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TPI questions

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by NoSmog73, Oct 31, 2001.

  1. NoSmog73

    NoSmog73 1/2 ton status

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    Can I take a tpi set up from a 305 camaro .Is this set up compatible with a stock 350 and what parts would I need to make the conversion and what parts would need to be modified,I do say thank you to all that can give me the info. Many thanks.
     
  2. Nonesuch

    Nonesuch 1/2 ton status

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    sure a TPI off a 305 will go right on a 350. and this is what you need from the donor car....EVERYTHING attached to the TPI including sensors, wiring harness, ECM, and the MAF sensor located in the air intake thingy(forgot the tech term), distributor, etc.....hell if you can just buy the whole car so you dont forget anything. J/K i know there is probably more but i cant think off it all....and actually it probably would be easier if you had the whole car!!
    Justin
     
  3. zakk

    zakk 1/2 ton status

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    BlazzinInOR (i think that is his handle, if i muffed it sorry!) did a TPI swap on his 406, he gave me lots of good info. I think he will be along for this post [​IMG] if you can get the whole car, it would be for the best.

    -Zakk
    '77 K5 SB 400 TH350 NP203 p/t 6" Lift D60 14BFF 4.10's 36"Wrangler II's

    [​IMG] CK5's MOAB 2002 OR BUST!! [​IMG]
     
  4. HarryH3

    HarryH3 1 ton status Author

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    It'll probably work as long as it's pretty mild 350. 305 TPI's came with 19 lb/hr injectors, while the 350's came with 22 lb/hr injectors.

    <font color=black>HarryH3 - '75 K5</font color=black>
    <a target="_blank" href=http://www.angelfire.com/super/ThunderTruck>www.angelfire.com/super/ThunderTruck</a>
    It's a great day to be alive...
     
  5. Chris Demartini

    Chris Demartini 1/2 ton status

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    <font color=blue>All TPIs had 19 lb/hr injectors, the ECM lengthened the pulse width in the 350s
     
  6. HarryH3

    HarryH3 1 ton status Author

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    That information is not correct according to everything else that I've ever read about TPI systems. GM even lists the 305 and 350 injectors under different part numbers. For example, for an 87-88 305 injector, the GM part number is 10108480 while for the 87-88 350 the GM part number is 10108481. AC Delco and Lucas also list separate part numbers for each size TPI engine. Manufacturers are not very likely to list multiple part numbers for the same part. It increases their stocking costs.

    You can often get away with using the 305 TPI on a mild 350, but you can only increase the pulse width so much. Once the injector is open all the time, then you can't do any more. Pushing past an 80% duty cycle tends to cause problems.

    Here's a quote from the book Chevy TPI Swappers Guide, by John Baechtel:

    For Example; at 85 percent duty cycle many injectors freeze in between opening and closing; they sort of flutter and reduce fuel flow by half. This is really good information to have if your pushing your combination right to the limit. If you step over it and get to the point where the injectors flutter, you can lean out and get into detonation right at the worst possible time - full throttle, high RPM.

    There are lots of folks that successfully run the 305 injectors on 350's. But if you do much heavy load work, such as towing, you can burn holes in pistons. It isn't pretty when an engine fails due to running too lean under high rpm and/or heavy loads.

    <font color=black>HarryH3 - '75 K5</font color=black>
    <a target="_blank" href=http://www.angelfire.com/super/ThunderTruck>www.angelfire.com/super/ThunderTruck</a>
    It's a great day to be alive...
     
  7. Chris Demartini

    Chris Demartini 1/2 ton status

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    <font color=blue>What about 89-92? Oh yeah I have Ford Mustang 19 lb/hr injectors in mine [​IMG]
     
  8. HarryH3

    HarryH3 1 ton status Author

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    For 89 TPI's they list 2 different part numbers for the 305 and two other different part numbers for the 350, for a total of 4 injectors for that model year. That's the latest year listed in the book I have.

    My TPI 383 likes 26 lb/hr injectors. [​IMG]

    <font color=black>HarryH3 - '75 K5</font color=black>
    <a target="_blank" href=http://www.angelfire.com/super/ThunderTruck>www.angelfire.com/super/ThunderTruck</a>
    It's a great day to be alive...
     
  9. HarryH3

    HarryH3 1 ton status Author

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    One formula in the Insider Hints book from Tuned Port Injection Specialties says that you can take the flow rate, times the number of injectors, and then double that to come up with an approximate maximum horsepower that the injectors can support. So 19 * 8 = 152 * 2 = 304. As long as you stay near or below that number, then you should be safe with those injectors.

    <font color=black>HarryH3 - '75 K5</font color=black>
    <a target="_blank" href=http://www.angelfire.com/super/ThunderTruck>www.angelfire.com/super/ThunderTruck</a>
    It's a great day to be alive...
     
  10. BurbinOR

    BurbinOR 3/4 ton status

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    HarryH3 is right on with everything he said (no surprise [​IMG][​IMG]). You can put the 305 TPI unit on your motor BUT change the injectors to either 22 lb/hr or 24 lb/hr (since the stock 305 injectors were 19lb/hr). I run 24 lb/hr ones on my 406 and they are enough for me............but I also don't rev that thing over 4500K, or at least haven't yet. Probably a moot point since it would run out of air around 5K anyway. With the larger injectors you need to put a new chip in the computer, especially since your setup going into your '73 will probably not have a VSS (vehicle speed sensor) or VATS (vehicle anti theft system)............lets not get into another pissing match about the VSS tho. (Those who read the links last week know what I'm talking about.) For the record, you do not have to have VSS operational, no matter what you are told. Lots of folks run TPI with no VSS and it is NOT a problem.

    Good luck, let us know if you need any more info.

    <font color=blue>'79 ONE TON TPI K5 - See it at---&gt;<a target="_blank" href=http://www.blazzinor.rockcrawler.com>www.blazzinor.rockcrawler.com</a>
     
  11. BobK

    BobK 1/2 ton status

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    Location:
    Petrolia,Ontario,Canada but working in Port Huron,
    I've got a 90-92 speed density TPI in my 71 blazer 4x4 SBC 350(375h/p),no vss,no vats...no problems.
    Here is a link to pic's of my TPI install.
    <a target="_blank" href=http://www.imagestation.com/album/?id=4292391623>http://www.imagestation.com/album/?id=4292391623</a>

    <font color=green>BobK<font color=green>
     
  12. BurbinOR

    BurbinOR 3/4 ton status

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    Meant to post this the other day............great job on that install. I like the photo album.

    <font color=blue>'79 ONE TON TPI K5 - See it at---&gt;<a target="_blank" href=http://www.blazzinor.rockcrawler.com>www.blazzinor.rockcrawler.com</a>
     

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