70 LT-1 bottom end pics. (What the hell?)

[Mark M.]

Re: 70 LT-1 bottom end pics. (What the hell?)

I would speculate an engine running on leaded fuel may be more apt to build lead deposits if it ran under some conditions appose to others. Rich intake, cold plugs, short driving runs , cold running temp., leaking rings ,leaking carb. Some oils may help a bit. Rotella CJ4 (compression ignition) type oils for diesels specing those additves are similar to S (spark ignited) oils of the past in their additives like zinc. Excessive fuel in the crankcase would most likely build deposits faster and oil type probably wouldn't help. I have an LT-1 engine in a car and when I tuned in the carb and distributor well, it became very reliable and one of the funnest street cars. That piece of white plastic may be from the oil pump shaft coupler or possibly teflon valve seals if they were added! How many miles are on that bottom end?

[Dennis D.]

Re: 70 LT-1 bottom end pics. (What the hell?)

I would speculate an engine running on leaded fuel may be more apt to build lead deposits if it ran under some conditions appose to others. Rich intake, cold plugs, short driving runs , cold running temp., leaking rings ,leaking carb. Some oils may help a bit. Rotella CJ4 (compression ignition) type oils for diesels specing those additves are similar to S (spark ignited) oils of the past in their additives like zinc. Excessive fuel in the crankcase would most likely build deposits faster and oil type probably wouldn't help. I have an LT-1 engine in a car and when I tuned in the carb and distributor well, it became very reliable and one of the funnest street cars. That piece of white plastic may be from the oil pump shaft coupler or possibly teflon valve seals if they were added! How many miles are on that bottom end?

Mark....
I agree completely with your assessment.
I've had the car 2 years. Dont know when the motor was freshened up in terms of time. Mileage wise, not more than 4k.
Judging from the condition of the internals, I doubt even that many.

[James G.]

Re: 70 LT-1 bottom end pics. (What the hell?)

If the cam sprocket were not changed I would think it could be off it...
I am planning on sending samples from the next change off for analysis as I am leery of the plastic cam sprocket and would like to know if there is reason for worry.
FWIW I run Amsoil for flat tappets with high zinc in anything without a roller - have used their break in oil (If not mistaken it's 1000 or 1500ppm ZINC) for years without issue on new flat tappets.

[Joe L.]

Re: 70 LT-1 bottom end pics. (What the hell?)

If the cam sprocket were not changed I would think it could be off it...
I am planning on sending samples from the next change off for analysis as I am leery of the plastic cam sprocket and would like to know if there is reason for worry.
FWIW I run Amsoil for flat tappets with high zinc in anything without a roller - have used their break in oil (If not mistaken it's 1000 or 1500ppm ZINC) for years without issue on new flat tappets.

James------


I can virtually guarantee you that the cam sprocket's nylon teeth have deteriorated. Even if all the teeth are still present (which is unlikely), they'll be worn and on the verge of separating from the aluminum sprocket.

All 1966-82 small blocks and all 1965-74 big blocks were originally equipped with nylon toothed cam sprockets. Want to replace with a nylon-toothed sprocket for originality purposes? They're very hard to find for small blocks with either "wide" (1966 only) or "narrow" teeth (all 1967-82) . GM has not sold one in SERVICE for about 40 years. The big block "wide" tooth nylon sprocket (all 1965-66 and 1967-71 SHP and HD) is long-since GM discontinued and difficult, if not impossible, to find in the aftermarket. The "narrow" sprocket (most 1967-74 except SHP or HD) is also GM discontinued but one might still find a few of them around.

Of course, I absolutely do not recommend using a nylon-toothed sprocket for ANY application. However, for those for whom restoration essentially amounts to a religion, I offer the above info.

[James G.]

Re: 70 LT-1 bottom end pics. (What the hell?)

The engine has never been unbuttoned and although I am loathe to crack it open, if the gear fails, it is highly unlikely that the pan and timing cover will be the only thing which I will need to remove.
It will get a quality double roller timing set IF I go in there-

[Dennis D.]

Re: 70 LT-1 bottom end pics. (What the hell?)

James...
Finished the pan gasket r&r. So far, no leaks front or rear.
I do notice a slight oil wetness at the bottom of the timing cover, up by the balancer. Probably the cover seal. When I decide to deal with that, I also install a Cloyes double roller timing chain. Did it on my L46 awhile ago.
20210606_191541.jpg

[Kenneth B.]

Re: 70 LT-1 bottom end pics. (What the hell?)

James------


I can virtually guarantee you that the cam sprocket's nylon teeth have deteriorated. Even if all the teeth are still present (which is unlikely), they'll be worn and on the verge of separating from the aluminum sprocket.

