Got a ? for the LT1 gurus

**OreoLt1** · 08-02-2008, 05:35 AM

I'm looking for a rotating assembly for a 93 Lt1 but am unsure of what will fit as far as cranks. I'm looking at (starts with a J and sounds like kegs)(not a sponsor) and they list assemblies from Eagle internally or externally balanced for Gm 350's with either a 3.480 or a 3.750 stroke.

My main ? is is there a differnece in the standard 350 crank and an LT based crank?

The engine I have spun a bearing on #8. I'm sure it can be machined.010 over but would rather just get an assembly. It's going to be a DD but would like to strengthen the bottom end slightly. I plan on going with the LT4 cam kit also upon rebuild.

Any help would be highly appreciated!

**LT1 > LS1** · 08-02-2008, 06:56 AM

I am not sure, but I could probably talk to some people that would know. I know the LT1 is the second generation smallblock, but I dont know how many changes it made.

**LT1 > LS1** · 08-02-2008, 07:00 AM

well, I dug up a little stuff

Few parts from the Generation II engine are interchangeable with the old generation I engine. It uses a new engine block, cylinder head, timing cover, water pump, intake manifold and accessory brackets

**5.0THIS** · 08-02-2008, 10:17 AM

The LT1 crankshaft uses a one piece rear main seal design, so a generation one (pre 86) crankshaft wont work.

**Grimpala** · 08-04-2008, 10:42 AM

You can run any crank you want from any gen I or gen II. If it's a one piece rear seal crank then you're golden, if it's a two piece seal crank then you have to have an adapter. I just built a 383 using a one piece block and a two piece crank, went together like clockwork and no leaks as of yet(knock on wood).

I know you can go to a 3.75 stroke with just some minor pan rail and cylinder bore grinding, but I think you can go a little bigger than that if need be. One thing you have to watch for with a stroker is the cam to rod clearance. A good machine shop should be able to help you with the clearancing.

**Grimpala** · 08-04-2008, 10:45 AM

You can also use rods, slugs, & rocker arms for any gen I and gen II sbc. A wide body rocker might contact the center bolt valve covers a bit, but a little work with a cutoff wheel and that issue can be solved.

Other than the reverse cooling in the heads, and the longer dowel pin on the cam, the LT1 is almost identical to the gen I sbc, and even more like the 87-mid 90ish roller blocks.

**LT1 > LS1** · 08-04-2008, 11:17 AM

I heard the lt1 is pretty much the old TPI 350 from the thridgens, with reverse flow cooling, and a new intake.....

**5.0THIS** · 08-04-2008, 01:42 PM

Originally Posted by Grimpala

You can run any crank you want from any gen I or gen II. If it's a one piece rear seal crank then you're golden, if it's a two piece seal crank then you have to have an adapter. I just built a 383 using a one piece block and a two piece crank, went together like clockwork and no leaks as of yet(knock on wood).

I've heard some negative things about the adapters, although I admit I dont have any first hand experience with them. If it were me personally, I'd just get a one piece crank for a one piece block.

**Grimpala** · 08-05-2008, 05:27 AM

In a perfect world, yes I'd rather use a one piece crank in a one piece block and two piece in a two piece, but so far I've had good luck with the adapter.

I don't think you can put a one piece crank in a two piece block, don't hold me to that, but I know that a two piece crank in a one piece block works fine with the proper usage of RTV silicone.

**Grimpala** · 08-05-2008, 05:31 AM

Originally Posted by nitrorustler41

I heard the lt1 is pretty much the old TPI 350 from the thridgens, with reverse flow cooling, and a new intake.....

I haven't gotten in the shop and put tools to metal, but I think that with minor modification a TPI and/or Vortec manifold would fit the LT1. This could open up a whole new world of intake/f.i. options.

I'm thinking that you could use a vortec single plane manifold with nitrous bosses and an elbow/LS1 throttle body setup. Drill the bosses for fuel injectors and be able to make a little more power than stock, plus, with a few computer tweaks and wiring changes you might be able to run a stock HEI style distributer instead of the opticrap.

**LT1 > LS1** · 08-05-2008, 07:47 AM

Originally Posted by Grimpala

I haven't gotten in the shop and put tools to metal, but I think that with minor modification a TPI and/or Vortec manifold would fit the LT1. This could open up a whole new world of intake/f.i. options.

I'm thinking that you could use a vortec single plane manifold with nitrous bosses and an elbow/LS1 throttle body setup. Drill the bosses for fuel injectors and be able to make a little more power than stock, plus, with a few computer tweaks and wiring changes you might be able to run a stock HEI style distributer instead of the opticrap.

that would be awesome. are you talkin, like a normally placed distributor, on the back of the motor?

