68 L79 cam, pushrods and lifters swallowed up, need help with parts / vendors Please

[Jim A.]

Bad News yesterday, I Took my 68 L79 to mechanic because it was back firing through carb. at first I thought the diverter valve diaphram had gone to lunch but...........Much worse than that

we found that the 327 had swallowed up it's camshaft, lifters, pushrods and who knows what else ! some pushrods were bent, some valves not opening completely

Back in May the car ate up it's timing chain just as I was pulling into the Northeastern Regionals in marlboro mass. Are the two events possibly related ?

I'm looking for info on what should be done to prevent any further damage to engine. Any suggestionsd are appreciatedAlso looking for best options on vendor of parts, Stick with stock GM or maybe put in a  little racey ?

So, Is it best to replace with all GM parts or are there much better stronger canshafts and associated parts out there please ?

Thanks in advance for help,comments,suggestions
Jim

[Duke W.]

Re: 68 L79 cam, pushrods and lifters swallowed up, need help with parts / vendors Pl

I'd like more detailed information on what you mean by "swallowed up". The small block valve train is exceptionally reliable if proper OE equivalent parts are used.

What is the history of the engine? Was it rebuilt recently and what parts were used?

I strongly suspect improper assembly and/or parts.

Common examples are installing pushrod guideplates without opening up the OE head pushrod bores. This is a surefire road to bent pushrods. Another is using excessive seat force and rate valve springs with an OE equivalent cam. This is a ticket to lobe and lifter failure.

Pictures of the damage will help, too.

Duke

[Jim A.]

Re: 68 L79 cam, pushrods and lifters swallowed up, need help with parts / vendors Pl

Thanks Duke,
Well i diddnt know quite how to describe it so I called it swallowed up...... with valve covers off When engine cranks some pushrods do not lift as far as others, if you rotate the pushrods manually you can see that some are bent. I have no idea what else to look for.

I have only owned the car for 3 years so I have little knowledge of the engine history. All I know is it is a CE short block assembled by Commonwealth Chevrolet in Boston Ma So expect to find all GM parts when I disassemble. and has had no significant work since. I am not an experiencede mechanic so this is first time i have seen inside of an engine. I can try to get some pics tonight. Car is at my mechanics shop now.

[Jim A.]

Re: 68 L79 cam, pushrods and lifters swallowed up, need help with parts / vendors Pl

So, anyone know of a qualified corvette engine rebuilder around Boston Mass

[Mark L.]

Re: 68 L79 cam, pushrods and lifters swallowed up, need help with parts / vendors Pl

Jim, there are a number of New England Chapter members who have utilized a handful of shops in the MA area. If you do a shout out to them I'm sure you'll get some good input.

[Duke W.]

Re: 68 L79 cam, pushrods and lifters swallowed up, need help with parts / vendors Pl

Thanks Duke,

I have only owned the car for 3 years so I have little knowledge of the engine history. All I know is it is a CE short block assembled by Commonwealth Chevrolet in Boston Ma So expect to find all GM parts when I disassemble. and has had no significant work since. I am not an experiencede mechanic so this is first time i have seen inside of an engine. I can try to get some pics tonight. Car is at my mechanics shop now.

I don't know when GM stopped offering 327 CE short blocks, but I can't imagine it could have been much into the 90s at the very latest. so time wise that engine is quite old, but how many miles?

I would think that lifter or lobe failure would have happened earlier unless the car has been sitting a lot in the last 30 years.

Duke

[Jim A.]

Re: 68 L79 cam, pushrods and lifters swallowed up, need help with parts / vendors Pl

Duke,
CEblock was installed in late Nov of 68 (I have documentation), then owner (friend of mine) went racing and put a rod throughh original block

[Duke W.]

Re: 68 L79 cam, pushrods and lifters swallowed up, need help with parts / vendors Pl

Do you mean to say that the rod went through the original block and the currently installed block is the CE block installed in 1968?

Duke

[Joseph S.]

Re: 68 L79 cam, pushrods and lifters swallowed up, need help with parts / vendors Pl

Jim, Send it to ABT Machine in Holliston. Owners name is Mike. They do all our machine work. You can use my name or shop name.

Good Luck, Joe

[Jim A.]

Re: 68 L79 cam, pushrods and lifters swallowed up, need help with parts / vendors Pl

YES that is correct duke

[Jim A.]

Re: 68 L79 cam, pushrods and lifters swallowed up, need help with parts / vendors Pl

Thank you Joe, I was going to talk to you before I made a move, dave strick is coming up tomorrow, let's see what the old guy thinks. I will let you know!

[Rod K.]

Re: 68 L79 cam, pushrods and lifters swallowed up, need help with parts / vendors Pl

In your original post you stated that "the car ate up it's timing chain" and without further explanation I'm theorizing that the chain jumped a tooth or a few (or broke?) which would lead to pistons and valves getting to know each other intimately, resulting in bent valves & push rods. Don't crank the engine any more until it's disassembled and checked to determine the extent of the damage. Best case you'll replace valves and push rods, worst you may have damaged guides, valve seats, etc. Good luck, been there, it's unfortunate but not a big deal like a spun bearing or broken rod.

[Jim A.]

Re: 68 L79 cam, pushrods and lifters swallowed up, need help with parts / vendors Pl

thank you Rod,
Some other members felt that because of the time between timing chain failure and cam failure was about 6 months with car being driven every weekend that it was unlikely that timing chain was the root cause. But who knows I will know more when I get it apart

[Dave P.]

Re: 68 L79 cam, pushrods and lifters swallowed up, need help with parts / vendors Pl

I'm curious. Is the L79 an "interference" engine? If the valve timing gets out of sync with the crank, does valve to piston contact really occur? (Duke can probably answer this.)

I know that that when the timing chain sprocket in my 350 horse 396 lost all its teeth and came out of time to the point it wouldn't start anymore, I put a timing set in it and drove it another 100k miles. No other work was required at the time. When the engine was torn down for overhaul a few years later there was evidence of slight exhaust valve contact, but I've never given it any thought as to whether the contact was from the timing issue or just valve float in an engine with tired springs and a 21 year old driver.

[Duke W.]

Re: 68 L79 cam, pushrods and lifters swallowed up, need help with parts / vendors Pl

Sorry, I can't answer. I don't know what if any vintage Chevy pushrod V8s are interference engines or not. Back in the day when we had steel and cast iron timing chain sprockets nobody worried about it. Then they foisted that nylon tooth cam sprocket on us...

I know that my Cosworth Vega and '91 MR2 have non-interference engines, and that's important to know since they both have fiberglass reinforced rubber timing belts that can fail suddenly if they're not changed IAW manufacturer's recommendation.

I had a friend back in the seventies that had a rubber timing belt fail on his Fiat 124 Spyder and it ate all the valves.

Duke