Carb adjustments when adding headers
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Joined: Oct 2002
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From: houston
Carb adjustments when adding headers
All,
I've got an 1982 e350 with a 460 and stock 4 barrel carb.
I've got a fairly bad exhaust leak and am thinking of going to headers and dual exhaust to solve it.
When I go to headers will I have to re-tune my carb? ie adjustments to screws or actually changing out jets? I'm very good with cars but have not ever touched a carb. If I would need major adjustments I think I might just try and replace the manifold gaskets and use some black high temp rtv to help it seal well.
Advice?
Thanks in advance!
Dave
I've got an 1982 e350 with a 460 and stock 4 barrel carb.
I've got a fairly bad exhaust leak and am thinking of going to headers and dual exhaust to solve it.
When I go to headers will I have to re-tune my carb? ie adjustments to screws or actually changing out jets? I'm very good with cars but have not ever touched a carb. If I would need major adjustments I think I might just try and replace the manifold gaskets and use some black high temp rtv to help it seal well.
Advice?
Thanks in advance!
Dave
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Joined: Jul 2003
Posts: 3,934
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From: iowa
Carb adjustments when adding headers
I would image that you would have to tune it a bit. I don't think you should have to re jet the carb. I have thought about the same thing. Hell maybe you don't need to adjust anything. I don't think the headers will change the amount of air comes thru the carb at all.
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Joined: Dec 1999
Posts: 1,903
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From: Copley, OH
Carb adjustments when adding headers
Headers will lean the engine out. The tuned extraction effect cuases a lot more air flow during valve overlap. You will probably have to rejet just a hair richer to match. read your plugs and act accordingly.
Posting Guru
Joined: Aug 2000
Posts: 1,127
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From: (near) Denver USA
Carb adjustments when adding headers
Yes, you will have to retune the carb, probably change jets.
The main reason is that the improvement in exhaust scavenging will decrease the amount of exhaust gas left in the cylinder when the exhaust valve closes. That allows combustion temps to increase, which can aggravate pinging.
Retuning the carb will help you get the most power benefit from the headers.
The screws control the mixture only at idle.
The main reason is that the improvement in exhaust scavenging will decrease the amount of exhaust gas left in the cylinder when the exhaust valve closes. That allows combustion temps to increase, which can aggravate pinging.
Retuning the carb will help you get the most power benefit from the headers.
The screws control the mixture only at idle.
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