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I'm attempting to rebuild a Rocket 350 (395558) for my '69 Cutlass S and it's turned ugly. I picked up a complete '72 stock 4bbl engine from a member on the forum, tore it down, and took it to a local machine shop. I included 2 pages of detailed instructions. It included checking all components for cracks, specified the BT/Mondello height gauge to use on the heads, etc. 4 months (and much harassment) later I finally picked it up. I asked them to show me measurements on the valves (7A heads) and they said "oh we don't have the gauge" (said they did when I dropped it off). I got it home and, when unloading the block I found this:
I called them Monday morning and said I found a crack in the block. I took the block back, the shop argued with me, then Magnafluxed it:
The owner said "well you didn't tell us to check it for cracks" and I said I dang sure did. In fact, it was step #1 on the instructions I gave you. He tried everything to wiggle and squirm out of it, then finally conceded the block was junk. I went home and checked the remaining components as best I could. Then I discovered he screwed up the rods and pistons:
This one was dropped:
It was scarred on top as well. I checked the other piston and he beat up the pistons at the wrist pin. He also torched the rods until they turned blue:
I went back up again, pistons/rods in hand, and showed him the damage. His answer was "we'll knock the burrs off the skirt, they'll be fine." The DSS pistons weren't cheap and I'd called the manufacturer prior to my trip. They said "dropped or damaged, replace them, no question." I called again while at the shop, put DSS on speaker phone, and they said the same thing. This guy flew off the handle, said "I'm not replacing anything" and stormed off.
Now I have to pick up the pieces. I found another block in a '73 Cutlass at a U-Pull-It yard.:
They moved the car for me so I could pull the motor, which I did this past weekend:
I tore the block down and, while it was a bear to get the intake, heads, and balancer off, the 395558 block looks good:
Sorry for your luck.
First question I would’ve asked would be “why would you machine a cracked block”?.
You need to let everyone know who it is if he’s not going to make it right.
You did right in having a list but maybe next time have them initial it as you go.
Here's where I need some help/advice. I have the Nodular crank from the '72 engine that the shop supposedly balanced. I have the 7A heads the shop rebuilt, although I believe it was incorrectly done. I ordered the Mondello gauge and measured the valve stem and rotator height on one head. A few of the valve tips were really beat up prior to the rebuild. It looks like they simply ground the damage off and reinstalled. Based on the '69 FSM the difference should be 0.030", however, that doesn't have rotators. Stem height on the head I checked was 0.040"-0.048" although one was 0.060". The 2 in bold are the ones I'm worried about. Are these measurements ok?
Next none of the rocker hardware was kept in order. I got everything back from the machine shop in a big bag. I have all of the hardware, in order, from the #8 heads. Can I use #8 rockers/pivots on a 7A engine? I did some searching but couldn't confirm the hardware was the same.
Is the '73 crank nodular? There's no "N" but, based on my research, the casting number says it's nodular. The 72 crank was polished, balanced, and stored horizontally by the shop that I had all the problems with. I'm thinking I'll take both cranks to shop #2 (when I find one) so there are options as needed:
I have to start looking for pistons again. I'm aiming for a 9.5:1 engine but the budget really took a hit with this debacle. Another set of DSS pistons is probably out.
And perhaps most importantly: does anyone have a recommendation for a good machine shop in the TN tri-cities area (Bristol, Johnson City, Kingsport), WNC (Asheville), or some reasonable driving distance from this area?
WOW! That is an unfortunate experience with the machine shop and one of my worst nightmares. So important to have a machinist that you can trust and knows what is what.
Wow, this is awful, sorry it turned out like this. The 73 motor you picked up looks pretty good. Good question on the crank, my 73 also did not have a N on it. It looks different from the lightweight cranks from the late 70's and 80's cranks. No one has a definite answer on these cranks that I have seen. I would not return to that shop and your bill should not be paid in full. Yes, the bridges and rockers are same except 64 and 65 heads, all the way to 1990. Of course with the awful job they did, an adjustable valve train is now necessary. That block might clean up with a hone, two pistons available in the 4.065" bore size for the Olds 350. Definitely get another shop to check it out.
First question I would’ve asked would be “why would you machine a cracked block”?.
You need to let everyone know who it is if he’s not going to make it right.
