brucep

I just bought a 66 327/350 as a fresh rebuild with about 500 miles on it. I take it out driving in 4th gear on the highway at 2500 rpm. I put it to the floor and bring it up to about 3300 when I hear a sharp loud noise I like when a half inch rock hits your windshield. It made me wince.

After this I slow down and notice the engine skips, has less power and I hear noises that sound like old noisy lifters. Before that the engine looked and ran like a fresh rebuild, with no lifter noise at all. Still has good oil pressure.

Without investigating I'm hoping it's something like a broken push rod or rocker malfunction. Tell me you've seen this before and it's an easy fix I can do myself.

Thanks
:mad


[Modified by brucep, 12:09 AM 3/17/2003]


[Modified by brucep, 12:10 AM 3/17/2003]

396 RAT

I would guess a bent push rod, but the loud noise scares me?

Allcoupedup

I'd do a compression test to narrow the scope of the problem.

67L36Driver

I agree with Allcoupedup, valve train parts don't normally fail at low rpm.
Did you have any spark knock prior to the bang? I heard a sound like that once and it turned out to be a hole in the piston.

Tyler Townsley

Broken rocker arm. May have bent a pushrod. Pull valve covers it should be rather obvious.

Tyler

brucep

Good easy suggestion Tyler.

I pulled the valve covers. I see the rockers are off to the side of two valves servicing the same cylinder. One rod is obviously bent, the other I'm not sure of. Any ideas what would cause this to happen to a supposedly fresh rebuild? And is the camshaft junk now? What do I do next?


[Modified by brucep, 2:15 AM 3/17/2003]


[Modified by brucep, 2:17 AM 3/17/2003]

jerrybramlett

Any ideas what would cause this to happen to a supposedly fresh rebuild?

Yep. Wrong or faulty push rods (too long). Rockers too loose. Badly worn rocker tips. Rocker slots too short for aftermarket cam lift. Wrong rockers. Previously over-reved engine. Rocker studs pulling out of head. Worn pushrod guides. Seizing rocker *****. Seizing valve guides. Worn valve stem tips. Homemade budget cylinder head "rebuild" re-using all old parts.

And is the camshaft junk now?

Probably not harmed. But you won't know for sure until you at least fire up the repaired engine or look at the cam lobes with the intake off.

What do I do next?

I'd inspect the studs, rockers, and push rods involved and replace the damaged parts. Then I'd light up the engine and see how it runs. I'd also watch that side with the valve cover off to see if it's oiling right. Afterward I'd take the bill for the engine rebuild to the shop that did the work, tell them what happened, and ask their opinion. You do have the invoice for the work, don't you? Sometimes engine "freshening" that is not backed with a receipt never actually happened.




[Modified by jerrybramlett, 8:17 AM 3/17/2003]

Tyler Townsley

Who adjusted the valves when the motor was redone? Usually the builder will get it close install motor run it in a little to make sure there are no leaks and break in the cam if necessary. Once that is done the valves should be rechecked before being driven. It is real easy to get busy and forget to go back and check the lash once the motor is in the car. I would replace the pushrod(s), adjust the valves, do a compression check and if it has good compression, run the motor. Oh yeah check all the other valves too.

Tyler

brucep

Thanks guys. Ifthe rest of the car is any indication, the rebuild was Ok, it just never had the proper follow up work done after the rebuild, beyond 2 oil changes. Car past through a lot of dealer hands before me. I think they freshened it to maximize profit and hasten the sale, but no TLC was applied.

It goes to a Corvette shop next week. I think I'll let him look at it before I do anything. Anybody have experience with Ron's Restoration in Fitchburg MA? That's where I plan to take it.

Kid_Again

...now for the bad news (believe, me, BTDT)....like jerry said, you do have the receipts for the engine rebuild, right?......look, NOBODY freshens up a motor to maximize profit, you maximize profit by NOT freshening up the engine, so be prepared for the worst...

...when i was buying the '65 roadster, i got a story that the engine was "fresh", 0.10 over, yadda, yadda (couldn't find the receipts, though)....well, the only freshening was the fraud it took to put 365hp decals on the valve covers (had to be someone my seller bought it from because this guy was NOT a gearhead)....among other things, i had solid lifters running on a hydraulic cam, the oil pump tube was ready to fall off, harmonic balancer off a 305 (and hence, wrong timing chain cover), stripped bolts everywhere, wrong distributor, wrong heads, '68 valve covers - other than that, perfect...

..be prepared for the worst and hope for the best....good luck


[Modified by Kid_Again, 6:28 AM 3/17/2003]

jerrybramlett

Nothing strikes fear in me like a Corvette ad that says "new paint" or "fresh engine".

Well, except a comment from the little woman at dinner like "my car has been making a funny noise for the last few weeks".

achapman

I can't comment on Ron's Restoration directly, but two members of my local Corvette Club vowed never to use him again. I have used the Corvette Connection, (978) 646-9996 , which recently moved to Middleton, MA just off Route 114. Good work reasonable rates.

I have also heard good things about the Stringray Shop here in Marblehead, MA, (781) 639-3527, although he is more expensive.

Rowley Corvette also has a good rep, in Rowley, MA, (978) 948-7730.

Hope that helps..... Good Luck - :cheers: