I just put a Holley 650 DP on my 289. Use to have a Edelbrock 600 CFM carb. After getting the Holley to stop leaking from just about everywhere, the carb runs good, but definitely running rich out the rear. I believe the stock jetting is .67 primaries and .73 secondaries. Any suggestions on what jet I should go with? Anyone running this carb on a 289. The carb idles nice, stumbles slightly when the throttle is opened. I'm running a mild cam, stock heads, Edelbrock intake and headers.

 

In my opinion you should have stayed with the Edelbrock but that's me. When you say running rich when are you seeing this? Do you have a wideband O2 to check it? When you say it idles nice but stumbles and had to fix numerous leaks you sure there's not dirt in it? Have you checked the float level since it can idle good but not deliver fuel as it was calibrated to. Is the accelerator pump linkage adjusted properly and the shot occuring at the slightest opening of the throttle? I used to calibrate carbs when I worked at Holley. Edelbrock made their calibrating easier and more precise. They could change the configuration of the primary boosters to a better design though.

 

Thanks for the great info kaboom10. I've had some problems but I think I've worked them out. The pump linkage was off and had to be adjusted both for the primary and secondary linkage. I changed the jets from .67 primary and .73 secondary to .64 primary and .70 secondary. Made a big difference. I'm running an oval air cleaner 15 inch which had a 2" filter on it. I went with a 4" inch which also helped. My stumble was a result of having a 2" plenum underneath the carb. It ran nicely with the Edelbrock, but caused a serious stumble when I hit the accelerator with the Holley. I replaced it with a 1" which has the holes and not open chamber like the 2" plenum. That got rid of the stumble. Timing was slightly off. I still get a smell of gas fumes at idle, but according to the plugs, I running at a brown at the electrode which means I'm running fairly well as far as rich or lean. I can tell you this, the Holley is day and night from the Edelbrock. Performance wise, the Edelbrock can't touch it. The Edelbrock is nice for cruising around, but does nothing for performance and seat of the pants acceleration. I'm running 2.75 gears in the rear which is hurting my acceleration off the line. I have a set of 3.5 which I may put back in, but then there goes my highway driving and gas mileage. But then again, with the Holley double pumper, I'm not counting mpg anyways.

 

You're welcome. Ah ha the open plenum of the spacer. You weren't covering that hole with accelerator pump timing and delivery. You can change pump cams and shooter sizes to come up with a happy medium. The plenum tricks the engine into thinking it has a different manifold and also increases the rpm range.