3.73 vs 3.90 gears

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Snowman51 said:
Carb is a holley 750 dp


Put jet extensions in the carb and play with the pump shot.

You have a carb problem.
 
sounds like you're pump shot is not working... With the engine idling, out of gear, rev it quickly... see if you get squirts of fuel into the barrels from the squirters. See if it's a consistant streem, or choppy, or no squirt at all.
... if it doesn't look clear, take a large philips screwdriver, undo the screw on the squirters, pull the squiters off (becarefull, they is a needle underneath that might get pulled out with it). Use some carb cleaner spray to clean the squirters, put them back. While there, take note of the number stamped on them... I think stock size is #31 squirters... you might need something bigger.

When the carb was rebuilt, would you have happen to know what kinda pump diaphrams they put in? You might need to go from the generic 30cc, to a larger 50cc pump diaphram, with the larger spring...

You should also see a Red or Orange pump cam on your throttle linkage assembly... You might need to use a larger Green or Blue one.

what size jets are in there?

is this a Vacuum secondaries carb? ... if so, your secondaries vacuum spring might be too stiff, not allowing your secondaries to open in time. I don't imagine it's the opposite situation, as a big block would not struggle if secondaries engage too quickly.
 
I'll agree that it may just be a carb issue. I tried a carter 750 with vac secondaries, had a bog like your describing off the line then past 1000 rpm it would run like a raped ape, but this is on a fairly hot 350. The carb needed a rebuild so I just put my 600 back on and haven't had any issues.

As for the gear dilemma, I have a 700r4 with a 2500 stall and 3.73 posi gears. The 3.73 works real well with the 700r4's first gear as it still allows you to use it on launch without having to leave it in second gear. Anything larger would result in you having to launch in second gear and you would probably never use first gear. People will say the gear drop from first to second will kill any time made on the launch, but if you shift at 5000-5500 it easily compensates for the drop. Plus your running a slightly bigger stall then me.
 
Hey guys thanks for all the info. I will be working on the carb this week and I will be sure to post the results. After talking to a hotrod buddy he said the samething. You guys are the best thanks a mill!!!! 😀 😀 😀 😀
 
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