Is this a NOS L79 "151" camshaft, or something else?

[Duke W.]

Re: Is this a NOS L79 "151" camshaft, or something else?

This is a L-79 crank, so it's Tufftrided and IIRC Chevrolet says that if you try to straighten them in a press they will crack, but it can be straightened with a peening process.

This engine was recently disassembled, so I don't think the crank was stored "wrong", and unless the engine was seized, which was not stated, I don't see how the crankshaft could be bent this much.

I'm questioning the veracity of the measurement. If you pulled a free spinning crank out of a block and measured .004" TIR runout, would you believe the measurement?

Duke

[Clem Z.]

Re: Is this a NOS L79 "151" camshaft, or something else?

This is a L-79 crank, so it's Tufftrided and IIRC Chevrolet says that if you try to straighten them in a press they will crack, but it can be straightened with a peening process.

This engine was recently disassembled, so I don't think the crank was stored "wrong", and unless the engine was seized, which was not stated, I don't see how the crankshaft could be bent this much.

I'm questioning the veracity of the measurement. If you pulled a free spinning crank out of a block and measured .004" TIR runout, would you believe the measurement?

Duke

the most i ever saw was .0025 and i did not straighten it and it ran fine. you put it in the block torque the caps and if it "spins" free good to go. if it is too far out just get the mains ground .010 under

[Dick W.]

Re: Is this a NOS L79 "151" camshaft, or something else?

they can straighten the crank in a press. i have seen them bend from the way they were stored. you are trying to line up 3 points if you don't enlarge the original push rod guide holes.the holes,the stud and the valve stem tip and also the rockers move slightly sideways during the lift .

The Kellogg cranks we ran in the hemi's would bend if you stored them on end. You had to hang them from a rack by the flywheel flange. They were not cheap off shore junk either. The were over $1,000 in the late '60's

[Scott S.]

Re: Is this a NOS L79 "151" camshaft, or something else?

There are way too many questions here for me to answer with my tired fingers that have just finished a 6300 word article for The Corvette Restorer, so I emailed you to call.

Hi Duke, I will email you back to find out a good time to call (and thanks!).

One thing that caught my eye is the .004" TIR runout of the crank. If it's that much I don't see how it could even turn in the block.

When I met with the engine builder after the disassembly and cleaning, he showed me (on what looked like a lathe-type measuring device) how the crankshaft was out of alignment. I thought I remembered the T.I.R. being .007. We talked about how the rebuild would go forward, and he said we needed to deck the block. I asked how are we going to do that without messing up the numbers, and I explained why the numbers were so important. He said if the numbers were that important, he would write them down and find a stamper so he could stamp them back in when he was finished (he's a racing engine builder, not a restorer).

I knew this was a very bad idea, so when we finished the conversation, I asked him to do nothing until I did some more research. There were some other things I wasn't comfortable about, so I picked up the disassembled engine soon after, and it has been sitting in a spare room since then. When I picked up the block (and all parts) and paid for the labor, there was no mention on the invoice of the T.I.R. on the crankshaft. I asked him about it, and he wrote .004 from memory. So it might be .007 or .004, but either way it needs to be straightened or replaced.

So my first question is why was the engine torn down. Did it seize?

I didn't even try to start it before disassembly. The car was stored in a warehouse belonging to my Uncle from about 1993-1998 (I need to ask my Uncle for the exact dates). In 1998 my Uncle needed the space, so I went with my Dad to get the Corvette. He spent about an hour prepping the engine, and then he got it started. I followed him back to the house, he parked it in the garage, and that's where it sat, until summer of 2008, when the restoration began. So from about 1993 to 2008 it ran once. I don't know if it was seized up or not, but it looked like it needed to be torn down and rebuilt, like the rest of the car.