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TPI Setup

Seafarer76

Seafarer76

1/2 ton status
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Las Cruces, NM
I have a new 383 in my 77 K5 and would like to get a fuel injection system for it. I have been considering adapting a stock system because of the cost, and have been leaning towards a TPI. I was just wondering if I can get some input from you guys on here who have done this before. I found a setup on Ebay that sounds fairly good, but....

[FONT=Arial, Helvetica, sans-serif]TPI parts included:[/FONT]
  • [FONT=Arial, Helvetica, sans-serif][/FONT][FONT=Arial, Helvetica, sans-serif]
    [*]90-91 Corvette stock speed density upper plenum (polished)
    [*]90-91 Corvette fuel rail
    [*]Stock LT1 fuel injectors 24lbs
    [*]Aftermarket aluminum adjustable fuel regulator
    [*]Distributor cover (polished)
    [*]Stock 48mm throttle body (polished)
    [*]Aftermarket air foil (polished)
    [*]Speed Density stock intake runners
    [*]Lower intake bolts up to pre-87 sbc heads.
    [*]Stock water neck
    [*]Engine Computer 730 ECM with factory prom.
    [*]Complete factory wire harness from 90-92 Camaro Firebird. Some wires may be clipped, but all main wires seem to be in tact.    [/FONT]
[FONT=Arial, Helvetica, sans-serif]I have invested over $750 piecing this Tune Port Injection system together for a future hot rod. Financing got tight and need to sell. My loss your gain.
[/FONT]
I should have put in my specs huh?

Its a 5.75" rod, 9.5:1 comp., fully balanced block/rotating assembly. The cam is a Comp XE256. The heads are big valve stockers (i don't have the number on hand). It currently has a Offenhauser dual-port with a Carter 9635 AFB (basically an Eddy 1906). I have coated Thorley headers with dual 2.5 through 50 series Flows.

[FONT=Arial, Helvetica, sans-serif]Thanks
[/FONT]
 
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What type of cam / heads do you have on the 383? With the extra cubes, you will run out of RPM pretty quickly with stock TPI parts. But it makes great power down low, you would have great cold starts and good fuel economy. If your cam is too aggressive, you might need some custom prom work. But I think that the system is good for trucks - more so that it was on the cars it was used on - and I have one of them.
 
GM made tons of great truck engines -- Just never put them into their trucks, lol

TPI is a fantastic injection system. I've got my 80 K25 tuned port injected, and even with an engine that isn't built for the EFI, and absolutely no tuning, I'm very happy with the way the thing runs...

As mentioned, it won't make much top end horsepower due to the limitations of the stock intake, but it will make earth shattering torque on a 383. Build your engine to make power from idle to 4500 rpm, using a cam that operates on at least a 112 degree lobe seperation angle, and you should be fairly good to go.

Also, go to www.chevythunder.com, and learn yourself on the electronics. You want to make sure that setup comes with absolutely everything, as you'll get nickle and dimed to death if you don't. My only regret is that I bought everything off ebay instead of buying a running TPI car, and trading TPI for carb on the car, and carb for TPI on the truck.
 
sorry about that...I edited the original post with my specs.

SierraClassic..
Here's the link for the ebay sale (linky), does that look like everything?
 
that looks like a pretty good deal, most likley you will have to have a custom chip and you will want to go to a heated o2 sensor becasue of the hedders. My advice is start reading up on tuning and get your self plenty of wiring digrams, I put TPI in my 74 k-5 and made the custom harness myself
 
What kind of Gas mileage do you guys get using TPI? Empty and towing. This is my tow rig for a small camper too. I also go off roading and hunting with it.
 
I'm running a reasonably similar engine with my TPI. Except I have a 350 with a Comp Cams 262, flat tops, and stock smogger heads. Good shape, but not exactly a high performance engine by any means. I've had little to no trouble with my truck running poorly at an idle upon hitting closed loop like many do, even with the 262 cam and it's 110 LSA. I also idle my engine at 850 rpm, as it is a standard, and that does help a fair bit.

