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Holly hesitation

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12-7-12
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I have a 650? Holly dual feed (not a dual pumper) on a 500 Caddy. I seem to have a slight hesitation when I accelerate fast (WOT) from idle or cruising. There is just enough to make you think it might not go, and then it takes off like a rocket. I have the original intake manifold but I needed an adaptor to go from the Q-jet to the new Holly. We just changed the jets out and it seemed to help just a little. I don’t seem to have the snap I once did. We just rebuilt it. We put Cad Company’s cam and lifters in, Keith Black pistons at 30 over and 10: 1 ratio. We redone the HEI distributor with new coil, weights and light springs, disconnected the vacuum advance. Is this the carburetor or is this a timing issue?

Thanks

I hope all have a wonderful and safe Christmas.
 
It's easy to fix you just need to adjust one or two things on your carb and change one small part. This is a very common problem with car motors and is usually easy to fix. I will P.M you with some info.
 
I'm guessing accelerator pump circuit. You can get different pump cams, one screw to change, also a couple positions you can mount. You can also get different pump shot nozzels if necessary, (I have used small number drills to get to right size) but waterthunder will fill you in! The 50 cc pump (don't remember what the 650 has on it) can cover up a lot of hesitation also.
 
Also check the float level. If the float level is low it will cause a lean spot and a hesitation.
Good luck
 
"Making it public" isn't really an option, especially over the internet, since every application is different.

For you guys who want to figure it out for yourselves......Just consider the fact that the drag of a prop opens the throttle blades much more at idle than a carburetor is designed for, and revs slower, under more load as well..

For the rest...Contact someone willing to share this information with you.

Felber
 
Update: problem fixed and I’m glad to help. I have only heard back from one of ya so I hope it worked for both of ya. If it didn't let me know because there are two more things left that will work also.
 
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