I'm guessing it wouldn't be too hard, but what all would be required to get a 455 to work in an '87 K5? Truck currently has a piece of **** 350 TBI that's driving me insane, and a buddy of mine has a 455 that needs rebuilt, sitting in his garage. Since I was going to get the 350 rebuilt anyway, I thought it might be interesting to get the 455 done instead, and have it swapped into the Blazer. The truck has a TH350 in it right now, but I'm not sure if that'd bolt up to the 455. Also know I'd have to convert to carb (don't want to drop the money on stand-alone EFI at the moment, as the truck needs some serious sheet metal work also), but again, I'm not sure what that'd entail, and I don't want to drop it off at a shop and say "Make it work!" and pick up a $3000 bill when it's all done.
CK5
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455 Poncho in a K5
- Thread starter Element
- Start date
supersize75k5
OrganDonorRacing.com
whats the real issue with the 350? is it really a piece or is it needing some maint. instead?
whats up with it?
whats up with it?
It's just a dogged out smogger engine. Going from a 375rwhp LS1 (which I still have, just the weekend cruiser now) to a sub-200hp boat anchor just isn't cutting it, plus, the engine has a constant hot idle oil pressure of less than 5psi, cuts out for no apparent reason (currently wasting money on parts trying to troubleshoot that), and has a pretty nasty cold knock. And, the idea of an old big-block Pontiac engine just seems fun.
New parts list on the 350, per this evening:
Cap, rotor, plugs, wires, coolant temp sensor, EGR valve, O2 sensor, fuel filter, air filter, multiple oil changes + Seafoam'd.
New parts list on the 350, per this evening:
Cap, rotor, plugs, wires, coolant temp sensor, EGR valve, O2 sensor, fuel filter, air filter, multiple oil changes + Seafoam'd.
sled_dog
1 ton status
what year 455? Ponchos were some of the worst of the "dogged out smog motors". like in the 7:1 compression range. I can dig the desire though, Ponchos are torquey engines.
Need an adapter to run the Pontiac engine with the Chevy transmission. They have different bellhousing patterns. BOP pattern vs Chevy.
Engine mounts, I simply do not know what to do about that. Sorry, no help there.
Oh and to go with the TBI to Carb, you need a fuel pressure regulator. A regulator with a return line. Like this one:
Return Style Fuel Regulator
I really like that regulator because it gives you the option of upgrading to multiport fuel injection later on(with the second regulator spring).
Need an adapter to run the Pontiac engine with the Chevy transmission. They have different bellhousing patterns. BOP pattern vs Chevy.
Engine mounts, I simply do not know what to do about that. Sorry, no help there.
Oh and to go with the TBI to Carb, you need a fuel pressure regulator. A regulator with a return line. Like this one:
Return Style Fuel Regulator
I really like that regulator because it gives you the option of upgrading to multiport fuel injection later on(with the second regulator spring).
JEBSR
1/2 ton status
You will need to to get an bell housing adapter so that it will bolt up to your existing trans. The motor mount plate will have to be moved. The fuel pump and starter are on the opposite side of the engine, so you will have to extend the main cable and reroute the other starter wires as well as extend the fuel lines to the fuel pump as well. As long as the donor motor is complete with all accessories there isn't much more you will need other than a little work. If you don't have all the accessories you will need to locate brackets for the engine. The alt and P/S pump on your rig can be made to work, the starter will only work if you change the nose cone on it to a Pontiac/olds style cone. Hope this helps.
Not sure on the year, but as it'd be completely rebuilt, it'd be designed for a bit more power than stock. My friend just mentioned it in passing yesterday, and I've been thinking about it since. I do think it's just the long block, no accessories, and I'm not sure if it's still got the intake and carb on top. Have to check today if I get a chance.
How would changing the truck over to a carb setup work with the stock TBI ECU setup? I know it'd come out, but with an OBD1 vehicle, does the ECU just control the engine itself? I know the trans is mechanically shifted, but all my experience has been with OBD2 vehicles, where the computer controls damn near everything.
How would changing the truck over to a carb setup work with the stock TBI ECU setup? I know it'd come out, but with an OBD1 vehicle, does the ECU just control the engine itself? I know the trans is mechanically shifted, but all my experience has been with OBD2 vehicles, where the computer controls damn near everything.
expect lots of fab and custom work to make that work... far from bolt up.. not worth it imo...
I think the 455 is a great idea. 
Displacement rules!
Plan on a complete powertrain revamp though. IMO a TH350 won't last long, although it can easily be adapted with an easy-to-make 1/8" plate adapter. A manual trans could be tricky with bellhousings and flywheels. TH400s are plentiful in BuickOldsPontiac pattern, but requires some mix'n'match to get a 4x4 output on it.
Lots to think about.
Displacement rules!Plan on a complete powertrain revamp though. IMO a TH350 won't last long, although it can easily be adapted with an easy-to-make 1/8" plate adapter. A manual trans could be tricky with bellhousings and flywheels. TH400s are plentiful in BuickOldsPontiac pattern, but requires some mix'n'match to get a 4x4 output on it.
Lots to think about.
My thought was, he said, "have it swapped in"...
If your gonna pay someone to do that, expect a big bill...
If your gonna pay someone to do that, expect a big bill...
