400 Carb

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awohlers

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Hi Everyone,

I have a 400, stock stroke and bottom end, comp cam, heads have been ported with new valves and springs, and a RPM intake manifold. For mostly street use I just ordered a Holley Street Demon 750. The Holley website as well as the local speed shop and auto parts store said to go with a 750 but my father and the older mechanic across the street said that is too much carb to go with a 650 street demon. What are your thoughts? I could always jet it down if I had to.

Thanks,
-Adam
 
Good carb for the street. What's the rpm range of your cam? A 650 would be fine for regular driving but you might lose some steam at the top end.
 
With a Street demon like a thermoquad, you can go bigger because of the air valve secondaries only open as much as needed. Chrysler put 800 cfm thermoquads on 318's. I'd go for the 750
 
“Jetting down “ or up is running the carb and almost always needs to be done.

Use the 750.
 
awohlers said:
Hi Everyone,

I have a 400, stock stroke and bottom end, comp cam, heads have been ported with new valves and springs, and a RPM intake manifold. For mostly street use I just ordered a Holley Street Demon 750. The Holley website as well as the local speed shop and auto parts store said to go with a 750 but my father and the older mechanic across the street said that is too much carb to go with a 650 street demon. What are your thoughts? I could always jet it down if I had to.

Thanks,
-Adam
Click to expand...


The 750 will be fine but you should invest a few bucks into a wideband setup if you don't have one. A wideband will really help you sort out the tune.
 
AndyF said:
The 750 will be fine but you should invest a few bucks into a wideband setup if you don't have one. A wideband will really help you sort out the tune.
Click to expand...
I ran an 800 double pumper on my 406 sbc, it ran like a bat out of hell and very good ! Also ran an 870 vacumm secondary at times, it got better mileage , but was a little slower than the double pumper.... JFYI
 
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