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Edit: Help me BUILD a 400 - 9/7 engine is back home.

Which engine

  • Pre 86 Block with 2 piece rear main

    Votes: 6 17.1%

  • Post 86 Block with 1 pc seal and Vortec heads

    Votes: 23 65.7%

  • Keep the smoking 350 in it, use the money to go somewhere fancy with your wife and maybe get nekkid

    Votes: 6 17.1%
  • Total voters
    35
chalet2506

chalet2506

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Sorry, I know this gets beat to death.

This is for my 72 Jimmy 4x4. Just looking for a good reliable engine that puts out a little more oomph than a stock motor. I'm going to keep my th350/np205 with 3.73 half ton axles and probably 33" tires. Thinking about adding a detroit. Mostly a street truck with a little offroad action when I hunt/fish.

Would like decent mileage out of the thing. Have kicked around buying a reman'd block locally, but can't seem to find anyplace that doesn't have mixed reviews on quality.

I have no interest in TBI or EFI. I already had Jet Performance reman my Q-Jet and its good to go. Plan on buying a decent intake, adding Corvette 2.5" ram horns for exhaust to increase performance but maintain the stock look.

I've been reading up, but I guess the main questions I have is which of these will be the best running based on what my fuel del and exhaust systems are. I think the vortec longblock is the way to go, but will the accessories I have on my 76 400 or 72 350 engines move over? Don't plan on keeping a/c so I'll just be running ps, water pump, and alternator.

GM Performance part# 12530282. 1pc rear main with Vortec Heads

http://www.summitracing.com/parts/NAL-12530282

or

GM Performance part# 12499529. Pre 86 style block with stock heads, etc.

http://www.summitracing.com/parts/NAL-12499529/
 
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Either of those are great choices and will serve you well. I would pick the one with the best warranty. I have the GM crate 290hp engine and it does just what i ask it to and has been VERY reliable.
 
I've read that's a good one. But also read that vortec heads are supposed to be pretty good stuff as well. There's really not a lot of cost difference, unless I have to get all new accessory brackets for the vortec longblock.

Not that I'm caught up in h.p. numbers, but if they'd list the output for the vortec longblock this would be a lot easier.
 
I saw that too. For ease of install and simplicity's sake the GM 290hp would be the winner but i believe you are correct as the vortec headed one probably makes more power but I don't know if you need anything special for it.
 
I would guess the one with the vortec heads is gonna make more power...and won't puke oil from the valve covers. :waytogo:

You'd need a vortec specific manifold for the Q-jet though so there is a bit more cost up front. It also has a roller cam, which helps a bit power wise.

Rene
 
I've looked around a little bit. I buy from Summit fairly regularly though, and their prices on what I've checked so far are right in line. Plan on keeping a mech fuel pump.

Seems like I'm getting a decent working knowledge about carbs, hei ignition, and older engine tech. Don't want any new fangled electro tbi'd computer related stuff on my ride.
 
tRustyK5 said:
I would guess the one with the vortec heads is gonna make more power...and won't puke oil from the valve covers. :waytogo:

You'd need a vortec specific manifold for the Q-jet though so there is a bit more cost up front. It also has a roller cam, which helps a bit power wise.

Rene
Click to expand...

Yep. The money I save by not buying cast aluminum perimeter bolt covers will help with the extra money for the quadrajet/vortec intake manifold.

Was thinking about this bad boy.
nal-12496820_w.jpg
 
Can keep the hotair choke with the GM intake. But have been thinking maybe I can get the Performer intake and convert to a manual choke.

Still up in the air though, that's why I'm asking. Thank for the input.
 
that Jet don't have an electric choke?
 
I would keep the hot air choke. I like it better than the electric choke as is KISS all the way. Either way you are fine though. Techincally with the electric choke in order to get the full benifit from it you need the heat riser from the exhaust and a few other little things. Unless its really cold where you live i wouldnt worry too much about it.
 
Those work OK but the cable tends to not like sharp beds AT ALL! LOL I'd keep the hot air choke if the carb is calibrated for it. Will run better and cause less issues.
 
Just installed a Jet #34006 stage 2 w/divorced choke on a Edelbrock #2101 manifold on a stock 400. Even with the extra weight of the camper (6200 lbs) I still have plenty of power.
I'd also go with the 290hp crate motor, relativly inexpensive and all your parts will bolt up.
 
Or I could just get the heads rebuilt on the 400 out of my Chalet, add an intake like you did and use it. That would save me some serious coin. It was running good. Oil smells a little like gas. Figured that was a head issue as I put a new fuel pump on it.

Thanks for complicating things. Sounds good, but I don't want to be swapping engines again anytime soon. 400's aren't the best on mpg. Power is nice though. Don't know why I can't make up my mind about these things sometimes.
 
newer vortec if carbed.

1 peice rear seal better.

roller cam in the motor = free power. if 96-up full vortec block. if not then it will take one with the parts.

still bolts in real easy. just need newer flexplate to fit motor and th350 pattern.
 
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