You did right in having a list but maybe next time have them initial it as you go.
I asked that exact question and his response was to say "well did you tell me to check it for cracks?" I said yes, verbally and in writing.
I'm working with my credit card company on reversing the charges now. As soon as I get an all clear I most certainly will!
Initialing is a great idea.
Regarding pistons I'm now looking at the L2321F30 Speed Pros with the -5.8cc dish.
I'd be getting those charges reversed from CC company. If you have proof in writing it should be good enough. That's crazy he even did all that work and never noticed the crack. Step one is always hot tank and check for cracks. Mark on here has better pistons available off the shelf than the old speed pros..Save the $$ and spend alittle more.. Someone will buy those other pistons and rods so not a complete loss.
I understand your apprehension about using the "dropped" piston and yes, the piston manufacturer will not stand by liability on such a thing, but you can have another shop mic it against one of the others to see if there was any change in the critical areas and can also be dye checked for cracks if you think that may be a problem. If only the one piston is damaged beyond usefulness, you could contact DSS to see if they would sell you one replacement, that should be less expensive than a complete new set. You may see some "blue" on factory rods, does not mean that they are suspect. The CSM states a minimum of .030" difference between height of the rotator and height of the valve stem end. Those that measure less than .030" should be replaced. Just my thoughts on the subject here.
I'd be getting those charges reversed from CC company. If you have proof in writing it should be good enough. That's crazy he even did all that work and never noticed the crack. Step one is always hot tank and check for cracks. Mark on here has better pistons available off the shelf than the old speed pros..Save the $$ and spend alittle more.. Someone will buy those other pistons and rods so not a complete loss.
Exactly why I mentioned the Mahle piston, he might get lucky on that 73 350, it may clean up with a hone to 4.065". I am hoping my 76 block will clean up to save machining cost. His current pistons might be useable but will give around 10 to 1 compression with his 7A heads.
To echo others... since you're talking about stock valve stem heights and stock rockers, I assume you're running a stock cam, thus this is just a stock refresh. That makes things quite a bit easier.
The blue marks on the rods mean they may have parked the rods in the heater a bit too long, or stuck them in further than needed - doesn't necessarily mean they were damaged in any way. Some shops just give them a quick brushing or cleanup to get rid of the blue.
I agree the piston should be replaced. There's a chance the skirt mushroomed in some strange way, or the piston will have a critical failure later. BUT, you should be able to buy one piston.
Mark on here has better pistons available off the shelf than the old speed pros..
What's his user name? I looked at the Mahle pistons but they don't seem to be readily available.
If only the one piston is damaged beyond usefulness, you could contact DSS to see if they would sell you one replacement, that should be less expensive than a complete new set
I think I'd need 2 pistons if I were to reuse the current DSS set. The drop damage and the beat up area around the bore are on different pistons. The wrist pins aren't centered on the rods but not sure how much difference that makes.
Yes, the hardware is the same.
That's excellent news. It also looks like the intake valve springs are the same so I can scavenge a few of these if needed. Looks like both intake and exhaust valves changed from 72 to 73.
I assume you're running a stock cam, thus this is just a stock refresh
That is a bit more than the stock 186/192 duration 350 automatic cam, closer and slightly bigger than the 70 4 spd cam. It should be a pretty good cam. What did your 7A heads CC at? What octane and compression ratio were you shooting for?
You know the stock rockers and hardware only work well with the stock cam, right? The stock setup isn't adjustable. That aftermarket cam will have a smaller base circle than the stock cam.
You can always just assemble it and check it - might be close enough. Just be prepared to buy something like the Comp roller tip kit.
What did your 7A heads CC at? What octane and compression ratio were you shooting for?
I haven't CC'd them yet as I was leery of the machine shop's work. I disassembled the heads and I'm glad I did. First half of the valve stem seals on one head weren't seated:
Then I pulled out the indicator and magnetic base to check valve stem to guide clearance: Spec is 0.0010-0.0027" intake and 0.0015"-0.0032" exhaust. I have a bunch out of spec, the worst has 0.0065" clearance
I heard from the CC company and they want detailed information. I have plenty...what a mess.
The stock setup isn't adjustable. That aftermarket cam will have a smaller base circle than the stock cam.
You can always just assemble it and check it - might be close enough.
