convert a 400 block to lt1?
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convert a 400 block to lt1? Hey, My dad Gave me a 400 block that he had laying around. I was thinking of, later on when my money gets better, and after i get the t/a runnin i could make it a 427. I was wondering if i can just bolt all the lt1 components on it and install it in a lt1 car with no problems?
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Joined: Mar 2004
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From: Texas
Sorry, it ain't gonna happen. Otherwise your big guns out there, like Tony Shepherd & Shawn Salazar, would have already bought a Dart block. Our LT's have reverse cooling passages and ,well, your standard block ain't gonna allow for the correct flow. I already looked into this ,just like you did.
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I have heard of some 409s, I believe it is a combination of a big bore and a little more stoke, sounds like the clearancing for the crank gets a bit extreme.
If going forged for NA then a 396 it easy and reliable, if you want to run a power adder a forged 383 keeps the pin further from the rings. If you want to save a few dollars a cast 383 is a bit cheaper to build and still plenty reliable form most.
In an engine build like this the extra power is not so much comming from the cubes as it is the heads/cam, sure a few extra cubes will not hurt power but to spend a lot more money for a few extra cubes does not make sense $$$ wise.
If going forged for NA then a 396 it easy and reliable, if you want to run a power adder a forged 383 keeps the pin further from the rings. If you want to save a few dollars a cast 383 is a bit cheaper to build and still plenty reliable form most.
In an engine build like this the extra power is not so much comming from the cubes as it is the heads/cam, sure a few extra cubes will not hurt power but to spend a lot more money for a few extra cubes does not make sense $$$ wise.
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Thats my next build. I am gettin' my heads done next week. 
Jeff Martin, a neighbor of mine (and long time hot rodder) has a 421 LT1 in his 99 GMC Sonoma. Normally when someone tells me they have a 421 I say 
, but Jeff Martin is a long time hot rodder who has had a couple of his cars featured in Chevy High Performance back in the 90s so I believe him. I have saw this beast run with a bad tune. Simply sick
, but Jeff Martin is a long time hot rodder who has had a couple of his cars featured in Chevy High Performance back in the 90s so I believe him. I have saw this beast run with a bad tune. Simply sick 
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Joined: Jan 2004
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From: Detroit,MI
I think I can shed some light here. The problem most guys have with going larger than 396ci is clearancing for the increased stroke. With a 396 you use a 3.875" crank, but with some of these larger 400+ inch motors, guys are using 4.000" cranks or larger. The problem then becomes that your stroker clearancing in the block can break through to the water jacket. Most guys at this point treat the situation by using a small amount of hard block so it seals the given area. Not the best way to fix the situation, but its what I have seen people do out there.
To be honest the most power I have ever seen out of LT1's was from a 383. It all comes down to heads and camshafts with these engines once you get to a certain engine size. Sure a 421 will have more low end grunt than a 383, but at what cost.
We have done several 383's and 396's here at APE that have made gobs of power both with and without power adders. On the budget side of things a 355 is never a bad choice and can be had in a shortblock form for less than $3000. The choices are many indeed, but my advice to go against the 400+ motors.
Now as far as putting that 400 block into the car, that is another post all together, but for what its worth I own an old school SBC Powered 97 Camaro.
To be honest the most power I have ever seen out of LT1's was from a 383. It all comes down to heads and camshafts with these engines once you get to a certain engine size. Sure a 421 will have more low end grunt than a 383, but at what cost.
We have done several 383's and 396's here at APE that have made gobs of power both with and without power adders. On the budget side of things a 355 is never a bad choice and can be had in a shortblock form for less than $3000. The choices are many indeed, but my advice to go against the 400+ motors.
Now as far as putting that 400 block into the car, that is another post all together, but for what its worth I own an old school SBC Powered 97 Camaro.
383 boosted, or a 355 boosted would be my choices... You can make a ton of power with the stock 350 cubes to begin with...with forged internals and the block setup just right...muhahaha...
Of course Im not looking for 1000hp so my options would differ from the next guys.
Of course Im not looking for 1000hp so my options would differ from the next guys.
Launching!
Joined: Jul 2004
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From: Florence, MS
what kind of power can be made from a 383 with good heads and cam? im looking into building one right now but was wandering if the lt1 intake is a big restriction? is the lt4 intake that much better then a ported lt1 intake? also what is better to go with 5.7" rods or 6.0" on a 383
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From: Detroit,MI
Originally Posted by 1BadAsZ
what kind of power can be made from a 383 with good heads and cam? im looking into building one right now but was wandering if the lt1 intake is a big restriction? is the lt4 intake that much better then a ported lt1 intake? also what is better to go with 5.7" rods or 6.0" on a 383
Give us a call at the shop, and we can give you a few options to choose from. We have the best shortblock pricing out there.
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From: That Southern Fried Space City
Originally Posted by 1BadAsZ
what kind of power can be made from a 383 with good heads and cam? im looking into building one right now but was wandering if the lt1 intake is a big restriction? is the lt4 intake that much better then a ported lt1 intake? also what is better to go with 5.7" rods or 6.0" on a 383
Going with a 5.7 over 6.0 rod is dependant on other factors as well. Generally forced inducted motors use a shorter rod to decrease dwell time and vice versa so it depends on what you are doing. Once again, this is an age old deal that sees alot of controversy and in the big scheme of things for what most people do, it really doesn't amount to much.
Lots of good information in this thread.
Figure out what size motor you want to run, then figure out if it's going to be N/A or Forced Induction, as that's going to play a key role in determining your compression ratio.
Once you've figured that out, have a set of heads ported to support that motor I.E. a 383 is going to require a much larger volume of air up higher in the RPM band than a 355 would, so the porter should take that into account and work the runners to keep the velocity up while allowing a greater volume of air to pass through.
Once the heads have been done, talk to any of numerous people out there who do custom camshafts, and let them know what your goals are.
The sky is the limit.
Oh, and I've personally seen a 406 LT1 also.
Figure out what size motor you want to run, then figure out if it's going to be N/A or Forced Induction, as that's going to play a key role in determining your compression ratio.
Once you've figured that out, have a set of heads ported to support that motor I.E. a 383 is going to require a much larger volume of air up higher in the RPM band than a 355 would, so the porter should take that into account and work the runners to keep the velocity up while allowing a greater volume of air to pass through.
Once the heads have been done, talk to any of numerous people out there who do custom camshafts, and let them know what your goals are.
The sky is the limit.
Oh, and I've personally seen a 406 LT1 also.