LS1 Rockers on LT1
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From: Kinston North Carolina
And their not as bad as everyones making them. The 2 years of 98 and 99 was when they were bad about spitting needle bearings. GMs actually got a bullitin. Anything on in the 2000s are fine. I know people running ms4s with them with no problems. The only reason why anyone should put aftermarket rockers on an LS1 is if their running a solid cam.
Hey everyone. Im new to this site and was doing some searching on this forum about putting LS1 rockers on an LT1. I have been researching it and plan to do this myself. The one thing i noticed everyone was doing is drilling the rockers to fit the 3/8 lt1 studs. This is IMO is completely pointless other than the gained lift. Why not get some Bigserts to adapt the rocker stud holes from 7/16 to 5/16. This will allow you to run the LS1 link bar to make em shaft mounted and do away with guide plates altogether. The only thing is, is ud probably have to buy diferent length pushrods of coarse. But the whole setup would do wonders for upper RPM valvetrain stability, which equates to HP.
https://ls1tech.com/forums/lt1-lt4-m...r-rockers.html
The Yella Terra shaft rockers I linked are designed to mount up like a traditional stud mount rocker. On an LSx engine, no machining is required. Whether that be the case on an LTx remains to be seen.
The only real concern I had was that if you were to drill the stock stud holes out to install 8mm threaded inserts, if there would be enough meat left over in the mount to keep it from cracking around the base under load.
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https://ls1tech.com/forums/lt1-lt4-m...r-rockers.html
The Yella Terra shaft rockers I linked are designed to mount up like a traditional stud mount rocker. On an LSx engine, no machining is required. Whether that be the case on an LTx remains to be seen.
The only real concern I had was that if you were to drill the stock stud holes out to install 8mm threaded inserts, if there would be enough meat left over in the mount to keep it from cracking around the base under load.
The Yella Terra shaft rockers I linked are designed to mount up like a traditional stud mount rocker. On an LSx engine, no machining is required. Whether that be the case on an LTx remains to be seen.
The only real concern I had was that if you were to drill the stock stud holes out to install 8mm threaded inserts, if there would be enough meat left over in the mount to keep it from cracking around the base under load.
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https://ls1tech.com/forums/lt1-lt4-m...r-rockers.html
The Yella Terra shaft rockers I linked are designed to mount up like a traditional stud mount rocker. On an LSx engine, no machining is required. Whether that be the case on an LTx remains to be seen.
The only real concern I had was that if you were to drill the stock stud holes out to install 8mm threaded inserts, if there would be enough meat left over in the mount to keep it from cracking around the base under load.
The Yella Terra shaft rockers I linked are designed to mount up like a traditional stud mount rocker. On an LSx engine, no machining is required. Whether that be the case on an LTx remains to be seen.
The only real concern I had was that if you were to drill the stock stud holes out to install 8mm threaded inserts, if there would be enough meat left over in the mount to keep it from cracking around the base under load.
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Yea they are very close. Only a few thousandths differece. And the reason for 5/16 is they are easier to find the inserts than 8mm. Im actually not even doin this to my LT1 right now. Im putting them on a set of double hump iron heads that im hoppin up for the 355 thats goin in my 69 nova strip car. One other thing im doin to them which i thought was pretty neat is im putting the 5/16 bronze guide liners in the the stock 11/32 hole to run the LS1 valves and springs. The total weight difference between the stock 1.94 int valve and the 5/16 2.00 LS1 valves retainers and keeper is like 30 grams lighter. So thats deffinity gonna stabilize that train somemore. I will be doin this to my LT1 when i get the funds to build my 408.
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Hmpf, apparently I forgot to click "post"...
I read all 5 pages of those 2 guys who did the conversion. With an open mind and unbaised opinion, I think I'm going to have to say I don't think it's a good idea. The guy used springs with a max lift of .525 for over 2 years, where the calculated lift of his cam + LS1 rockers is around .560. I think that beating on the motor for 2 ears with his springs maxed out like that would've resulted in failure right away. So like the last post stated, it's a fair assumption that with the right geometry, you're not actually getting 1.7 ratio. But, cheap mod for ~1.6s for a person like me on a zero budget (anyone want to XMas me their old shorties? lol)
I read all 5 pages of those 2 guys who did the conversion. With an open mind and unbaised opinion, I think I'm going to have to say I don't think it's a good idea. The guy used springs with a max lift of .525 for over 2 years, where the calculated lift of his cam + LS1 rockers is around .560. I think that beating on the motor for 2 ears with his springs maxed out like that would've resulted in failure right away. So like the last post stated, it's a fair assumption that with the right geometry, you're not actually getting 1.7 ratio. But, cheap mod for ~1.6s for a person like me on a zero budget (anyone want to XMas me their old shorties? lol)
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Hmpf, apparently I forgot to click "post"...
I read all 5 pages of those 2 guys who did the conversion. With an open mind and unbaised opinion, I think I'm going to have to say I don't think it's a good idea. The guy used springs with a max lift of .525 for over 2 years, where the calculated lift of his cam + LS1 rockers is around .560. I think that beating on the motor for 2 ears with his springs maxed out like that would've resulted in failure right away. So like the last post stated, it's a fair assumption that with the right geometry, you're not actually getting 1.7 ratio. But, cheap mod for ~1.6s for a person like me on a zero budget (anyone want to XMas me their old shorties? lol)
I read all 5 pages of those 2 guys who did the conversion. With an open mind and unbaised opinion, I think I'm going to have to say I don't think it's a good idea. The guy used springs with a max lift of .525 for over 2 years, where the calculated lift of his cam + LS1 rockers is around .560. I think that beating on the motor for 2 ears with his springs maxed out like that would've resulted in failure right away. So like the last post stated, it's a fair assumption that with the right geometry, you're not actually getting 1.7 ratio. But, cheap mod for ~1.6s for a person like me on a zero budget (anyone want to XMas me their old shorties? lol)
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Hmpf, apparently I forgot to click "post"...
