350 LT1 long block

[rholbrook]

What is a good price for a LT1 long block with the aluminum heads? My plans are to get it machined for a Scat 383 rotating assembly, clean up the heads, bigger cam and multi-port injection for my boat. My goal is 400HP+ on regular gas. Its going to replace a 260HP 305 that works good at lower elevations but needs help up here. I continually have 2 big tubes behind my boat and I want some more power.

I have a motor lined up for $450 but I have no idea what they go for.

Incidentally, I will have the motor coming out of it for sell as a long block.

 

[MikeGyver]

It's not really possible to make that much power on stock LT1 heads naturally aspirated. Heads and a matching cam is everything. Stroking it and changing the cam won't hardly do anything because the heads are the bottleneck on those.

 

[B2-Bomber]

the max power on LT1 heads is around 425hp. and it's not super hard to get. but on pump-gas that's a pipe-dream. Those reverse-cooled engines, with the fast-burn combustion chambers love compression. But around .750" lift cam the flow is maxed.

 

[rockdog]

What out drive do you have on your boat? Merc alpha's don't like a lot more than 300 ponies. I have the same gutless 305 in my crestliner. I'm going to change it out for an L31 crate from summit. It is a new crate from gm, has vortec heads and roller cam for a little over 2 grand. With a good single plane intake and 600 cfm carb you should be a little over 300 horses.
If your 305 is the same as mine,(2barrel carb ) your lucky to be pushing 200 horses. The extra 100 horses will really make a huge difference in your boat.
My old boat had a 260 horse 350 in it and weighed half again more than my crestliner. It would run circles around my gutless 305. Worst motor gm ever made!

 

[B2-Bomber]

The l31 heads have the exact same ports as the lt1. But with a non reverse-flow cooling. They also were equipped in '96-'99 Chevy trucks. So a j/y engine could be found easily.
Be forewarned, l31s do have a known head cracking issue. But are still an amazing engine.

 

[Greg]

.... But around .750" lift cam the flow is maxed.

That is a shit-ton of lift @ the cam....

 

[rholbrook]

My current 305 is a 260HP multi-port FI now. It just doesnt have any torque so thats what I am really after. I really like my boat but it just doesn't have enough out of the hole.

My BIL has a repair shop and he builds a ton of motors. He seems to be the guy everyone goes to for their airboat motors too. He currently has a airboat in his shop right now getting the motor out of a Z06.

His personal airboat has the 6.2L supercharged motor. When he bought the motor he got to choose whether he wanted the Cadillac CTS V Emblem or the Corvette ZR1 emblem. Lingenfelter provided some nice upgrades to it as well to give it an extra 100hp. That would be a fun motor in anything but an airboat.

I tend to think that if he tells me he can get 400hp+ out of it and a whole bunch of torque, I tend to believe him. I don't know what all he has planned for it because I don't understand the lingo but it will be fun to see what it will do.

 

[Tacoma]

That is a shit-ton of lift @ the cam....

That's what I was thinking. Holy cripes. LOOOOTS of other issues to very, very precisely consider w/that much lift...

 

[rholbrook]

I forgot to mention that I have a Bravo 3 duo-prop. I know that my parts list does include a ProComp Xtreme Marine Cam. I did remember that part. I have no idea what the lift on it is.

 

[rockdog]

I forgot to mention that I have a Bravo 3 duo-prop. I know that my parts list does include a ProComp Xtreme Marine Cam. I did remember that part. I have no idea what the lift on it is.

The bravo will like the ponies a lot better than my wimpy alpha. Your boat is newer than mine. My nephew put a 383 stroker in his. It seems to scoot along pretty good. Hell I'd be happy to just be able to go to strawberry and be able to get up on plane within half a mile!

 

[Greg]

I forgot to mention that I have a Bravo 3 duo-prop. I know that my parts list does include a ProComp Xtreme Marine Cam. I did remember that part. I have no idea what the lift on it is.

Comp cams... i don't think Pro Comp makes cams..... yet.

Probably around .490-510 lift.... that's a much more usable cam lift height for a warmed up SBC. The mention of .750 lift at the cam is absurd.

I'd highly recommended getting a cam that's a hydraulic roller and add a set of 1.6 ratio roller rockers, you can make power all over the RPM range versus a flat tappet cam. Get one that comes on around 1,500 RPM to work with the torque of the 383... and should still be good for 5,500-6000 RPM if you need it.

The price for the engine sounds reasonable, have you added up the grand total for rebuilding that motor and turning it into a stroker? The only reason I ask is because I had considered building up a 383 for my truck, but swapping in a newer 6.0 truck engine will get you similar power for much less money and if you shop around you can probably find a good runner that doesn't need a rebuild. With a few simple changes and a tune you can get 450 HP & TQ out of a 6.0l engine.

 

[Tacoma]

^^ What Greg said about roller rockers and cam, x2.

 

[MikeGyver]

the max power on LT1 heads is around 425hp. and it's not super hard to get. but on pump-gas that's a pipe-dream. Those reverse-cooled engines, with the fast-burn combustion chambers love compression. But around .750" lift cam the flow is maxed.

lol wut