2nd opinion wanted on my carb issue

4speedBench · August 1st, 2009, 06:32 PM

Recently had a date correct carb rebuilt by Sparky for my 442. It has had a "dead spot" and a bit of "chugging" at cruising speed. If you have your foot into it or the secondaries engaged it pulls nice and hard...as it should.

A buddy of mine who is a big GTO guy (and a better carb guy than I) checked it out. He dialed it in better (mixture wise, etc) and said he believes the issue is that the primaries may be too lean, thus needing to try larger jetting.

I tend to agree as it definetly prefer "more gas" and is acting up at the lightest points of pedal pressure.

Thought I'd see what you guys think before pulling the carb.

Thanks

88 coupe · August 1st, 2009, 10:12 PM

Quote:

Originally Posted by 4speedBench

........ rebuilt by Sparky for my 442 ........ <snip> ........ Thought I'd see what you guys think ........

Ask "Sparky" what he thinks.

Norm

rocketraider · August 1st, 2009, 11:33 PM

Quote:

acting up at the lightest points of pedal pressure

You're sure it's not vacuum advance related?

jensenracing77 · August 2nd, 2009, 05:39 AM

Quote:

Originally Posted by 4speedBench

Recently had a date correct carb rebuilt by Sparky for my 442. It has had a "dead spot" and a bit of "chugging" at cruising speed. If you have your foot into it or the secondaries engaged it pulls nice and hard...as it should.

A buddy of mine who is a big GTO guy (and a better carb guy than I) checked it out. He dialed it in better (mixture wise, etc) and said he believes the issue is that the primaries may be too lean, thus needing to try larger jetting.

I tend to agree as it definetly prefer "more gas" and is acting up at the lightest points of pedal pressure.

Thought I'd see what you guys think before pulling the carb.

Thanks

is your engine completely stock and did you tell sparky what mods were done to the engine? some mods will have little to no affect on the carb but others will. if you have a different cam that pulls a different vacuum he will need you to take a couple different vacuum readings at a couple rpm ranges. i would say call him first. he has a warranty with his carb service.

4speedBench · August 2nd, 2009, 06:56 PM

Thanks.

I did speak with Sparky a while ago, should call him back. He thougt it needed mixture tuned better and perhaps a vac leak. As far as mods, NO. It is bone stock. Sparky and I did discuss that the motor was out of an automatic but we would jet it to stock 4 speed calibration.

I'll see what he says...

MN71W30 · August 3rd, 2009, 04:35 PM

Quote:

Originally Posted by 4speedBench

Thanks.

I did speak with Sparky a while ago, should call him back. He thougt it needed mixture tuned better and perhaps a vac leak. As far as mods, NO. It is bone stock. Sparky and I did discuss that the motor was out of an automatic but we would jet it to stock 4 speed calibration.

I'll see what he says...

I had the same troubles, It ended up being a vacuum leak because the fuel canister was plugged into the wrong port, double check all vacuum ports. Check the timing and adjust the idle mixtures it could be lean.

Bobsw32 · August 4th, 2009, 10:34 AM

It does sound like a lean condition and as everyone pointed out that can be caused by a vacuum leak....... One way to test this is to unhook and plug ALL vacuum lines attached to the carb and the intake manifold....This includes the power brakes...... Then take it for a drive and see if it fixes the problem... If this does not fix it then check with SParky, he's good on the carb.

August 1st, 2009, 06:32 PM	#1 (permalink)
4speedBench Registered User Join Date: Mar 2009 Posts: 73	2nd opinion wanted on my carb issue Recently had a date correct carb rebuilt by Sparky for my 442. It has had a "dead spot" and a bit of "chugging" at cruising speed. If you have your foot into it or the secondaries engaged it pulls nice and hard...as it should. A buddy of mine who is a big GTO guy (and a better carb guy than I) checked it out. He dialed it in better (mixture wise, etc) and said he believes the issue is that the primaries may be too lean, thus needing to try larger jetting. I tend to agree as it definetly prefer "more gas" and is acting up at the lightest points of pedal pressure. Thought I'd see what you guys think before pulling the carb. Thanks __________________ '68 442 Sport Coupe,455 4 speed(M20)& Bench 3:42 Posi. Force Air Induction Added.

August 2nd, 2009, 06:56 PM	#5 (permalink)
4speedBench Registered User Join Date: Mar 2009 Posts: 73	Thanks. I did speak with Sparky a while ago, should call him back. He thougt it needed mixture tuned better and perhaps a vac leak. As far as mods, NO. It is bone stock. Sparky and I did discuss that the motor was out of an automatic but we would jet it to stock 4 speed calibration. I'll see what he says... __________________ '68 442 Sport Coupe,455 4 speed(M20)& Bench 3:42 Posi. Force Air Induction Added.

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August 4th, 2009, 10:34 AM	#7 (permalink)
Bobsw32 Registered User Join Date: Feb 2009 Posts: 119	It does sound like a lean condition and as everyone pointed out that can be caused by a vacuum leak....... One way to test this is to unhook and plug ALL vacuum lines attached to the carb and the intake manifold....This includes the power brakes...... Then take it for a drive and see if it fixes the problem... If this does not fix it then check with SParky, he's good on the carb.