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#1 |
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carb gasket help plz.
I have a stock factory intake manifold "like one pictured" and the original quadrajet carb, my question is I was given 3 gaskets. a thick one a thin one and a thin metal one. so can anyone tell me if I need all three? and if so which order do they go?
h e l p ... p l e a s e
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1971 K5 CST Blazer 1965 Chevelle Malibu 283 (sadly sold) 1968 Camaro 327 1968 Honda mini-trail z50a #377 1966 uh 1-D Huey |
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#2 |
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Re: carb gasket help plz.
You only need the thick one with the inserts.
The inserts prevent over tightening the carb. MOD
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Chad '71 GMC 2500 Custom Ol Blue '72 Custom Deluxe Highlander Stuffed Olive '73 Trans Am '13 Silverado 2500 Duramax Storm Trooper |
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#3 |
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Re: carb gasket help plz.
the metal shim should be used with that type intake, otherwise the exhaust that warms the base of the carb will burn through the gasket material and cause vacuum leaks and burn fuel at the primaries before it gets to the cylinders. I bought a big block with a spread bore carb when I was a young lad and couldn't bring the timing down and the raw gas fumes burned my eyes, it ran like poo, when I pulled the carb, the exhaust had burned through the gasket and was burning the fuel. I bought the shim with gaskets and it ran like a champ....
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Thanks, Joe.. 1969 C/10, 348 C.I., 3X2 bbl. V8, 2004r , LWB. Last edited by hamjet; 08-06-2014 at 06:20 AM. |
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#4 | |
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Re: carb gasket help plz.
Quote:
so can you tell me which is first? im thinking the thick base gasket is the first then the metal then the thin gasket? dave
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1971 K5 CST Blazer 1965 Chevelle Malibu 283 (sadly sold) 1968 Camaro 327 1968 Honda mini-trail z50a #377 1966 uh 1-D Huey |
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#5 |
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Re: carb gasket help plz.
I believe thats correct, its been along time, but it makes sense in that order...
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Thanks, Joe.. 1969 C/10, 348 C.I., 3X2 bbl. V8, 2004r , LWB. |
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#6 |
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Re: carb gasket help plz.
You NEED to know what year the carb and intake are. For some, like the 1969 427/390, it's a weird setup with a metal gasket and two composite and they must go in the right order. Vettenet has a ton of info (and a supplier of the correct ones) because it's a common issue.
On my '70 402 truck you need only the thick one with the "anti overtightening" inserts as mentioned. But if you had a carb and intake from a '69 you could wind up with a massive vacuum leak as it requires the right gasket stack to cover some open paths. Sorry, I know this only makes it more confusing for you.
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1970 GMC Sierra Grande Custom Camper - Built, not Bought 1969 Pontiac 2+2 427/390 4-speed Coupe 1969 Pontiac 2+2 427/390 4-speed Convertible |
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#7 | |
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Re: carb gasket help plz.
Quote:
the intake and carb are feb of 1971. the carb I bought nos and the intake came off a 71 c10 w/402. hope this helps?
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1971 K5 CST Blazer 1965 Chevelle Malibu 283 (sadly sold) 1968 Camaro 327 1968 Honda mini-trail z50a #377 1966 uh 1-D Huey |
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#8 |
425hp409
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Re: carb gasket help plz.
You "do not" need the steel shim gasket, it is only used with the earlier intakes that have the carburetor exhaust crossover holes that are drilled from the carburetor to the exhaust passages. See photo for the ones that use the steel shim. Only use the thick one with the inserts with your intake.
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Charles 68 SWB, Dad bought new, now 396 & factory ac 64 Impala SS, 409 425HP, 4 speed AC 64 Bel Air Wagon, 400 Small Block 57 Bel Air all original 283 w/Factory Air 77 GMC Sprint, 454/425HP 67 Olds 442, all original 90 ZR1 Corvette |
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#9 |
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Re: carb gasket help plz.
I've always used the thick one and only the thick one and had no issues
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"Some Days Chickens And Some Days Feathers" Dale XNGH ECV Sam Brannan 1004 R.I.P. 67ChevyRedneck R.I.P. Grumpy Old Man |
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#10 | |
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Re: carb gasket help plz.
