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gm 383

brian wafer

brian wafer

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my nephew blowed the 305 in his 96 gm truck,crank shaft broke! he order a new gm crate 383. motor comes with valve cover oil pan,no intake. what should he do ! he wants to replace injectors,and was going to stay with stock intake and manifolds. is it possible to install bigger ones or do stock ones do the job. its not going to be a race truck but he would like for motor to run stronger than the 305. any advice on what improvements he should do. motor should be in, in another week! any help appriciated!
 
Is it the HT383?
I'm just throwing some questions out Brian...
Is there a difference between 5.0 and 5.7 injectors?
If not try them with a different tune to fire them longer?
 
not quit sure what it is ,he works up north . and is gone for 14 days, he order the engine before leaving. all he told me was that it was a brand new motor,no core. it should be in next week.
 
Try posting in the injection section!
 
I had to step to a 454 sized throttle body and 454 injectors to satisfy my mild 383. I used a higher output fuel pump and adjustable regulator to get the fuel pressure dialed in. There will be some tuning involved for sure, I am using the EBL set up, there is a lot to learn.
 
I believe the HT 383 came with Vortech heads and roller cam but also a four barrel aluminum intake
 
I was looking at this engine quite a few years ago for my 85.
I found it a bit odd they used a slightly different bore/stroke arrangement than the popular 350/400 setup
Nice engine too!
 
nephew should arrive tommorrow! i will get more spec then. pickup a 96 so vortec not tbi. he,s got 14 days to make it run ,so he will probably make it run with what he has and see how she pulls. parts are not rapidly accesible here,especially when your looking to modify.
 
brian wafer said:
nephew should arrive tommorrow! i will get more spec then. pickup a 96 so vortec not tbi. he,s got 14 days to make it run ,so he will probably make it run with what he has and see how she pulls. parts are not rapidly accesible here,especially when your looking to modify.
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Needs to be tuned or it will melt itself. Those have no way of knowing it's running lean under throttle, whether it feels ok or not, it's going to be running VERY lean.

I'd strongly caution against doing anything other than moving the vehicle around the yard with a 305 tune/fuel on a 383 until I knew fueling and timing was at least close enough to keep it from destroying itself. That would be an expensive lesson.

It will run, not much doubt there. It might even feel like it runs good. But you may not know how serious the problem is until the engine comes apart of its own accord.
 
what if he used a 350 ecm. we got one in a old truck. it would be richer than a 305. i have a otc genisys i suppose i can read the fuel trims being its 96 obd2. i supposed the ecm would have to be reprogramed or replaced to adjust right. . like greg ducato said maybe 454 injectors. i know he wanted to use it for his next trip ,but harming or blowing engine is no good.
 
brian wafer said:
what if he used a 350 ecm. we got one in a old truck. it would be richer than a 305. i have a otc genisys i suppose i can read the fuel trims being its 96 obd2. i supposed the ecm would have to be reprogramed or replaced to adjust right. . like greg ducato said maybe 454 injectors. i know he wanted to use it for his next trip ,but harming or blowing engine is no good.
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I don't know enough about the SBC Vortec setups to comment on injectors. On TBI/TPI it's a pretty simple calc, but that ridiculous Vortec CPFI is apparently different than a "normal" injection system, so I don't know.

Higher flow injectors can bandaid a problem, as can bumping the fuel pressure up somewhat, without tuning. It's not the right way to do it because the PCM still can't modify fueling under WOT based on AFR, and at least on earlier setups, if you over-fuel, the system can only compensate for so much at other than WOT. But if that genisys will let you see AFR and/or whatever is used to see how much fuel the PCM is adding or subtracting, you'd be able to at least have a good idea that your other than WOT fueling is good. The only way to make sure WOT fueling is good though, is to use a wideband O2 setup.

A 350 tune is going to be closer for sure. As hot as engines tend to get on break in, I'm not sure I'd want to be knowingly running the engine lean, but also not sure how you'd get around that problem.
 
On my 383 TBI with vortec heads I had to do a lot To make it run correctly.
the minimum is a lot bigger injectors. I run 90#, a higher flowing pump, an adjustable fuel pressure regulator, and a major tune.
I went with the EBL flash programmable ECM and worked on it.
You can get the program fairly close, fairly quickly, and can drive it but not hot rod it. It takes awhile to fully dial it in.
 
ok i got more information its a ht 383. manual says its a replacement for 96 to 99 gm pickups with 350 cid. for optimum performance ecm has to be recalibrated.so he would like to try a recalibration ,but where or who would be best place to go to. he will run truck with a 350 ecm.read( installation note).

http://www.chevrolet.com/performance/crate-engines/small-block-ht-383e.html
 
If he isn't planning on a lot of future mods I would just send his specs to TBI Chips and be done with it. If he is planning on doing stuff in the future then I would do EBL flash programmer from Dynamic EFI. But that requires some homework and playing with it.
 
I think that at the very least you are going to have to make the MPFI upgrade from the CPFI spider if it hasn't already been done. Then the PCM will need to be sent in to be reflashed. Does TBI Chips deal with OBD II PCM's? I think that if the PCM had the L31 tune it would be more apt to work for the short term, than with the L30 tune you currently have.
 
thanks captain! i,ve been reading on tbi chips web site ,and i,m not sure he can work on vortec,s. since the truck came with a 305 he is looking for a 350 pcm. can you school me on the difference between the L30 and L31 tune. truck will be hopefully running in a few days. he needs it to go to work, so its going to be a band aid for now. were trying to find the most information possible for the next step!
 
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