carb issue
Thread Starter
Melting Slicks
Joined: Apr 2002
Posts: 2,103
Likes: 0
From: Tucson AZ
carb issue
I have a Holley 650 DP sitting on a 1970 LT-1 (should be a 780 vac secondary). Primary jets are 67, secondary are ??. Car hesitates when moving slowly from a stop, but does OK when launched. Under hard acceleration, there is noticeable black smoke.
I am thinking the carb is too small AND the primaries are jetted to small causing a major lean issue under slow speed acceleration, and the secodnaries are jetted way to big or not receiving enough air to create the correct mixture.
The exhaust smell lingers for some time after the car is turned off.
I am looking to get a 750 DP (until I can find the right carb) thinking this will help, rather than rejetting the 650. Any thoughts, opinions on my next move?
I am thinking the carb is too small AND the primaries are jetted to small causing a major lean issue under slow speed acceleration, and the secodnaries are jetted way to big or not receiving enough air to create the correct mixture.
The exhaust smell lingers for some time after the car is turned off.
I am looking to get a 750 DP (until I can find the right carb) thinking this will help, rather than rejetting the 650. Any thoughts, opinions on my next move?
Drifting
Joined: Apr 2002
Posts: 1,736
Likes: 37
From: Stockton Ca
Re: carb issue (Robert N)
One of ther mags CHP I think, ran a carb article. They tried several sizes and measured everything imagineable. What I found interesting was that the 650 had just a little more down low "off idle" and the huge carb "850" had just a few more on top. Also the BSFC was better on 750. The reason being that the signal from 650 was so strong that it was pulling more fuel. The 750 produced the best overall power and the best fuel curve. At least that is how I understood the article. Did i miss anything?
