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tuned port injection question


john davis

I have a 75 with edelbrock6090 heads dynomax headers comp 268h cam 700r4 tranny with 3.70 gears curently running a edelbrock performer rpm intake with edelbrock 750 carb I would like to switch over to tpi a mechanic friend of mine has a set up off of a 88 camaro with 60000 miles on it. everything is there except fuel pump what would be the best way to solve fuel pump set up can I get one to go in the tank or will I have to use an frame mounted variety if so what would be a good pump and cost and how much psi would i need?
tpi fuel pump

you need a pump that will always put out at least 45 psi at the fuel preasure regulator. a frame mount pump is easyier and costs about $260 -300 for a pump rated for continous use(jegs part #129-1602 is $239.99) plus you need to run a return line to the tank(thats the other $20-$60)
I just put a TPI unit in my caddy.The fuel pump I used was a rail mounted unit rated at 43psi this pump I got through Jims performance for 99 bucks. Another pump you can use would be a ford unit (rail mount) for 86 to 90 trucks with EFI rated at 43psi cost 110 to 160 bucks. If you stay around 42 to 45 psi you'll be ok. When you change camshafts use an adjustable pressure regulator crane makes one,but all it is, is a screw in the top with a disc inside to increase or decrease spring tension. My system consists of a new wireing harness,a computer for 1992, and a reprogramed chip. the mass air flow has been replaced with a speed dencity sensor and MAP sensor. It's an 85 unit and the cold start injector is dormant. To get the parts you need try jim at www.jimsperformance.com He has most of all the conversion parts and was very helpful Tom
why would I have to change the cam is the cc 268h wrong for tpi?

the 268 cam while not ideal will run in tpi the best cams for tpi have a 113-115 lobe center split and a 220 deg or less intake @ .050 duration and 230 @ .050 or less exst duration as both the computer and the long tubes on the tpi manifold don't work well with more overlap as it causes reversion into the intake runners at low speeds (THAT'S MOST LIKELY WHAT HES REFERRING TOO);) that makes the sensors in manifolda little :J
I just put the 268h cam in about three months ago so I aint going to change it the mechanic who has the tpi set up is quoting me 750 dollars for the tpi and 500 dollars to install it plus I will have to buy a fuel pum everything else is there do you guys think this is a good price?
TPI why?


You didn't say why you wanted to convert to TPI. If it is for more power don't do it. The factory TPI is very limiting because the chip controls everything. In addition, the runners aren't big enough and neither are the injectors. The intake is very restrictive (48cc). And finally, the computer will limit you to 5500 rpm.

The setup you already have will let that motor breathe a whole lot better.

I drive an 86 TPI, it's fine for over the road but not for racing.
the reason for the tpi is two fold one it would increase my fuel millage I hope by about five miles to the gallon also my mechanic said that it would increase my horse power by around 50 is he full of malarky do you think? after its all said and done I will have around 1500 dollars in the setup I am starting to think it would not be worth the effort especially if there are no performance gains also 1500 dollars buys alot of gas what do you all think?

the tpi will help your gas mileage but I would not expect any total increase in hp as you will pick up in the low and mid range but lose on the higher rpm ranges over all Id skip this swap!!! :( you will have more increase in mileage by changeing to a 2.87 or other low number rear gear(and you will still have good performance except from a dead stop)

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