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Big Block (BOP)& TH400 ?

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by 45acp, Aug 15, 2001.

  1. 45acp

    45acp 1/2 ton status

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    Long story shortened. I need a TH400 that will fit the doubler that Stephen (ORD) is building for me and a engine that will fit up to the TH400. The best choices are as follows:
    1. Chevy big block, and a TH400 with 32 spline and 1 3/8" stickout length of the output shaft. This would also be called a "K" case (the 4wd version is the "K"). This combo would bolt together with little problem but is very hard to find.
    2. Chevy big block, and a TH400 with 32 spline and 2 1/2" sickout length of the output shaft. This one is ment to bolt to a NP208. This combo would require a 2" adapter to make it work and that makes the overall length greater.
    3. Third option is a Buick, Olds or Pontiac big block, with a TH400 (no adapter) or Chevey big block with adapter to TH400 that was ment for the BOP big block. This one is available to me.

    Now the question regarding the use of a BOP big block. The bolt pattern on the engine to transmission is different but what are the other differences? What about engine mounts and anything else I do not understand will be issues? How available are custom engine parts for these engines verses Chevy? I need some help on this option so I can decide what transmission to buy. Give as detailed a post as you can since this is a important issue right now. Thanks,

    <font color=red> Bill, "Shop Rat" </font color=red>
    <a target="_blank" href=http://coloradok5.com/gallery/Shop-Rat>http://coloradok5.com/gallery/Shop-Rat</a>
     
  2. pcorssmit

    pcorssmit 1/2 ton status

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    Not the most popular swaps, but all the 455s (BOP) are strong runners and often available cheaper than BBCs (used). Plenty of room for them in a full size. Caddys also share the same bolt pattern (500s, 472s, etc.)

    Pete

    '83 K5, 350 TBI (ex 6.2), 700R4, NP208, Dana 60/14 bolt, 4.56s, Detroits, 3" lift, 15-39.5x15 TSLs
    '97 Dodge 2500 4x4 CC LB Sport, Cummins 5 spd
     
  3. Mudzer

    Mudzer 1/2 ton status Author

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    I have often thought about installing one of my old Pontiac engines into my K5. It would be relatively easy. I have seen many pontiac engine swaps in Chevy trucks. In fact, I know a guy who is so into Pontiac's, he installed them in all his Ford utility work truck fleet! The dimensions of a Pontiac are similar to a Big Block Chevy. The motor mounts will have to be fabbed, but you should be able to use the complete mount from any big Pontiac car and weld or bolt the frame mounted motor mount to your crossmember. I think I could even get TBI to work on a Pontiac pretty easily. The thing is, I can guarantee you can buy a Pontiac in either 400, 428 or 455 cubic inches much cheaper than you can buy a Big Block Chevy. If you had to rebuild it, the prices are slightly higher but the initial cost is not, so that makes it much more affordable. Plus, I would be willing to bet you cant make the power from a stock BBC or SBC as you can with a stock 455 - For the money. Get that I said "For the money". Of course I am going to get totally swarmed by all those Chavvy people out there complaining about "My Big Block will beat your Big Block", all I have to say is - Did your Big Block chevy cost $100 and come from an old Station Wagon, had been setting for 5 years, pulled off the 2bbl intake and installed a 4bbl, installed a camshaft which was way too big, and headers to the tune of 12.50 1/4 mile times? Doubt it. [​IMG][​IMG]

    http://www.krepower.com/

    Mudzer 1978/91 K5
    <font color=blue>www.mudzer.rockcrawler.com</font color=blue>
     
  4. Emmettology 101

    Emmettology 101 3/4 ton status

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    The Pontiac engine swap is ne I am pondering also. Cant beat the Poncho low end torque!

    Jegs sells an adapter that is made by TCI(i think it is TCI) that adapts goes between the tranny and engine and is around $60.....

    Not sure on the motor mounts, haven't got that far in research yet. I have been putting that stuff on the back burner.

    Mike

    <font color=green>"It's like a sore dick deal, You cant beat it!"</font color=green>

    <a target="_blank" href=http://www.geocities.com/emmettology101>www.geocities.com/emmettology101</a>
     
  5. 45acp

    45acp 1/2 ton status

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    Pete, Do you know of anyone on the board that is running a caddy or any of these combos that I could get in touch with?

    <font color=red> Bill, "Shop Rat" </font color=red>
    <a target="_blank" href=http://coloradok5.com/gallery/Shop-Rat>http://coloradok5.com/gallery/Shop-Rat</a>
     
  6. Donovan

    Donovan 1/2 ton status

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    I had a Caddy 500 in my blazer so if you have any questions let me know. It was the best engine swap I ever did. When I have enough money I will be putting one into my 74 truck in place of the 454.

    Donovan
    Bigger is Better
     
  7. Mr.Chevy4x4

    Mr.Chevy4x4 1/2 ton status

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    Well when you get to that point, I want first dibs on the 454!!! ;-)

    '85 K5 : Run it til it breaks, then fix it and go again!
     
