J-13gtp

iTrader: (1)

Just when I think I get a break everything falls apart again. But anyway I have a new set problems. As some might know I recently purchased a complete lt1 engine out of a Caprice. So all was good until I started the tare down and found that the block was cracked, first failure. So I begin looking for another block to replace the cracked one. I find a bare block and purchase it and at this point I'm pleased with myself since I got this block for a good price. So I finally get the first block completely tore down and get the internals ready for cleaning/etc at a local machine shop. I pack everything up and head straight for the machine shop. I pull up and discuss things over with the man that runs the shop and we decide to step out and look over what I got in the back of the truck. He then proceeds to tell me that the pistons are to small, at this point in time I realize that all my time and money just went out the window, and that the complete engine I had bought earlier was actually a baby lt1. So I pack everything back home. Now I'm stuck with all this parts now.

I know the pistons and the heads wont work. But my question is, will the crankshaft and connecting rods out of baby lt1 work in a lt1?
Any suggestions at this would be greatly appreciated.

ss.slp.ls1

iTrader: (36)

The stroke and rod length of a L99 (baby LT1) are identical to a LT1. Therefore I assume the crank and rods are identical. Only the bore is smaller, thus the pistons are smaller.
You should be able to cut/polish the crank, recondition the rods and use ARP rod bolts, and you might even be able to overbore the L99 block to a 4.000" bore and reuse some stock LT1 pistons with new rings and all new bearings. If you have the cash, install some nice Mahle forged aluminum pistons. Should make for a good 350/355 (if you open up the bore to 4.030" with some 4.030" forged pistons) to bolt on a LE/Ai top end.

luckyou03

iTrader: (8)

Sounds like my bad experiences... I had a bad lt1 block so i drove about 200 miles to pick up another one. Gave it to my machine shop and they bored and assembled it doing a horrible job. the cylinders still had wear in them on my fresh engine. and they cracked a ring and installed it anyways.. so i found a new machine shop and bought a 3rd lt1 block and they machines and assembled it right.

rkinney

I believe the L99 "baby lt1" uses a 3" stroke crank (same main journal size) and a 5.94" rod as well as a smaller bore.

J-13gtp

iTrader: (1)

So i should be able get a set pistons and it well work. What about the rod pins well they be the same.

ss.slp.ls1

iTrader: (36)

Where did you get that from? Not doubting you, just want to know what it really is. I read it's only a smaller bore, but to be down more than a liter in displacement, seems like it needs more to be smaller/shorter.

EDIT: You are probably right. With my math, if the baby LT1 did in fact use the same stroke as a LT1, then it would need ~2.46" piston, whish I doubt it uses, lol.

piston diameter = sqrt((2*265)/(8*3.48*pi))
=2.46...

265 - cu in displacement of a baby LT1 (I think)
3.48 - LT1 stroke
pi = 3.14159...(duh)

J-13gtp

iTrader: (1)

Forgive me if i sound dumb. But if i get what your saying then i wont be able to use the baby lt1 internals for a lt1 setup?

ss.slp.ls1

iTrader: (36)

If the stroke and rod length are in fact smaller, then no, you can't use any internal pieces from the baby LT1. I'd sell it and look for a rebuildable LT1 short block. All LT1's have "327" cast on the side of the block, that's how you'll know it's a 5.7 liter.

rkinney

I have read it in a few different places, one being the online gm service manual when I was a tech. You can also find the info on the net. That is how you can make a current "302". It was also in one of the magazines where they took the crank from the l99(4.3L, 3.75" bore) to make a 302 with the LT4 top end package. I am sure you can find the article by doing a search. Of course it does require different pistons due to the different stroke, but that little bitch will rev.

rkinney

On another forum a guy built a 302 for his impala and he said he used the l99 crank, l99 rods, and stock lt1 pistons. I kinda wonder what the piston to deck height came out to. Not sure if the piston compression height is different between the LT1 and the L99. I'll do some more searching.

rkinney

You should be able to use the stock LT1 pistons with the l99 crank and rods, but will give you a 302. You would need to get the crank rebalanced for the heavier pistons which could cost some money. Depends if you want a 350 or a 302 and how much power you plan to produce. Not sure of the strength of the L99 internals.

J-13gtp

iTrader: (1)

Back to square one then. Id like to have the 350 so using l99 internals is out. Another question, wIll any average sbc 350 crankshaft work in the lt1?

joelster

Never turn down cubes dude. 350>302 all day long. They will throw arguments out there that the 302 can rev higher....bs......The opti limits us to 7000rpm. 350's can run that high too. Anyone that tells you different is simply wrong. Go get yourself some LT1 internals. Leave the L99 crap for the taxis.