ok so i have a 1994 LT1 and i had it machined line honed and ect to be converted to 4 bolt billet caps since its a YSI rebuild with a good amount of estimated power when its done.... well my engine builder which normally does BBCs and other big blocks, some SBCs and some LT1s is telling me that he has about 3 or 4 new timing chain/gear sets and they are a little loose due to the machine work for the 4 bolt conversion.... he said since LT1 stuff is kinda limited that the smallest one is still a little loose, too loose to put back together anyways.... guys i have no idea what my options are and like i say he has built some LT1s but this is a new situation for him as well.... is there no place the builds custom size timing chain sets, im sure there is a right way to fix this problem and i see thunder racing has a bigger crank sprocket for $40 but who knows if that will work on my 1994 or if it wil be enough to take up the slack, also maybe converting to the vented opti with the bigger timing cover can maybe be an option but i really dont wanna go that route plus i dont think it 100% fixes this issue... any help is greatly appriciated!!!! jake

 

Sounds like the line hone has created too much play in the timing set. A crank sprocket from a SBC will work fine.

 

what boost and what heads are you going to run? i am trying to decide for my build, running 12 psi but cant decide on heads

 

did you use the cheap caps? my builder said the cheap caps are so hard that when you do the line bore it tends to take more out of the block, which makes you use special timing chain sets that compesate for the bore. so what you saved on the caps you spend in the timing set and electric w/p. so it sounds like you will have to run a sbc timing set and use an electric w/p.

link to timing sets...

http://store.summitracing.com/partde...5&autoview=sku

http://store.summitracing.com/partde...0&autoview=sku

http://store.summitracing.com/partde...5&autoview=sku

 

What you had happen is your machinist 'sunk the crank', ie machined the block side more, thus the crank is closer to the cam. This also, at the very least, changed the deck height of the piston tops to the block surface.

If everything else checks out, as mentioned, the only solution is a custom double-roller standard SBC timing set and converting to a vented optispark as well as an electric waterpump. No real other options, as there is no such thing as a "custom chain", in that they all have to conform to the tooth spacing on the gears, thus a complete custom set has to be used for proper tooth spacing on the gears and gear link spacing on the chain.

It really does suck to have that happen, especially on a block that has had quite a bit of machine work done to it...

See if the machine shop will redo all the work you had done prior (bore, hone, 4-bolt conversion, decking, etc) on a new block if you supply the block as this one is, basically, unuseable (I mean really, for the extra $1k+ you would have to spend to do a vented opti, EWP, GEN I custom timing set it is unuseable). Most times the machinist will see it as a 'cheap' way out and readily agree. To be honest THEY should replace the block and redo all the machining, but getting most places to do that is damn near impossible.

Just explain the situation, I am certain the machinist has had to deal with this before on other motors, and once you explain there is not a timing set available to fix this on THAT year motor he will understand he has to do something to make it right.

Do NOT allow him to tell you that slack is OK, as all you have to explain is the optispark does all engine timing for the computer and it will not time right if there is slack.

 

that happen to me on my 383. mine was a lil loose but never caused a problem.
and as far as deck height, i was running -28cc dished piston. didnt have to worry about valve hitting ****

 

thanks guys, so are you telling me the only way that could have happend is someone sank the crank???? how could it have been done in any other way???? i already run a electric water pump, so the other way would be to go with a 96 vented opti with the 96 timing cover and ect and go with a smaller sbc timing chain/gear kit???? thanks for the help as well....


but atthe same time when that procedure is done the area is machined evenly all around or it wouldnt even work.... im thinking possibly that this is a very commom thing and you just have to deal with it if you have a 1993 or a 1994 LT1.... i really dont think the machinist made an error, but anything can happen.... jake

 

mine was a 97 and it happend. it also caused a huge oil leak that i had to fix......front and rear mains.
they could have directed the honing more toward the caps. it should have been thought of prior to honing. most guys that are use to building small blocks and big block are old school and dont have to worry about these problems.

