Took my engine to the machine shop.

A few years ago I bought a Camaro drag car. The body was shot from sitting but the 350 engine had a lot of good parts on it......World Product heads, forged pistons, it was balanced, roller rockers, MSD distributor and box, airgap intake with 750 DP carb, electric water pump, etc. I also kept the B&M TH350 and a lot of other parts and scrapped the car.

I tore the motor down and found that on break in they had wiped 2 cam lobes. I think that was the only time on the car as there was still very purple trans fluid in the trans and no gear oil had ever been put in the rear end, it was bone dry and clean.

I have a yearning to drag race again and am going to build a little T altered for the brackets, nothing special, 1200 pound car that should run in the tens (hopefully). So I took the engine block and pistons to a local race engine builder for machining and to check it over. Usual stuff, run shot through it, deck, line bore, cam bearings, brass freeze plugs, and stuff like that.

Today he called me and said I had given him the wrong TRW pistons, these could not have come out of this engine. I assured him they did, and he said the bores had ZERO clearance ! So he is going to hone the block to the proper size and do all the other stuff that should have been done originally.

I am so happy I didn't just clean it up and try to run it. It was evidently done by some machine shop because the numbers on the pad were ground off and numbers like .020, 5.7, .010, etc were stamped there and the inside of the block was painted with Gyptol even.

Guess it pays to check over even engines put together by a so called expert !

Don

Sounds like you got lucky!

Wow! So the tighter ther better isn't always good!

Glad you found out that way! Could have been real expensive if you had run it

Yep, the machine shop guy said if it would have been run much it would have torn things up. I will also save some money because they can reuse my old 20 over pistons, and it won't have to be rebalanced. I wasn't looking for cheap but it will be nice to be able to reuse as much of it as I can.

Don

That's for sure. Recycling is best in today economy

Got lucky this time Big

Don, with zero clearance I don't know how it ran long enough to wipe out cam lobes.

Any scores on the pistons?

Was it difficult removing the pistons & rods from the block?

You should have a ton of fun running an altered.

No, Bob, that is the weird thing. The pistons look absolutely brand new, not a mark on them, and they slid out just like they always do. The block had no ridge and even the bores looked good, but I just wanted a clean up hone.

But the guy was adamant that they had no clearance. Yep, I figure a little T altered with a simple tube frame will be fun. Years ago I had an Austin Bantam roadster drag altered and would like to recreate it, but they are so tight in the cockpit, even compared to a T body. You also have to sit high in the Austin whereas you can sit deeper in the T.

I got my appetite for racing again when I ran my 27 at the Billetproof drags, but that car is just too squirrely and has no traction, even with slicks. (I also didn't like running the 27 to 7,000 rpms with no scattershield ) I am going to put some real slicks on this one, better than the old school Firestone slicks I had on the 27.

Don

Seems like you'd notice they were that tight when you took it apart?! [S

BoB

Tripper said:

Seems like you'd notice they were that tight when you took it apart?! [S

BoB

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I know. He was as puzzled as me. [S Bet those rings really seated though !

Don

What did the bearings look like? is it possible the engine was never even started and the original owner never even started it-just put his old favorite cam back in with two bad lobes & never noticed it?

440Clark said:

What did the bearings look like? is it possible the engine was never even started and the original owner never even started it-just put his old favorite cam back in with two bad lobes & never noticed it?

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This is where my mind went reading about the cam.

440Clark said:

What did the bearings look like? is it possible the engine was never even started and the original owner never even started it-just put his old favorite cam back in with two bad lobes & never noticed it?

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No, it had been started, there were metal shavings in the pan. Bearings all looked great, so I think they pulled a Gas Monkey Garage stunt and didn't break in the cam properly. I don't think the motor was run long, maybe they had the roller rockers set too tight too.

The motor was built by some shop because of all the information stamped on the front pad and the gyptol that was painted inside the entire block. Most home builders don't go to the trouble of stamping clearances and other info on an engine.

The sin is, they really had some good parts they bought for the motor, so they weren't trying to cheap out. Looks like they just got a motor that was built on Friday at quitting time.

Don

So with all the talk recently about bad cams, watching Gas Monkey wipe 2 cams in 2 different new motors, it makes you wonder how common this is. Seems like thats a huge problem now.

Was it always like this "back in the day"? If I was an engine builder I'd be afraid to build a flat tappet motor!

It's all to do with the oil. Most of the additives have been removed. Don't need them in late model roller cam motors. Were removed to help emissions and gas mileage. They were also hard on cat convertors.

There were times when you'd lose a cam due to not breaking it in correctly. The problem nowadays is they took the zinc out of our oils and that is what was allowing flat tappet cams to live.
When a cam is lost now it's generally due to not putting breakin additive in the engine to start with then, not adding the zinc additive every time you change your oil. All this still won't save all the cams because the lifter bores are not squared to the cams well enough anymore.
I don't know of any engine builders that actually check the lifter bores when they build an engine. I bought a new Bowtie block for my last latemodel engine, put it together and lost 4 cams on the breakin stand, the last time I disassembled the engine I took it to a friend of mines machine shop to have brass lifter bores installed. When he went to bore them the boring machine only hit on one side of the top and one side of the bottom, I had use Ford bushings so he could cut enough material away to square them. I never lost another cam after that so, I've had them checked every time since.

I'm a firm believer in Lucas oil treatment. I've never lost a cam on an engine that I've ran it in. Don't know what all is in it, but I know it works for me.

BigIrish said:

So with all the talk recently about bad cams, watching Gas Monkey wipe 2 cams in 2 different new motors, it makes you wonder how common this is. Seems like thats a huge problem now.

Was it always like this "back in the day"? If I was an engine builder I'd be afraid to build a flat tappet motor!

Click to expand...

When I see GMG break in a new motor I cringe. They do it exactly the way you shouldn't. Instead of getting the motor to fire immediately and then bringing the rpms up to 2000 or 2500 for a half hour, they start it and then let it sit there idling ! Wonder why that bearded wonder/super engineer/ head mechanic hasn't figured that one out ?

I also like Lucas Break in additive. Lots of zinc and we use it on flat tappet motors every oil change, but just half a bottle instead of a whole bottle, like we use to break in a cam. Never lost a cam yet.


Don

The last couple of cams I've done, I've sent to a place in Colorado that breaks them and the lifters in on a machine. They submerge everything in a special oil and run it with the correct pressure on the lifters to simulate valve springs. I just install then cam, put the numbered lifters in the correct hole and start 'er up. It's cool to start a new motor up and be able to just let it idle while checking everything else out. And at $50, it's well worth it to me.

I've never heard of a service like that..........very cool. What is the name of the place, may have to use them on the 350 I am doing.........it's going to have a pretty stout solid lifter cam, I think.

Don