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Old 02-22-2015, 02:30 AM   #51
mechanicalman
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Re: HELP! Install Gen 3 Firebird TPI W/computer into 71???

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Originally Posted by Steve Van Gent View Post
Does anyone know, is the TPI the same from the 305 and the 350? Is the computer programmed the same? If I found a 350 TBI, could I rip off TBI and replace with TPI from the 305?
Depends on the year of the TPI. 87 and above use canted center intake manifold bolts like the TBIs do, 86 and 85 use straight bolts.

TBI engines are torque oriented, will not produce much power above 3,500-4,000 RPM. However, that is where a TPI shines. TPIs with TPI heads will go to 5,000 RPM before they start gasping for air. NO2 works really well on cars with intake breathing problems LOL.

The 305 engines used 19 lb injectors and the 350s used 21 lb injectors. They used the same computers but different PROMs.
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Old 02-22-2015, 01:10 PM   #52
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Re: HELP! Install Gen 3 Firebird TPI W/computer into 71???

I have a early TPI setup on my 79 crew cab. I have a 355, cammed, Edelbrock intake, vortec heads, SLP runners, headers etc Etc. I used a painless harness, easiest way to do it in my opinion. I did not beleive the lose of power at 4500 5000 rpms till I had it tuned , dipped dead at just under 5000.

Setup works good, would not be my preference now, but I had multiple setups so I figured I would use it.

Any questions, ask
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Old 02-22-2015, 01:44 PM   #53
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Re: HELP! Install Gen 3 Firebird TPI W/computer into 71???

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I have a early TPI setup on my 79 crew cab. I have a 355, cammed, Edelbrock intake, vortec heads, SLP runners, headers etc Etc. I used a painless harness, easiest way to do it in my opinion. I did not beleive the lose of power at 4500 5000 rpms till I had it tuned , dipped dead at just under 5000.

Setup works good, would not be my preference now, but I had multiple setups so I figured I would use it.

Any questions, ask
Are your SLP runners the "Siamese" type? Did you remove the area of the plenum between the runners?

https://www.google.com/search?q=TPI+...oQsAQ&dpr=0.95
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Old 02-22-2015, 02:24 PM   #54
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Re: HELP! Install Gen 3 Firebird TPI W/computer into 71???

Stock SLP runners. Did not do any mods to them
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Old 02-22-2015, 02:47 PM   #55
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Re: HELP! Install Gen 3 Firebird TPI W/computer into 71???

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Stock SLP runners. Did not do any mods to them
Are they "Siamese" (runners casted together) and did you modify the PLENUM between the ports in order to utilize the open area of the "Siamese" style runners, if you have them.
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Old 02-22-2015, 03:04 PM   #56
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Re: HELP! Install Gen 3 Firebird TPI W/computer into 71???

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Stock SLP runners. Did not do any mods to them
If you have the "Siamese" style runners (side by side runners cast together), and did not modify the plenum, you are not gaining much if anything over the stock runners.

I had that problem on my 88 formula 350. I put "Siamese" runners on it, cut out the area between the tubes on the plenum and gained about 2-3,000 RPM. The Siamese runners have a short area at the top of the runners where the 2 tubes are actually combined into 1, and if you don't modify the plenum by removing metal between the ports, the runners won't do anything much for you.

My friend with a TPI 383 had a pair of Siamese runners. After opening removing the area between the tubes on the plenum, he opened the runners themselves up all the way like both runners combined just short of the bottom of the runners then transitioned them to enter the Edelbrock intake. Pulled strong to 6K+.
This will solve your RPM "problem" if you consider it to be one.
https://www.google.com/search?q=TPI+...oQsAQ&dpr=0.95

As you can see in the pics, some choose to take them out all the way and even into the intake manifold before they knife edge the transition. I believe the farther you go, the farther you put the power band into upper RPM's as you shorten the final runners (long runners=low end torque, short runners=top end power). It's like you have the main plenum, then 4 staggered plenums kinda like tri-y headers only in reverse. I suspect it's the best set-up there is.

One of the reasons this works is because the plenum is too small and the runners too long to begin with. Notice a "Super Ram" has a bigger plenum and shorter tubes.

My friend has since installed a Stealth Ram manifold, I don't think he gained a thing up top over what he did to the Siamese runners and I think he lost some bottom end.
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Old 02-22-2015, 03:11 PM   #57
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Re: HELP! Install Gen 3 Firebird TPI W/computer into 71???

My goal was low end torque, as I use the crew for pulling my car trailers.. Only reason I used them ws because the stock ones look ugly, and they get even uglier with the more dents in them..

I can satisfy all my challenges by installing a Gear Vendors, more gears would be cool, the 700r4 and the 410's and smaller than stock tires take away from top end. My truck loves to run at 2100-2400 rpms, and it cruises just fine for, even pulling the trailers
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Old 02-22-2015, 03:16 PM   #58
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Re: HELP! Install Gen 3 Firebird TPI W/computer into 71???

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My goal was low end torque, as I use the crew for pulling my car trailers.. Only reason I used them ws because the stock ones look ugly, and they get even uglier with the more dents in them..

I can satisfy all my challenges by installing a Gear Vendors, more gears would be cool, the 700r4 and the 410's and smaller than stock tires take away from top end. My truck loves to run at 2100-2400 rpms, and it cruises just fine for, even pulling the trailers
It should! Those are torque monsters! I'm surprised more people don't use them for towing.

I read where a guy filled his tubes up with water and put them in the freezer to remove the dents. I never have done this but it sounds possible.
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Old 08-07-2017, 09:24 PM   #59
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Re: HELP! Install Gen 3 Firebird TPI W/computer into 71???

update- we ended up putting this in my 65. My kid sold his 71 and bought a Miata. Go figure...

Here is final product pics.

http://67-72chevytrucks.com/vboard/s...14#post8011114
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