 

yeah but does it not have to be symetrical all around???? and what is done has to be done perfectly for a perfect circle???? if so that would mean there couldnt be any done more on one side or another.... but like i say im new to this issue so im not saying, im asking... jake

 

good point but your telling me the cheaper ones would be made of stronger, better billet steel???? but no mine were $500 for the caps alone, maybe those are cheaper ones i dont know but they cost me a bunch LOL anyways thats kinda hard to belive they use stronger stuff for the cheaper ones but anything is possible these days

 

they are supposed to machine the main caps to compensate for that. that way most of the meat thats getting cut out is in the caps. ive had main caps come loose and they had to stretch them and machine the bottoms where its flat and a line bore. did not effect the timing chain at all.

 

yeah but still if you bore the caps more wouldnt it be off???? or am i wrong when im thinking that the bore itself needs to be perfectly symetrical??? which would mean the same take from the block as there was the caps.... sorry for all the questions, but thanks for the info as well!!!! jake

 

no. cuz your machining the flat part of the main cap. wich brings the cap bearing closer to the block. so you machine the hole like you always would. you would be cutting most of it off the cap. you would be cutting hardly anything off the block. thats just how my machine shop does it.

 

Fact of the matter... THE MACHINIST F*CKED UP!

Honestly, THEY are supposed to know how to line bore/hone and not sink the crank. It is done all the time. When they mess it up it gets sunk into the block instead of staying 'on bore'. No two ways about it.

It really is frustrating to give EXACT and PERFECT information, just to have someone argue with you and say that you are wrong.

Tell you what, go call at least a dozen machine shops. Explain it to them. Let them tell you what *SHOULD* have been done, and what *DID* happen. Hell call some premier engine builders that are famous throughout the US, they will explain how it is F*CKED-UP!

On a regular GEN I SBC you can get special timing sets to deal with it *IF* you want to. For the LT1 motors that DOES NOT EXIST. You have to run a special GEN I SBC timing set. And, as mentioned if you do that you need to run a 95+ vented opti conversion and an EWP.

Don't ask for info, and when you get it you try to argue about it. We were nice enough to supply the info, now go validate it SO YOU KNOW!

Otherwise, why even ask???

 

And if you are being timid about this because you don't want to go telling your machinist he fucked up, suck it up, you have to. Stand up for what you need taken care of.

The machine shop should come right out and explain how it is messed up... And your mechanic should know how to deal with this as well, otherwise he isn't much of a mechanic (ie, lack of experience), and should stay away from motor rebuilding.

 

500.00 for just the caps, man you got robbed! i used pro gram caps as recommended by my engine builder ( who builds monster truck and pro mod engines!!!!!) and they where only 250.00. so something is very wrong there. and the cheap *** hard caps is why you tend to take more of the block instead of the cap. have you ever tried to drill a broken bolt out of aluminium? if your not very carefull the drill bit will walk towards the aluminium because it is softer than the bolt. try it sometime. you'll understand what happens then.

x2!

 

my caps were like 500 also.

 

let me explain something to you guys, on LS1tech there are ALOT if idiots that think they know EVERYTHING when 90% dont know **** and talk a big game and honestly i dont know if you guys know any more than i do so i asked a few questions back, no big deal.... i was just simply asking back a few questions not arguing with anybody.... can you read when i said i was just asking, not saying???? read my words before acting like a baby!!!!!!


and thaks for the info as well and i didnt mean to argue if you guys took it that way.... jake

 

I agree completely with Jake on this. That is why I always give the advice that you should ONLY listen to the people who actually have done these types of builds themselves. There is alot of bad information that gets circulated around here.

Jake, have you considered the Cloyes double roller timing set? That is the "tightest" set I have used and would probably work fine on your engine. Off the top of my head I believe it's part number 9-3145. It's pretty inexpensive too. I have a brand new extra one here if you would like to try it without purchasing one first. I'd be glad to send it to you and if it works, just pay me then. If not, send it back to me. The only stipulation is that you must run an electric waterpump.

Jason

 

Isn't there an LT4/extreem timing set that has an oversized crank gear? Might want to search some boards. I really think there was a different gear set if the standard LT1 timing set had too much slack.

But if your going to have allot of boost then i would certainly want to go with a double roller timeing set.