I recently dropped in a 350 ho crate engine with my brother since the 305 decided to quit its life here. As of now I have my stock q jet on it with a cracked accelerator pump. But its still turning great thriottle response and 17 mpg. A mechanic told me that its really choking the motor and to go with a 700-770 cfm holley or demon. I am not sure on what to do.

Thanks for looking

Here is an article from car craft that used a 750 holley with good luck.

http://www.carcraft.com/projectbuild...all/index.html

Here's a Carcraft article about my choice.

http://www.carcraft.com/howto/57178/index.html

What does that mean?

That's what's known as an "ignorant statement". The q-jet will flow at least 750 CFM (check the tech articles for getting a q-jet to flow to its full capacity), which is more than that engine can use. Putting a 770 CFM Holley on it would be known as a "downgrade".

Very simple - fix the q-jet.

Notice they used a double pumper carb, not vacuum secondary (the 770 CFM carbs are vacuum secondary).

What does that mean? I don't know, but I was told it when I had a mechanic adjust my kickdown cable and put a new choke on the q-jet. (I may be writing it wrong. I know very little about carbs and could be mixing it up with something else)

I noticed it was a double pumper, and read in my brothers holley double pumper manual that it will destroy a overdrive transmission. So that can't be good.


Thanks for the replies. I'm keeping my q jet and saving a lot of coin because of your help.

It's not the "double pumper" part that destroys overdrive transmissions - it's the geometry of the throttle arm for the transmission throttle valve cable, which would also be the case with a vacuum secondary Holley or an Edelbrock Performer. The simple fix is to install a "geometry corrector" bracket.

But, keeping the q-jet is still the right answer.

What he might be trying to say is the accelerator pump is not working correctly because the pump plunger seal is cracked. If that was the case, it should be bogging or backfiring when you depress the accelerator pedal. But, you said it had great throttle response, so it isn't adding up.

Ahh okay, I understand it now. So its the geometry. Makes sense.

My brother has a 700 holley classic double pumper which I was going to use because its new. But I was afraid because of what the manual said. So a corrector bracket would allow me to put on a double pumper? Just wondering if his carb would have been okay on my motor if I did use it.

No backfiring, but there was a bad hesitation when I hit the gas once to aovid a person on their cell phone. Other than that I have been keeping my motor under 2500 rpm for break in.

Thanks for the info master moderator