mbp9997

First off excellent site, you people are great! Im very appreciative of all the information.

Right now, Im working on my brother's 73 GMC Jimmy with the GMPP 290 horse longblock crate motor in it (8.5:1 w/ 76ccheads). The truck has 37" tires and 456 gears with lockers front and rear. built TH350 w/ no stall.

The motor as I said is a 350 LB with about 10K on it. It has the truck's original intake, cam, quadrajet, but with the big coil HEI and was in it when we bought it.

Here's my question: We are starting on a budget build ($1500 max) and are shooting for 350-400 horses/torque at the crank and right now we are probably at 260hp 300ft/lbs at the crank. No we wont ever dyno it, so just seat of the pants.

Here is the plan and please tell me what you think:

67cc RHS Pro Torker Vortec heads: are they worth the money?
Comp Cam Xtreme energy XE256H cam and lifters #12-234-2: Specs: I .447 @256 E.454@268 Separation:110
Edelbrock dual plane with the Quadrajet rejetted on top?
New compression~9.5:1

What do you all think about it? Any better ideas for a small lumpy idle and pretty good torque through mid?

Thanks in advance!

mbp9997

Sorry I meant to right 64cc for the RHS heads.

1997bird

iTrader: (2)

The RHS heads are a very nice casting. These heads used to be the Pro Topline's until Comp Cams bought them out.

jmm98LS1

iTrader: (28)

The cam you selected won't give you the horsepower (or the lumpy idle) you're looking for, but will provide lots of low-mid range torque. Personally, I'd look at the next 2 bigger cams in the XE line, the XE262H and XE268H. The 268 is as big as you should go on the stock stall converter. It'll give you a strong midrange and get you in the mid-upper 300's for hp, and will have a very slight chop at idle. The 262 is a little tamer but will still have a noticeable idle. Either of those cams paired up with those vortec heads would give great hp/tq for what you're looking for IMO. You should call Comp and ask for their recommendation though, they'll give you better advice than any of us will, lol.

cwaldt

iTrader: (4)

Also take into consideration what you want to be able to do. Do you want it to look and sound good or do you want it to perform on the street and in the mud?

1997bird

iTrader: (2)

I would still stay on the smaller side of things as far as the cam goes. Those 37" tires are going to need all of the torque they can get to turn them over. The heavier the tire the more TQ is required by the motor to get them rolling properly. Big tires plus mud without low end TQ means alot of digging to get out.

mbp9997

Thanks for the quick responses.

Yeah I know Im not going to get a musclecar lope out of it, w/o sacrificing bottom end;esp. w/o a stall. But I was thinking my small cam would have plenty of low end grunt with a little bit of lump. So will I still be short on my HP goal?

What I didnt say before was that even with 37" boggers (about 105lbs per wheel/tire) the ole SBC LB that's in it w/ 456 gears will still do everything its asked. We just wanted to get a little more power to give better response and a better ability to sling mud the size of bowling ***** up to ranges of 1 mile...haha.

But, seriously just looking for more low-mid range and better response and a couple horses to go with it. I was just wondering if anyone had used this setup and what to expect. And whether anyone had anybetter ideas for low-mid.

JMM98LS1..do you think that the 262 or the 268 will NOT sacrifice bottom end? I did call Comp and they recommended the 256.

Formula350sd

Yeah if you want to sling serious mud a little more horsepower on top at higher rpm is going to be key with 4.56 gears I wouldn't worry about 37s being too much to spin my stock bronco moves out pretty good (all things considered) on 35s and thats with 3.55 gears

jmm98LS1

iTrader: (28)

If comp recommended the 256 then that's what I'd run...the 262 & 268 will not have the bottom end that the 256 will, that's for sure. My thought was with the addition of the vortec heads, the port velocity you'd pick up would restore most of the low end tq lost by running the 262 or 268...but what the hell do I know, lol. My guess would be somewhere around 330-350hp and a silky smooth idle with the xe256h.

mbp9997

35's are no problem (on 3.73) and the 37" MTRs (stock and 456)were no problem...but 37" boggers are freakin heavy... 105lb wheel and tire combo.

I am inclined to agree with you, but thats what Comp said. Im not sure what Im going to do in the end. We need just a hint of lope (not the 256?). Comp told me the 256 would be noticeable...but hey thats why I asked all of you for advice and input.