Any Carb Gurus out there want to comment?

[Pman1961]

I have been discussing my timing and carb situation with a good adviser currently but he was unavailable yesterday evening and just wanted Club Cobras opinions. What Vector1 has commented is what I've been told that the street style carb is designed for higher vacuum. I previously had been idling around 1100rpm. When I put more timing in the motor it seems to have better idle quality and therefore I tried the idle at 1000 to 1050 with the fans running. The motor was assembled at KCR and used a new SS750 Quick Fuel that I had bought for a 408w. When the initial advance was 20 degrees or lower having a wider timing curve it required opening the primarys up a whole bunch just to idle and the idle would get really lazy quick below 1100 rpm especially when the fans kicked on because it was idling with initial timing. Last night was my test to see how much initial advance I could take before any starter drag and I was able to go to a full 34 degrees without any issues. Only issue is the idle mixture screws were not sensitive turning them out so I'm thinking the setup within the carb is not compatible with my motor with low vacuum. I feel as others the Q850 would be the correct carb for my motor. Just was curious how these perform on the street if they are more of a race style carb. By the way my timing curve currently is 20-34. I can modify for 26-34 which seems to be okay or lock it out. Opinions on locking out are welcomed also.

[blykins]

Originally Posted by Pman1961

I have been discussing my timing and carb situation with a good adviser currently but he was unavailable yesterday evening and just wanted Club Cobras opinions. What Vector1 has commented is what I've been told that the street style carb is designed for higher vacuum. I previously had been idling around 1100rpm. When I put more timing in the motor it seems to have better idle quality and therefore I tried the idle at 1000 to 1050 with the fans running. The motor was assembled at KCR and used a new SS750 Quick Fuel that I had bought for a 408w. When the initial advance was 20 degrees or lower having a wider timing curve it required opening the primarys up a whole bunch just to idle and the idle would get really lazy quick below 1100 rpm especially when the fans kicked on because it was idling with initial timing. Last night was my test to see how much initial advance I could take before any starter drag and I was able to go to a full 34 degrees without any issues. Only issue is the idle mixture screws were not sensitive turning them out so I'm thinking the setup within the carb is not compatible with my motor with low vacuum. I feel as others the Q850 would be the correct carb for my motor. Just was curious how these perform on the street if they are more of a race style carb. By the way my timing curve currently is 20-34. I can modify for 26-34 which seems to be okay or lock it out. Opinions on locking out are welcomed also.

Q series carbs are absolutely fine for a street engine.

Also, on locking out the advance, I'd do it. With a Cobra, you usually go with a quick curve anyway, and it doesn't take much to get past initial timing once you get rolling. If your starter can handle it, I'd do it.

[scottj]

For street, with a big cam, I always ran locked-out and a custom Holley HP. Engines were 434cid and 264/272 @ .050 solid rollers. Carb size was 1.45 venturi with 1.75 throttle bores. Timing was 35-36 degrees depending on the heads and compression was 9.5 to 10.8, again depending on the heads. Throttle response and drivability rivaled my current fuel injection.