SBC LT1 / vortec compatability

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Dirtybob
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Re: SBC LT1 / vortec compatability

Post by Dirtybob »

CGT wrote: Thu Oct 01, 2020 3:22 pm Im pretty sure the difference is the length of the dowel pin. Seems like Ive gotten a late model step nose sbc cam that came with 2 different length pins.
that and the pilot hole on the nose of the cam is 0.5" x ~1.06" to accomodate the vented (later style) opti-spark.
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Re: SBC LT1 / vortec compatability

Post by prairiehotrodder »

so i got a little carried away and pulled the motor apart without marking the pistons. Now i see they have no numbers or notch that points to the front of the motor. However this is what they do have : B ---> stamped on the top. Does this mean back ? I've never seen an arrow or any markings telling you how to put in a piston pointing to the back.

EDIT : also the cam does look like it just has a longer dowel pin than any factory roller cams i've ever seen. I most likely won't be using it. I started cleaning up a TBI block today and its not a roller cam block. I'll likely put in the cheapest comp cam in the book. Probably one of the -2 cams.
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Re: SBC LT1 / vortec compatability

Post by ProPower engines »

CGT wrote: Thu Oct 01, 2020 3:22 pm Im pretty sure the difference is the length of the dowel pin. Seems like Ive gotten a late model step nose sbc cam that came with 2 different length pins.
I just built a LT-1 and the center of the cam nose is drilled deeper as well as a longer locating pin.
A regular cam gear fits but it has to be the deeper recessed gear to clear the cam retainer button head torx fasteners.
They also make a good true roller 9 keyway lower gear setup as well to fit both the LT-1 lt-4 and the vortec style cam drive parts
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Re: SBC LT1 / vortec compatability

Post by turbo camino »

Any timing gear made for the stepped-nose cams, either 87-93 Gen1 or LT1/LT4, should have clearance for the cam retainer plate and bolts, as the stepped-nose cams were never used without the retainer plate. Changing to a different style bolt with a fatter head can cause clearance issues. Some aftermarket timing sets didn't allow quite enough clearance on the backside of the cam gear, though they don't technically hit anything it's common to grind a tiny bit off the heads of the retainer bolts just for peace of mind.

The dimensions of the stepped cam nose, either Gen1 or LT1, are the same. Bolt pattern is the same.

Aftermarket cams sold as "LT1/LT4" that have the long dowel also have a deeper hole behind the dowel, so that the cam can be retrofitted to Gen1's by simply driving the dowel in deeper to match the Gen1 length. Factory LT1/LT4 cams may not have the deeper hole in the cam and so require either cutting the dowel or pulling it and replacing it with a shorter one.

The service manual says:
When installing the piston and the connecting rod, the stamped arrow on the piston must point to the front of the engine while the flange on the connecting rod must face toward the front of the piston on the left-hand side and face toward the rear of the piston on the right-hand side.
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Re: SBC LT1 / vortec compatability

Post by ProPower engines »

turbo camino wrote: Thu Oct 01, 2020 9:56 pm Any timing gear made for the stepped-nose cams, either 87-93 Gen1 or LT1/LT4, should have clearance for the cam retainer plate and bolts, as the stepped-nose cams were never used without the retainer plate. Changing to a different style bolt with a fatter head can cause clearance issues. Some aftermarket timing sets didn't allow quite enough clearance on the backside of the cam gear, though they don't technically hit anything it's common to grind a tiny bit off the heads of the retainer bolts just for peace of mind.

The dimensions of the stepped cam nose, either Gen1 or LT1, are the same. Bolt pattern is the same.

Aftermarket cams sold as "LT1/LT4" that have the long dowel also have a deeper hole behind the dowel, so that the cam can be retrofitted to Gen1's by simply driving the dowel in deeper to match the Gen1 length. Factory LT1/LT4 cams may not have the deeper hole in the cam and so require either cutting the dowel or pulling it and replacing it with a shorter one.

