I have a D150 with a mild 360 that is need of a new carb. It has approximately 9-1 comp, 480 lift cam, 833 trans, and 3.91 gears. My question is would I be better off with a mech or vacuum secondary carb? This truck is built to play its not a daily driver, and by no means am I trying to build a race truck out of it.

Most stick cars/trucks, respond much better with mechanical secondaries.

Thats what I thought. I'm thinking I need a 650. I just bought this engine as is it runs okay I can tell its got great potential. The ignition is hacked up the previous owner set it up using the lean burn computer and the carb isn't up to par, but it holds 60 psi of oil pressure, it starts right up even in this blistering cold we have been having.

you will get better mileage on the vac carb. Every time you move the throttle you activate the secondary squirters on a DP carb.


properly tuned you wont tell the difference..

I'm gonna vote vac secondary too.

Motor is mild. It will not require the immediate fuel delivery of a dp. NOR will the engine react fast enough to need full air flow/wide open on both ends.

Also,a truck is heavy, which is a strike against a dp, again because it slows down the ability of the engine to react/draw air.

A vac secondary tuned right (secondary spring selection if we are talking holley) will work better in this application

Okay so I believe I found the carb I like. Its a 670 Holley Street Avenger.
http://www.summitracing.com/parts/CMB-03-0237/

I think you'd be happier with a 750 3310 vs, any mild 360 with bolt-ons respond well with this CFM.

Double pumper, always.

I love mech carbs. A good Holley DP is the most tunble, best responsive carb on the market.

Depending on traction low traction go up to 750 DP good traction 650 DP. Do not over jet out of the box is very close the only consideration would be power valve and squiters.