engine guys, need more torque on 383 stroker

[bigjimzlll]

Ogier,
I wasn't trying to be a smart azz....I know all of the CFM formulas too. I always fall back on what GM did, and ofcourse personal experience. For a daily driver with a max rpm of 4500rpm, im sure the 600 would work OK, im also sure a properely tuned Qjet would be better. The Qjet is a little more than 600cfm. GM used 750s and 780 holleys with good sucess<sp>.

On the 455 im sure there was no hesitation or bogginess with a 600cfm carb, but there was a few HP left on the table.(IMO) Maybe im just out of touch(with pure street) tunning.

[browndawg71]

the 1000cfm 4150 hp series aint useless on my street driven 468

[RON WOODGEARD]

Geeeze Guys, This guy needs help and ya'll all want to argue.. AND WHOEVER SAID A 4x4 CAN'T BE FAST

There is NO WAY to tell what a cam is in a motor, You need to get ahold of the previous owner and or builder and find out what you have. Or take it out and put a Mic on it. and that's a lot of work. Some cam companies do put markings on their cams though and that makes it much easier...
From what your typing, it sounds like the cam is too Radical, ( IE: Lopey sound ) SO it's going to depend what you want ??? Are you towing ? If so you'll want to change the Cam, Are you doing some 4 wheel off roading ? I would change the cam also then,,,, But if none of these things are the case and you just like the looks of a 4X4, Then you can go to a 2400 to 2800 Stall convertor, and tune that carb. Yes there are formulas for generalization of carb size, But in those formulas, it doesn't cover Heads, or Valve sizes, or compression ratios, headers or not, or exhaust pipe size.. you will want the smallest carb that will give you good throttle response. but yet allow the motor to receive enough fuel throughout the rpm range. And that requires some fiddling and or a Fuel-air ratio gauge. The fuel ratio gauge will take all of the guess out of it. A 600 to 650 CFM on a small block "USUALLY" does the job for torque.

To build Torque, You want Higher Static compression. 1:94 valves, They breath very well up to 5000 RPM, small tubed headers, and good flowing exhaust. (There's always an exception, and I'm sure someone has built a torque small block that will out pull a Deisel and did it way different then this.)

The cam I have in my Torque Motor is split duration, 272/282 and Lift of 442/465 I'm also using an Off Road/Towing Convertor. a 600 CFM Edelbrock, small tubed headers, 2-1/2" exhaust with Glasspacks exiting at the rear, A blueprinted distributor, 12 degrees initial advance with 32 full advance coming in at 1000 RPM. pertronix ignition with a Jacobs Omni pak. 410 rear gears, with 32-12/50 tires. I pulled a four horse trailer up hills very well, and could go to the Desert and Rock crawl..10 to 12 MPG unloaded depending on my foot, and it dropped to 8/9 loaded.

[Budweis]

Originally Posted by RON WOODGEARD

The cam I have in my Torque Motor is split duration, 272/282 and Lift of 442/465

thats the exact specs on my cam i just put in and havent got to start it yet, hopefully ill be happy with it. if i remember right its range is 1500-4500 rpm. for gears im running 4:56 /manual tranny.

[RON WOODGEARD]

Originally Posted by Budweis

thats the exact specs on my cam i just put in and havent got to start it yet, hopefully ill be happy with it. if i remember right its range is 1500-4500 rpm. for gears im running 4:56 /manual tranny.

For what the Cam is intended to do, And what I was doing with it,,,,,,It's great.. The Motor would really surprise me when It would have to really grunt.. But It runs out just above 5000 RPM. But then, that's what it's supposed to do....

[ThunderTruck]

I have a similar problem with my '72 2WD C-10.

I built a 383 years ago (I was 15 and thought I was tough but really just dumb...), and it has always just been way too revvy and high-strung for a street truck.

Here are the basics of the build:
800cfm Edelbrock Thunder series Carb
Weiand Team G Single Plane Intake manifold
World Industries heads with 220cc intake runners, 64 cc combustion chamber - I think it is running 10.5 to 11:1 compression...
Crane Cams Flat tappet hydraulic cam - Advertised Duration 294/300, Lift .502/.516
1.6:1 Roller Rockers
MSD Ignition
Headers with 3" true dual exhaust and LOUD mangaflow? mufflers

I'm running the stock SM465 Muncie with 3.73 posi rear end, and it is just really boggy and hesitant below 3,000 RPM. I have it rev limited at 6,000 but seems like it would rev to 8k if I let it.

Here are my initial thoughts....
1. Run some break-in rockers with a 1.35:1 ratio? Maybe more expensive and difficult than just swapping the cam and keeping the 1.6 rockers, but just throwing it out there.
2. Install a dual plane manifold? Edel brock makes some affordable options. Maybe keep the single plane and run a restrictor plate?
3. More restrictive/quieter mufflers

I'm trying to avoid swapping the heads and cam. I live at 5,500' altitude so maybe I can get away with the high compression on pump gas. I've re-jetted the carb per Edelbrocks recommendations and it helped a little bit. I can't run the initial timing any less than ~18 degrees without backfiring/flames coming out carb and/or starting issues.

