The Stovebolt Site Forums The Shop Area The HiPo Shop 379-V6 HEI ? Holly 500 ? what can i do ?

Driveline:

379ci V-6 gas engine, SM-420 4spd tran's,T-case not sure it's gear driven has
4hi 2hi N 4lo 2lo like the old old dodge's, 5.13 gear ratio 8-19.5 tire's. 60" cab to axle 7FT flat bed. . . engine is alittle doggy but sound oil pressure is 63psi@3,000rpm 57psi@750rpm Hot even!. . .

I was thinking to get some more pep out of my GMC kicking her up to the 500CFM 2bbl holley carb then updateing the ignition.....

I would like to run an HEI but if i can't are these point deletion kit's any good ?

I did do a compression test about 10 or 12k mile's ago the low cyl had 126psi the high had 132psi. . . so if 125 is good than i got a healthy one it's an AMSOIL baby it get's amsoil fully synthetic straight 60.

Mikey's tune up every spring:

bosch platnium plug's, 11mm wires, brass cap/rotor,copper points,fuel filter, and the valves get reset and snugged up. . .

it don't like 87 octane gas run's like hell so i run 93oct.

well I need the extra power ! so than how do you get more POWER! . . . . holley/HEI

fresh tune up and carb kit on the old tiny 2bbl still doggy as hell. . . :mad:

am i exspecting to much from a 40+ year old truck ? I would think a 6.2L V-6 gas engine would have more gut's than this. . . :whistle:


Mike

If you should decide to go with either of the aforementioned modifications; would suggest running a performance "baseline" first and then a comparison after you make to modifications. This will tell you how much you gained (or lost) with the modifications.

Jon.

replace it w/a small block V8, a 400 if ya want to rock-better mileage/power/parts availability/few lbs weight savings

i am using the crane cams points elem. kit on my 460 f*#@ it is great has a built in rev limiter 2 wires to hook up. i like it i would sugest a msd 6a ignition box and a pertronix flame thrower coil. that is the combo i have and i think i got h.p gains

as Much as i love the 400 and hate the 350, I'm happy about not hearing 350 i thank you greatly. . . on this truck i would keep the Big
V-6 If i can get more power great if not i'll deal with it as is. . .

You seem to have your Duck's in a row guy I trust your opinion here. . .
Here's is what i'm sorta picking up as your thought's.

1. the HEI is more of workability thing not really going to effect power. . .

2. the holley 500 may over power the V-6 and dog it out. . .
i did your carb kit sugestion she got peppy on the lower end but still mushed out once the R's got up over 2 grand. . .


I got question for you can the exhaust effect power a good deal on these big V-6's ?

I got the stock manifold's ( one leak's ) blowing threw 2-1/4" single exhaust. . . Could i be losing my power on the out flow and not the in flow ? as if that's the case a bigger carb will dog it out worse ?


:confused: :confused:

The 379 was a "torque-monster" producing max torque at 1600 RPM. Max HP produced at 3600 RPM (lowest RPM of any of the V-6 G.M.C. engines). Since cam profile, head design, intake design, etc. are based on low RPM and torque, installing a larger carb may hurt your performance at low RPM due to decreased air velocity, and not help the high end since the RPM is not going to be increased without changing other components.

That said, the engine should pull strong to 3500`3600 RPM.

Since you did the carb, things to check might include fuel filter, fuel pump, and fuel sock (in the tank), distributor advance, etc. Also, while difficult to set up, a leak-down test on the fuel line might prove interesting.

[Opinion- others may differ!] As to the electronic ignition, I don't like the *&^%$# things! Seems like every individual calling us with a strange carburetor problem has a "points elimination" conversion. It is the FIRST question I ask when someone starts telling me about their "carburetor" problem. The two most common carburetor problems we see these days are the PE conversion and the use of deathanol.

Remember that cell phones were not necessary until we had electronic ignitions. Now they are needed to call the tow truck! ☺

I will grant that, as long as they work, the electronic ignition will fire plugs in an oil burning engine, and will extend the life of spark plugs. I see no other benefits.

Jon.

so this could be more of a fuel flow problem rather than an air flow issue ? . . .

2 fuel filter's are new. . . the clear inline one i put up by the carb and the one under the cab where tha fuel line come's out of the tank. . .so there's on inside the tank ? is there one in the carb as well ? fuel pump is older looking i haven't changed it in almost 9 year's i've had the truck. . .

so bigger exhaust pipes won't help any thing ?

" torque montser " hmmm 379-V6 = 190hp@3600rpm 280TQ@1600rpm. . . .the 305-V6 = 165hp@3800rpm and 260TQ@1600rpm. .. .

I would like to have seen the 379-V6 be more like this:

175hp@3600rpm 380TQ@1750rpm. . .

Mike

Hi, I'll second rdavid.
the 6066 GMC forum covers all of this from HEI to Holley and more. I had a big bolt a couple years ago with the 478 (I think) V-6 and was looking into those things, but wound up selling the truck.

I suggest you try the 87 octane gas- your engine doesn't have enough compression to take advantage of the high octane stuff, and 87 has exactly the same additives as the 92 octane stuff in the same brand nowadays. You may find that you get more power with the lower octane gas.

If you want more power get the cam reground and/or mill the heads for more compression.