Fellas -

Rebuilding a Holley carb for my 401 and have a few questions. It's a pump gas motor with 9.5:1 compression, Edelbrock heads (unported), Torker single plane intake, and has a custom Harold Brookshire solid flat tappet cam (108 LC, 255/255 @ .050, .587/.587). Running a T-10 4 sp. Going into my 71 Javelin for street and road race use.

Carb is a Holley 4150 series 800 dp - it's a 4780-5, dated 2809 (28th week of 2009, I think). Holley says it came with 71 front and 85 rear jets (when disassembled, had 71 and 82), and has a 6.5 power valve (looks like it currently has a 3.5). The larger 85 rear jets make up for the lack of power valve in the rear/secondaries. It has a 30cc accelerator pump on the primary side and a 50 cc on the secondary side. It has a two corner idle circuit.

I have a Holley trick kit and a rebuild kit. The carb was disassembled, cleaned with mineral spirits, brake cleaner, and compressed air. I checked the carb body with a straightedge and it does not seem to be warped. Now it's time to reassemble it and put it on the 401, which I will be breaking in on my test stand.

Here are my questions - -

Should both of the squirters (accelerator pump shooters) have a needle below them? When I disassembled the carb, only the front one did. Doesn't look like the rebuild kits or the trick kits come with spares.

Recommendations on squirter size? I have .031 front and rear now.

As for the power valve, should I start out with the 6.5 or is the cam large enough that I will need a 3.5? The one that's in there now has a "3" and a "5" stamped on it; I'm assuming it's a 3.5, but the numbers are not adjacent.

Should I stick with the 71/85 jets?

Anything else I need to worry about at this point?

Thanks,

Scott

I would recommend going back to the stock jetting,and 3.5 power valve for break in. You don't want it to run too lean during that time,you can lean on it later on.
There should be a check valve under both squirters. 31's are a good starting point.
Keith

Realized when reassembling it that the carb had 3 corner idle - - both sides are drilled on the front metering plate. This would have been a swap or a modification; it would have come with 2 corner idle from Holley.

So, I found this spring on my bench when I was taking the carb apart. Could have come from somewhere else, but I'm thinking it's part of the carb. Does this look familiar? It's about the same size and shape as you'd see in a ballpoint pen.


Here are a few pics of the assembled carb. Yes, I did remove the choke.