about as low as you can go and FI may require 100-200 more.



Duke

If a 375 HP FI engine won't idle under 1000-1100 RPM, there's something else wrong with it. I think I've said this before.

Same for a 365 HP. I don't understand why they won't idle at 850 RPM.

[George J.]

Re: L76 valve lash

Michael,
even back in the day, there were tuning specs that called for the idle to be "at least 900rpms". If you can get yours to idle that low, great. I can get mine to, but there are other driveability issues that it then exhibits. The car likes 1100-1200, and runs fantastic, starts and runs fine in 90+ weather, even after sitting, on ethanol laced pump gas. I'm fine with it.

George

[Timothy B.]

Re: L76 valve lash

IMO, if you need 1100-1200 rpm to idle your stock GM engine you are covering up other tuning issues.

[Michael H.]

Re: L76 valve lash

Michael,
even back in the day, there were tuning specs that called for the idle to be "at least 900rpms". If you can get yours to idle that low, great. I can get mine to, but there are other driveability issues that it then exhibits. The car likes 1100-1200, and runs fantastic, starts and runs fine in 90+ weather, even after sitting, on ethanol laced pump gas. I'm fine with it.

George

I agree with Tim, above. There's something else that isn't at factory specs if it won't run properly below 1000 RPM.

If you set the idle at 1200 RPM because it's easier for you to drive that way, that's a different matter.

[Stuart F.]

Re: L76 valve lash

Perhaps some of the driveability issues are gearing related; I know mine would be a lot easier to drive with a 4.11 than with my 3.36, specially any SHP w/close ratio tranny.

[George J.]

Re: L76 valve lash

Yes, I said the car likes it, and I, at that rpm. I can certainly get it to idle lower, but it just seems better a little higher. I also know that with the dated wires it really didn't like the lower end of the idle numbers, and since I've gone to better wires, I haven't tested lowering the idle.

George

[Joe C.]

Re: L76 valve lash

Yes, I said the car likes it, and I, at that rpm. I can certainly get it to idle lower, but it just seems better a little higher. I also know that with the dated wires it really didn't like the lower end of the idle numbers, and since I've gone to better wires, I haven't tested lowering the idle.

George

I had the same set of LL dated wires on mine for ten years with no issues. I was even running 0.045" spark plug gaps with a low resistance coil and bypassed ballast resistor. Not a skip or miss with all that voltage running through them in order to get a spark to jump a 0.045" plug gap. Last week I replaced them with a set of 8.5 mm MSD wires that I custom made for the engine. There is no difference that I have seen nor felt, so far.

[Joe C.]

Re: L76 valve lash

Perhaps some of the driveability issues are gearing related; I know mine would be a lot easier to drive with a 4.11 than with my 3.36, specially any SHP w/close ratio tranny.

There is a tremendous difference in drivability between a 1963 L76 and a 1964 L76. Not even close. Totally different animal. There are LOTS of guys who drive their pre 1964 L76's with 3.36 gears. Never gonna happen with the 30-30 equipped version.

[George J.]

Re: L76 valve lash

Joe,
I had an immediate improvement. I'll never use them again, unless they are improved.

George

[Joe C.]

Re: L76 valve lash

Joe,
I had an immediate improvement. I'll never use them again, unless they are improved.

George

Their quality suffered drastically sometime after I bought mine in 2002, and currently. Symptoms people describe point to an inferior job of attaching the end terminals.

[Stuart F.]

Re: L76 valve lash

Right you are Joe. I sometimes wish Chevy would have assigned a different option code between 63 and 64. It can be confusing. However, believe my point of driveablity concerns due to gearing may still be valid, I just shouldn't use my tame little 63 as an example. Note: Back in the day, that tame little 63 never lost out on the road to any stock 64-66 L-76 or L-84 (for that matter) with lower gearing (higher numerical), and it runs even better today with 46k on the clock.

I too have run LL dated wires since the late 90's, along with Electronic Ignition w/by-passed ballast resistor and low resistance coil. It will make redline w/o missing a beat in 1st, 2nd and 3rd (too chicken at my age to try for 4th).

Stu Fox

[Timothy B.]

Re: L76 valve lash

Stu, your a wildman :-) I would like to see you try that 3461 carburetor without the spacer and see if the lean surge goes away.

I too installed the LL wire and pulled a end off after being very careful installing them. To there credit, the wire was replaced after sending it back. No other issues I can report with there wires..

[Stuart F.]

Re: L76 valve lash

Tim;Thanks for the, er, compliment. Been running the 3721SB of late as it is soooo good. Have the 3461S back together for another test, but am in no hurry. It's been so darn hot lately, not in the mood to experiment in the garage. I have read some where something akin to what you recommend (trying it w/o insulator stack) and that is that it may be experiencing a loss of venturi signal and perhaps that may be due to the fact that the 3461S does not have the deflection tabs on the primary clusters like a 3720 series. I've tightened up the primary shaft and modified one of the primary throttle butterflies to match the transition slot exposure of the other (fully closed one showed no slot while the other showed a peek or perfect little square).

Summer driving awaits and I don't need no "herky jerky" 3461S to spoil my fun.

Stu Fox