wht97ws6ta

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.

thesoundandthefury

iTrader: (3)

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.

wht97ws6ta

The only thing u would have to drill is mabey making the stud holes deeper. U may have to drill on into the intake port, but thats no big deal. As far as the insert, im going from the origional 7/16 hole to 5/16. Not reusing the 8mm bolts. Prolly get some allen head hardened bolts.

wht97ws6ta

U also have to consider that u are somewhat distributing the load between 2 bolts now be the shaftmounts ties them together.

thesoundandthefury

iTrader: (3)

Is the thread diameter on a 5/16 bolt the same as that of an 8mm bolt?

wht97ws6ta

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.

Formula350

iTrader: (3)

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)

wht97ws6ta

You got me a little confused here. And i know that everyone has their on way of looking at some things. I just wish people would grow out of the tunnel vision and step back and look at the whole picture. Just because sich and so ran the wrong springs doesnt mean its a bad idea. Setting the springs up wrong doesnt have one thing to do with a rockerarm. And having the right rockerarm geometry would only insure that u are getting everybit of ratio or valve velocity u can get. The idea is to set the rocker up so that is has minimum travel across the valvestem tip. If the rocker centerline is to high in relation to the valvetip then u have lost velocity. In this case the downward motion is comprimised for side to side motion, due to the angle of the arc or part of the circle u are using. If the centerline is to low then u havent lost as much velocity, but have induced side loading on the valve resulting in lots of valveguide wear. But anyways instead of using someones mistakes as a stumbling block, use them as a building block. I think u will be amazed at what u can find.

thesoundandthefury

iTrader: (3)

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:

The second guy, "Outkast," said this:


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.

wht97ws6ta

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.

Formula350

iTrader: (3)

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.

Revelation Z28

iTrader: (10)

what about going 7.4 rods with the LS1 rockers?

LOL aww how sweet

Formula350

iTrader: (3)

You're now TinkerBell for that remark

CodeRed2000SS

drew u are the man... enough said haha

wht97ws6ta

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.

wht97ws6ta

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.

CodeRed2000SS

yea i know haha, this year the goal is to get some scratches on the back bumper.....

1989GTA

"Also GM PP guide plates ($45) and hardend pushrods if you have them or not. "

Why do you need guideplates with shaft mounted rocker arms?

wht97ws6ta

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.