i have a 350 out of a 92 van the things i have done to it are, long tube headman headers with true dauls ultra flow mufflers/edelbrock 1405-600 carb/edelbrock performer intake 2104/this is my cam specs (Advertised duration: 278 intake/290 exhaust
* Duration at .050 in. cam lift: 222 intake/234 exhaust
* Gross valve lift: .467 in. intake/.494 in. exhaust
* Lobe separation: 114 degrees
* Basic rpm range: 2,500 to 5,500
* Good idle, daily performance usage, and mild bracket racing
* Cruise rpm: 3,000 to 3,400
* Recommended compression ratio: 9.5:1 to 10.75:1)/stock 700r4
i was told i needed a stall at 2600-3000. if you guys could help me in any way to ad more horsepower or correct me if i'm doing something wrong it is greatly appreciated. i want to run 12's without nitrous or low 13's right now i'm at mid 13's

 

You need at least 3000 RPM stall, 3500 would be better.

Dump that carb. Holley or Demon 750 DP required here. You need a Performer RPM or Weiand Stealth for top end power. I believe the cam RPM range should actually be 2500-6500 (given the other specs quoted).

Cool air intake makes an amazing difference. I picked up 60' and 1/4 ET vs. open element this year with the '57.

You don't say what gears you have. 3.42 minimum, 3.73 better.

Traction. Going to need it. Sticky tires, boxed or tubular LCAs (LCA relocation brackets a very good idea), poly bushings. Hope you've already done subframe connectors.

 

actually i have 3:42 non posi but have a posi unit with 3:08 i need the big silver pin for it though. haven't really done any suspension stuff except take that big bar that goes from one side to the other that ways about 40-60lbs off i have only had this motor and stuff done in the last month. see this is an everyday use car and kinda on a budget how bout carb spacers do they do anything

 

Put the sway bar back on. its not slowing you down.

What cylinder heads are on it now?

Stock heads do not flow enough air to make a lot of horsepower.
They will severly limit the performance reguardless of other mods.

You can check the casting number by removing a valve cover.
Look between the valve springs. The last three digits are the relivent ones.
Some stock heads have good potenial once modded for extra flow, some are a waste of time.
You can improve the stock heads by porting them and installing larger valves or buy aftermarket hiperformance heads.

The compression ratio of the motor may/ probabily is too low.

This will depend on the pistons you have (flat top, dished etc)
and the cylinder heads, combustion chamber size.

Needs to be right around 10:1 compression for max street performance on available hi octane pump gas.

get a 750cfm carb (any 750cfm carb Holley Edelbrock, demon carter) All will work well when properly dialed in. And a hi rise dual plane intake like a edelbrock performer RPM. It will fit under a stock hood with room to spare with the right GM drop base air cleaner.

The cam is fine, a good choice for a street performance car.

Some stock th700r4 transmissions have quite a low stall converter. Like below 1700rpm.

For maximum performance you'd want a 3000/3500stall converter with the lock up functional. these cost more but thats the joys of racing with a th700r4.
You want a aftermarket converter that is based on a GM 9.5 or 10" lockup converter. Not a modified restalled 12"

A corvette/ iroc/V6 S-10 GM converter has a higher stall ( 2200 on a 350ci motor. It will help and are cheap.
But plan on sinking some money into a decent high stall lock up converter if you really want to go fast. Remember 9.5 or 10"

.Yank Converters

Read an know all the tech information on selecting a high perf lockup converter here. There will be a test........

You'll want to get a 3.73 or 4.10 rear gear (depending on your rear tires diameter) . Remember you'll still cruise at a very reasonable rpm on the highway in OD.
That motor likes to cruise at 2200 to 2500 on the hi-way.
Don't wimp out on the rear gear ratio.
It won't help mileage.
With that you'll need some sticky hi perf street/ strip tires to put the power to the ground. get some BFG drag radials or some M/T et streets. None of the usually traction mods will work worth a hoot with out decent tires. Buy the tires first

Heads, converter, tires , rear gear will get you there.

You'll need a neck brace too.

 

What heads are on it?

If they're the stock van heads, throw them away; or forget about getting any more HP (flow) out of it. All the cams and carbs and intakes in the world can't force more air molecules past those stupid swirl ramps in the intake ports.

 

thanx alot guys i'll take all the advice i can get

 

Duh. I completely missed the heads. For some reason, I assumed something better than truck heads. Must have had it confused with another post.

 

i have a set of 305 tpi heads and a set of heads for a 305 but they have a combustion chamber 1/2 inch smaller than the tpi heads don't know if that is good or not but a few people told me a smaller combustion chamber is better

 

Check the casting # cast near the valve springs under the valve cover.

If you have 081 or 416 heads ( last three numbers) that you have a good 305 head.

It has good performance potential but will need work.
Will need a full porting job and new larger 350 motor sized valves
and a valve job. You would want to either "pin the studs" or have them machined for screwin studs.
Yes the combustion chambers are small. (58cc's) makes it easier to get a high compression ratio with flat top pistons.
Compression helps especialy with a larger than stock cam.

If you're not willing to put in the work to modify them then buy some aftermarket performance heads.

I recommend Protopline Iron lightning 200cc heads with 64cc chambers.

if you would like information on porting and modifying 305 heads for more horsepower, search my past posts. Search Sitting Bull's and rhuarc30 and rhuarc31.
Lots of relevent info and pics here.

But check and verify the head castings you have first before you start.

 

You can actually make a carb spacer that is better than any store bought one right at home.
Get a piece of birch wood that is the thickness you desire.

use a carb base gasket to trace out the shape.
Cut , drill, saw and file it to a finished contour You can make many types open , divided, four hole , tall, short etc

Experimentation will tell you which shape your car likes the best.

Birch wood is one of the best materials to make a carb spacer out of because it is a good isolator of heat. A cooler carb will perform better.

you'll need some longer carb mounting studs now.

That should keep ya busy for a while.

 

thank you guys for all your help i'm learning alot