**Grimpala** · 08-05-2008, 12:01 PM

Originally Posted by nitrorustler41

that would be awesome. are you talkin, like a normally placed distributor, on the back of the motor?

Yeah, everything lines up oil pump/cam gear/dist hole. So in theory it should work. All you would need the opti for is for the optics, and there might be a way around that with a crank trigger of some sort.

**bigrondownhiller** · 08-05-2008, 03:15 PM

Originally Posted by Grimpala

I haven't gotten in the shop and put tools to metal, but I think that with minor modification a TPI and/or Vortec manifold would fit the LT1. This could open up a whole new world of intake/f.i. options.

I'm thinking that you could use a vortec single plane manifold with nitrous bosses and an elbow/LS1 throttle body setup. Drill the bosses for fuel injectors and be able to make a little more power than stock, plus, with a few computer tweaks and wiring changes you might be able to run a stock HEI style distributer instead of the opticrap.

I dont think the vortec would fit. I think it has a different bolt pattern. They do make 87-95 small block manifolds that will fit. I don't remember where I saw it but you could use a distributer too, I just don't know if it will clear the cowl.

**5.0THIS** · 08-05-2008, 03:47 PM

Originally Posted by nitrorustler41

I heard the lt1 is pretty much the old TPI 350 from the thridgens, with reverse flow cooling, and a new intake.....

No, it really isnt. LTx heads flow alot better than L98 heads. The ignition is obviously different. And the intake design is alot more horsepower oriented on the LTx motors. There's a reason L98 guys ditch not only their intakes, but also their heads. There is a lower intake manifold made for those guys who want to use the vortec heads with their upper TPI type intake setup.

**OreoLt1** · 08-05-2008, 04:49 PM

Thanks you guys for all the info!

I found a crank kit turned .010 on rods and mains. I'm going with that kit, a new rod for the damaged one, all new rings, seals, etc. Also a lt4 hot cam kit. I know I'll have to do the grinding of the crank pin so that it will fit the 93dist. I would have went with a 95 vented opti but the dist. on the vehicle is brand new. Thanks to the previous owner before getting rid of it!

I alo drilled and tapped the weep hole on the water pump and ran a nipple and a small hose to it so if the pump does fail and leak it won't leak on the dist.

I have heard that I will need a new prom once the hot cam is installed. Is this true? i have also heard that some use the stock prom and never have an issue?

**N20LT4** · 08-05-2008, 05:29 PM

Originally Posted by OreoLt1

Thanks you guys for all the info!

I found a crank kit turned .010 on rods and mains. I'm going with that kit, a new rod for the damaged one, all new rings, seals, etc. Also a lt4 hot cam kit. I know I'll have to do the grinding of the crank pin so that it will fit the 93dist. I would have went with a 95 vented opti but the dist. on the vehicle is brand new. Thanks to the previous owner before getting rid of it!

I alo drilled and tapped the weep hole on the water pump and ran a nipple and a small hose to it so if the pump does fail and leak it won't leak on the dist.

I have heard that I will need a new prom once the hot cam is installed. Is this true? i have also heard that some use the stock prom and never have an issue?

Yes you will have to have the PCM tuned after the HOT cam for optimum results.

**OreoLt1** · 08-05-2008, 06:42 PM

Originally Posted by N20LT4

Yes you will have to have the PCM tuned after the HOT cam for optimum results.

Are we just talking about getting programming for max performance or are we looking at not idling, running like crap,etc?

Are there any vendors that sell proms to correct for this that are reputable?

**N20LT4** · 08-05-2008, 07:42 PM

Originally Posted by OreoLt1

Are we just talking about getting programming for max performance or are we looking at not idling, running like crap,etc?

Are there any vendors that sell proms to correct for this that are reputable?

To achieve maximum power, driveability, etc.

Is the LT1 motor in question a '92 or 93? If so, I would strongly recommend either Harris Performance or MadTuner for a custom chip.

**Grimpala** · 08-06-2008, 04:53 AM

Originally Posted by bigrondownhiller

I dont think the vortec would fit. I think it has a different bolt pattern. They do make 87-95 small block manifolds that will fit. I don't remember where I saw it but you could use a distributer too, I just don't know if it will clear the cowl.

I would think that as long as the runners lined up that new holes could be drilled in the manifold. A little tig work, and some new holes and it 'should' work. As for the cowl, chevy didn't screw me over too bad like he did you f-body guys, I've got a canyon worth of room under the hood to play with.

I'm just day dreaming right now, until I get out iin the shop and dick with it I'm not 100% sure.

All I know is that I'm tired of the opti and I think that I can make a little more power with a better manifold.