The service manual says:
When installing the piston and the connecting rod, the stamped arrow on the piston must point to the front of the engine while the flange on the connecting rod must face toward the front of the piston on the left-hand side and face toward the rear of the piston on the right-hand side.
Cloyes has a factory roller cam specificd double true roller 9 key way setup.
It fits all timing covers with lots of clearance including the plastic covers.
Makes a nice change from the sloppy sets as they can be had in -.005 and -.010 shorter lengths. =D> =D>
No block grinding required. I have used maybe 30 of them to date all applications no issues. =D> =D>
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Re: SBC LT1 / vortec compatability

Post by 1980RS »

prairiehotrodder wrote: Mon Sep 07, 2020 10:00 pm will the cam / lifters and the rods / pistons out of a 93 buick roadmaster LT1 go into a 96-98 350 vortec truck engine ? I have the roadmaster engine and i'm trying to build another ultra low buck JY motor for my sons jr. street drag car 1980 malibu 4 door. I haven't taken the motor apart yet but i 'm thinking it might have factory flat top pistons, powder metal rods and a bigger cam than the vortec truck motor ? can anyone verify this ?
Brian
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Re: SBC LT1 / vortec compatability

Post by gmrocket »

ProPower engines wrote: Thu Oct 01, 2020 10:00 pm
turbo camino wrote: Thu Oct 01, 2020 9:56 pm Any timing gear made for the stepped-nose cams, either 87-93 Gen1 or LT1/LT4, should have clearance for the cam retainer plate and bolts, as the stepped-nose cams were never used without the retainer plate. Changing to a different style bolt with a fatter head can cause clearance issues. Some aftermarket timing sets didn't allow quite enough clearance on the backside of the cam gear, though they don't technically hit anything it's common to grind a tiny bit off the heads of the retainer bolts just for peace of mind.

The dimensions of the stepped cam nose, either Gen1 or LT1, are the same. Bolt pattern is the same.

Aftermarket cams sold as "LT1/LT4" that have the long dowel also have a deeper hole behind the dowel, so that the cam can be retrofitted to Gen1's by simply driving the dowel in deeper to match the Gen1 length. Factory LT1/LT4 cams may not have the deeper hole in the cam and so require either cutting the dowel or pulling it and replacing it with a shorter one.

The service manual says:
When installing the piston and the connecting rod, the stamped arrow on the piston must point to the front of the engine while the flange on the connecting rod must face toward the front of the piston on the left-hand side and face toward the rear of the piston on the right-hand side.
Cloyes has a factory roller cam specificd double true roller 9 key way setup.
It fits all timing covers with lots of clearance including the plastic covers.
Makes a nice change from the sloppy sets as they can be had in -.005 and -.010 shorter lengths. =D> =D>
No block grinding required. I have used maybe 30 of them to date all applications no issues. =D> =D>
You have a part# for that double roller that fits all blocks?

Does it Even the opti spark Aluminum cover?
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Re: SBC LT1 / vortec compatability

Post by prairiehotrodder »

1980RS wrote: Fri Oct 02, 2020 9:52 am
prairiehotrodder wrote: Mon Sep 07, 2020 10:00 pm will the cam / lifters and the rods / pistons out of a 93 buick roadmaster LT1 go into a 96-98 350 vortec truck engine ? I have the roadmaster engine and i'm trying to build another ultra low buck JY motor for my sons jr. street drag car 1980 malibu 4 door. I haven't taken the motor apart yet but i 'm thinking it might have factory flat top pistons, powder metal rods and a bigger cam than the vortec truck motor ? can anyone verify this ?
Brian
The short answer is "YES"
it does have flat tops but it has the normal old style forged connecting rods.

Does anyone know what this means : B---> on the top of the piston ?
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Re: SBC LT1 / vortec compatability

Post by ProPower engines »

[/quote]

Cloyes has a factory roller cam specificd double true roller 9 key way setup.
It fits all timing covers with lots of clearance including the plastic covers.
Makes a nice change from the sloppy sets as they can be had in -.005 and -.010 shorter lengths. =D> =D>
No block grinding required. I have used maybe 30 of them to date all applications no issues. =D> =D>
[/quote]

You have a part# for that double roller that fits all blocks?

