Im trying to decide on which engine i should put into my truck eventually. Im wondering what is differnt besides the exhaust ports being higher and what does that higher port do. Also what has a stronger stock block. Another question i have is what ignition does the lt1 use.

thanks,
Matt

 

The LT1 takes plain old SBC One-Piece RMS internals, and the block itself is nearly identical to a 86+ Rollerized SBC, however the front has an an additional hole machined into it for the water pump shaft, and the cooling system on an LT1 is Reverse-Flow, cooling the Heads first, and using the hotter water to keep the block warm and loose, LT1 heads and SBC are also nearly the same with the exception of the cooling, so the CANNOT be swapped either way... The Lt1 also has a DRY intake manifold and is not water cooled, the cam gear on an LT1 timing chain has a spined hole in it (93-94) or a clover drive for the LT1s Unique OPTI-Spark distributor...

They are very similiar but have subtle differences..

 

LT1 heads flow better than anything GM made before them and as well as many of the aftermarket lower level Gen1 heads, of course if you use Vortecs on a Gen1 you get LT1 flow because the ports and chambers for the Vortec heads were swiped from the iron LT1 heads.
Block stregth would only be an issue if you were looking at a very radical poweradder/forced induction setup. The single biggest limit to the LT1 is the factory pcms rev limit of a little over 7000rpms it simply can not control spark beyond that but the motor itself is still fine. Really the LT1 and one piece rear main gen1 motors are pretty stout 450hp and 6500rpms being perfectly reliable as long as you keep it well lubed some guys far exeeding the 450hp and some taking it right up to the 7000rpm pcm limit. Many of the old rules do not apply these days would you believe that the iron head LT1s are 10:1 with cranking compression around 200psi and run on 87 octane, better yet guys are pulling the heads on old cop cars with over 150K and finding crosshatch in the bores so cylinder wear is almost non-existent.

 

Yes that was another thing I noticed when I worked at the machine shop,
I have NEVER seen an LT1 where you couldnt still see the factory honing marks!

 

just stroke that 400 u have in your truck that should work and be cheaper than buying a lt1 and then adding stuff to it

 

would i be able to run my msd set up on that distributor or what would i have to do

 

Aftermarket ignitions can work with the LT1 but unless using nitrous or boost offer about no gains. The stock ignition is about as hot as an aftermarket coil in an HEI, going hotter mostly results in increases plug wear.