All 1966-82 small blocks and all 1965-74 big blocks were originally equipped with nylon toothed cam sprockets. Want to replace with a nylon-toothed sprocket for originality purposes? They're very hard to find for small blocks with either "wide" (1966 only) or "narrow" teeth (all 1967-82) . GM has not sold one in SERVICE for about 40 years. The big block "wide" tooth nylon sprocket (all 1965-66 and 1967-71 SHP and HD) is long-since GM discontinued and difficult, if not impossible, to find in the aftermarket. The "narrow" sprocket (most 1967-74 except SHP or HD) is also GM discontinued but one might still find a few of them around.

Of course, I absolutely do not recommend using a nylon-toothed sprocket for ANY application. However, for those for whom restoration essentially amounts to a religion, I offer the above info.

Thats what I did with my 70 LT-1 & 70 454. It was the cause of many blown motors in the 70'S My brother blew up the motor in his 70 GTO after only 5000 miles on it in the day.

[Patrick H.]

Re: 70 LT-1 bottom end pics. (What the hell?)

These photos are from a 1972 small block.
I started it for the owner one spring, and had no oil pressure.
As you can guess, the nylon pieces jammed the oil pickup, and the pump couldn't suck any oil.

Replacing the timing chain also fixed the irregular idle and timing issue the car had. No surprise.

[Duke W.]

Re: 70 LT-1 bottom end pics. (What the hell?)

I always recommend the OE replacement truck double roller chain. It's available in a number of different brands, but all are made by Cloyes and you should be able to find the complete set for about 25 bucks.

This is NOT the Cloyes aftermarket timing set that sells for close to a hundred bucks. The OE truck replacement chain has 0.200" diameter rollers. The Cloyes aftermarket rollers are 0.250" diameter, and you need to check carefully for interference with the block. Unless you are doing 9000 rev clutch drops the truck replacement chain in typical vintage car service will outlive all of us.

Duke

[Joe L.]

Re: 70 LT-1 bottom end pics. (What the hell?)

I always recommend the OE replacement truck double roller chain. It's available in a number of different brands, but all are made by Cloyes and you should be able to find the complete set for about 25 bucks.

This is NOT the Cloyes aftermarket timing set that sells for close to a hundred bucks. The OE truck replacement chain has 0.200" diameter rollers. The Cloyes aftermarket rollers are 0.250" diameter, and you need to check carefully for interference with the block. Unless you are doing 9000 rev clutch drops the truck replacement chain in typical vintage car service will outlive all of us.

Duke

Duke------


You're right; the double roller truck chain will last longer than any of us are going to need it. Without a doubt. However, I still only use and recommend the Cloyes 9-3100 True Roller timing set for small blocks and 9-3110 for big blocks (with flat tappet cams).

[Joe L.]

Re: 70 LT-1 bottom end pics. (What the hell?)

The engine has never been unbuttoned and although I am loathe to crack it open, if the gear fails, it is highly unlikely that the pan and timing cover will be the only thing which I will need to remove.
It will get a quality double roller timing set IF I go in there-

James------

A "non-invasive" "clue" to indicate deterioration of the cam sprocket is to observe the timing mark illuminated by a timing light. If the mark "jumps around", even a little, the timing sprocket is worn or deteriorated. If it "jumps around" a lot, you're "living on borrowed time".

[James G.]

Re: 70 LT-1 bottom end pics. (What the hell?)

I took everything said AS A FAIR WARNING regarding driving the car, so I didn't!
And THANK GOD I heeded everyone's advice... mid August when I pulled it down, it was missing a couple of nylon teeth already.
Put a New Cloyes chain set and used NOS pan rail, water pump, and timing chain cover gaskets with new damper seal, which had the same part number in it as the GM seal I removed.
Gave me a chance to really clean the engine well, and swap out the original plug wires, clean the boomerangs and sides of the block PLUS I feel so much better about driving the car now.
I also sent my balancer to Damper Doctors as it had slipped on the hub by about 20 degrees and rearward 1/16".

Made sure to not use any silicone sealers and didn't paint anything. BUT wow was I able to clean!!!
100_9528.jpg
'And in the process found the CGZ on the side of the engine block!
100_9552.jpg

[Terry M.]

Re: 70 LT-1 bottom end pics. (What the hell?)

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Dennis
It took me a long time to notice this picture. Is it your damper? The color is not what I would expect on the subject Corvette.

[James G.]

Re: 70 LT-1 bottom end pics. (What the hell?)

That is the counterweight on the crankshaft - which still doesn't explain the blue paint.

[Mark F.]

Re: 70 LT-1 bottom end pics. (What the hell?)

That is the counterweight on the crankshaft - which still doesn't explain the blue paint.

could it be Pontiac blue?