Hot Rods A few Questions for Modern Carb Experts

I fought with having enough initial timing in the small block in my 55. It has a XR292 solid roller in it. I found a set of bushings that let me get some more initial timing in it and it really helped the idle. They were more expensive than I wanted to pay, but at the end of the day it was worth it, at least for me.

https://4secondsflat.com/MSD Distributor Tuning.htm

 

I've heard they're decent carbs too. I've had pretty good luck with Summit branded stuff. Thanks!!

 

Thans for that link, I am going to pick up a set of their bushings to try more initial.

 

I just did an msd where I put a small bolt and nut in the slot and profiled the head to give me the advance I wanted. call PTC and give them all your info. let them build you a converter. you wont be disappointed.

 

They have great reviews among a certain group…..I had an original Holley one on a 400 SBC in a 3/4 t pickup. Was the most trouble free carb I ever had. I have a 500 new in the box if I ever remove the dual quads I’ve been using for 6+ years..

 

Filled out their spec sheet, we'll see where it goes. Thanks again!!

 

You'll be glad you put a double-pumper on it when you do.
This one works great: Holley 0-4779S Holley 4150 Double Pumper Carburetors | Summit Racing

Maybe shop around for a slightly used model with 4-corner adjustments, like a Quick Fuel. New carburetor pricing is insane now.

 

You ain't kidding!! The same Street HP I bought two years ago is now $150 more. Even Edlebrocks are way up. The Summit branded carbs are still pretty reasonable.

 

Pretty much confirmed the VS isn’t getting it done. Switched to the lightest spring in the secondaries and it made a noticeable improvement down low. Still hesitates a bit as the secondaries open, but it rips once they do.

 

Some would say that the term 'modern carb' is an oxymoron because carbs are old school but I like 'em.

 

Does the accelerator pump feed fuel from idle to wide open throttle or does it quit before the secondaries open? Is there any adjustment for pump timing or duration?

 

I don't have a good way of confirming that one way or the other with the engine running since the accelerator pump is mechanical and the secondaries operate on vacuum. It does seem to work ok though, as it will light the tires up when i nail it off idle. There are no dead spots off idle, just that hesitation after punching it before the secondaries open. If I operate the throttle with the engine off, the pump runs out of shot well before WOT. I didn't think it was supposed to provide fuel through the entire range though?
The accelerator pump is adjustabe via cams, but in all my messing around with it, I've found the stock cam on hole #2 works best. IT is set to Holley's spec so it begins feeding fuel as soon as you touch the throttle. They make a bigger pump, but I think it would be overkill on my setup.

 

Have you tried a heavier spring on the secondaries to slightly slow down the opening of the throttle plates a little? If they open too quickly it can cause a lean "flat spot" until there's sufficient air flow to start pulling fuel thru the secondary nozzles.