timing went bad...

[DaneAmerica]

1966 Buick Special Deluxe 300-2 ST300.

I set dwell and timing on my freshly rebuilt 300.. as a 4 cylinder. 30 dwell and 24 advance at idle with the vacuum hose on.

Drove it to the muffler shop.

Exhaust sounds great now. Driving it back started to hear what I hoped was the fan tapping something. Pulled over and got a tow truck back to the house.

I re-timed the engine correctly set to 4 stroke 8 cylinder 30 dwell 33 advance at 2500 rpm. Runs WAY better.

Motor is making a noise.. sounds like the passenger side.. rocker or bent pushrod..

I need some advice if there is a trick to identifying where or what my problem is.

There is no tapping sound when it idles and gentle throttle, only when I'm on about half throttle.

I was going to check compression to try to identify the problem cylinder, but it there is a faster or better way to diagnose please advise.

Thanks!

 

[Bob]

There is timing information in the 1966 Buick Chassis Manual on page 60-50 CLICK HERE.

Setting the timing is covered in the manual CLICK HERE. Go to page 68-34. Vacuum and mechanical advance limits are on page 68-28.

Initial timing is always set with the vacuum line disconnected and yours should be at about 2.5-3 degrees. Most engines do respond favorably to a little more timing. When you check your mechanical advance the vacuum line should also be disconnected. With a stock unmodified distributor, you will never get 33 degrees of advance at 2500 rpm. I suspect you may have had your vacuum advance plugged in to get that.


"There is no tapping sound when it idles and gentle throttle, only when I'm on about half throttle."
- This sounds like too much advance and usually described as pinging. Disconnect your vacuum advance and see if it goes away.

Generally most people would use a stethoscope to move in on a tick or noise. If a stethoscope is not available in the backyard, use a long and probably heavy screwdriver tucked to your ear and move it around. If you identify it as coming from under a valve cover, remove it and use your hearing device to move in on it.

 

[DaneAmerica]

The sound is still here while cruising when I jab the throttle or apply over 1/2 throttle.

I can hear a ringing sound like a bell from the same area while idling.

Tackling timing

This might come across as stupid, but hell I've been here a few years and come up with some doozies. So I want to work this timing stuff and the high RPM drop. I want to set the timing, but the service manual calls for 500 rpm at idle in gear. So at what idle speed should I set NOT IN GEAR to adj...

forums.aaca.org

After following Jim Cannons advice on timing... I found I was getting no centrifugal advance.

I cleaned the weights and replaced the springs with new.. the same or maybe slighlty weaker.

Replaced the old vacuum advance with an accel adjustable and turned it all the way to the left.

With vacuum advance hose off and plugged, in drive with a block and e-brake, my engine will not idle at 500 rpm. At 550 it barely runs.. but I was able to confirm 30° dwell.. then turn the distributor slightly to hit 2.5° initial timing (no centrifugal no vacuum). Barely runs, oil light flashing on and off speratically with low rpm.

After putting it back into park, it popped up to 650 rpm and the centrifugal advance is much more responsive, matching the graph in the manual pretty close at 8° around 1000 rpm.

Bringing it back down to idle I checked the vacuum pressure from carb is only at 9 inHg, Jim Cannon said it should be like 15-17 in Hg.

Plugging the vacuum tool into vacuum advance and pumping it up does increase timing and rpm and it holds pressure.

I put it all back together and drove it and still hear the sound.

I turned the actual distributor to adjust initial timing and tightened it down. Then when or how do I use the timing light up and down buttons?

I have innova 5568.

I really appreciate the help. I am not 100% certain the timing is perfect yet. I want to rule out bad timing for the sound but my gut says otherwise.

 

[GL03]

If you have a stock camshaft generally speaking anything close to 18 in. of vacuum at idle. An engine with an aftermarket camshaft, "street race" with a little more than stock is going to drop your vacuum at idle. "Race" camshaft definitely will give drop it so much more. It is common for camshafts not to be so stock specific to year your vehicle was built even the replacements are a bit more performance.

You could just redo the timing by finding maximum vacuum with a smidgen back staying close to your timing that showed on your timing gun. Also think about the carburetor adjustment method in which on the idle mixture screws you go in or out, as soon as it bogs you go back a bit, and it is set there.

An exhaust leak at the flanges can sound like an engine noise.

 

[DaneAmerica]

Timing is set good. Idle is set up good.
Exhaust is tight all around.

Clacking sound remains the same.

Going to take a look at the pushrods and lifters.

 

[LARRY70GS]

Sounds like what you are hearing is detonation. You can do damage to the engine like that. Your method of setting timing is very risky and inexact for a number of reasons.

First, you should set initial timing with the vacuum advance disconnected and plugged. Second, the stock timing specs ONLY apply IF the engine still has the same distributor as it did when it left the factory. If you haven't owned the car since new, the distributor may have been changed out. If that has happened, then stock timing specs no longer apply. Distributors differ in the amount of mechanical advance built in. The stock 300 distributor for 1966 is part number 1111147. Stock initial timing is 2.5*




Setting timing at higher RPM also has it's pitfalls as well. Setting maximum timing by revving the engine to 2500 RPM does not guarantee that all the mechanical timing is in. Stock distributor springs don't allow full advance until 4600 RPM. If there is more advance left, and it will add to the advance you set. Always disconnect and plug the vacuum advance when setting initial or maximum timing.

Power Timing your Buick V8

I thought I would try and compose this post to answer timing questions I see all the time on this BB. I see alot of questions about what initial...

www.v8buick.com

 

[DaneAmerica]

Should I buy TA Performance ready to run distributor and re-time? I want to be CERTAIN what I'm hearing is detonation as a result of bad timing.

 

[Bob]

If you disconnect the vacuum advance and leave it that way, then set the initial timing to say 5 degrees. Then drive it with the vacuum advance plugged off, do you have the problem? Your advance timing light should be reading 0 if you are using 5 degrees on the balancer.

 

[DaneAmerica]

Reporting back.. plugged off vacuum advance. Initial timing set to 5. It still makes the sound. At the same time.

One last tidbit, I have break in oil in there now. Before disassbly, I could throw in the 20w50 I'm planning to use and see if it still does it. Could a lifter be empty?

If something is damaged, I should see debris in the oil pan or filter right..

 

[DaneAmerica]

Finally got confirmation from the muffler shop...

Exhaust manifold leak on passenger side. I just ordered a set of Remflex 13-010 gaskets. They'll be here Monday and then we will see.

I guess an exhaust leak would fool me the first time I ever heard it