wcsinx

I hear ya, and I think we're in agreement. "Ooomph" is a difficult thing to quantify, but running a carb that's correctly sized to the application can certainly have a SOTP effect while not significantly affecting peak HP. Perhaps that is what was being referred to?

damoroso

Thanks, I thought you were refering to vacuum, which I understand. However, now the rest of the statement doesn't make sense to me. The engine will only draw what it's VE allows at speed correct? So the carb is a restriction to what degree is a matter of design. It's CFM rating, as long as all carbs are measured with the same bench mark or standard can be off as far as actual CFM are concerned, but would be relative to one another. Therefore, it's difficult to see how a 670 could flow more than a 750 of any manufacturer.

Thanks for indulging me though, I think we all can agree that like anything else, personal prefrence will come into play!!

Duane4238

Regardless, some of us like our Q-jets and some of us like our Holleys. You're not going to change someone from one side of the fence to the other. We've all been through these disagreements, and nothing is ever settled or agreed upon. Amen!
Duane

sweeet76

Sometimes I can feel it stumble or miss when starting normal from a dead stop. It almoast feels like it is not getting enough gas. I have the book by Doug Roe but I guess I'm still not sure how to adjust the fuel and air mixture screws.

damoroso

First, verify your timing and make sure you don't have any vacuum leaks. There are a couple quick ways to check for vacuum leaks. At operating temp, take the air cleaner off, and slowly put your hand over the primaries and see if the engine picks up any. If it does, it's a good bet you have a vacuum leak. You can also spray carb cleaner, starting fluid or even use an unlit propane torch around the base of the carb and intake fittings to see if the engine speed picks up. If it does, you found the leak...

In adjusting the idle mixture screws, remember, on the Q-jet, there is no dedicated idle circuit. It's idle/cruise so the idle mixture screws will effect the cruise too. Set the idle mixture to get the most vacuum you can, connect a guage to manifold vacuum and work from there, making sure you get both sides even. Are there any other issues with the carb or does it run well in all other situations?

sweeet76

Actually it seems to sputter at times when starting from a dead stop and normal acceleration. I'm not even sure if the air blades on the secondaries are opening or how to check for it. Its almost like i'm trying to overthink this whole problem therefore missing out on the normal way to solve it.

johnt365

Can you post a picture of the choke side of the carb?

sweeet76

Actually I'm beginning to think it might be the timing and not the carb. I just drove it again and it seems to want to go but can't, if you know what I mean. I'm going to check it in the AM. I just had some new aluminum heads oinstalled and that is the only thing different.
I will post my findings and thank everyone for the help.