whats the best intake and carb set up thats going to make the best hp on a stock Brandnew 502 mag 415 crate long block. I live in salt so I want to go with Merlin intake because of the brass lined cooling. I've been told single plane?, 800 cfm holley? Whats the difference between single and dual plane. Anyone know what model number intake and also which carb, i see there are several different mounting bases (4150, 4500) mechanical, vacuum secondary, electric chock manual, and so on.

Im repowering with the same engines. Stealth dual plane and holley 850 w/electric choke is what Im going with. Dual planes seem to give better low to mid torque than single. This is where I spend most of my running time anyway. If you want max power from those longblocks then headers, cam change and single plane would certainly do it.

4150 is for the standard carbs. 4500 is for Dominator carbs which you do not need.

The Merlin intake will work fine. Its a single plane. I would probably use a 4 hole spacer also. Go with an 800cfm mechanical secondary carb. You don't really need a choke, but if its an option, go with an electric.

just ordered a Merlin 063034 intake, did a search online and found it brand new for 345 minus 25 bucks!!!!!!!! Thats 170 bucks cheaper than summit or jegs!! We will see if i get it!!!! Carb, the cheapest i can find is 497 through jegs or summit.

now should i just do a Holley RED marine fuel pump? I would like to do a psi gauge so i know if i have pressure too.

What a good not too expemsve msd ing system, dist, and box?

I could just use my 454 dist, and ign sytem right?? its from a non mag 330hp

what will the 4 hole spacer do?? what brand do you recomend and where to get one? I don need some kind of spacer, becuse tha carb linkage hits the intake and does sit flat on the intake mounting surface, i only need a 1/8-1/4 to clear the intake. What size spacer, with the merlin single place im running

I've heard a lot of good things about the HVS super suckers http://www.summitracing.com/parts/BRO-HVSS4150-4AL/
The 4 hole spacers will generally help with low/mid range power and throttle response on a single plane intake.
On a Dual Plane intake, an open spacer will generally help on the top end.

Keep in mind that these are small gains, probably 10hp or so.

any idea of gain going from stock 502 mag intake to aftermarket dual plane or good single plane?

Minimal gains at best on a stock engine. The stock magnum dual plane intake manifold is pretty decent.

I used the Merlin dual plane intake as recommended by the fine folks at Derebery who sell a lot of the 502 415hp long blocks. I already had Holley 850's. I've got dyno sheets from last year engine build if you want them.

I think the big gains are going to come from using different carberators. The intake manifold didn't appear to do any better than the merc one, but I don't have any merc dyno sheets to compare.