351C motor rebuilt

[Sly_drums]

Hi guys, today my old 351C 2V engine needs a serious rebuilt.

My car is 72 CJ Grande, it had a 351C 4V CJ motor from the factory but this motor was swapped years ago for a 2V motor coming from a 72 Ranchero. The C6 trans was swapped for a C4, which has been changed a few years ago for a brand new one.

I believe it has open chambers 2V heads. I swapped the 2 barrel intake and carb for a Weiand Xcelerator 4 barrel single plane intake and a 600 cfm vacuum secondaries Holley carb.

The car also benefits from a new 2.5 inch Pypes exhaust with x-pipe and Street pro mufflers, and the classic Hooker Comp headers.

This motor runs OK but burns a lot of oil when pushed, not that much when cruising... It's 41 years old.

It has a cool top end power until 5000 RPM (because of the single plane intake) but lacks a bit or torque in the low end for my taste. I guess the car still has the factory 3.25:1 axle ratio.

Now I have to choose which route I want to go. My aim is to get somewhere near 300 HP at the rear wheels (means 350 @ crank ?), usable on the street with sufficient torque in the low end and still good top end power. I don't want to reach 7000 RPM, and I don't want to change the axle ratio. I won't be racing.

My initial aim was to rebuild a 4V motor and selling the Weiand 2V intake, 2V headers etc. (as the car came 4V from the factory)... A guy near me (France) sells a pair of Aussie quench/closed chamber heads in good shape, which IMO can be a really good alternative, and so I can keep the headers and intake.

What do you think ? I want to awake this baby and raise the compression ratio, get usable power on the street for a weekend driver. Budget isn't that much of a problem.

Thanks a lot !

 

[mus72]

OK I'll give my 2cents worth keep you're heads get a good 3angle valve job and make sure to use good 1 piece valves check the head cc's and get a set of 0.30 under forged pistons at 10.1 a 270comp cams magnum kit with hydraulic roller rockers ,match port the intake and headers and the carb tuned to suit you should be around the 350 mark a little porting would help. ps the rockers run with guide plates so you would need hardened push rods don,t order until you do a mock build to check length you might want to deck the block. electric fan will also release a few horses more than you might think.

Good luck whatever way you go.

 

[hyena429]

300 wont be hard to get with a 2 or 4v motor...All counts what you want...But a single plane intake is not good for a 2v motor on the street...Heck im building my 4v up too 425-450ish and im still going to run a dual plane manifold...Single is more for racing...My freind had a chevy 350 with a single plane and complained about it not having enough low end..We told him that was too much manfiold for a average street motor..Got it replaced with a dual plane and that sucker would pull stumps out of the ground and still rev high enough......Even know i stand up and love my 4v motor..Sounds like a 2v build is what you are looking for...Unless you just wanting to go back stock.

 

[CZ-75]

I agree with the others... Stay with your 2V heads. Put on a dual plane manifold like the Edelbrock Performer. Then put in a CompCam cam with hydrolic rollers and new 1 piece valves. You can stay at the stock compression ratios and get close to 400lbs of torque on a nice flat curve.. HP should peak out just shy of 400 HP at the flywheel, which would be at least 300 at the wheels.

 

[Wolverine]

To make it easy, build the motor to the specs of a 1971 351C CJ or a 1971 351 Boss. Takes all of the guessing out of what manifold, cam, pistons, blah blah blah.

You'll get your 300HP, you'll get a good idle, and you'll get plenty of torque through the RPM cycle. Especially with that 3.25 rear end....there is nothing like having the right rear end to go with the right front end.