Bad Combo?

[Joe383]

Ya the castings. Some times you can tell from the pattern on the front of the heads. Good chance you have swirl port heads. If you could get a cheep set like $200 for a complete set than I would say get some iron L98 heads. There a 64cc chamber, have 1.94 intake valves, bolt to your existing intake and use your self align rocker arms. There like a 160cc intake runner. Good head up to around 350 HP. Good head on a mild truck motor if you have a small cam. If it was me I would get a good 700R4 back in there first. It will give you more low end and an overdrive. It is a good transmission if you treat it rite. Don't tow or climb passes in overdrive and your good.

 

[rich weyand]

You don't need the O2 sensors if you are not running TBI.

Yes, go long-tube headers. Hooker 2452.

2.25" is plenty, unless you go serious horsepower.

Don't use an Edelbrock cam. Go with something like the Comp Cams 12-235-2.

The Edelbrock carb is OK, but, if you are buying a new carb, the Qjet is better.

 

[RangRayy]

I'm looking for a good 700r4. Funny that's how my Gpa burnt it up towing a 5th wheel camper from Missouri to Florida. A lot of hills to go through. A local shop said he could put the innards of a 700r4 into my existing th350 case. Thought that was a bit strange.

 

[RangRayy]

You don't need the O2 sensors if you are not running TBI.

Yes, go long-tube headers. Hooker 2452.

2.25" is plenty, unless you go serious horsepower.

Don't use an Edelbrock cam. Go with something like the Comp Cams 12-235-2.

The Edelbrock carb is OK, but, if you are buying a new carb, the Qjet is better.

What about intake? Weiand a good one to go with? Since I plan on one day adding a supercharger.

 

[Joe383]

No very few parts interchange between them. My neighbor rebuilds them for performance and dose conversions. He works on and builds hot rods for a living. There are like 3 or 4 cars on my block that he has done a 700R4 swap in too. Ya the 12-235-2 cam would be a better cam but I thought every thing being in a matching kit would be easer for him. If you are to mix and match stuff the other cam would be a killer cam for a little performance. Has a little more duration and better LSA and ICL. Might not do as well in the bottom end but definitely would have more mid and top end. Would have a slight lope to it too which would sound cool. I think a Q jet would require a little tuning for both cams. I think the Edelbrock would be easer for him to tune and would be pretty close out of the box sense it is meant to work with the cam. Thought I would try to make things as simple as possible. A good running Q jet would be the best choice though if you can find one. I would take a good Q jet over any other carb any day.

 

[Joe383]

Any aftermarket intake will be better than the one you have. The weiand intake will not work with there supercharger. There supercharger replaces the intake manifold. Weiand make good intakes too though.

 

[RangRayy]

If I go carb then I would want my cam to be off idle to 4500rpm. But like I stated with a th350 trans behind it and my gears it would suffer on the low end. At least that's what Brian at TBI Chips told me... So I am going to fork over a lot of cash to get a trans and rear end swapped in.

 

[MadOgre]

If I go carb then I would want my cam to be off idle to 4500rpm. But like I stated with a th350 trans behind it and my gears it would suffer on the low end. At least that's what Brian at TBI Chips told me... So I am going to fork over a lot of cash to get a trans and rear end swapped in.

First off unless you can buy a Q-jet that has had the fuel well plugs PERMANENTLY sealed, you will just be wasting your time! Next best option would be a street demon 625 cfm carb.

Headers will kill low end torque unless you make loads of power. Or run shorty headers. Tri Y headers would be best but are about $800. If you do run long tube headers use a 1 5/8" primary

Single Y exhaust can increase low end torque in applications below 200hp

Edelbrock intakes rock the Weinds every day of the week. Its just a fact that the Edddy intakes are the best intakes for $ and have way less accessory fitment issues then other intakes.

The Best power will be from a carb and Comp Cam or another after market EFI system. The stock TBI is very limited for power.

The factory TBI swirl port heads will make better low to mid range torque and will offer the best fuel economy. Im not sure what casting #s swirl. Can you take a valve out? to look? You might be able to see from the intake side of the runner, it should have a large shelf by the valve guide, inside the runner.