  8. Ryeguy

    Ryeguy 1/2 ton status

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    I've got a Caddy 472 sitting between the frame rails in my '87 Blazer. Fits nicely. I used a BOP (Caddy) TH400 that was modified with a Chevy 4wd output shaft (while it was rebuilt).

    --Rob
     
  9. DesertDueler

    DesertDueler 1/2 ton status

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    I would put a Pontiac motor in if you want to switch over. I have a Pontiac 350 in my 69 Firebird, and it runs 11.15 at 121 MPH in the 1/4 mile. Can't beat the low end torque!!!!

    86 Blazer 4"lift 35" MTRs locked front, still 1/2 ton axles.Other vehicles 69 Firebird with 525 hp,and a 70 GTO www.geocities.com/modifierperformance
     
  10. pcorssmit

    pcorssmit 1/2 ton status

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    There was some talk w/in the last week or so about caddy swaps, try a search.

    As for the TBI, I was really considering this a few years ago when I put in the 350. I've got a 400 out of my old Firechicken that would have worked well (after I swapped out the 292 cam), but I couldn't figure out how to make the distributor work w/a stock TBI setup. If you didn't run a computer distributor, it would work, but I wanted one.

    Pete

    '83 K5, 350 TBI (ex 6.2), 700R4, NP208, Dana 60/14 bolt, 4.56s, Detroits, 3" lift, 15-39.5x15 TSLs
    '97 Dodge 2500 4x4 CC LB Sport, Cummins 5 spd
     
  11. Sparky87k5

    Sparky87k5 1/2 ton status

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    If you decide to swap a Cad engine, don't use ultra low rear end gears. Cads like to run with 3.54's &amp; 3.73's when running 33" or 35" tires. I swapped a 500 into a Sub about 4 years ago and tried it with 4.56's &amp; 33" tires. Poor choice as I had lots of oil temp due to the huge main &amp; rod bearings. Swapped out 4.56 for 3.54's and what a difference. Power was as strong but oil temp dropped at least 50 - 75 degrees. Fuel mileage jumped 15-20% and engine just felt stronger. Cads are not hi reving engines, make great power between 1600-4000RPM.

    87 K5, D60 & 14FF, 5 sp & NP208 & 383 stroker. Build it Bulletproof and take it fishing!
     
  12. Donovan

    Donovan 1/2 ton status

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    Pete it is very easy to change the distributor to a computer one. Use a pontiac HEI and just change all the guts with the Chevy HEI 7 pin. I did this to my caddy engine and run the Holley pro injection off of the 7 pin distributor. The HEI as far has I now are all the same inside but the bodys are different. The Caddy distributor shaft is the same one as the chevy but the body is totally different.

    Donovan
    Bigger is Better
     
  13. Jeff427

    Jeff427 1/2 ton status

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    You can see pics of Donovan's 500 powered Blazer on the Mud Dog Off Road site Mud Dog Off Road Club

    <a target="_blank" href=http://lyonsdesign.bizhosting.com>Lyons Design Web Site</a>
     
  14. pcorssmit

    pcorssmit 1/2 ton status

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    I thought about that, but didn't think it would work, trying to put small-cap parts into a large-cap distributor. Wasn't sure about running it backwards, either.

    Pete

    '83 K5, 350 TBI (ex 6.2), 700R4, NP208, Dana 60/14 bolt, 4.56s, Detroits, 3" lift, 15-39.5x15 TSLs
    '97 Dodge 2500 4x4 CC LB Sport, Cummins 5 spd
     
  15. Donovan

    Donovan 1/2 ton status

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    Pete you can get a large cap 7 pin distributor for a Corvette and it will look just like your pontiac HEI distributor. That is what I did. It shouldn't care which way it turns because it is just taking a firing signal and it is a batch fired fuel injection.

    Donovan
    Bigger is Better
     
  16. Donovan

    Donovan 1/2 ton status

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    Hey Sparkey was you running 3.54 with 33" tire? I would love to put a 500 in my 86 1 ton crew cab and I was trying to figure out what gears I need. Did you have a manual or auto? The dually has 4.56 in it now and a 465 tranny. I have thought about keeping the 4.56 and installing a NV4500 what would you do? You have to love those 500 they run so awesome. My brother races a 500 in his 73 Nova and it runs 11.7s in the quarter in Denver and he shifts it a 5200rpm's.

    Donovan
    Bigger is Better
     
  17. pcorssmit

    pcorssmit 1/2 ton status

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    So you can use a distributor from a TPI 'vette w/ a TBI system? Would one from an early TPI Camaro/Firechicken work then, too? Not that I plan on changing out the motor at this point, but would like to know for future ref. Have always wondered if this was poss.

    Pete

    '83 K5, 350 TBI (ex 6.2), 700R4, NP208, Dana 60/14 bolt, 4.56s, Detroits, 3" lift, 15-39.5x15 TSLs
    '97 Dodge 2500 4x4 CC LB Sport, Cummins 5 spd
     
  18. Donovan

    Donovan 1/2 ton status

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    Yes you can use a TBI distributor with a TPI. They both run a 7 pin setup.

    Donovan
    Bigger is Better
     

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