Originally Posted by CHEVILLAC
I've searched this forum quite a bit and I think I have a basic understanding of carbs. My confusion comes from several sources of conflicting information so I'll give all the information I can about my truck and hopefully you guys can help me figure out what changes I need to make.
I have a '61 chevy short wide that is my daily driver right now but fairly soon will be driven on the street mostly and will see a few runs down the strip several times a year during the summer months. I live in Oregon so that should give me about 4 months a year to play around, so I want it to be streetable and good fun down the strip too.
It has a 12 bolt truck open rear end with 3.08 gears, a TH350 with stage 2 shift kit and 2300 stall. I just bought my boss' old race motor and this is where it gets fun. It's a 350 bored .030 over, flat top 4 relief pistons, forged crank, h-beam rods, 2.02/1.60 valves, 1.6:1 high tensil stamped rockers, Weiand Team G single plane air gap manifold, hei dizzy with MSD module, high output coil, no vacuum advance and the lightest springs available on the centrifigul adv. so it gets full adv. right off idle, I think he said total timing was 30deg. at 3500rpm? 10.5:1 CR and the cam is a summit k1108 (specs below)
Duration at 050 inch Lift: 244 int./254 exh
Valve Lift with Factory Rocker Arm Ratio: 0.508 int./0.533 exh.
Lobe Separation (degrees): 114
Camshaft Manufacturers Description: Rough idle, excellent high-end horsepower. Needs 10.5:1 and higher compression, 3,500+ stall, and gearing. 350+ c.i.d., bracket race cam.
He says this motor ran 450HP at 6200RPM on the Dyno with some kind of carb style fuel injection system which did not come with the motor so I need to figure out what carb will work on this motor for my application (described above) without changing anything except mayme my stall and rear end. Which brings me to another question (perhaps for another thread)?
I have a corporate 8.5" 10 bolt out of a 79 camaro with 2.41 posi that I was thinking of putting under the truck but I don't think it would hold up with that gear ratio and nobody makes a 3.08 or 3.73 gear set for the series 2 carrier so I don't know if I should change get a series 3 carrier and gear set for that rear end or for the truck 12 bolt, and will the 3.08 12 bolt open rear get me by until I save up the money for the propper rear end solution?
Thanks in advance for all help. You guys are a great wealth of knowlege and I'm somewhat new to the technical aspects of hot rodding though I do have a basic grasp on what will generally make things go faster or slower.
First, what heads? You may not have enough compression ratio for that cam- or it may be too high for pump gas. You'd really like to know the exact chamber volume to take milling the heads (if it was done) into consideration.
All CR figured w/a zero deck/0.041" head gasket:
76cc heads, unmilled decks = about 9.1:1 compression ratio. Milled down to 70cc, will be about 9.7:1.
64cc heads will get you enough, just under 10.4:1, and all the CR you can use w/iron heads, if not too much.
IMO that's just too much cam unless you bring the rest of the engine in line w/it (correct CR, sufficient valve spring pressure, a higher stall converter and lower rear gears).
A 3310 could work OK, or a double pumper (650 to 750) once the stall/gears are dealt with.
The distributor needs to be set up w/a lot of initial timing and a limited amount of mechanical advance. You can use a vacuum advance limited to 10 degrees, hooked to a ported vacuum source.
The 8.5 corporate rear end is strong, but the bearings ride on the axles and are often worn and need replaced. If that's the case, upgrade the rearend to a 30 spline limited slip differential (Eaton is often recommended) and axles to match. It would be better if you posted this on the Trans/Rearend forum...
Edit- my usual calculator is misbehaving, had to edit the results.