Extremely rough idle.

[geezer#99]

So you got a little slack in the chain!

Are you gonna replace it or just put some timing in it?

[Custom/20]

Originally Posted by geezer#99

So you got a little slack in the chain!

Are you gonna replace it or just put some timing in it?

I'm doing it the right way and replacing the chain and sprockets.

[BrianG]

Originally Posted by Custom/20

I'm doing it the right way and replacing the chain and sprockets.

I am curious as to how the chain could become that worn in a year and a half. Was it not replaced when it was rebuilt a year and a half ago? If not, I'm curious as to what caused to problem. A learning opportunity for me and many others. Thank you for coming back and keeping us updated up till now. I think many of us appreciate it and are wondering how this turns out.

[randy500]

Originally Posted by Custom/20

Oh no lol. I should have mentioned that the engine was rebuilt a year and a half ago. It just started doing this 3 days prior to me post in this thread. I was leaving my friends place. It was warming up and when I kicked the electric choke off it just idled really bad. I found out that trick from a video by eric the car guy on YouTube. https://youtu.be/4_f5ukZVri8 Definitely saved me some frustration.

This statement is what you want to troubleshoot. You forced the choke off which likely caused a carburetor problem and not a timing chain problem. Check the carburetor operation like I stated previously and forget about timing chain problems.


In your first post you state the timing is less than it was before it started running bad. The timing is less because the RPM is less which results in less centrifugal and or vacuum advance, or the timing just changed... this is probably part of the running bad problem. Adjust the timing...

Timing chains don't jump a tooth, its virtually impossible, the teeth on the upper gear if nylon strip off. If the motor was rebuilt at any time in the past it does not have a nylon timing gear so forget about the cam timing as a problem.

[Custom/20]

I have checked all possible places for a vacuum leak and it does not have any. With vacuum advance still hooked up at a forced 800 rpm my timing is at 6 degrees before top dead center. I have checked the carburetor for any stuck linkage and there are no problems. I have tested the vacuum advance to see if it operates correctly and it does. Secondaries are not stuck and fuel is not dumping. I have checked the pcv valve. There is almost double the max amount of play in the timing chain. I have tried adjusting the timing. Tried running without a pcv. I'm going to stick with replacing the chain. I'll be sure to post to see what happens.

[geezer#99]

6 degrees with vac hooked up tells you you have likely 10 or more degrees atdc. Way retarded timing. You don't set timing with the vac hooked up.
WArm up the motor completely, plug off the vac advance, idle it down to 700 rpm and then setting your timing at 12 to 14 degrees. Turn the idle back down, hook up the vac and adjust your mix screws.

[Custom/20]

Originally Posted by geezer#99

6 degrees with vac hooked up tells you you have likely 10 or more degrees atdc. Way retarded timing. You don't set timing with the vac hooked up.
WArm up the motor completely, plug off the vac advance, idle it down to 700 rpm and then setting your timing at 12 to 14 degrees. Turn the idle back down, hook up the vac and adjust your mix screws.

Yes i know you dont set timing with vacuum advance still plugged in. To me adjusting the timing will only delay the true problem at hand.

[BrianG]

Originally Posted by Custom/20

Yes i know you dont set timing with vacuum advance still plugged in. To me adjusting the timing will only delay the true problem at hand.

I think they are just trying to save you the time, money, and trouble of swapping the chain. They just don't go bad that quick generally. Try the easy things first then if you still need to, go on to the harder things. What are you really out to set it at 12 or 14 and run it for a while?

[Custom/20]

Hello everyone. A little update. I dropped the pan and removed the timing chain cover. There's no slack in the chain but the distributor is way off. The oil wasn't milky when I drained it and It was not burning oil or coolant. Going to do a compression test before I go any further. If the compression test is all good then it looks like I'll finally be doing the cam swap iv wanted to do plus a distributor .

[Boog]

I'm no professional engine builder mind you but those pics are suspect. The rotor is pointing toward the number 6 terminal on the cap and the timing dots on the gears are facing each other instead of both of them on top. This tells me the engine is not at top dead center. Was the damper at tdc when you removed it?

[Custom/20]

Originally Posted by Boog

I'm no professional engine builder mind you but those pics are suspect. The rotor is pointing toward the number 6 terminal on the cap and the timing dots on the gears are facing each other instead of both of them on top. This tells me the engine is not at top dead center. Was the damper at tdc when you removed it?

Yes. That's what I was confused about

[RichardJ]

There is no problem there.

I agree that turning the crank and watching the distributor rotor produced more than desired degrees of rotation free-play. I also agree that the chain should not have much wear in so short an amount of time.