I read all 5 pages of those 2 guys who did the conversion. With an open mind and unbaised opinion, I think I'm going to have to say I don't think it's a good idea. The guy used springs with a max lift of .525 for over 2 years, where the calculated lift of his cam + LS1 rockers is around .560. I think that beating on the motor for 2 ears with his springs maxed out like that would've resulted in failure right away. So like the last post stated, it's a fair assumption that with the right geometry, you're not actually getting 1.7 ratio. But, cheap mod for ~1.6s for a person like me on a zero budget (anyone want to XMas me their old shorties? lol)
I read all 5 pages of those 2 guys who did the conversion. With an open mind and unbaised opinion, I think I'm going to have to say I don't think it's a good idea. The guy used springs with a max lift of .525 for over 2 years, where the calculated lift of his cam + LS1 rockers is around .560. I think that beating on the motor for 2 ears with his springs maxed out like that would've resulted in failure right away. So like the last post stated, it's a fair assumption that with the right geometry, you're not actually getting 1.7 ratio. But, cheap mod for ~1.6s for a person like me on a zero budget (anyone want to XMas me their old shorties? lol)
Yeah, both of those guys took the "quick and dirty" approach.
There were a few details that were never mentioned anywhere in that thread that I'm willing to bet were never taken into consideration when this idea was being hatched.
The first is that an SBC/LT1 camshaft diameter is 48mm, vs. 55mm's for Gen III. So right there from the get-go, if all other things were equal, there's a 7mm "gap" that needs to be compensated for.
The second is that the Gen III engine blocks have a raised cam, so the pushrod angle between the two blocks is different.
The third is that the stock LT1 pushrod length is 7.200", vs. 7.400" for stock LS1. So once again, if all other things were equal, by using the stock length LT1 pushrod you're shortchanging yourself some lift.
The OP said:
To run them, you must drill out the bolt hole to the size of your rocker studs. 3/8 or 7/16.
You must then use the lock nuts that you would use for a set of standard SBC roller rocker arms. Cost around $40
Also GM PP guide plates ($45) and hardend pushrods if you have them or not.
You must then use the lock nuts that you would use for a set of standard SBC roller rocker arms. Cost around $40
Also GM PP guide plates ($45) and hardend pushrods if you have them or not.
I spoke with two local shops in my area and both feel that the pushrod size should not change. It was suggested to check that the rocker is correctly aligned with the valve tip. I'll be checking it out this week so I'll post pics of what I find.
My valve springs are good to .600 and my cam @ 1.7 will go to .589
My valve springs are good to .600 and my cam @ 1.7 will go to .589
Moral of the story: this can be accomplished, it's just going to require somebody who isn't going to rely on a bunch've guesswork and hunches, but willing to take the time to get all of the correct measurements and get some hard numbers.
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Yea you cant assume anything when it comes to building motors. And i know not everyone has all the tools to do stuff like this. And most engine builders arent even remotely interested in something like this. But im young and curious so by gosh ill try something if i know i can make it work. But i should have the setup working on a conventional SB here in a month or so. And i will be hanging that puppy on the dyno. Only downfall is i will be comparing them to stock stamped steel rockers unless i can find some rollers to make dyno mules out of.
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Well those are good points TSATF (your new nickname, unless you want me to call you something else lol), but with all that factored in then, what is the rocker ratio of those 1.7s on a GEN I/II engine? If it's 1.5 and doesn't drop way down compared to stock(I believe stamped ones end up around 1.4 at full lift) then it'd be a good upgrade for stock rockers since you gain roller fulcrum 
If someone could list all the right steps needing to be done, this might not be bad. The one thing they did, that I'd do over what Wht is, would be drill out the rockers but in a drill press.
If someone could list all the right steps needing to be done, this might not be bad. The one thing they did, that I'd do over what Wht is, would be drill out the rockers but in a drill press.
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I honestly dont know what length pushrod its gonna take. Just depends on how much i will have to cut the stud bosses down to get the rocker geometry dailed in. Im pretty sure the conventional SB stuff is gonna be longer than 7.400 with flat tappet cams. LT1s are gonna be shorter due to the hyd roller lifters. They may be in the neighborhood of 7.400 may be even shorter. If im not badly fooled i believe Lt1s are either 7.400 or 7.600 i cant rightly remember.
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Yea man. I like how u got the starting line to drop about 3'' there in that pic with the blue meanie leavin. Makes it look like its poppin a wittle whillie there. Haha. I can do better than that with da pro stock lawnmower. Heak i cut a 2.31 60' with it peddling it to keep it down lol. I gotta pick on ya man. Haha.
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My goal is wheelie bars if i make back to the track with the lawnmower. That dang track bite is pretty abrassive on the lower back. Lol If i would have had the bars that nite im quite sure i could have run a low 11s in the 1/8. Oh well i guess if i dont run it again then a 12.41 at 53 mph is an aight 1/8 mile for a lawnmower.
