TPI Caprice?
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Joined: Jan 2008
Posts: 140
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From: Columbus, OH
Car: 1986 Sport Coupe
Engine: 305 Carbed
Transmission: th700r-4
Axle/Gears: 2.73
TPI Caprice?
Is it possible? My friend has a Caprice, and I think it would be pretty bad *** with TPI ontop of it.
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From: Lynn Haven/Panama City, FL, USA
Car: 88 Monte SS
Engine: Super-rammed L-98 383
Transmission: T-56 6-Speed
Axle/Gears: 8.5" G-BODY G-80 3.73
Re: TPI Caprice?
Sure it is possible and pretty easy for that matter. Like mentioned, if it is a94-96 it would have either an L99 4.3L LT-1 look-a-like, this would be the code on the SPID located in the trunk lid. This the white sticker located on the roof of the trunk. If it is the 5.7L LT-1, it would also be on that SPID. If this Caprice is an 87-93 model, with either the LO3 5.0L TBI or the LO5 5.7L TBI, it would be really easy to convert it to a TPI, and with the already existing TBI harness. It just takes some meticulous re-pinning of the TBI harness and the (Green or Yellow 32 pin 7730 connector) from the 90-92 TPI 7730 ECM, and some minor re-wiring of the under-hood wires, and it will work fine. I've done a few of them, and a few LO3 TBI RS Camaro's. There is a plethora of information on such swaps, and just simply ask for help with well thought out questions, and you will be very successful in your project. HTH's.
Joined: Jul 1999
Posts: 10,950
Likes: 27
From: Orange, SoCal
Car: 1990 Pontiac Trans Am
Engine: 355 TPI siamesed runners
Transmission: Tremec T56
Axle/Gears: 12-Bolt 3.73
Re: TPI Caprice?
A Caprice/Impala forum would be your best bet. I'm sure its been done before.
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Joined: Dec 2006
Posts: 584
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From: toledo
Car: 1987 Z28
Engine: LG4
Transmission: T5
Axle/Gears: 3.23
Re: TPI Caprice?
without getting rid of the swirlport heads your porlly not going to see much to any performance gains.....
i know because guy i know slapped a tpi setup on a 89 fullsized blazer and got a ton of tq added and lost top end hp
tried bumping fuel pressure/tuning it/advanced timing...everythign and still ran like poo. Ended up pulling the tpi off and running a holley carb and never looked back. I may even do the same after adding up how much its gonna cost to build my 327tpi project up from stock setup right now
i know because guy i know slapped a tpi setup on a 89 fullsized blazer and got a ton of tq added and lost top end hp

tried bumping fuel pressure/tuning it/advanced timing...everythign and still ran like poo. Ended up pulling the tpi off and running a holley carb and never looked back. I may even do the same after adding up how much its gonna cost to build my 327tpi project up from stock setup right now
Thread Starter
Member
Joined: Jan 2008
Posts: 140
Likes: 0
From: Columbus, OH
Car: 1986 Sport Coupe
Engine: 305 Carbed
Transmission: th700r-4
Axle/Gears: 2.73
Re: TPI Caprice?
I don't think it is a TBI, he just rebuilt the carburetor, which TBI's don't have, right? I'm gonna check the VIN today to see what the car came with, be cause it definitely still has the original engine.
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Joined: Dec 2006
Posts: 584
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From: toledo
Car: 1987 Z28
Engine: LG4
Transmission: T5
Axle/Gears: 3.23
Re: TPI Caprice?
oh i thought i read it was a 89 which is all tbi(friend owns a junkyard...lol)
but yah 88 had the LG4/305 and a weak 350 carb'd(smog motor).
putting a tpi unit on either motor will see more tq but almost no gain in horsepower due to the tpi is lacking in cfm flow. iirc tpi flows like 250-300cfm stock and a quadrajet flows in the neighborhood of 750cfm
id stick with the carb if your looking for performance and having to spend a ton of money to upgrade from stock tpi later to match a carb's performance
but yah 88 had the LG4/305 and a weak 350 carb'd(smog motor).
putting a tpi unit on either motor will see more tq but almost no gain in horsepower due to the tpi is lacking in cfm flow. iirc tpi flows like 250-300cfm stock and a quadrajet flows in the neighborhood of 750cfm