 

[MadOgre]

Oh and you don't need to spend $2000 on a re gear. Just spend $200 on a complete new used axle, with the appropriate gearing like 3:42 or 3:73

 

[MadOgre]

If it were me I would junk that whole TBI system. I guess you could sell it on ebay for $3-500. Then I would put a carb intake and a carb. Stock HEI dizzy(non TBI) and a Comp Cam. You could go with a roller cam(1500-5500) or a flat tappet hydraulic lifter(Idle-5000) run some shorty or long tube headers(You can run long tubes now that you have the power) And port the heads. Not much though. just clean up the slag and sharp edges.

 

[MadOgre]

I wouldn't bother with a tranny swap unless yours blows up! If you did go with a 700r4 for some reason you would need to find an 88' and up 4L60 otherwise they are junk!

 

[MikeB]

with headers? I read that they're not meant for engines with less than 300hp. Also that a single exhaust with 3 in pipe is better than duals

If you do the math, 2.25 x 2 is 12.5% more area than 3.00 x 1. However, a single 3" pipe is probably more than adequate for your average street 350. Heck, that's what the previous generation Camaro SS used. Also my F150's 360hp 5.0 engine.

 

[rich weyand]

If you want off-idle to 4500, you can go with the Comp 12-300-4 cam and get 422 lbft at 2500 rpm and have 300+ from 1000 on up. That's what I did, and I love it. No winding up over 4500, though. Changing the tranny governor by going one size heavier on one weight moves the shift points down 500 rpm to make best use of it.

With that much whoopee in the bottom, I wouldn't mess with the rear end. Just keep the short tires on it. I have 31" tires and G80 limited slip on a 3.78:1, and punching it off the stop -- no brake-torquing or anything, just punching it -- will break the rears loose. If you keep 29s on it, or even go smaller, which will lower it a bit too, you will have plenty out of the hole. 27" tires are still pretty good size compared to auto tires. 27s with the 3.08:1 would be like the 29s with 3.3:1. Cheap gear change.

Weiand (no relation) makes good intakes, but I haven't used one since the 1970s, so my experience with them is dated. The Edelbrock dual-plane manifolds are good, though.

Supercharging I know nothing about. Bear in mind though, that the highest-torque engine GM put the TH350 on had 410 lbft of torque. If you are planning on going higher than the 422 lbft you can get with the 12-300-4 cam, you need to be rethinking the whole drivetrain, and getting beefed up components, including the suspension.

700R4s can be persnickety. They have to be set up right. So be careful doing that. The early ones are junk compared to the TH350. And the 700R4 doesn't like to be lugged, so you are probably going to have to change gears if you go that route.

The Qjet is the better carb, but it is harder to tune. The way to go about it is not to buy one off the shelf, but get one made up for the setup you are building. Talk to Sean Murphy at SMI, and he will tune you one up to match your build for about what an off-the-shelf one would cost you.

 

[RangRayy]

I wouldn't bother with a tranny swap unless yours blows up! If you did go with a 700r4 for some reason you would need to find an 88' and up 4L60 otherwise they are junk!

You answered my question I was about to post. If the th350 would be okay with the intake and carb cam. Now which rear end 3.42 or 3.73 with the above combo?

Also with the HEI what would be best? I heard it needs vacuum assist

 

[MadOgre]

If I go carb then I would want my cam to be off idle to 4500rpm. But like I stated with a th350 trans behind it and my gears it would suffer on the low end. At least that's what Brian at TBI Chips told me... So I am going to fork over a lot of cash to get a trans and rear end swapped in.

With a carb and flat tappet cam(Idle-4500) you will make gobs of power off of idle. GOBS and GOBS! So you could wait on the gears but like I say just buy a used rear end with better gears for $200 or less, if you want to re gear.

IMO the RV cam solid/flat tappet cam is the way to go. The first gen blocks ran those cams with good life expectancy. The roller would be nicer for peace of mind but they all start at 1500-5500 RPM.

But unless you are the guy that has to be first to the next light maybe 1500 RPM is where you start to step on it. MY self I hate tromping on it from a stand still! I always like to be moving before hammering on it. So I could live with the 1500-5500 cam and like it just fine.

Just depends how you drive. 1500 RPM in 3rd is usually about 30 -35 mph or about 10 mph in first.