I'd thought about this. What's the best way to check it after assembly. Bump the engine over slowly with a breaker bar and watch for binding?
The problem probably won't be binding, probably too much play for proper preload. If it has .0065" clearance on any guides, those heads need more work, not good. My fresh #6 heads had around .003" according to my measurements. You want that on the center exhaust guides or valves can stick.
Call Dale Walksler, owner of Wheels Through Time
828-926-6266
Dale lives on the property. I'm not certain what's up with his museum hours this time of year. You may get a recording. You can also look him up on the Internet to find his home telephone number. Leave a message if you get a recording. If someone knows of a good machine shop in the TN/NC tri-cities area Dale will know.
Ditto what "olds 307 and 403" said. Most shops that are not familiar with Oldsmobile engines will try to sell you a Chevrolet 11/32" valve guide only to find out that it is too tight on the inside diameter to work with an Oldsmobile valve stem. And the bronze guides you may have looked at for 11/32" valve stems would be the same....too tight! They can be made to work by reaming them or honing them to the proper diameter after installation.
Ditto what "olds 307 and 403" said. Most shops that are not familiar with Oldsmobile engines will try to sell you a Chevrolet 11/32" valve guide only to find out that it is too tight on the inside diameter to work with an Oldsmobile valve stem. And the bronze guides you may have looked at for 11/32" valve stems would be the same....too tight! They can be made to work by reaming them or honing them to the proper diameter after installation.
Good to know both about the quality of the Supercars Unlimited parts and the Chevy valve guides. It gives me a good source for parts.
I found a set of 693P 0.030" over pistons that should be for a SBO. Based on what I can find it's an old Nylen or Ertel part. There is very little info available about these. The only reference I've found is here: https://classicoldsmobile.com/forums...or-year-86658/
Sorry to hear about your troubles. I live about 30 minutes south of Asheville and, to be honest, wouldn't trust any machine shops in this area - especially with my Olds stuff. Lots of shops down around Charlotte due to the racing seen but they're all Ford and Chevy. Bernard Mondello is located in Tennessee. Have you tried contacting him?
Sorry to hear about your troubles. I live about 30 minutes south of Asheville and, to be honest, wouldn't trust any machine shops in this area - especially with my Olds stuff. Lots of shops down around Charlotte due to the racing seen but they're all Ford and Chevy. Bernard Mondello is located in Tennessee. Have you tried contacting him?
Bernard is in CA.
I recommend my guy in Jax Fl. He’s the best and has all the BHJ fixtures to do it right.
I found Mondello in Crossville, TN but, unfortunately they closed up shop a few years back. It appears that Mary, Joe's widow, has left the state and is now in Hawaii: https://en.newsner.com/animals/servi...-restrictions/
I compared pistons today and did some measurements/calculations on dish for each. Left to right are the OEM 72 pistons, OEM 73 pistons, and the 693P pistons. The 693s should be 6.0CC and I calculated 7.24CC, however, the other calculations were off by about the same amount. I did measure top of wrist pin bore to piston top with a set of calipers and the aftermarkets seem to be about 0.025" shorter. Am I correct in saying I can deck the block 0.025" to balance this out?
You sure can, my block is getting decked .020". Those pistons may still be at the factory .025" in the hole even after decking. You will be a bit over 9 to 1 with those pistons.
Ditto what "olds 307..." posted. Also keep in mind that the replacement head gasket, most likely Felpro, will be about .042" compressed versus the OEM factory steel shim head gasket which is about .017" compressed; thus the .025" deck cut will maintain geometry. Now If you also have your cylinder heads cut more than about .020", you may run into intake manifold to cylinder head alignment issues if you do not have the intake surface of the cylinder head cut as well.
Ditto what "olds 307..." posted. Also keep in mind that the replacement head gasket, most likely Felpro, will be about .042" compressed versus the OEM factory steel shim head gasket which is about .017" compressed; thus the .025" deck cut will maintain geometry. Now If you also have your cylinder heads cut more than about .020", you may run into intake manifold to cylinder head alignment issues if you do not have the intake surface of the cylinder head cut as well.
Good point, along with the heads being cut, even just a clean up, only the factory shim style intake gaskets may fit. I tried using Ultraseal gaskets on two different heads that were milled, not even close. When I take my parts in to be balanced, I am dropping off my RPM intake for a clean up cut.
