[Samuel]

Hey,

I recently replaced my stock 67's intake manifold and carburetor with a victor jr. and a holley 650 double pumper. It is running fine now except for when I floor it. When I hit the gas hard the motor stalls and backfires. When I start it up again and it runs fine (until I floor it again). Could it be the timing (it is currently set at 4)? Or do I need a higher flow fuel pump? Or is it because there is too much fuel, do I need to turn the jets down on the carburetor? Or is there a chance that my new carb and manifold cant run with my stock heads and cam? Any input/suggestions would be greatly appreciated.

Thanks,

Samuel

[sdtsdt]

Experiment with your timing ... You can probably run a little more ... try bumping up in 2 degree increments and see how it performs. But, do be aware that if you have too much advance, it can make for harder starting. Sometimes it is just trial and error to find the best timing ... Also, check the carb operation. Check the linkage for the accellerator pumps. You want the secondary pump to begin squirting as soon as linkage engages... If there is a "lag", your engine will actually get a gulp of air before additional gas is delivered. This can cause a bog and a pop thru the carb ... Also, you can use a vacuum gauge to adjust your idle quality ... Go to holley site to get info on adjusting carb ... it is not too difficult on the double pumpers ...

[12run]

That's quite a leap going from stock to Victor Jr. and Holley DP. Holley has some excellent tuning tips on their website. My guess is that you're going to have to play around with the timing and accelerator pumps at the very least. When I put a new engine in my '69 I played with it for a week until I got it to suit me. If you don't have the patience or the know-how, find someone that does. For my friends that usually means me. Good luck.

[dnult]

I have a dumb question. Is a 650DP a mechanical secondary carb?

[joe69rs]

Originally posted by dnult:
I have a dumb question. Is a 650DP a mechanical secondary carb?

Yes.

[dawg]

it sounds like an intake leak to me.
did you ensure that the surface was clean and did you torque the manifold in sequence and to the proper torque?

[Samuel]

I got another problem now. I started it last night, no problems. But I backed it down my driveway and when I got to the end, it sputtered and stalled . I tried to start it a few times and then lifted the hood. I found that there was gas flooding out of an outlet in the top of the carburetor everytime I tried to start it. I got it started once more and it only ran for a few seconds. It sounded very rough and unhealthy. Any ideas on how I can fix this?

[joe69rs]

I think you have too much carb and way too much intake for a stock motor. You'd probably be better off with a 650 vacuum secondary carb and a performer intake.

[Nantooch]

Sounds like a stuck needle valve and float. Better pull the bowl and check. Prolly some debris in the line jammed you up.

[jschunke]

I had a very similar problem - gun
it and it stalls and backfires
into the intake. After installing an
Edelbrok air-gap performer and new
plugs it was fine. My guess is you need
new spark plugs. The air-gap and
performer q-jet is a fine combination
for my '67 350. Those backfires probably
destroyed the fuel valve in the carb.