id stick with the carb if your looking for performance and having to spend a ton of money to upgrade from stock tpi later to match a carb's performance
Senior Member
Joined: Dec 2006
Posts: 584
Likes: 0
From: toledo
Car: 1987 Z28
Engine: LG4
Transmission: T5
Axle/Gears: 3.23
Re: TPI Caprice?
if the owner of the car has a boat load of money id go tpi.
but since the car is a carb'd car already id suggest looking into a dual plane edelbrock performer rpm intake and edelbrock 600cfm carb
also, is this a dd car or a weekend bruiser? kinda big detail
but since the car is a carb'd car already id suggest looking into a dual plane edelbrock performer rpm intake and edelbrock 600cfm carb
also, is this a dd car or a weekend bruiser? kinda big detail
Thread Starter
Member
Joined: Jan 2008
Posts: 140
Likes: 0
From: Columbus, OH
Car: 1986 Sport Coupe
Engine: 305 Carbed
Transmission: th700r-4
Axle/Gears: 2.73
Re: TPI Caprice?
DD, but he does not care about gas mileage or anything, he just wants to smoke his tires like my LB9, lol
Member
Joined: Apr 2006
Posts: 290
Likes: 1
From: Columbus
Car: 88 Formula, 72 Nova, 68 Chevelle
Engine: L98, mild 350, L79 327
Transmission: 700R4, M20, M20
Axle/Gears: 9b 327,10b 373, 12b 331
Re: TPI Caprice?
Last edited by FormulaL98; Feb 5, 2009 at 07:29 AM.
Senior Member
Joined: Dec 2006
Posts: 584
Likes: 0
From: toledo
Car: 1987 Z28
Engine: LG4
Transmission: T5
Axle/Gears: 3.23
Re: TPI Caprice?
Then tell your buddy to look for a good dual-plane manifold and a carb to to put on it, a cam swap too (hydrolic flat tappets can be had for about 100 bones with the lifters). Steeper gears could be had from the junkyard, as well as possibly a used posi. A little 100 shot of nitrous would do that Caprice right also! 

Re: TPI Caprice?
Sure it is possible and pretty easy for that matter. Like mentioned, if it is a94-96 it would have either an L99 4.3L LT-1 look-a-like, this would be the code on the SPID located in the trunk lid. This the white sticker located on the roof of the trunk. If it is the 5.7L LT-1, it would also be on that SPID. If this Caprice is an 87-93 model, with either the LO3 5.0L TBI or the LO5 5.7L TBI, it would be really easy to convert it to a TPI, and with the already existing TBI harness. It just takes some meticulous re-pinning of the TBI harness and the (Green or Yellow 32 pin 7730 connector) from the 90-92 TPI 7730 ECM, and some minor re-wiring of the under-hood wires, and it will work fine. I've done a few of them, and a few LO3 TBI RS Camaro's. There is a plethora of information on such swaps, and just simply ask for help with well thought out questions, and you will be very successful in your project. HTH's.
can you direct me to where where I can find specific information in regards to the re-pinning and harness mods required to do this. Please
to be more specific I want to swap a 91 tpi 350 into a 91 Caprice 5.0.
Joined: Dec 2004
Posts: 16,926
Likes: 1,016
From: Mile High Country !!!
Car: 1967 Camaro, 91 z28
Engine: Lb9
Transmission: M20
Axle/Gears: J65 pbr on stock posi 10bolt
Joined: Apr 2010
Posts: 514
Likes: 44
From: New Jersey
Car: 87 Monte Carlo SS
Engine: 89 350TPI Transplant
Transmission: 2004r
Axle/Gears: 3.73
Re: TPI Caprice?
You should also check out a website named "chevythunder.com". Allot of TPI swap information there.
Good Luck.
Good Luck.
Re: TPI Caprice?
Been there:

