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Bent exhaust valve 383 chevy?

2K views 11 replies 8 participants last post by  xxllmm4 
#1 ·
Hey everyone,

Well I was driving down the road, came to a stop and bam! It sounded like I ran over something. And started running like crap. I pulled the valve covers and the number 8 exhaust valve is bent and stuck about half way down.

I'm pretty sure the only way to bend a valve is from contact with the piston. The engine has about 1500 miles on it and has a gear drive. So before I tear into it what do you think happened?

Thanks
 
#2 ·
Could be several things...valve stem or guide got hot and seized in the guide, so piston tagged it, sheared valve locks and valve dropped, broken spring allowed valve to hang open and piston tagged it. There are more ways also.

Is the retainer still connected to the valve locks and valve stem??

Entire stem still held to rest of valve??
 
#4 · (Edited)
A little more info, I really figured the timing gear broke a tooth (sill haven't got that far)

I bought the heads off ebay, Pro Topline Vortec. There where not set up as advertised they claimed .550 lift and I never checked. After some broken valve springs, and some smashed oil seals. I replaced the springs and all the seals with Viton seals and beehive springs / retainers for extra clearance. They measured .547 clearance with the new setup. My cam is .530. At any rate the intake valves are nasty from not having oil seals. I put some fuel system cleaner in about a hundred miles ago and now suspect some carbon chunks broke off and got jammed in the exhaust valve seat.

I got the manifold off tonight, hopefully I have some time tomorrow to get the head off. This is not how I wanted to end the summer LOL
 
#5 ·
Yikes!!!...0.017" is not nearly enough if thats your coil bind measurement.

You need springs for 0.600" lift minimum, there are a few LS springs and also the new Comp conical springs that are capable.

I had to face this same dillema with my Fast Burns, I chose the Comp conicals.
 
#8 ·
I hope you pulled the engine right out.This is not an in car repair.Im guessing this engine was assembled,not blue printed? refresh,repair,replace all parts damaged.
BTW running without valve seals is not a big deal, we used to do it all the time in the seventies.It will only smoke a second on first start up.

give the gear drive system to Richard, he will show you how to deal with them,,
 
#11 ·
I had the same problem when I bought a set of 461's refreshed, mild port & polished, and what the guy said was 7'000 rpm springs that he uses in his circle track car.:( Number 5 exhaust valve spring broke at 7'000, tagged the piston, and broke the valve guide.:smash::pain: It cost me over $400 to fix the guide, cut the heads for bigger springs and replace one valve.:mad::evil::mad:

Lesson learned: NEVER rely on what the seller claims! :rolleyes:
 
#12 ·
Well, I got the heads off today and removed the valves. The one valve is bent, and all the exhaust valves are galled to some extent. It looks like insufficient valve guide clearance. The bent valve just kissed the piston you can hardly feel the ridge. I will be taking the heads into a reputable machine shop I have used before.

They are ProTopline Vortec's I have already dumped to much money into them with beehive spring and roller rockers but what the hell, should I have bronze guides installed while their out?
 
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