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best heads for a sbc 383 for towing?

General engine tech -- Drag Racing to Circle Track

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1989TransAm
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Post by 1989TransAm » Sun Jan 04, 2009 7:15 pm

I have a 2000 Tahoe 4x4 that came with the L31 motor. That motor comes with the 8 poppet injectors instead of the TBI. I replaced it with a 383 and the cam used was 206/212@.050 and 254/264 seat to seat. Lift was right around .475" which is max for a stock vortec head.

I also went with smog legal 1 5/8" shorty headers and upgrade exhaust to the factory muffler. I also installed the K&N CAI. I had the Tahoe dyno tuned. I feel if you are spending that much money you need a tune to get the maximum performance.

Anyways I could not be happier with the way it turned out. Plenty of power right up to 5000rpm and the shift point. People who have road with me have commented on how "peppy" it is. I have the dyno chart and it put down 287rwhp and 346rwtq. That is through a 4L60E and a transfer case.

On the highway I get 17+mph. Bottom line is for what you want to do I agree with the above posters that your cam is going to be a little large.
Last edited by 1989TransAm on Sun Jan 04, 2009 8:02 pm, edited 1 time in total.

bones263
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Post by bones263 » Sun Jan 04, 2009 7:57 pm

ok i agree with you guys on the cam it came with the short block i bought it with out the heads the guy sold them seperate so ineed to buy some heads or should i rebuild the heads that are on the 350 in the truck for this motor? also this block is a roller block so if i need a cam should i go hyd. roller and buy every thing for that or stick with a std hyd. cam also what cam should i get? I would like to stick with the tbi and i could buy the bbc inj. pod. and yes its automatic od. also could go smaller tire these are about done. Thanks you guys are alot of help on this!

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Post by 1989TransAm » Sun Jan 04, 2009 8:12 pm

By all means go with the hydraulic roller cam. Factory parts new and used are all over the place if you are missing anything. Just sellect the cam you want. Your budget will dictate which heads to buy. If you buy Vortec heads you will need a matching intake manifold. If you buy used Vortec heads for rebuild check them for cracks.

I had a friend looking to do what you are going to do and he found some Vortec heads for free. By the way with your shortblock you will need to check things to see what compression ratio you will wind up with. I would not go over 9.5:1 with the iron heads. 9.3:1 would be very good with 87 octane.

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Re: best heads for a sbc 383 for towing?

Post by af2 » Sun Jan 04, 2009 8:17 pm

bones263 wrote:. we have emissions gear ratio is if this is to much motor for the tbi i could take all the compuetr stuff out and go with a carb and intake as long as it passes the emission tail pipe test.
Not knowing where you live, that question is not answerable. In California the visual test is the first thing looked at as the hood opens.

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Post by bones263 » Sun Jan 04, 2009 8:19 pm

it has the dish piston 9.67 at 64cc i live in ohio, akron and they don't open the hood.

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Post by needforspeed66gt » Sun Jan 04, 2009 8:32 pm

We actually do quite a few of the TBI towing motors, but like has been said - if you don't have the ability to tune the old and very dumb TBI computer it will not run well at all. Our package basically doubles the rear wheel power while still passing CA smog (sniffer and visual), small comp roller cam, World Sportsman II heads w/ EO # , T&D throttle body spacer & fuel line extensions + the BBC fuel pod as stated before. Since you don't have to deal with smog I would run a different set of heads as I'm not a fan of the World Products stuff due to the extra work needed on them.
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Post by gmc406 » Sun Jan 04, 2009 11:01 pm

rustbucket79 wrote:Agreed that if you have overdrive you have too much tire diameter for the gear ratio. IMHO you don't have enough gearing for towing even with stock diameter tires unless you don't have much for hills in your area.

We tried the 383 build/vortec heads in an early 90's tbi setup, even with a GM tech who's knowledgeable with EFI and had his own chip burner, it was a dog. It idled/ran OK, but was less than awe inspiring. We had headers and dual exhaust, edelbrock vortec performer intake, tbi adapter, Holley (IIRC) oversize TB.

At the risk of being flamed here, I feel the best heads are the ones you removed with the small intake runners and port swirls. You have a setup that will spend the bulk of its time from 1200 to 3200. The vortec heads (and engines) are great, but if you've driven in one you'll notice the computer has no problem dropping down a gear and letting it rev to 5000 or so. I don't think the tbi does much above 4000 other than make noise, now you've added another 10% displacement to it. I too would recommend a smaller cam, anything in the 200 to 208 range @ .050 intake will do the trick.

I don't know if I would build another "performance" tbi engine, I mean a job is a job but I certainly wouldn't recommend one ever again.

