L72 Trip to machine shop

[shor]

Well, here is the next batch of photo's
L72 machine shop

[shor]

The cylinders have never been bored before and Nick, my machinist, recommended .030 over for the rebuild. I told Nick that I really didn't want to go .030 over and that I wanted to keep the block as factory original as possible. He said that we could easily go .005 over without a problem, if I wanted to order custom made pistons. The pistons would be expensive and the lead time was uncertain(summer months!!). After thinking about it, and employing the 24 hour rule(wait 24 hours before doing anything), Nick came up with an idea. We will keep the standard bore and just power hone the cylinders. We are going to order TRW replacement pistons, standard size, and send them to be teflon coated. The coating adds about .004 to the pistons so that combined with the new rings will be a great fit. I want to use the same pistons but Nick insists we get new ones, there is some pitting and other age issues with the original pistons(trust you master engine builder, I was told!)Sound like a plan?? I will keep you updated as we progress.

[Chevy454]

Pictures look good! Now, I don't want to sway you in any way, as I'm not sure what kind of rebuild you are after, but you might want to reconsider the TRW's. I know a LOT of people use them, but in recent years the quality has lessened quite a bit. I thought this was just "bar talk", but when we rebuilt dad's L-72 last summer, we ordered the correct L2268 replacement pistons, and when we cc'ed them, they averaged about 6 cc's less than they were supposed to (28cc vs. 34cc). This is how they probably came from the factory, but when I do it again, I'm probably going to with Ross or JE pistons...they are more expensive, but are also a lot more "correct". Just my 2 cents [img]/ubbthreads/images/icons/smile.gif[/img] .

[shor]

Thanks Rob, that sounds like good advice. I am heading over there Sat. and will research the pistons furthur.

[Chevy454]

I didn't want to come off as a "know it all", just passing along something that I found out. I have heard good things about the Ross and JE pistons, except for the price. But, I will spend the extra money next time, so I can be a little more precise with my engine specs.

[BBIGG BLOCK 396]

I have to agree with you guys on the ross pistons,they cost a little more but they are worth every penny!I have a set in a 427 and they are great.When I build another engine in the future you can bet ROSS PISTONS are going in it also.

Bobby [img]/ubbthreads/images/icons/laugh.gif[/img]

[shor]

Here are some more photos after coming out of the hot tank.
There is a clearly visible (MA) crayon mark on the block. The (A) doesn't have a slash on it though and I think that maybe it should be an (N) because my car is an MN code?? Have you guys seen this before? I have not read about it in Ed's book nor Mcneish's. Is this a known marking or did I just discover it?
l72 bare block/crayon

[T Billigen]

Shor, where is the chalked MN located on the block? Can you get a picture of your vin number on the pad by the oil filter, I want to see if it similar to mine.

[Stefano]

Shor,
It looked like MN to me the first time I looked at your pictures. But, that is what I would expect it to read, so my eyes might be playing a trick on me.

There aren't to many original drive train Yenkos or COPOs left. Even fewer of those remaining which have never had their drive trains apart.(Or even out of the car.)

Your find is certainly new info. to me. I am curious as to what our resident Restorers and Members have experienced.

I can still remember a few years back when Dana Mecum first exhibited this rare find and numerous local "experts" were scrutinizing your Camaro.

The 'Bloomington Gold' Corvette Guys were satisfied with the originality and Correctness of the Castings and stampings but were completely thrown off by the dates and time line.

Many couldn't understand how a bock was cast in January, Pad stamped in March and united with a Body trim tagged in May.

[YENKO DEUCE REGISTRY]

Shor;
Two '70 Yenko Novas have been found with the engine application code written on both sides of the block, in yellow, upside down!
M