Time, tools, and skill required to replace bent valves?

[LeeH]

My 80+ mph downshift to second (instead of upshift to 4th) at the track yesterday has left me with the symptoms of bent valves.

The engine only has around 4000 miles on a rebuild. What's it going to take to get the car back on the road?

[Early_S_Man]

Found any broken rockers?

If you have all of the necessary parts and tools on hand ... one weekend [two-day] job at leisurely, careful. methodical pace:

Day 1 -- remove engine, disassemble & clean up parts, evaluate the damage ...

Day 2 -- replace bent/broken stuff, reassemble, time cams, reattach induction & exhaust, reinstall engine.

[yelcab1]

I would say it is practically much longer than 2 days. You would not know what you have to buy until you are finished ripping it apart. It would then take you at least a week to get the parts, and then 2 more days to put the whole thing back. My guess, is 10 days.

[Steve@Rennsport]

I would never install any new valves without grinding the 3 angles and checking them for concentricity.

As yelbcab1 said, this is not a 2-day job unless you are a shop and do ALL of your own machine work in-house like we do.

[ChrisBennet]

What about the rod bearing on the cylinders that bent the valves?
-Chris

[FenderGuy]

Lee

sorry to hear about your engine troubles

[Jeff Alton]

This requires some serious inspection. Chris is right in asking about the bearings. I rebuilt a 3.6 that had 6 bent valves. The adjustment screws in the rockers were also bent. Oh and it cracked two guides as well. Steve rebuilt the heads for me with all new valves and guides. I had the rockers magnafluxed too. The valves had just "kissed" the pistons as you had to look very very very close to see any markings on the pistons.

Cheers

[len911]

Been there done that! I ended up replacing 6 exhaust valves and doing a complete valve job a few years ago. Just upgraded to a Rennshift shifter. Too late for you, but I have a Robotek listed in the for sale section... Cheap insurance... Lou

[DonDavis]

Sorry 'bout that, Lee. You know I'll be there and I'll bring my engine stand. Use it as long as you like.

[Jeff]

+1, except for the engine stand part.

[FenderGuy]

+2, I don't know how much I could do, but eager to learn

[Az911]

Lee I can help you with the engine drop I've done it before and it's easy.

Also time to buy my wevo shifter to keep this from happening again.

[cstreit]

I'll typically do valve guides on bent-valve engines. More often than not, the valve guide is damaged. Possible piston damage, they'll need to be checked...

...and depending on how bad the over-rev was, rod-bolts may be suspect. You can often tell by how bad the divots are in the pistons...

[LeeH]

I bought a compression test kit today. I did the test cold and without the aid of the long adapter.

The number were:
60, 120, 80, 0, 0, 5

I wonder if I'm not getting the threads seated well enough since I'm just twisting the braided hose to tighten the adapter into the spark plug hole. It's hard to believe that the engine would run at all with these numbers. It actually ran OK above 2000 rpm.

[yelcab1]

Lee

Hand tightening is enough for this test. Trust the numbers, you are toast. One bent valve is as bad as 6, because the engine has to come out.

Good luck with it.

[LeeH]

Oh c'mon... let me briefly fantasize that it's only my lack of experience using a compression tester that caused these number and not my poor shifting at the track!

[CharlesJones]

Hi Lee,
I did exactly the same thing as you - trying for fourth and got second at high speed. It took me a little while to fix because I was a complete novice mechanics wise, but everything went fine - I found no broken rockers or damaged pistons - just 6 bent exhaust valves. It was all a very worthwhile experience for me because I learnt loads and now don't fear working on my car. I recommend it.

[Porsche_monkey]

My throttle stuck and I did the wrong thing...

Took me several months, but I re-did the entire engine. You might find that once you get into it, you want to be sure it's 100% done.

[len911]

It happens.... I missed 4th and went into 2nd at VIR about 5 yrs ago. Figure I spun the eng to about 9K. Ouch! Here's proof, six drunken sailors ... Worst part was that I did it on my first run. Wife was ticked since she could not drive for the rest of the weekend. Lou

[LeeH]

Originally I was going to have all you guys in Phoenix come over for the drop. I had a little time this afternoon and it's pretty much all over except for the four big bolts. Anybody in Phoenix is welcome to stop by for the actual drop Saturday a.m. I'm in Ahwatukee. 602-300-0309