Before you go farther, repeat that test. See if cam movement is translated directly to the distributor.

[randy500]

Originally Posted by Boog

I'm no professional engine builder mind you but those pics are suspect. The rotor is pointing toward the number 6 terminal on the cap and the timing dots on the gears are facing each other instead of both of them on top. This tells me the engine is not at top dead center. Was the damper at tdc when you removed it?

None of that matters, he used a timing light, I presume on the number one cylinder and got 6 degrees advance. You can have the rotor in any position if you start number one wherever the rotor is with number 1 cylinder at TDC. I also don't think he lost the pin in the distributor gear since he was able to get 6 degrees advance on number one. The rotor is just not where it is usually timed from. I guess a compression check will show that it has good compression and there is nothing wrong internally in the engine.

Then he can go back to the usual troubleshooting procedure and set the timing, carb adjustments, etc. Verify all cylinders are firing, etc.

And BTW, that turn the crank and check distributor movement procedure is now just what I thought it was...a completely useless test that tells you nothing (proved by your chain not being loose at all). The test is just not precise enough and the distributor gear clearance is included in the test.

[paul blair]

Have you removed the spark plugs and see what they look like? They will tell you some thing about each cylinder! Good luck

[Custom/20]

Originally Posted by paul blair

Have you removed the spark plugs and see what they look like? They will tell you some thing about each cylinder! Good luck

Yeah and they don't look to bad.

[Custom/20]

OIk so i just took the rotor off of the distributor and saw how much play there is in the assembly and there really isn't much.

Here's a video: https://youtu.be/zV__6jsM7dA

[garyd1961]

Make sure your #1 piston is TDC on compression, check to see if timing mark is zeroed, back timing mark back 12 degrees, put distributor in with rotor pointing directly at the #1 tower on the distributor cap. Start engine and set timing with light.
Another thing you can do to check the cam. Mark all the push rods then turn the engine over a few revs and see if the marks move.

[bryanw1968]

It doesn't really matter which way the rotor is pointed as long as at TDC the #1 cylinder is getting spark first. However, it is a good reference to have the rotor pointed toward #1. Also, make sure your distributor is tight. I've had them slip under load because they weren't tight enough and retarded the timing. If you end up having to start over tuning always time for highest vacuum at idle then tune the carb.

[hdpete98]

Check for a loose rocker arm which would indicate you wiped a cam lobe.

[Custom/20]

Originally Posted by hdpete98

Check for a loose rocker arm which would indicate you wiped a cam lobe.

I've checked all the lifters and they were all good. I'm going to be doing a compression test and then adjust the timing.just been putting it back together. Just need to get the ballancer all the way on and fill it up with coolant.

[Custom/20]

Hello everyone. A little update. I finally got it up and running and upon startup it wasn't as loud as I thought it was going to be. It was loud but tolerable. It took a little bit of cranking but it started. During warm-up I did not see any oil leak from the balancer or oil pan so thankfully my old timing cover seal and oil pan gaskets are still good. Before startup I advanced the timing a little bit by just turning the cap. After I kicked the choke off it still idled the same but a little better. After I let it sit for about 30 minutes I did a compression test and here are the numbers.

1: 150 | 2: 105
3: 153 | 4: 149
5: 150 | 6: 150
7: 151 | 8: 149

After seeing that the number 2 piston compression is low I decided to just bump the idle up to 1000 but I decided to lower it back down to around 750. After doing that again started adjusting the mixture screws again and when doing that the idle started increasing a lot and the idle smoothed out perfectly. It runs amazing now. Runs extremely smooth at 800rpm in park, reverse, and drive.

I did read that the piston rings do spin while it is running so maybe a 2 rings got lined up for a short period of time? I'm going to do another compression test tomorrow. Btw it doesnt burn oil or coolant. Nothing comes out of the little bit of exhaust that I have.

I'll be sure to come back and update on anything that goes on.

[72_swb]

Ill jump on this one lol. glad you got it running again.

Did you check for a broke valve spring on Number 2

[72_swb]

Plus you should start with compression check cold then hot. See if the numbers change encase you get a crack in the cylinder wall. It will seal cold then heat up and open when hot . Which I don't think is your prob.

[Custom/20]

Originally Posted by 72_swb

Ill jump on this one lol. glad you got it running again.

Did you check for a broke valve spring on Number 2

Yep. Everything is good. No bent pushrods, no broken springs. The only thing is the number 6 exhaust valve rocker stud is pulled out a little bit which is causing my lifter tick but nothing else is wrong.

[72_swb]

is it a flat tappet. When you said you checked the lifters did you pull them out? just curious.