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I ordered a new holley mechanical fuel pump today. I got a double roller timing chain and a gasket kit. One question. The gasket kit comes with intake restrictors wtf are these? it looks like they go into the ports that run under the carb. my current gasket doesn't even have those ports in the intake gasket. do I need them? what are they for?

They restrict intake air flow at mach I believe. Like what they use in Nascar to slow cars down on the slower tracks. They been talking about using them at Texas Motor Speedway for a couple of years.

http://www.theoldone.com/archive/int...r-velocity.htm

They are for the crossover that runs under the carb. They will restrict the amount of hot air that runs under the carb to heat it in cold weather operation. At least I hope that is what you are talking about!!!

Jram, the restrictors that NASCAR mandates at Talladega and Daytona go between the carb and the intake manifold.

Dave's got it. If you let that exhaust cross over, on some (alot) of carbs it'll mess'em up. Warp them, toast them, etc..

Cool I figured I was wrong but it got some responses, and now I know.

so I should use them?

Yup, I sure would. If cold weather operation is not a concern, you may want to consider blocking off the heat riser port completely. Might want to wait for the chebbie guru's to jump in here, I'm a Blue Oval guy primarily, been around chebbies a bit though.

Dave is right about the cross over restrictors.
It does aid in fuel atomization, it prevents fuel from puddling at the bottom of the intake when the motor is cold.
For performance though I would block them cross overs off. Most of the performance intakes and or heads don't even have cross overs. Depending on your intake and or heads you may not even have cross overs. If it don't have the ports then you don't need the block off plates or restrictors.

Hey, I've never actually looked... Where do those two little mini crossover ports go? Do they just pick on one cylinder on each side? Why does the exhaust bother to go "across"?

Originally posted by kcress
Hey, I've never actually looked... Where do those two little mini crossover ports go? Do they just pick on one cylinder on each side? Why does the exhaust bother to go "across"?

Posted by Dave Severson:
"They are for the crossover that runs under the carb. They will restrict the amount of hot air that runs under the carb to heat it in cold weather operation. At least I hope that is what you are talking about!!!"

kcress, the exhaust gases pulse into the chamber under the carb from each head, heating the manifold to help atomize the fuel/air mixture. You'll be glad you have 'em on a cold morning on a street-driven car. The guys who mainly drag race with their cars plug them so that the mixture will be cooler and thus denser.

Thanks tech. But I need more mechanical detail.