mysterious crank
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Launching!
Joined: Nov 2005
Posts: 282
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From: Baytown (dirty bay) , TX
mysterious crank this weekend while putting in my lt4 hot cam, we noticed that my crank was an after market forged crank. does that probably mean the rods and pistons are forged too? also, would it be ok to drive my car with the stock valve springs and pushrods until i get stiffer springs? Do you have to pull the heads to replace the valve springs and pushrods?
You can lay odds that if your crank is forged, whoever built the motor probably used other forged parts. But the only way to check is take it apart. Drop the oil pan to look at the rods, pull the heads to look at the pistons. 
I'd get better valvesprings than stock. Even LT4 springs (well, back in the day) could be had for cheap (I sold a set for like $25 shipped, new, a few years ago). Are you running aftermarket rockers, or stock? I seem to recall stock springs being no good past .500, and lift with 1.6 rockers on the hotcam put you at .525".
You probably don't need new pushrods, but they're a good upgrade. Valvetrain stability is very important. I like the Trick Flow's from Summit. And no, you don't have to pull the heads to replace springs & pushrods... don't even have to pull the intake. Use a compressed air spark plug adapter to hold the valve up, or pull the spark plug and feed about 10' of rope in to the cylinder, rotate the engine (gently) until it won't rotate, and remove the spring. The rope will keep the valve from dropping. Once you're done with that cylinder, back the engine rotation off and pull the rope out. Pushrods come loose when you loosen the rocker arms... but you would have had to have them out when changing the cam too.
I'd get better valvesprings than stock. Even LT4 springs (well, back in the day) could be had for cheap (I sold a set for like $25 shipped, new, a few years ago). Are you running aftermarket rockers, or stock? I seem to recall stock springs being no good past .500, and lift with 1.6 rockers on the hotcam put you at .525".
You probably don't need new pushrods, but they're a good upgrade. Valvetrain stability is very important. I like the Trick Flow's from Summit. And no, you don't have to pull the heads to replace springs & pushrods... don't even have to pull the intake. Use a compressed air spark plug adapter to hold the valve up, or pull the spark plug and feed about 10' of rope in to the cylinder, rotate the engine (gently) until it won't rotate, and remove the spring. The rope will keep the valve from dropping. Once you're done with that cylinder, back the engine rotation off and pull the rope out. Pushrods come loose when you loosen the rocker arms... but you would have had to have them out when changing the cam too.
Thread Starter
Launching!
Joined: Nov 2005
Posts: 282
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From: Baytown (dirty bay) , TX
i ran my car right when i got it and it ran a 13.9. and i was a crappy driver and i was on 245 street tires. thats way too fast for a stock lt1. could it be a stroker motor?? when we put the cam in it, we found out it had 1.6 rr's. and now the possibility of a forged bottom end.
TECH Junkie
Joined: Nov 2003
Posts: 3,265
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From: CHITOWN
Originally Posted by 98vortecbw
i ran my car right when i got it and it ran a 13.9. and i was a crappy driver and i was on 245 street tires. thats way too fast for a stock lt1. could it be a stroker motor?? when we put the cam in it, we found out it had 1.6 rr's. and now the possibility of a forged bottom end.
What the hell? Lt1s willl go High 13s low 14s all day long.
Who told you a stock LT1 cant go high 13s?
Well looks to me like if the bottom end was built, then that cam would have been bigger than stock too. And if the rockers were already 1.6's then you almost without a doubt had bigger springs too.
Launching!
Joined: Dec 2004
Posts: 242
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From: Cana, VA
Originally Posted by dhdenney
Well looks to me like if the bottom end was built, then that cam would have been bigger than stock too. And if the rockers were already 1.6's then you almost without a doubt had bigger springs too.
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My stock vert went 14.0 flat on Goodyear GS-C's. At nearly 3900 lbs. I'd say a 13.9 would be possible for a stock hardtop or T-top car.
Seriously, we could prognosticate with envelopes to our foreheads all day long here on this interweb thingy, but the only way to know what you really have in your motor is to take it apart and look. Dropping the oil pan would tell you about your rods and pistons. You could see a brand on the pistons from below.
But then, dropping the oil pan ain't exactly an easy task... It took me ruining my motor to find out I had a 4-bolt main block a couple years ago (Chevy dealer replaced my motor under warranty back in '97).
Seriously, we could prognosticate with envelopes to our foreheads all day long here on this interweb thingy, but the only way to know what you really have in your motor is to take it apart and look.
Dropping the oil pan would tell you about your rods and pistons. You could see a brand on the pistons from below.But then, dropping the oil pan ain't exactly an easy task... It took me ruining my motor to find out I had a 4-bolt main block a couple years ago (Chevy dealer replaced my motor under warranty back in '97).
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