I'm interested to hear any and all thoughts on the easiest and most economic ways to calm this beast down!

[Coley]

Originally Posted by ThunderTruck

I have a similar problem with my '72 2WD C-10.

I built a 383 years ago (I was 15 and thought I was tough but really just dumb...), and it has always just been way too revvy and high-strung for a street truck.

Here are the basics of the build:
800cfm Edelbrock Thunder series Carb
Weiand Team G Single Plane Intake manifold
World Industries heads with 220cc intake runners, 64 cc combustion chamber - I think it is running 10.5 to 11:1 compression...
Crane Cams Flat tappet hydraulic cam - Advertised Duration 294/300, Lift .502/.516
1.6:1 Roller Rockers
MSD Ignition
Headers with 3" true dual exhaust and LOUD mangaflow? mufflers

I'm running the stock SM465 Muncie with 3.73 posi rear end, and it is just really boggy and hesitant below 3,000 RPM. I have it rev limited at 6,000 but seems like it would rev to 8k if I let it.

Here are my initial thoughts....
1. Run some break-in rockers with a 1.35:1 ratio? Maybe more expensive and difficult than just swapping the cam and keeping the 1.6 rockers, but just throwing it out there.
2. Install a dual plane manifold? Edel brock makes some affordable options. Maybe keep the single plane and run a restrictor plate?
3. More restrictive/quieter mufflers

I'm trying to avoid swapping the heads and cam. I live at 5,500' altitude so maybe I can get away with the high compression on pump gas. I've re-jetted the carb per Edelbrocks recommendations and it helped a little bit. I can't run the initial timing any less than ~18 degrees without backfiring/flames coming out carb and/or starting issues.

I'm interested to hear any and all thoughts on the easiest and most economic ways to calm this beast down!

Start a new thread for this......

Hijacking a thread is not neighbourly....lol.

Seriously tho', start a new thread for your information search.

Coley

[CC69Rat]

4:11 gear swap, 2800-3200 stall converter and you'd see a big jump off the line.

Camshafts make horsepower in a different RPM range based on the Stock-to-Performance ratio. The bigger the cam, generally speaking you'll need to have more RPMs to get that cam into it's happy zone. For example, a slight performance street cam will make power in the 1500 rpm range, but a bigger lumpy / choppy cam needs a little more RPM to get it into it's wheelhouse. The Stall converter will allow the RPMS to come up a bit more into that range before your truck starts to pull away from a stop light / dead stop scenario. This is why you feel that power a bit more from a roll now.. Give it that same RPM off the line, it will come on strong there too.

This will impact your fuel mileage. Absolutely. But it will give you the bottom end youre looking for. 383 is known to be a torque monster but it just takes it a little time to get wound up.

I'd start with a stall, see how you like it. Somewhere in the 2500-2800 RPM range. TCI Streetfighter is a good one IMO.

[toolboxchev]

Do a proper tune up, set up an adjustable vacuum advance unit. Finally tune the carb.

Look here:http://www.crankshaftcoalition.com/w...EI_distributor

and again:http://www.crankshaftcoalition.com/w..._compatibility

There is a ton of info on here, do a search and see what your particular builds is wanting to produce more power. Its all trial and error, get some basic diagnostic equipment. Its a great learning experience.

[Mike C]

You should start a new thread, especially not tagging on one that's 14 years old!

Your heads will be fine with a smaller cam. But for what you want, that's the only way to get there. Move to a cam with around 220 degrees of duration at .050 and move on down the road.

You can make improvements with tuning and tweaking, but when the component that dictates everything else is wrong for your goal, it's just wrong.

[harpo231]

My 383

HP & Torque: HP 420/ FT 450 LBS
Compression Ratio: 10.0:1
.480 Intake .486 Exhaust
229 Intake / 230 Exhaust duration
@ .050

Ignition Timing:

34 degrees total at 3500 RPM ...

[HO455]

Some things he can check is compression and vacuum. By doing a compression check knowing he has a good engine could reveal that the cam has a bunch of overlap that is bleeding the compression off at low rpms. If that is the case a set of bleed off lifters like Rhoads may be helpful. Checking vacuum at idle and just off idle will add more information to the cam puzzle.
Checking distributor advance curve will be good information to have. Get ahold of an adjustable timing light and a tach/dwell meter (if you don't have a tach installed). Disconnect and plug the vacuum advance port from the carb. We don't want the vacuum advance skewing the numbers. Start by checking timing at idle and write the number down. Then check it 200 rpms higher and write the number down. Continue in 200 rpm increments writing the numbers down until you get no more changes. Obviously having some help makes this much easier. Once all the numbers are recorded you can see what is going on (Put it on a graph if it helps.). These may reveal the mechanical advance is stuck or too slow of a curve is installed for the modifications done to the motor.
Once these numbers are obtained then a plan of action can be formulated.

[hjewell2]

Originally Posted by browndawg71

the 1000cfm 4150 hp series aint useless on my street driven 468

[Steeveedee]

Put a blower on it. Problem solved. Blowers tame a cam like nothing else, and give you instant torque...assuming that the rest of the stuff you can do has been done. The blower will add some tuning requirements, too.