Does it Even the opti spark Aluminum cover?
[/quote]

There is a specific timing set for the LT-1/LT-4 but there is also a set for the late model 1 piece rear seal blocks which covers from 89 to 2000ish. Also available in -.005 and .010 shorter.
FYI they are in the thin Cloyes supplemental HP catalogue but when I get time I can look them up again
for you or contact cloyes directly.
I also believe there is a couple other brands I have seen as well but chain was off shore gears US made.
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Re: SBC LT1 / vortec compatability

Post by F-BIRD'88 »

Why all this parts swapping. Why are you not running the
complete 350 LT-1 engine as is?
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Re: SBC LT1 / vortec compatability

Post by turbo camino »

prairiehotrodder wrote: Fri Oct 02, 2020 10:46 am it does have flat tops but it has the normal old style forged connecting rods.

Does anyone know what this means : B---> on the top of the piston ?
From a few replies back:
When installing the piston and the connecting rod, the stamped arrow on the piston must point to the front of the engine while the flange on the connecting rod must face toward the front of the piston on the left-hand side and face toward the rear of the piston on the right-hand side.
If there is something that looks like an arrow, it points to the front.

The L31 PM rods are better than the old rods. As was said very early on in this thread, there's nothing special or better about the LT1 internals.
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Re: SBC LT1 / vortec compatability

Post by Monzsta »

Just a note on driving that longer pin in. I just got done with a build using an LT4 HotCam. That pin wouldn't move and began to mushroom and bend. So I cut it to length and dressed the end. I don't know if you could save the cam if that pin broke off but I for one wouldn't want to try.
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Re: SBC LT1 / vortec compatability

Post by gmrocket »

ProPower engines wrote: Fri Oct 02, 2020 5:42 pm
Cloyes has a factory roller cam specificd double true roller 9 key way setup.
It fits all timing covers with lots of clearance including the plastic covers.
Makes a nice change from the sloppy sets as they can be had in -.005 and -.010 shorter lengths. =D> =D>
No block grinding required. I have used maybe 30 of them to date all applications no issues. =D> =D>
[/quote]

You have a part# for that double roller that fits all blocks?

Does it Even the opti spark Aluminum cover?
[/quote]

There is a specific timing set for the LT-1/LT-4 but there is also a set for the late model 1 piece rear seal blocks which covers from 89 to 2000ish. Also available in -.005 and .010 shorter.
FYI they are in the thin Cloyes supplemental HP catalogue but when I get time I can look them up again
for you or contact cloyes directly.
I also believe there is a couple other brands I have seen as well but chain was off shore gears US made.
[/quote]

The double roller part # for the LT1 with one piece rear seal and opti spark Is what I’m looking for
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Re: SBC LT1 / vortec compatability

Post by turbo camino »

Monzsta wrote: Fri Oct 02, 2020 9:04 pm Just a note on driving that longer pin in. I just got done with a build using an LT4 HotCam. That pin wouldn't move and began to mushroom and bend. So I cut it to length and dressed the end. I don't know if you could save the cam if that pin broke off but I for one wouldn't want to try.
Yes. Seems like someone already mentioned this, about GM cams and aftermarket being different in how they deal with the dowel pin thing and backwards compatibility...
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Re: SBC LT1 / vortec compatability

Post by 1980RS »

When I worked for GMC back in the late 90's they were using all the left over LT1-4 bottom ends in the 1 ton trucks. I bought a core engine that had low oil pressure at Idle. Pulled it apart and the 350 had a forged steel crank, 4 bolt main, windage tray and PM rods. Pretty good deal for $50 with 8K on it. If I take it apart I will just stick a HV oil pump in it as it spins to 6500 pretty easy. All the LT1 bottom end stuff changes with the Vortec stuff.
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