Technical Did the Machine Shop Ruin the Block?

Hey guys. I have a '57 Pontiac Chieftan Safari 9 passenger. My friend has a '55 Pontiac Custom Safari. Last year I went up to Montana and bought a 347 stock engine bolted to a Jetaway. They are installed and run great. Lots of power, great oil pressure and smooth shifting.
My buddy had me pick up a rebuildable 347 from the same guy, for his Safari. On tear down there was wear but nothing too bad. Crank good. Upon asking around, the name of this one shop in Watsonville kept coming up as THE guys to mill the block, etc. So after almost three months, the block and heads were "ready". My buddy picked everything up and put it aside in the garage until he was ready to build. Didn't check too close as the reputation of this shop was so good.
Once it came time to build he checked everything out very close. Turns out the stone for milling the block must have skipped and made it wavy. Like 006 to 010 wavy. He took it back to them and no apologies, no manning up. They took it back to re work.
Looked good this time. He assembled the lower end. We just looked close. They cut one side so that the flat top pistons are pretty much flush. No room for expansion. Maybe the head gaskets allow for the clearance. Their "fix" for the side where the stone skipped, was to lop off another .010. Now the piston actually rises above the deck of the block.
My question is: are there any ways to compensate for what was cut off? Like a stroker plate? Or can one use thicker head gaskets to compensate for the material cut off the block? Or did they ruin this 347 block? The work wasn't cheap. They never once apologized. And they never admitted any fault on their part. My friend is unhappy about the whole scenario. Any ideas to fix? Thanks for reading this. Robert

 

Can the top of the pistons be shaved? Sounds like they cut the hell out of it

 

The only way I know what would fix it would be a custom set of pistons with a different pin height...

 

Let me start out by saying " I don't know much about Pontiacs. Some engines come stock with the pistons slightly above the block. If you can get head gaskets that will give you clearance at a resonable price, you can probably make it work. Ideal? No. Sorry to hear about the machine shop's lack of ethics.
Pete

 

So now you have a block with 2 different deck heights ? Sounds troubling at best ! IIRC those poncho blocks have non adjustable valve trains. That could be a lot of extra expense to try & make that alone right , without the screwed up quench & compression ratio ...

 

Got a couple of 347s around here...Gonna watch this thread, good luck!

 

Most Pontiac head gaskets crush to .042", there are some others that are thicker. Check with Jim Butler Racing, they will know what it needs.

 

found this
"The basic block is compact and rigid. Its deck height is relatively tall at 10.24 inches as measured from the crankshaft centerline upward. The deck surface is very thick and uses ten 1/2-inch-diameter bolts"
"The deck should be machined to provide a smooth and consistent surface for optimal gasket seal. Generally measuring somewhere near 3/8-inch thick, it can be machined liberally without worrying about compromising its integrity. Any time material is removed from the deck surface, you need to physically verify that the cylinder head bolts do not bottom out with the cylinder head installed."


Dont know if this measurement helps but could help determine how much was removed

 

Don't bandaid it. Take it to another shop and have them cut the other side to match. Then you aren't trying to get different lenth push rods, and different thickness head gaskets and wondering why the intake manifold leaks. Do it right and then you won't regret it later.

 

@2OLD2FAST is right, the valve train is non adjustable, but if you are in this block for $$$ already the heads can be fixed. It will take a bit of work that you can do at home, but I think it will come out cheaper than custom length push rods.
You can tap the heads and use screw in studs along with Sealed Power HT951 lifters. The lifters will convert the rockers to push rod oiling instead of the oil coming through the rocker studs.
You will need to make a tapping block with accurately located holes, one hole is 3/8” and the other 7/16”. Using the tapping block and some hardened washers pull a stud, turn the block around so you can pilot your 7/16-14 tap straight, remove the block, put the stud in with some thread sealer and do the procedure again for the next stud. Oh, and let the block float, do not tighten it down when tapping. If your 347 rockers balls are good you will need to get a set (used?) of 1.5 Pontiac rockers with the oil holes in the push rod seats, the studs will be $25 on eBay, $80 worth of lifters and some SBC rocker nuts will get the job done. I made the tapping block pictured from 1" bar stock and if you are careful you can accurately lay out and center punch the hole locations and drill the block on a drill press.
I have bought Pioneer brand before and there are Elgin studs on eBay now, and the stud pictured requires no machining to the head, there is no jam nut required.
As far as the pistons go you need to accurately measure the piston to deck. You might want to fly cut the crown of the pistons on the bank where they cut the deck too much but then again if those pistons are just a few thousandths above the deck with .042 gaskets I doubt you would ever get into trouble. Realistically a 347 will not be a high revving race engine that you will be beating on, I don’t think you will get a piston to strike a head. JMO.

 

Well that sucks.
Been working with MidWest and have hits and misses. The more i stay on them the better the results.
I would check with your circle of friends and check on where not to go to get things repaired. I refer to Larry Blevins in Prunedale for referrals, been good so far.
The only shop in Watsonville that i would take anything of value to is off of Rogrigues and Beech, but it sold a few years back and i am not sure of the quality now.
To me , shaving the pistons seems to be the best choice now, unless you prefer the litigious version. Better served in small claims court ( under $5000 ).

 

Thanks for all the info. I think he should sue Marinos to get his $ back,and then disassemble after careful measurement of the piston clearances at the deck. Have another machine shop shave the one to match the other side. Then determine how much to have a machine shop shave the piston tops if there is enough material to do so. Will have to consult my manual to see if maybe those pistons assemble flush, or close to flush with the deck. Appreciate the ideas and info here. Robert

 

You didn't screw it up so you shouldn't have to fix it, take the machine shop to court and have them find you another engine.

