Engine Builders!!

well im buliding a '72 400 sbc 4 bolt +.030 i bought a brand new eagle crank new 5.7 scat rods and KB hypereutectic pistons and have a cran energize cam 210 duration and 440 lift. the heads are stock cast iron units all new 2 years ago with a 3angle valve job. and for christmas i got a $200 gift card to ebay and ive always wanted to run a tunnel ram on mt 55 chev and wondered if the 400 could handle it with 2 jetted down 600 holleys

thanks for any hep

 

Holley make a 450 cfm

 

sorry posted it to soon the 450cfm carb from holley is for a tunnel ram set up.they are mech not vacume sec,

 

Two 600s might be a little much for the RPM range of that cam. Holley has a 450cfm 4bbl that would give u better low end if u wanna run dual 4s.

edit:i need to learn to type faster

 

I would probably try 390 VS or even the 450 VS (rare), before I tried the 600s, but they will work....if you use VS carburetors, get the "reference kit" from Holley that links the secondaries together.

 

It'll run, but I think you're gonna have a pretty bad low end bog. I'm assuming you're using 1.94 heads, but the same goes for 2.02 heads. You don't have much cam, especially if you're serious about the 210 duration. The Crane Energizer that is advertised has 266 degrees of duration with .440 lift, still not much. Your power band is pretty much shot when that tunnel ram would just be gettin goin. It's not an issue of 2 jetted down holleys, with vac secondaries the motor is only going to take what it needs in the high RPMs. The issue is going to be lack of intake velocity at low RPMS with the huge runners of the tunnel ram. You would be much better off with the RPM air gap

 

The Crane Energizer is kind of a pussy cam for a tunnel ram application. (particularly on 400 inches.)

If you want to do the tunnel ram, you should rethink your cam and heads. A cam in the 288-290 advertized duration (236in/244ex @.050) with about 488/512 gross valve lift would be a better choice.

And, you would want to add 202/168 valves to your iron heads and port th eshit out of em. A better idea is a decent set of aftermarket iron or aluminum heads which would flow better than most ported factory heads.

And, or course, the tunnel ram, big cam, good heads will send you to the torque converter and ring/pinion store...your stock stuff won't cut it.

The bottom line...If you slap a tunnel ram on your motor it might look cool, but it won't be the best idea for all around performance. Will it be OK? Yea, probably. There are guys around here who have six or eight carbs on a stock smallblock and get by just fine.

Good luck, -Abone.

 

Definitely a bigger cam and more compression (10:1 or better) would really wake it up.

 

Thanks