With your smaller cam, you should be pretty much good to go, even on a stock tune to start with. The cam is also suited to the TPI's powerband, and should be making amazing torque by 2200 rpm. Just keep in mind that she won't flow past 4500 rpm, which can make passing someone on the freeway a bit scary if you have low gearing.

I sent the ebay seller a couple of questions about the setup, and will let you know what I think once he gets back to me.

Like 1979jimmy350, I haven't driven my truck on the street since the swap, not since it was still a 2wd 3/4 ton pickup with a stock carb 350, TH400, and 3.73 rear diff actually, so I can't help much with regards to if it made a significant difference on my mileage right away or not. I'm expecting between 15 - 18 mpg highway if I take it easy though.
 
Ok, I compiled a list of things that may be missing from that setup, and if it winds up that everything I can't see is not included, that setup is not worth 400 bucks, unless you've got your heart set on the shiny plenum, lol! It may possibly need an additional 400 bucks worth of parts to make complete, depending on what all is missing...

As soon as I know, I'll let you know, and I'll also post up a more in-depth post with regards to what all is involved with installing one of these things onto one of our trucks, and making it a nice clean installation, and not a hackjob :)
 
I'd probably be looking at new injectors too, 24lb's are 350 injectors, and probably won't work well trying to feed a 383. About $200 I'd say.

If you don't ever like to drive fast, TPI might be fine on your motor, but mine runs out of steam quite fast, and it's a 355.
 
i've got tpi on my truck...stock 350. it is actually pretty fast..it surprised me because everyone said it was going to be slow... i drive in the fast lane on the freeway and when i need to pass people i put the pedal to the floor and zoom past them. kinda of bad though...two tickets in less then two months(speeding) i'm an idiot.:doah: now i drive slow.:D
 
It will be quick, but off-the-line quick and running out of steam are two different matters. 70MPH+ are easy, but a system based on a 305 engine is taxed even on a 350.

Unfortunately, properly feeding TPI on a bigger motor gets expensive as soon as you look at a new intake.
 
I'm personally of the opinion that 24 lb injectors should be plenty for a 383. The 305s used 19 lb injectors, and 350s used 22 lb injectors stock. If you assume a similar increase of fuel requirements for a 383 at a 33 ci increase, 2 more lbs per hour should be pretty close, esspecially on a relatively mild 383 like you have.

That said, these engine are built to make torque, not high revvin horsepower, and I think your 383 is built that way. Even if you can only get 4500 rpm out of it, thats still pretty close to as high as you'll want to rev a 383 that isn't built for more anyways. All my mechanical engineering buddies tell me that the forces involved even at 4500 rpm are simply incredible, and find it amazing that an engine will stay together at close to 7000 rpm at times, lol
 
I'm running stock 350 injectors on mine, and it's lean across the board. Mine is nowhere near radical. All changed components are going to affect fueling AND timing, as most of us know, but mentioned for a person "new" to this.

Of course, tuning can take care of SOME of the issues, but running injectors at their max isn't the "correct" way of doing it.

With the manual trans (465), if you want any sort of acceleration with each shift being roughly half what you started at, 4500RPM isn't much. :)
 
Thats true enough, I had done some tuning on my truck and while it was mildly lean across the board before, a couple of chips have it doing a pretty good job of fuelling the engine, with the injectors running about a 65 - 70% duty cycle most of the time. The granny gear is great for that, a guy can get a pretty wide range of RPMs without going fast, for tuning on the driveway :D

But yeah, 465 isn't used for racing anyways, horrible tranny choice if that is what you want :D My truck is built to pull, not to go fast. I rarely do anything more than kick the snot out of some little hondatard at a red light, lol!

Again, if you want a go fast engine, and plan to do any real high speed accelerations etc, TPI isn't the best choice, but if you want an engine that will pull absolutely anything you put behind it by making huge torque, and will still start on the 3rd crank on the coldest day of winter, or if you drive in areas of wild elevation changes, EFI, and TPI in specific is where it is at, in my opinion!
 
Hey man!

Finally got a reply from that ebay seller, and I'm gonna reccomend holding out for a more complete setup.

This one is missing at least 4 - 500 bucks worth of stuff... Only thing it has going for you, in my opinion, is the shiny plenum...
 
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