Done that:

The real benefits are better reliability, more consistent starting and running, more torque available for heavy bodies with lower (numerical) rear gearing, better cruising fuel mileage, and cleaner operation. Presuming the B-Body already has a TH700-R4 transmission, the low ratio first gear should help overcome almost any low ratio rear axle, and the OD range of the trans is going to help a lot with cruise economy. If the car has a TH200-4R (1988 may be a little late for that trans) the rear gears really need to be investigated.
If the car has a ridiculously low axle ratio, as some did, changing to 3.08 or slightly higher gearing will help the low end.

Done that:

The real benefits are better reliability, more consistent starting and running, more torque available for heavy bodies with lower (numerical) rear gearing, better cruising fuel mileage, and cleaner operation. Presuming the B-Body already has a TH700-R4 transmission, the low ratio first gear should help overcome almost any low ratio rear axle, and the OD range of the trans is going to help a lot with cruise economy. If the car has a TH200-4R (1988 may be a little late for that trans) the rear gears really need to be investigated.
If the car has a ridiculously low axle ratio, as some did, changing to 3.08 or slightly higher gearing will help the low end.
Joined: Jan 2005
Posts: 10,450
Likes: 510
From: Hurst, Texas
Car: 1983 G20 Chevy
Engine: 305 TPI
Transmission: 4L60
Axle/Gears: 14 bolt with 3.07 gears
Re: TPI Caprice?
Been there:

Done that:

The real benefits are better reliability, more consistent starting and running, more torque available for heavy bodies with lower (numerical) rear gearing, better cruising fuel mileage, and cleaner operation. Presuming the B-Body already has a TH700-R4 transmission, the low ratio first gear should help overcome almost any low ratio rear axle, and the OD range of the trans is going to help a lot with cruise economy. If the car has a TH200-4R (1988 may be a little late for that trans) the rear gears really need to be investigated.
If the car has a ridiculously low axle ratio, as some did, changing to 3.08 or slightly higher gearing will help the low end.

Done that:

The real benefits are better reliability, more consistent starting and running, more torque available for heavy bodies with lower (numerical) rear gearing, better cruising fuel mileage, and cleaner operation. Presuming the B-Body already has a TH700-R4 transmission, the low ratio first gear should help overcome almost any low ratio rear axle, and the OD range of the trans is going to help a lot with cruise economy. If the car has a TH200-4R (1988 may be a little late for that trans) the rear gears really need to be investigated.
If the car has a ridiculously low axle ratio, as some did, changing to 3.08 or slightly higher gearing will help the low end.
Joined: Dec 2004
Posts: 16,926
Likes: 1,016
From: Mile High Country !!!
Car: 1967 Camaro, 91 z28
Engine: Lb9
Transmission: M20
Axle/Gears: J65 pbr on stock posi 10bolt
Re: TPI Caprice?
For the throttle cable you might be able to use one off a thirdgen or lokar.
the throttle cable will be determined by year 85-88 or 89-92 wrap around style.
rockauto.com sells the tv cable or you can do lokar for both. The lokar uses a stud so if you use a throttle cable by them you need there tv cable.
the throttle cable will be determined by year 85-88 or 89-92 wrap around style.
rockauto.com sells the tv cable or you can do lokar for both. The lokar uses a stud so if you use a throttle cable by them you need there tv cable.
Last edited by Tuned Performance; Dec 28, 2019 at 10:02 PM.
Joined: Dec 2004
Posts: 16,926
Likes: 1,016
From: Mile High Country !!!
Car: 1967 Camaro, 91 z28
Engine: Lb9
Transmission: M20
Axle/Gears: J65 pbr on stock posi 10bolt
Re: TPI Caprice?
For throttle cables they have 24 or 36 and are cut to fit if you want it shorter.
https://www.lokar.com/throt-cable-kickdowns.html
https://www.lokar.com/throt-cable-kickdowns.html
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