64 idle issue

[Bill C.]

Car is a 64 327/365. I adjusted the lifters using the John Hinkley/Duke Williams method. Car seems to run stronger but now I can't get it to idle. At a stop light it will idle normal for a few seconds then start to drop off and stall. Timing is at 10 BTDC.

[Timothy B.]

Re: 64 idle issue

Bill, Are you saying the car will not idle after warm up. Can you keep the engine running with the accelerator at fast idle.

You may want to re-adjust the A/F mixture screws on the carburetor after the engine warms completely.

[Joe C.]

Re: 64 idle issue

Car is a 64 327/365. I adjusted the lifters using the John Hinkley/Duke Williams method. Car seems to run stronger but now I can't get it to idle. At a stop light it will idle normal for a few seconds then start to drop off and stall. Timing is at 10 BTDC.

The tighter the valve lash, the longer the effective duration and the longer the overlap period. The longer the overlap period (and the higher the valve lift during the overlap period), the lower the idle vacuum.

Either your valve lash was grossly too wide before, you set them too close now, or your idle speed was set too low to begin with. Recheck the lash carefully. It is safer to set lash on the wide side rather than on the tight side, ESPECIALLY ON THE EXHAUST VALVES. Some folks, including myself, like to compromise the Hinkley/Williams settings at .025/.025 which gives more of a margin for expansion (although the margin in the Method is sufficient, provided they are set CAREFULLY). The wider setting also provides slightly better idle vacuum and drivability. The factory setting was compromised from the original .025" design setting, to .030, which I agree, is too wide. This was done to address drivability issues.

Once the lash is properly adjusted, the initial (static) timing should be set to 12 degrees BTDC, and the curb idle adjusted to 900 RPM.

[Bill C.]

Re: 64 idle issue

Used the earlier version and set them at .026/.026. Idle was set at 750-800. Idles ok in the garage thru warm up. Doesn't start to act up until I run it on the street for a few miles and the engine is hot. I can keep it running with the accelerator. I'll give the timing a bump to 12 and raise the idle speed and see what that does. thanks...

[Bill C.]

Re: 64 idle issue

Timothy...see response to Joe on when it occurs. I did play with the mix screws several times. Idles nice in the garage with a warm engine. Not so nice with a hot engine. thanks

[Boyan B.]

Re: 64 idle issue

What ignition vacuum canister are you running?

[Richard G.]

Re: 64 idle issue

A good friend of mine just went through this same scenario using the same method of valve adjustment. It ended up with the same idling issues. Turned out it was some of the valves were just too tight. He reverted back to the factory adjustment procedure and it runs better and idles like it should now. I always did the adjustment while the motor was running. However I understand the issues associated with oil all over ones newly rebuilt project.
I would try it again with a little extra clearance or go to another valve adjustment method and see it that doesn't help the situation.

[Duke W.]

Re: 64 idle issue

There's no freakin' way you can get a 30-30 cam to idle acceptably at less than about 900 with the valves lashed at .023/.023", which is necessary to avoid beating up the valve train as explained in the paper. You need to go through the idle speed/mixture adjustment procedure with a target idle speed of no less than 900 or whatever it takes to achieve at least 10" manifold vacuum. Less than 10" can cause loss of vacuum advance, which will destabilize idle and lead to engine stall.

Heck I idled my 327/340 with the Duntov cam and 8" VAC at about 850 to get acceptable idle quality and start-off, and the Duntov cam has a lot less overlap - about the same as the LT-1 cam and they will both pull about 12" at 900.

Also verify that you have a functioning 8" VAC, the centrifugal starts at about 700, and is all in at about 2350. With 12 initial this should yield about 30 degrees total idle timing, and it should be steady.

Most 30-30 cams that have been indifferently adjusted are probably in the range of .030-.034", so they will idle better due to the lower effective overlap, but I cringe at the shock loading that the valve train is being subjected to.

Some guys like to run loose clearance on the 30-30 because it has better driveability, which is just more proof that the 30-30 cam is WAAAAAAAY too big for decent road engine performance and driveability, but loose clearance and the attendent slamming of the valves into the seats at higher than clearance ramp velocity is what causes valve recession.

Duke

[Bill C.]

Re: 64 idle issue

Duke...bumped idle to 900. Test drive, hot engine...so far so good, idle seems to hold. Timing still at 10... you recommend 12...correct
Bill

[Duke W.]

Re: 64 idle issue

I actually recommend up to 16 if the engine can tolerate that much without detonation, and 16 is actually about 14 due to the timing tab not being accurate with the big balancer. This has been discussed in some detail (see archives). The total centrifugal should be 24 @ 2350, and 24 + 14 = 38.

Also, setting the initial timing on these engines is tricky. The centrifugal starts at about 700, so you have to set the timing below this value - say 500 when the engine is barely running.

A better way is to disconnect/plug the vacuum advance, rev the engine to 2500-3000, observe that the timing no longer advances then set it at 38 degrees with a dial back timing light. Then rev it to at least 6000 to make sure it doesn't advance any more. Otherwise the limit bushing may be deteriorated or missing.

Using a dial back light negates the timing tab error, so when you move the mark back to zero on the tab and read the timing light dial, you are looking at the true advance.

You should also use a vacuum pump and timing light to verify that the VAC is functioning properly.

There is a lot to be gained on most engines - both performance and driveablility, by just making sure that the advance mechanisms are functioning properly, and some engines may benefit from changes - to a more optimal VAC or centrifugal curve.

Your engine's spark advance map is optimal as is, so it's just a matter of checking that it is to OE spec and running as much initial advance as the engine will tolerate without detonation and understanding how to properly set the initial or total WOT timing as discussed above.

Idle speed should be set with a known accurate test tachometer. Even when new the in-car mechanical tach could be off at least 100 revs at idle, and now they are nearly 50 years old.

Duke