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#78684 06/11/2007 4:34 PM | Joined: Apr 2002 Posts: 99 Wrench Fetcher | | Wrench Fetcher Joined: Apr 2002 Posts: 99 | OK guys, I know this question is both basic and not from the normal Stove Bolt era but I know you all can help.
I just bought my 44 year dream ride, a 62 Corvette with a 327 300HP engine.
Problem is it runs very rich as evidenced by plugs being very black and car leaves black marks on drive way just below exhaust outlets. (Black is not from tires).
Engine start fine but will give a backfire when cold and you goose the throttle. Backfire goes away when warm. Black carbon on plugs can easily be chipped away with fingernail. Plugs were wet. Plugs and wires appear to be in very good condition and appear to have been recently replaced.
I put in reg gas but think I need to go to higher octane because of dieseling at shutoff. Spec compression ratio is 10.5/1
Questions:
1. Can some tell me where the mixture adjustment is located on this carburator?
2. To adjust mixture (lean-rich) do I need any special tools or gauges?
3. How do you determine a starting point, normal mixture from which to make adjustments?
4. What is a good reference manual to read up on carb adjustments. | | |
#78685 06/11/2007 7:04 PM | Joined: Nov 2002 Posts: 2,766 Carburetion specialist | | Carburetion specialist Joined: Nov 2002 Posts: 2,766 | Assuming you have the original Carter AFB (3269s manual, 3310s automatic):
(1) two idle mixture control screws in front, screwed into main body at approximately a 30 degree from horizontal angle.
(2) straight bladed screwdriver
(3) 3/4 turn to 1 1/2 turns from LIGHTLY seated.
(4) Chevrolet factory shop manual
It is OK to make basic adjustments to carb, but before major (rebuild) carburetor work, check the ignition system throughly on a diagnostic oscilloscope. NINETY-THREE percent of ALL carburetor problems are ignition. If the previous owner has installed one of the @#$%^&* electronic points replacements, remove it first and put back the points before you adjust the carburetor. A defective ignition system will cause ALL of the symptoms you describe.
And while the only 'Vette I ever owned was a 1963, in my opinion the 1962 was the best looking of them all!
Jon.
Good carburetion is fuelish hot airThe most expensive carburetor is the wrong one you attempt to modify. If you truly believe "one size fits all," try walking a mile in your spouse's shoes!The Carburetor Shop | | |
#78686 06/11/2007 7:17 PM | Joined: May 2006 Posts: 8,351 'Bolter | | 'Bolter Joined: May 2006 Posts: 8,351 | Originally posted by carbking:
NINETY-THREE percent of ALL carburetor problems are ignition. That is exactly what I was thinking! i had a similar problem, turned out to be that the timing needed to be advanced.
Bill Burmeister
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#78687 06/11/2007 8:41 PM | Joined: Mar 2005 Posts: 1,029 Member | | Member Joined: Mar 2005 Posts: 1,029 | It will run like crap if it is timed to not ping with regular unleaded. | | |
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