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carb spacers?


Murphy

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Stopped by O'Reilleys Auto Parts last nite on way home from work for misc stuff, and they have a fair display of performance parts. Anyway, this guy was drilling one of the staff about carb spacers. Disappointed that the car (mustang)ran worse after installation. Got me thinking, so I did a little research.......info is all over the map, any opinions on the usage of space with a Qjet & stock intake or a performer intake??

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Honestly I have never used one, but logical thinking comes into play when talking about spacers... It doesn't make sense to me, unless your carb has a high cfm, and a high output of fuel pressure (much higher psi than stock) I don't see how a spacer could help you in any way with performance.

 

Your essentially forcing the gas to travel a longer distance and therefore increasing the time between when the carb jets the gas into the engine and the engine actually receives the gas.

 

Now if u have a high performance car, a forced induction hood scoop that your an inch or two short on, and a fuel pump and regulator pushing about twice the amount of pressure into the motor, then I think a spacer is warranted. But if not, I don't really see a point aside from cosmetics.

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well mine responded very well to a spacer, it all depends on your set-up, only real way to know is a dyno or at the track, I can say that I have never seen any benefits when used with a Q-jet

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There are all types of spacer combos for performance. Trail and error can get pricy with good spacers. A dyno or test and tune can be helpful finding the right combo. I doubt that a spacer would help with you Q-jet.

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While I cannot speak to the Q-jet results; I have had good results with Holleys. It really depends on the engine set-up and I have found them to help on the top end for the most part. They tend to help the velocity of air entering the cylinders. Normal street cars would not show much gains.

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My engine was dynoed with and without a spacer. The 1" spacer gave an extra 10hp at the upper rpm ranges, but took a little away at speeds below 4000 rpm. This was with a 468 and a Holley carb.

The trade-off is hood clearance...if I decided to use a spacer, I'd have to use a shorter air filter which probably hurts the output more than the spacer would help.

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I mostly agree with all responces to your question. HVH makes a spacer called a Super Sucker that is open at the top and tapered at the bottom(maybe it's the other way around), but either way with a high HP engine with 10:1, or better compression you will make significant gains on top end and if you have a high stall torque converter any bottom end losses will be insignificant.

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Fuel pressure doesn't really work like that. In race engines pressure is around 7 to 8psi to the carb. Stock carb engines run around 3 to 5psi. Holley's can only handle 9 to 9 1/2psi. High Pressure pumps are only used to be sure there is enough volume to be there when you need it and a regulator is used to hold it back down to 7 psi. As far as intakes are concerned, ever see a sb2 intake or a sheet metal Intake? They are very tall. The concept is the taller/longer runner has more time to atomize the fuel and air better which is essentially what the idea is for spacers. Every engine is different and you can never tell if yours can gain by using 1 unless you try it. With that being said Patrick James of Pro Fuel Systems has told me that if you engine picks up with a spacer your carb isn't tuned right for the car.

Honestly I have never used one, but logical thinking comes into play when talking about spacers... It doesn't make sense to me, unless your carb has a high cfm, and a high output of fuel pressure (much higher psi than stock) I don't see how a spacer could help you in any way with performance.

 

Your essentially forcing the gas to travel a longer distance and therefore increasing the time between when the carb jets the gas into the engine and the engine actually receives the gas.

 

Now if u have a high performance car, a forced induction hood scoop that your an inch or two short on, and a fuel pump and regulator pushing about twice the amount of pressure into the motor, then I think a spacer is warranted. But if not, I don't really see a point aside from cosmetics.

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