You can get a cheap cc kit for less than $50 and verify easily that way. Don't rely on measurements, that's not a perfect circular depression. Regardless, we're talking about 1 or 2 cc which won't affect the final compression ratio very much.
Location of the piston at TDC is important, and highly variable.
You'll want the shop to do a test assembly of the short block to see where the pistons really fall, then cut the deck based on that. Determine your final configuration (desired compression ratio, actual head volume, head gasket thickness, desired depth of piston in the hole), and they'll cut the deck to get you there. More likely than not they have to mount the block ****-eyed so the pistons actually end up level. Don't just say "cut X" unless you're really certain and already did all those measurements yourself - with the pistons in the block!
The block casting and machining process back then was very forgiving, and it's hard to know exactly what condition your parts are in until it's been checked.
Ok help me understand here, maybe I missed something.
You get a cheaper piston only to have to pay to cut a block that may not have needed to be cut in the first place? I don’t understand the logic there. Thank you.
Ditto what "olds 307..." posted. Also keep in mind that the replacement head gasket, most likely Felpro, will be about .042" compressed versus the OEM factory steel shim head gasket which is about .017" compressed; thus the .025" deck cut will maintain geometry. Now If you also have your cylinder heads cut more than about .020", you may run into intake manifold to cylinder head alignment issues if you do not have the intake surface of the cylinder head cut as well.
That's good news. If I need to tailor the final CR it looks like Cometic makes a variety of head gaskets. The thinnest appears to be 0.027" thick,
You'll want the shop to do a test assembly of the short block to see where the pistons really fall, then cut the deck based on that. Determine your final configuration (desired compression ratio, actual head volume, head gasket thickness, desired depth of piston in the hole), and they'll cut the deck to get you there.
Good advice. When I stop at the shop I'll go over that with them.
Ok help me understand here, maybe I missed something.
You get a cheaper piston only to have to pay to cut a block that may not have needed to be cut in the first place? I don’t understand the logic there. Thank you.
Fair question. At least 2 of the DSS pistons are damaged and they weren't what I'd specified initially. I'll take them to the shop with me but, at a minimum, the wrist pins need to come out and the bores checked/cleaned. I'm not sure what I'll find but, based on everything else shop #1 did, I have little confidence. Something similar happened a number of years ago with an ATK engine I bought. I put it in a Jeep and it coughed up the cam bearings 272 miles later. Couldn't get my money back on it so I got a warranty replacement engine, installed it, and sold the truck. I lost confidence in ATK.
H I ordered the Mondello gauge and measured the valve stem and rotator height on one head
Just want to mention that one of my customers bought the Mondello gauge a year or so ago. I was using it to set up a set of heads for him and something simply was not making sense. I actually found an original GM gauge on ebay and bought it. The Mondello gauge was nowhere near correct I have a drawing of the GM gauge at the shop I can send you if you want. Probably should post it here too.
Ditto what "olds 307 and 403" said. Most shops that are not familiar with Oldsmobile engines will try to sell you a Chevrolet 11/32" valve guide only to find out that it is too tight on the inside diameter to work with an Oldsmobile valve stem. And the bronze guides you may have looked at for 11/32" valve stems would be the same....too tight! They can be made to work by reaming them or honing them to the proper diameter after installation.
There are very few guides that you can just install in a head and not size to the proper id. Mater of fact I cant think of any at all. I size every single guide I install. I use the same part number universal guide for almost anything with an 11/32 stem valve. Then I size them to fit the valve. There are too many variations of valve stem diameters to not check it. Different manufacturers seem to have different ideas as to what size a particular valve should be, especially the better performance ones
I bet if you ask 50 machine shops how they check valve guide clearance no more than maybe 5 of them will tell you that they use a bore gauge
Just want to mention that one of my customers bought the Mondello gauge a year or so ago. I was using it to set up a set of heads for him and something simply was not making sense. I actually found an original GM gauge on ebay and bought it. The Mondello gauge was nowhere near correct I have a drawing of the GM gauge at the shop I can send you if you want. Probably should post it here too.
I dropped everything off at Mountain Machine last night and reviewed all the components in detail. We had a good conversation on the rework needed and he thought the 73 block was a great score.
February 2nd, 2021, 05:22 PM