Quote:
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1971 K5 CST Blazer 1965 Chevelle Malibu 283 (sadly sold) 1968 Camaro 327 1968 Honda mini-trail z50a #377 1966 uh 1-D Huey |
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#11 |
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Re: carb gasket help plz.
Hello
No they are not . Some are opened up at the ends and some are not. As stated if the exhaust is opened to the carb base you need the metal one. |
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#12 |
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Re: carb gasket help plz.
can anyone else add to this?
3=no 1=yes
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1971 K5 CST Blazer 1965 Chevelle Malibu 283 (sadly sold) 1968 Camaro 327 1968 Honda mini-trail z50a #377 1966 uh 1-D Huey |
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#13 |
425hp409
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Re: carb gasket help plz.
As stated, you only need the steel shim gasket if the intake has the holes drilled through to the exhaust like the picture I posted. The holes are at the ends of the slot in front of the primaries. You ONLY need the thick gasket.
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Charles 68 SWB, Dad bought new, now 396 & factory ac 64 Impala SS, 409 425HP, 4 speed AC 64 Bel Air Wagon, 400 Small Block 57 Bel Air all original 283 w/Factory Air 77 GMC Sprint, 454/425HP 67 Olds 442, all original 90 ZR1 Corvette |
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#14 | |
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Re: carb gasket help plz.
Quote:
But if the heat crossover isn't drilled, odds are he just needs the fat gasket as you say. You know what's probably a real ***** to diagnose? Someone with the wrong gasket on an engine where the heat crossover has been blocked at the head so that it's not a huge leak, but a vacuum leak nonetheless.
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1970 GMC Sierra Grande Custom Camper - Built, not Bought 1969 Pontiac 2+2 427/390 4-speed Coupe 1969 Pontiac 2+2 427/390 4-speed Convertible |
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#15 |
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Re: carb gasket help plz.
well when the engine builder performed the brake-in by running the engine on a stand for 20 min, he did say there was a vacuum problem. and he used only the thick gasket. and he said when he plugged the vacuum line from any of the carb ports to the distributer it added 10 degrees to the timing. so?..... is it a problem in dist?
any help would be appreciated. dave
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1971 K5 CST Blazer 1965 Chevelle Malibu 283 (sadly sold) 1968 Camaro 327 1968 Honda mini-trail z50a #377 1966 uh 1-D Huey Last edited by yote1234; 08-07-2014 at 02:23 PM. |
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#16 |
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Re: carb gasket help plz.
Honestly I would take the manifold part number and figure out what the application was and then look up that year and model. I'm happy to assist, I have parts books for the '69 Impala and for our trucks.
What you describe with the distributor sounds like a vacuum leak, and here's my theory as to why: - At idle there should be no vacuum advance and connecting the correct ported vacuum to the dist should cause no advance. Manifold vacuum would, but not the carb ported vacuum when hooked up correctly. - With a vacuum leak they probably had to open the throttle blades wide enough at idle that it's uncoveriring the transfer slot (or whatever its called, I'm an EFI guy) thereby causing vacuum to be present at the ported vacuum port. 425HP409 has a photo above of the one that absolutely needs the shim gasket. You can see the holes at the outside end of the slot up front, and that goes right to air down at the exhaust head riser. What I do not know is whether some Q-Jets require a full gasket such that otherwise they'd leak at the body. I think you're fine with the fat single gasket, but would need to know the original application of the manifold and carb for me to feel right saying either way. A local shop wound up drilling holes through my primary blades to get a stronger signal, and I don't think its needed for a ZZ502. I probably have a vacuum leak myself, but I think mine is on the underside of the intake (a whole separate story).
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1970 GMC Sierra Grande Custom Camper - Built, not Bought 1969 Pontiac 2+2 427/390 4-speed Coupe 1969 Pontiac 2+2 427/390 4-speed Convertible |
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#17 | |
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Re: carb gasket help plz.
Quote:
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1971 K5 CST Blazer 1965 Chevelle Malibu 283 (sadly sold) 1968 Camaro 327 1968 Honda mini-trail z50a #377 1966 uh 1-D Huey |
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#18 |
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Re: carb gasket help plz.
heres the carb I have #7041209 quadrajet
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1971 K5 CST Blazer 1965 Chevelle Malibu 283 (sadly sold) 1968 Camaro 327 1968 Honda mini-trail z50a #377 1966 uh 1-D Huey |
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