To rebuild or not rebuild, that's the question!

[tirebird]

I was talking with a local engine builder who works on regular cars and race vehicles too,..top notch. The subject of my engine came up and I told him I was thinking seriously of rebuilding the heads(#3964291), with new valves, hardened seats and new valve guides, rocker arms, etc. My engine only has about 24k and it leaks/burns a quart of 15w-50w Mobil 1 every 500 miles or so. Most of that I believe(by the puff of smoke when I start it warm) is from the original and infamous big block valve guides in combination with the super slippery Mobil 1.

But, the engine builder says it's a good time to do the block too,..new rings/bearings, polish the crank, new roller camshaft, etc. boring it .30 over.

My question is, I don't know if the "while we''re at it" argument is valid. I know any block can benefit from some freshening but I'm more than a little leary about "0" decking the block and erasing the "T0417CRR" numbers/letters off the front pad of this crate replacement LS6. Once they're gone they're gone and I will not go the "restamping" route or the acid route to reproduce or resurface those numbers.

What do you guys think?

Thanks

[@wot]

Rebuilding is your decision, but you can deck a block without touching the numbers. Good engine builders do it all the time.

[SamLBInj]

[ QUOTE ]
My question is, I don't know if the "while we''re at it" argument is valid. I know any block can benefit from some freshening but I'm more than a little leary about "0" decking the block and erasing the "T0417CRR" numbers/letters off the front pad of this crate replacement LS6. Once they're gone they're gone and I will not go the "restamping" route or the acid route to reproduce or resurface those numbers.

What do you guys think?

Thanks

[/ QUOTE ]
You have a CRR block or a CE block, CRR is not crate replacement its the code for 1970 Chevelle LS6.

[tirebird]

Sam. I should have said warranty replacement instead of crate. It was bought by the second owner from Berger Chevrolet in 1972.

Dean. I didn't know that, thanks. Sounds like I should shop for another engine builder.

John

[jfkheat]

Shouldn't a warrenty replacement engine have a CE number stamped on it?
James

[tirebird]

James,..this subject, the stamping on my engine, has been discussed before on this site with no clear resolution. All I do know, according to several articles written by the 2nd owner(original owner was B F Goodrich) in various hot rod publications, is that Berger Chevrolet sold him this engine in 1972 as a warranty replacement LS6. There's still some disagreement about whether it should have been labeled that way but all the arguments are immaterial at this time. That's the engine in my car with those stampings(block and head),.and I love driving it. I'm not a collector so I'm not worried about "flipping" the car for more money. However, I do want to keep it as original as possible unless it needs to be rebuilt, and that's why I'm asking the gearheads on this board for their opinion about rebuilding the block.

[Bill Pritchard]

Unless you're out to get the last bit of ultimate performance from your engine, or the 24K miles have been 'hard' miles, it's unlikely you really need a complete rebuild. Why not just pull the heads, have them freshened, and put them back on. If you still have oil consumption problems, then you will really know you need a short block rebuild. And as Dean says, any competent machine shop these days can leave the stamp pad untouched when decking the block.

[olredalert]

Tirebird,

------Can you give us your reasoning for using Mobil 1???
------I had an oil consumption and lifter noise problem with the crate 502 in my Suburban with Mobil 1. A very good local engine builder told me to switch to 15/40 good quality regular oil. This quieted down the lifters a ton and cut my oil usage in half. Oh yah, I have just over 130,000 miles on the motor now, and it uses a quart per thou. It has also surprized a few 5-liter Mustangs and gets right around 17 miles to the gallon without trailer. Thats about 2 miles to the gallon better than the 454 I took out. There was quite a bit of computer re-programming involved in getting this mileage figure.........Bill S

[markjohnson]

Upon re-reading this thread the "215-270HP truck motor" comment almost comes across as insulting. General Motors saw fit to produce and stamp these '72 produced engines as 1970 LS6 CRR emgines and that's what they are and always be. It is a real LS6. Tirebirds' is a real LS6. I'd like for someone to show me a truck motor that comes with rectangular port heads and a solid lifter camshaft. Alan Colvin has even looked into these several years ago and could not explain the engine suffix. If anything, it's much more rare than the common #512 1970 block.

[tirebird]

Wow you guys are great. First, Mark you, of course, win the bet. It is a #289 block 4-bolt block. However, because of the TransAm hood scoop, it has an aluminum Corvette intake manifold, #3963589.

I, like many of you, would love to solve the mystery of my and probably dozen of other #289 4 bolt engines with #291 heads. Even Alvin Colvin, the author of "Chevrolet by the Numbers", had a correction on his website for his Chevy bible regarding the #289, ” Some blocks have 4-bolt mains...several 4-bolt main blocks have been found."

Why did the Tonowanda plant use this block for warranty replacements and not the #512? It's an intellectual exercise that has no practical application. But, like all mysteries, it would be fun to know the answer.

Bill, you ask a good question. I've always used Mobil 1 in all my previous cars; a 63 Stingray and a 69 Z28 with a DZ302. I think it's the best oil to control wear, to keep the engine clean, and to prevent damage during high engine speeds and/or with high temperatures. I've seen high mileage, even abused engines taken apart that used Mobil 1 during their lifetime and was impressed with how little wear they've suffered. And, wear is what, most of all, I want to prevent with this rare block and heads.

Now, even with that said, the engine builder echoed what I've heard from other experts, that the Mobil 1 is so slippery it may be the reason so many people have oil consumption problems, with oil slipping past the oil control rings and the valve seals and guides. But, other than consumption issues and, of course the expense, I don't think I'm damaging my engine by using Mobil 1.

I've replaced the valve seals and I've decided that may be the extent of my rebuilding. If I do any work on the car this winter, it will be only to the heads for valve guides, hardened seats, and a general stuff. Thanks again everyone.

John