We never tried it, but it would have been interesting to put a small 4 bbl carb on it, I think it would have helped.
Sounds like tune was still the issue. There's no reason whay that engine shouldn't run well. It's OBD 1 and they can be tricky. A lot of people will just turn their heads and walk, or throw a carb on it. My TBI truck just hit the 12's (2400 feet alt) and get a little better than 20mpg's. It's possible, but it takes the proper tuning to do it. It's no race machine by no means, but it's fun to drive. I don't think I have any better parts in my engine than what he's got. I believe he may have been better of with a 454 TB than the Holley, they run better.

I agree with you on the swirl ports.

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Post by bones263 » Mon Jan 05, 2009 12:11 pm

so it looks like vortec heads are the way to go! should i use a gm head or aftermarket like patriots or eq? I have a perf. rpm intake and a edelbrock 750 carb, any hyd.roller cam recommendations?

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Post by Horndog » Mon Jan 05, 2009 12:31 pm

Small port alum "good" heads like Edelbrock's 170/180cc E-Tec heads.
Hydraulic roller cam, 1-5/8" long-tube headers into 3" collectors. Finish exhaust in 2-1/2" pipe. Re-flashed ECM for the added cubes, etc.

Alum heads do a good job of dissipating heat, lessening the chance for detonation.
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Post by cfm » Mon Jan 05, 2009 2:01 pm

Sorry to get off engine topic, but I spend a lot of time around tbi's. No matter how you build the engine, you need 4.10 gears to accelerate these heavy unaerodynamic bricks. Having the 4L60E with these gears and factory size tires will still keep rpm down low on the highway.

Gear is most everything. Engine is the rest.

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Post by bones263 » Mon Jan 05, 2009 11:32 pm

i am going to run the vortec heads should i use the 906 or the o62 heads is there any difference or a aftermarket style ? do the voetecs have a 170cc runner or are they bigger i see some listed as 180 and 190cc? who makes the summit vortecs in there cat. would that be a good one or how out the pbm heads?

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Post by Ron Golden » Tue Jan 06, 2009 12:34 am

With 3.55 gears, 31 inch tires and a 700R your rpm at 70 mph will be 1885. At that rpm you'll be completely out of the engines useful rpm range, regardless of how small the cam is.....especially is you try to tow anything.

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Post by cfm » Tue Jan 06, 2009 8:34 am

bones263 wrote:so it looks like vortec heads are the way to go! should i use a gm head or aftermarket like patriots or eq? I have a perf. rpm intake and a edelbrock 750 carb, any hyd.roller cam recommendations?
So, your going carb ?
What about your trans (4l60E is compuer controlled and will need a stand alone tran computer) and emmissions ?
===============================
Have you done some research and talked to people over at sites like www.fullsizechevy.com or etc ? I see your only posts here are on this topic. Yes, many here can help you, however I mention the other site because it is set up specifically for your type vehicle.

You seem to be jumping between TBI and carburetor. They have different requirements: skill level, knowledge, parts selection, $$$$$, and etc. Either way - carb'd or TBI - what you are trying to do is not a small undertaking.

Plus, again, as I have mentioned, and others have mentioned, please take the gearing advice seriously no matter which way you end up.

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Post by mike ramirez racing » Tue Jan 06, 2009 9:38 pm

bones were do you live? is smog an issue? I'm from Nor Ca we have strict laws.

I had a 90 suburban 4x4 it had 3.73's and 31" tires and a TBI 350. What a turd! I was gonna do a 383 or 400 w/TBI and put 4.10's but decided to sell it and get a dually. Your set up you should consider your crusing/towing RPMs and make it as efficient as possible. Usually in the 2200-2700 RPM range. I had to tow in drive, I didn't have a tach so I didn't know my RPM's. You need all the torque you can muster down low to get all the weight moving and not use a boat load of fuel to do it. I would use smaller cc runner heads like suggested. also a little stall speed for towing(add an external trans cooler) and step up to 4.10's. Remember with OD the final drive ratio is like 2.87 to 1. Use the Edelbrock TBI manifold and the 454 TBI injector Pod. I'd keep the cam small, 450-480 lift, 208@.050 on a 112 LSA. Also check out Turbo City, they do custom TBI and cams and computers.
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Re: best heads for a sbc 383 for towing?

Post by falcongeorge » Fri Jul 31, 2020 8:27 pm

I did a motor for my brothers hunting truck years ago, similar application, heavy, big camper, 33" tires, 3.73's plus he also wanted the motor to be really responsive at small throttle openings for quiet bush crawling, I used the much maligned SP2P and a Crane HMV260 (260/272, 204/216 .427/.454, 112) it worked very well and got excellent mileage (20-21 imperial MPG @ 60 mph :shock: ). My experience is the Crane HMV line was under-rated by most guys, I used them quite a bit, and as long as you used your head in camming the application, I thought they were very good. His only complaint was he didn't feel it had enough power for passing at 60+ mph, but he was comparing it to an earlier motor with a Perf rpm and a 227/234 hyd roller, that motor wasn't worth a crap for bush crawling, on balance, he thought the second combo was better suited to his needs. Long story short, I agree with everyone else, cam is too big for what you are doing.

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