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Carb to TPI Conversion

Discussion in 'The Garage' started by 78blazaer, Feb 27, 2005.

  1. 78blazaer

    78blazaer Registered Member

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    I am thinking of converting from carb (Q-Jet) to TPI on my 1978 K5
    Anybody have done this kind of upgrade before? I need some ideas and please share your experience, lesson learned etc.

    My K5 have a 350 with manual trans. I've been watching Ebay for TPI for sale.
    Is a donor IROC-Z camaro will work for my 78 K5 TPI conversion? What is the compatible year/model donor should I look for?

    Thanks is advance.
     
  2. Russell

    Russell LB7 Tahoe Status Premium Member GMOTM Winner

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    The thing I am going to urge to you the most is that you buy a parts camaro / firebird that has been totalled, or has a rod knock or something. No ebay setup is truely complete, and you'll find yourself nickle and dimed to death trying to get all the little parts and peices it didn't come with.

    As far as the physical setup goes, the 86 is the best year of TPI goes in your case, if you want to run a MAF. Avoid the 85 setups like the plauge, it can be identified by the piggy back MAF burnoff module. It is very prone to failure, and is over all an inferior model. 87-89 setups are still MAF, but the physical intake will need to have the bolt holes modified, and you will need a small cap HEI with the remote coil. Some later setups also had the cold start injector removed, having the cold start enrichment programmed into the ECM.

    If you wish to run Speed Density, you need a 90-92 setup. They will need the small cap HEI, and will need to have the intake modified to fit your old style heads (bolt holes, can be done with a die grinder)

    Now, there are a couple different things that can help you decide wether to run Speed Density, or MAF. Both have their pros and cons. Speed desnity is an overall more efficient setup, as it is newer technology, and it does not have the expensive MAF. MAFs do not like a rough ride, or any sort of dirty air. They have a very small filament that can broken if the setup is jarred really hard. Also, the MAF is a major bottle neck, it does not flow very well, and just goes to lower just how high you will be able to get your engine to rev up. On the other hand, the speed density setups will not take any sort of engine modifications without a new chip. So, if you don't plan to take her off-road and beat on her a bunch / running a more radical engine, then go MAF, otherwise, go speed desnity. If you are running a larger displacement engine such as a 383 or 400, go speed density.

    As far as stuff you need to install into your truck to accomodate the new EFI system, there isn't a whole lot to do.

    First off, you'll need to buy a TPI in-tank fuel pump, put it into an 87+ Blazer tank, and install it in your K5, This immediately takes care of the fuel pump issue. You'll need to replace all of the rubber lines with high pressure fuel injection line. The steel braided lines from the 87+ trucks with TBI is awesome for this :) The TPI pump is a direct bolt in replacement to the TBI pump that'll be in the EFI blazer tank.

    Next, you'll need to install a VSS. The easiest way to do this is to put a 85 mph speedometer with the green sensor on the back on. You can feed the signal it puts out directly into the MAF ECMs. If you don't want an 85 mph speedo, or something, you can buy a VSS that goes inbetween the transmission and speedometer cable, in either the 2 pulse per mile that MAF systems need, or 4 pulse per mile the later speed density systems need.

    Finally, you'll need an 02 sensor installed into the exhaust you are running. With manifolds, you'll need to take them to someone who can weld on cast iron, or you are pretty much guranteed to crack your manifolds, with headers, you'll need to install the bung into one of the collectors, and depending on how hot your engine runs, you may need to get a heated 02 sensor.

    You also need to make sure that you get the setup that you need for your truck. Aka, get a 305 setup for a 305 / 327, and a 350 setup for a 350 / 400. TPI is a fantastic system as far as the electronics go, its the actual physical intake that turns most people off from this system. It'll only flow well enough to get a 350 revved up to about 4800 rpm. There are a bunch of expensive aftermarket parts you can buy to replace the stock intake with, and get the setup to flow for 500 horses if you want, but the cheapest option is to install an LT1 intake. You can get them off ebay for less than 200 us, and then ship them to the guy at www.lt1intake.com to get it machined for your block / get the chip you need burnt etc. The other thing that you need to look at is the injectors. they are 19 lb/hr for the 305 setups, and 22 lb/hr for the 350 setups. If you are running a higher horsepower setup, you need more fuel to go along with the air. You can buy aftermarket injectors for your setup. Ford, and Chevy both used basically the same injectors, but Ford ran ones with a higher flow rating, some as high as 30 lb/hr. The stock 5.7 LT1 intake would have 24 lb/hr injectors in it.

    For any information you could possibly need about TPI, check out www.chevythunder.com -- Its very indepth, and covers absolutely everything you need to know about installing TPI into other vehicles / the way TPI works, and other specs :)
     
  3. Hossbaby50

    Hossbaby50 3/4 ton status

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    It looks like alot of the stuff has been outlined in the post above. I have to go to work in a couple minutes, but I will read this post again later and put in some of my issues and experiences. I did the carb to TPI swap on my truck about 1.5yrs ago.

    Harley
     
  4. dyeager535

    dyeager535 1 ton status Premium Member

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    Also, '88(?)-up had VATS...HAVE to get another chip burned to even get a VATS equipped ECM/PROM to start.

    So earlier MAF better in that regard.

    MAP generally considered the better system all around, just not as "plug and play".

    If your engine is bone stock, and you don't have plans to change it, then burning your own "chips" may not be in your future. If you end up going MAP, or want/have engine mods, you might as well start planning on chip burning too.

    Oh yeah, and don't forget cold start injector. Bad idea, good if you can eliminate that as well, but pretty much going to require custom chip to get rid of it. (again the year/VATS issue comes into play)
     
    Last edited: Feb 28, 2005
  5. Russell

    Russell LB7 Tahoe Status Premium Member GMOTM Winner

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    If anyone needs it, I have a little VATs signal generator I made. The guy I bought my ECM off of swore up and down that it had VATS, but after I got it, I found that it was an 86 ECM, without vats. I have no idea if it works or not, but whoever wants it can have it for free.
     
  6. 78blazaer

    78blazaer Registered Member

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    Based on the information you provided me, I will look for an 1990-92 TPI Camaro or Firebird donor. I will go with Speed desity system since my truck will be subjected to dirt and mud. I will either find an 85 MPH speedometer or get one of those inline VSS. For the fuel pump, I will look for 87 and up TBI equiped fuel tank to fit the TPI pump. High pressure fuel lines is a must and heated oxygen sensor probably the way to go. I will look for LT1 intake and will have it machined to fit my 350 motor. WOW! This forum is really awesome. Thank you for all for your input. These information will surely get me started to the right direction. Wish me luck.
     
    Last edited: Mar 1, 2005
  7. dyeager535

    dyeager535 1 ton status Premium Member

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    ON the TBI tanks, be very careful. You'll need the sender regardless, but the stock designed tank is pretty weak...they attached the plastic inside baffles with bolts, and it tends to break pretty regularly.

    You can buy aftermarket TBI tanks (all steel) for around $120, so don't beat yourself up trying to find a "good" factory one. You might get lucky, if so great. In any case, pull the sender out and look at any used tank before purchase.
     

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