 

Any quality machine shop is going to have insurance and even if they don't, making your buddy's deal right will be cheaper than all the bad mouthing in the end. They should realize that. Everyone makes mistakes.

 

In the end, it can be fixed, no big deal and all your worry about pistons flush or not flush is a non-issue. There is no requirement that says they have to be flush or not flush. Heck, racers will run stuff .035"+ out of the block with a thick enough head gasket to prevent piston-to-head contact.

All you have to worry about is piston clearance to the head when installed. If this isn't a high rpm deal, .025" piston-to-head will be plenty, with an .041 gasket pistons could stick out of the block .015 and still be perfectly fine. Going to rev it over 5500 rpm, then .035" piston-to-head would be a more appropriate figure.
It does effect compression ratio calculations, so you'll need to do the math there.

Just have the other bank of the block cut to match the shorter side and go with it.

Anything milled off the block may have to be accounted for with either head gasket thickness or intake face milling to insure proper intake fit.

Convert the rocker studs to adjustable would be the smartest thing to do, even if the motor is going back to stone stock internally, it gives you more lee-way for parts fit.

 

I would think if different thickness head gaskets are available this would work fine; they both do not need to be the same. Not on a Pontiac, but I have run almost zero deck heights on street engines and never had a any concerns. I would install the crank and a piston on each side and take some measurements, don't waste any seals it just for testing. Most engines have at least .015 to .020" clearance so .010" off is no big deal.

Now for the lifters/push rod. A .010" change is very tolerable with internals of stock hydraulic lifters if your camshaft keeps it's original base circle. All this was learned when rebuilding these engines in the 60's. I remember from an instructor to check base circles to head or block resurface to use the original push rods. If you think about a Chevrolet adjustment, with it running, from start of no ticking to the bottom of the lifter was at least 4 full turns of a 3/8" fine thread adjuster nut. Measure that and see your allowable play. If is a concern cut one of your push rods, thread the inside, and use a screw to make it adjustable. Install the rocker system and use the adjustable push rod to get the length you need, remove the rocker system and send it to Smith Brothers in Oregon and get them in 2-3 days. About .030-.045" under the spring clip on the lifter will work fine.

Yes this is some work but on every engine I build I do it anyway...It's what some bozo called blueprinting 30 years ago and that word got passed around like the Holy Grail. My dad and instructors called good habits and common sense.
Good luck and nothing in my opinion is ruined

 

So you cut four pistons and now four are lighter than the other four ! how is that going to work ? I'd find another block and another shop. Good luck on getting them to pay you anything.

 

Cut the other side the same and get pistons made. JE pistons will make you pistons all of their pistons are cut from blank forged slugs.

 

These two are saying the same thing I said, and I think they are right.

I think you can still use the pistons you have, but when you don't do things right it always costs you more later.

 

A lot depends on the head gasket and how close to the deck the ring lands are. I would prefer on my mill that the dock be zero decked but I guess we aren't building a race car. LOL

 

I just went through this same situation a couple of months ago. My block (327) was decked to read .017 down on three corners and .006 down on the other corner. A slope on one side going from .017 to .006. When I discussed this with the machine shop (Southworth in Eugene Or.) he actually had the nerve to laugh out loud and say "I'll bet you wish you hadn't measured it". Within tolerance for them. I then took the block to Grant Springer Engines also in Eugene and had them redo the decking ending up with near zero all around. Both sides equal.
My disappointment was realizing what can pass for O.K. at a machine shop.

 

I know it's a bit of a drive from where you are, but I'd think about getting the block over to Tim McMaster at Hanford Auto and let him get you fixed back up. He's well known for his y-blocks, but he isn't restricted to jut y-blocks. He's a HAMB member.

 

I agree. They sound like hacks. It's probably salvageable, as some have stated above. You just have to figure what it would cost to get back to the point of reference. Having to change to adjustable rockers etc.

I think if it were me, I would talk to a reputable machine shop and have them give you their opinion. That way you can make an educated decision.

 

Sure are a lot of posts from non-machinists here, that's for sure...."get another block", "different piston weights on one side if you mill them", "flush or not flush", "get custom pistons made".....yeeesh.

Cut the other block deck to match. go to a thicker head gasket if you need to recover some distance...if the flat top pistons need to be cut, a .010" cut is just a little less than 5 grams weight, not even enough to worry about rebalancing in in a race balance job and certainly not enough to even be a blip on the radar for street or factory balance.

Some guys just don't have a clue about the reality of fixing this.....

Yeah, it sucks the shop did such a shoddy deck cut job, but it isn't the end of the line for the engine block.

 

How much does the piston stick up? If it is .004, you are fine. If it is .040, you might be fucked.

-Abone.

 

How will the intake manifold fit now???

 

Choose a head gasket thick enough to make up for the material cut off the block and it won't fit any different than it did stock....

 

Later Pontiac's, '65 and up have intake surface on the heads 90 degrees to the deck, not 100% sure about the early ones, but I believe they are 90 degrees also. You either cut the head or the intake the same as you cut the deck if it's a lot. Most don't worry till you start cutting .020" or more. You can run into the intake not setting flush if the valley cover gets in the way.

 

The machinist milled my intake to compensate for decking the block and milling the heads. The only downside is that the intake will only fit that block and heads now...

 

That's one of the things about dealing with decades old nostalgic parts.......you never know what you bought till you get it home.