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.

[COPO]

I saw a '72 casting date CRR LS-6 engine on Ebay about a month ago.

[tirebird]

Thanks Bill, that's seems to be the consensus among my local buddies and the members of this board. It seems the prudent path and it's a lot cheaper than the engine rebuild.

John

[Charley Lillard]

One quart in 500 miles is nothing I would worry about. It's not your daily driver. I would leave it alone. I sure wouldn't bore it. 24000 miles it should not need a bore.

[markjohnson]

On the subject of these 1972 casting LS-6's, I have one and have seen several others so there are definitly a number of them out there. Mine is also gang stamped TO610CRR with no VIN #. The block is a #289 block, not the #512, and has a F-7-72 casting date. Even the cylinder heads are 1972 castings with the rectagular port/closed chamber configuration. This motor has never been apart until I purchased it and verified what it was. Don't forget that motor has factory forged pistons and they tend to burn a little until they warm up to operating temp. It's a hot rod, they require more maintenence than a regular car. If you feel that you have to rebuild that motor, just use a good Fel-Pro permatorque head gasket and you'll be fine. NO WAY would I ever attempt to deck that motor and have the machine shop forget to stop the grinder, answer the phone, pass on to another machinist, and lose those numbers on the front. It doesn't need it. Bad things do happen. Too risky.

[budnate]

[ QUOTE ]
One quart in 500 miles is nothing I would worry about. It's not your daily driver. I would leave it alone. I sure wouldn't bore it. 24000 miles it should not need a bore.

[/ QUOTE ]

thats what I was thinking, take a afternoon and replace the rubber valve seals under the springs and set the valves bet that cures about 80% of the oil usage.

[Mr70]

Mark
Is your #289 Block a two bolt main block?
Many Cars got this from 1972 +,rated anywhere from 215HP-270HP.
But mainly I refer to this as a 72-78 Truck Motor.

[markjohnson]

Most of the #289 blocks I've come across are two bolts, but I've pulled the pan and it is a factory four bolt main, steel crank, 7/16 rod engine. Even the heads are 1972 #291's with the #569 aluminum pancake intake manifold. The camshaft is even stamped the correct number as a stock LS-6 camshaft. I would almost bet that tirebird's LS-6 is also a #289 block. Like I said, I've seen a few of these 1972 LS-6's and can only conclude that Tonowanda ran a batch of these for whatever reason. The normal LS-6 crate engine that everyone knows came with rectangular port/open chamber heads and lower compression. By the way, this has ran 11.80@112 with headers,through the mufflers, on BFG drag radials.

[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

[SamLBInj]

I use synthetic oil in all my new vehicles, work trucks, harleys, ect How many are using it in there muscle cars?
Also, is that Slick 50 still around, I remember in the commercial a bunch of white coat scientist guys all used regular oil and one guy was a using a quart of this stuff, They all drained the oil and let the motors run, all siezed except for the slick 50... Im pretty sure it was slick 50, could have been something else, anyone remember?

[markjohnson]

If you go ahead with the head rebuild this winter, please make replacing those heavy two piece welded valves your first priority along with good retainers and keepers. These motors were notorious for breaking/dropping valves and this usually wipes out an entire motor. This is especially true on 4-speed cars with Ronnie Sox/Dave Strickler wannabes, but a great idea on all these old performance big blocks. Even the cheapest Manley valves are a vast improvement in performance and reliability. This is something I need to get around to also. By the way, we probably have the same intake. It is the #569 aluminum low-rise pancake manifold. I know you have the shaker hood on your 'Bird, but if you could fit the earlier GM aluminum hi-rise on the motor, it's worth quite a bit more power. Worth the effort.

[bigchevydaddy]

On Mobil 1 --

My work truck has had Mobil 1 since new. Recently found a broken head bolt, and pulled both heads to replace all head bolts and inspect. Was very surprised to see on this 90K- mile engine that there was no ridge in any of the cylinders and the original hone marks were still visible on the cylinder walls. Can't argue with no wear. BCD.

[markjohnson]

By the way, I use Mobil One synthetic religiously in all of my street and race cars. They were first, they are they are the best. I punish my equipment much harder than most enthusiasts and have never had an oil related failure.

[SamLBInj]

[ QUOTE ]
By the way, I use Mobil One synthetic religiously in all of my street and race cars. They were first, they are they are the best. I punish my equipment much harder than most enthusiasts and have never had an oil related failure.

[/ QUOTE ]
Our overall fuel bill went noticably down when I switched all the trucks to synthetic,it more than pays for itself in the short and long run.. http://www.yenko.net/ubbthreads/images/graemlins/headbang.gif
Hey, we dont get this from the Arabs do we? Knowing them they probably hold the patent.. http://www.yenko.net/ubbthreads/images/graemlins/smirk.gif

[olredalert]

-------I have nothing against Mobil 1. I also cannot account for my experience, just an anomalie. I guess I may have broken my 502 in incorrectly as I had to make a run to Carlisle within about 300 miles of installation and took the break-in oil out at that point and went to Mobil 1. Maybe things didnt have a chance to seat correctly??? For the period after that trip until I changed back to regular oil people thought I had installed a diesel in my Suburban. The lifters were unbelieveably noisy. Since I have never even had the valve covers off this engine I have no idea how it is wearing, but am very interested in seeing what the inside looks like when I do take a look-see.........Bill S

[SamLBInj]

I always did the swapping after the first 2,000 oil change and never had a problem..then every 3k miles after..

[tirebird]

Yeah, Mark I would like a high rise manifold, but the only way to do that would be to get rid of the shaker hood or modify it by bolting/welding it to the hood. That would be ugly

Yep, if I do rebuild it this Winter, new valves, guides, seals, springs, retainers, hardened seats, and a mild port and polish job.

Thanks,

John

[Kurt S]

[ QUOTE ]
Yep, if I do rebuild it this Winter, new valves, guides, seals, springs, retainers, hardened seats, and a mild port and polish job.

[/ QUOTE ]
Hardened seats are not necessary. Maybe with a monster cam with huge seat pressure. But on a stock street motor, keep the valves adjusted and it will be fine.....