My first Vette - first question
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Cruising
Joined: Dec 2002
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From: Jupiter Florida
My first Vette, '63 327 - first question
The previous owner modified the engine with an unknown cam. The timimg mark can not be adjusted to the correct 8 deg BTC without the engine stalling. I suspect the distributor was installed a couple gear teeth off from the original location. I have set the dwell, mixture, cleaned the plugs, etc and she still idles like a drunken sailor (reeeealy rough!). A gauge on the carburetor air line to the vacuum advance shows it centered around 10 psi but jumping about 4 psi above and below.
Since the engine is so much more simple than the current technology, I know there can only be so many possibilities.
Any ideas other than wild cam and/or misplaced distributor? :confused:
Can cams cause an engine to run this rough at idle? (My experience up to now has only been with unmodified engines.)
[Modified by jetlag203, 1:38 PM 12/30/2002]
Since the engine is so much more simple than the current technology, I know there can only be so many possibilities.
Any ideas other than wild cam and/or misplaced distributor? :confused:
Can cams cause an engine to run this rough at idle? (My experience up to now has only been with unmodified engines.)
[Modified by jetlag203, 1:38 PM 12/30/2002]
Safety Car
Joined: Apr 2001
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From: Middleboro/Boston MA
Re: My first Vette, '63 327 - first question (jetlag203)
A gauge on the carburetor air line to the vacuum advance shows it centered around 10 psi but jumping about 4 psi above and below.
I know my shop manual at home has a troubleshooting section
where it shows various vacuum conditions and the possible problems for each condition.
You need to pick up a manual and take a look.
Yes a wild aftermarket cam can create a very rough idle and usually
creates a lower manifold vacuum than stock.
How does it drive thru the RPM's ??
Heel & Toe
Joined: Jul 2002
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From: scottsdale az
Re: My first Vette, '63 327 - first question (Crazyhorse)
can you adjust the timing by ear to get a smooth idle? if so do it then drive it and set the full advance by the sound of pinging. frequentyl the ring on the harmonic balancer moves around. Also make sure you have good fresh gas in the tank, one time I had good gas in the tank and lots of crud in the fuel line. I set up a rig to flush the line with a surpluss holley fule pump and worked wonders.
Le Mans Master
Joined: Feb 1999
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From: Mobile AL
Re: My first Vette, '63 327 - first question (jetlag203)
I would check the location of the timing mark on the harmonic balancer to see if it indicates true top dead center for #1 cylinder in relation to the tab on the timing chain cover.
I would also check to see if the distributor vacuum advance is working at idle.
If the previous owner has installed very light distributor advance weight springs, I would replace them with heavier springs that would give a consistent zero mechanical advance at idle speed.
Finally, I would readjust the valve lash. If it is a solid lifter cam, I would set the lash to about .030" to see if that improved the idle vacuum. If it is a hydraulic cam, I would set the rocker nuts at 1/2 turn down from zero lash.
If I didn't already know how to do these tuning steps, I would find a local person to work with me the first time I tried them.
I would also check to see if the distributor vacuum advance is working at idle.
If the previous owner has installed very light distributor advance weight springs, I would replace them with heavier springs that would give a consistent zero mechanical advance at idle speed.
Finally, I would readjust the valve lash. If it is a solid lifter cam, I would set the lash to about .030" to see if that improved the idle vacuum. If it is a hydraulic cam, I would set the rocker nuts at 1/2 turn down from zero lash.
If I didn't already know how to do these tuning steps, I would find a local person to work with me the first time I tried them.
Drifting
Joined: Aug 2000
Posts: 1,805
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From: Annapolis MD
Re: My first Vette, '63 327 - first question (jetlag203)
A "large" cam can make the engine need much more than 8* initial advance. The cams in my boat motors (which are really not too radical) need at least 16* initial advance to not stall when in gear, they will idle out of gear (no load) down to about 12* initial but that's it. I'd follow the suggestion of adjusting the advance so it idles ok then see what you get for the adjusted initial and total advance.
-Greg
-Greg
Team Owner
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From: Washington Michigan
Re: My first Vette, '63 327 - first question (GregP)
Basics first - like Jerry said, verify the balancer index mark to "0" on the timing tab at #1 TDC, using a piston stop tool. You wouldn't believe how many "hot-rod" engines I see with mismatched balancers and timing covers; the index mark was moved 8-9 degrees counterclockwise on '69-up balancers, and so was the tab on the timing cover - many people don't know this, and when they're done swapping parts around, it generates lots of posts about "I can't set my timing". :cheers:
Thread Starter
Cruising
Joined: Dec 2002
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From: Jupiter Florida
Re: My first Vette, '63 327 - first question (Crazyhorse)
Once the engine is above 1500 rpm or so, it is relatively smooth but does surge. I adjusted the hydraulic valves to 1/2 turn down from zero. The previous owner installed roller rockers and I think the only reason for that was to be compatible with a wild cam.
I will buy the piston tool that verifies it is at TDC see if the timing mark has moved. I never knew that the outer ring could slowly migrate.
I also have the maintenace manual, but with all the modifications that have been made over the past 40 years, it might not cover all posibilities for trouble shooting.
Thanks for the suggestions.
I will buy the piston tool that verifies it is at TDC see if the timing mark has moved. I never knew that the outer ring could slowly migrate.
I also have the maintenace manual, but with all the modifications that have been made over the past 40 years, it might not cover all posibilities for trouble shooting.
Thanks for the suggestions.
