Hi all, GREAT info here--I have learned a lot from looking at some old threads.

I built a 305 last summer with the following specs:

.030 hypereutectic slugs
Comp XE262 cam
New Summit HO HEI dist.
500 CFM Edelbrock carb (performance model)
Unported 416 heads
Edelbrock SP2P intake

I have yet to fire this motor (I know, I know). While it is still out of the car, are there any real problems here? Is the 500 cfm carb enough? I have a number of Q-Jets lying around, as well as a Holley 650 double pumper. What about the intake? I think it was originally intended to improve mileage. It has very small runners that I thought would make for great throttle response with the 500 cfm carb. I do have an older style Edelbrock Performer intake that I could use. Any power estimates on this combo? I will be running 1-5/8" headers and plan to find some high flow mufflers (right now the car exhausts through side pipes).

Also--I don't know the rear end gearing of my car, but I'm sure it's stock. It's an '83 Sport Coupe, so probably 2.73 or 3.08 gears, right? Will these work well with my combo or do I need to look at 3.42-4.10 ratio?

Thanks for your opinions.

 

You have the engine .030 over, a very good cam, and probably 10.0 comp ratio and yet the intake manifold is ancient technology. Ditch the SP2P and go with a weiand 8000 or one of the newer edelbrock intakes. The SP2P is not going to breath enough for you. And also I don't think 500 cfm is big enough. You will have great throttle response but will probably run out of top end (just a guess) at about 4500 RPM. And did you have 1.94 intake valves installed in the heads or are they stock 1.84? that cam should breath up to about 5600 RPM so this combo will require good intake and exhaust.

 

if it were my engine id have one of them qjets on there, a 500cfm may be just enough, but id emagine a better flowing carb would help over 4500-5000 rpms. qjets can really open up if you file down the secondary air-valve restricter.

sounds like a decent build-up though, get that thing in a car!!

heres something to help you decide a rear gear;

http://www.f-body.org/gears/

plug in TH350 gear ratios:

1st- 2.52
2nd- 1.52
3rd- 1.00

using that calc you can find the estimated potential for speed.

 

I'm with 65panhed on most of this. The only thing I disagree on is where the cam will probably max out. I think it'll probably run up to 5000 or just a little over that, but it's gonna have a seriously flat torque curve. As you can see from my minor disagreement, 65panhed nailed this one straight up. Edelbrock only has a slight advantage manifold wise, but in all honesty it isn't much. Either intake will make you happy. If you have a stock Q-jet, use that instead of the 500 cfm unit you've got in there. It'll be worth a couple extra H.P. and lb. ft. throughout the entire powerband. If you're using an auto-trans, I'd stick with a stall speed in the 2500-3000 area. Just my Hats off to 65panhed.

 

Thanks for the replies. The heads were a great deal and had just been completely rebuilt when I bought them, but they still have the smaller 1.84" intakes. I need to check the cranking compression on the 350 that is in the car now--I'm beginning to think that I'd be better off with the 350 if it's healthy. I could swap the XE262 into the 350, along with my Performer intake. That ought to be good for around 300 horses, shouldn't it? The 350's greater torque output would better offset the crummy rear gears that are in the car now as well.

 

Comp says the XE262 hydraulic flat tappet has a powerband of 1300-5600. Typically, that assumes a 350. In a 305, the effective powerband will be shifted up, perhaps as much as a couple of hundred RPMs.

That cam in a good breathing 305 should top 300 GFWHP. 1.84" intakes are going to limit that somewhat. Whether the 350 would top 300 depends entirely on the heads it has - if they're 882's, you'd be very lucky to get that much.

That being said, 5600 RPMs in a .030"-over 305 makes a 500 CFM carb borderline small, too small if 5800 RPMs. The typical experience is that a bigger carb will actually do better than the formulas would indicate. On a 350, the 500 is an economy carb.

I'd say go with a q-jet, or some other larger carb. I'm no fan of Performers, but there's no need to go into that here.

 

The Edelbrock SP2P was designed as a low rpm high torque manifold.. Best suited to a very small cam with more than stock lift. Something like 190-195 intake 210 exhaust @.050" and as much lift as available (.420"+) 1.6:1 rockers help.

The XE 262 is much bigger and works better at a higher rpm band. A performer manifold is a better match. 308's are too low a gear for that cam. 3.73 or 4.10's are just right.

The 350 with the 305's heads ( ported with larger valves) and the XE cam and performer intake would be a lil screamer with 4.10's

 

Thanks for all of the great advice. Now I just have to research how to swap to a 4.10 gear set...

 

Some S-10 pickups came with them.

 

I had heard that some S-10s have 4.10 gears. Forgive this posting in the wrong forum, but do you have any more info on the necessary parts to make the rear gear swap? My vocabulary is a little lacking when it comes to rear ends, but are all outer housings the same, and just the carriers, axles and gears different? If I found an S-10 with 4.10s, could I use the gears and carrier in my housing with my axles (assuming that the S-10 has the same number of splines on its axles)? What about the spider gears?

Thanks again for all of the help.

 

Do a google search using drivetrain, gear, auburn, power trax etc as key words.

308's use the same carrier. 2.73's require a spacer or a carrier swap ( 2 series to 3 series) all the swap and compatability info are there. Most s-10's are 26 spline most
older third gen rears are also 26spline.
it takes a trained drivetrain pro with the knowledge, experience and tools to set up rear end gears. critical.

I do them at home in the driveway cause I know how and have to tools. You're going to need help with this one.

 

Thanks for all of your advice F-Bird. I'm initially going to see if I can find somebody selling an entire rear assembly with 3.73-4.56 gears for a fair price, and if that fails I'll have someone set it up for me. My experience with having gears set up in this area is that it is VERY expensive; I'd like to avoid that if possible.