How bad did I hurt my engine? - Team Camaro Tech
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post #1 of 26 (permalink) Old Oct 6th, 03, 06:47 PM Thread Starter
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Yesterday I had my 69 out for a drive. I had along my 14 year old son and a friend of his. The twisted my arm and made me do a good old burnout, followed by a handful of second with more rubber on the pavement, and then >> a BLOWN SHIFT into 3rd. The motor over revved, (about 6500rpm) and then began to miss badly. I managed to limp home with my tail between my legs and put the car away.

I'm really limited on time right now to look at this as I'm helping my parents downsize and move into a retirement home.

What do you think I did to my car? How bad is this going to hurt?

Thanks! [img]graemlins/sad.gif[/img]

Doug
'69 SS clone w/numbers matching 327, M-20 & 8.5 rear swap (3:73 posi)
'65 327/300hp Corvette Coupe (regrettably sold years ago)
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post #2 of 26 (permalink) Old Oct 6th, 03, 07:49 PM
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what motor? i'm actually surprised 6500 hurt it, but it sounds like you hurt something. i'd start pulling plugs and checking for unusal signs of anything on them. it's real hard to say why its missing, without hearing it or looking things over. is it a constant miss, or only at certain rpms, etc.? just start looking, do a compression test too, it could be a bent valve, or broken spring, a bent valve will show in a compression test. at any rate good luck with it, hopefully it will be an easy fix (it should be, imo)

Sean

1968 rs with an old school 354" SB2.2 pump gas motor.

Repetition does not transform a lie into a truth.

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post #3 of 26 (permalink) Old Oct 6th, 03, 07:50 PM
 
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i'd let it cool down and restart it and see if it's a fluke.

if not, find out what cylinder is missing, or just take out all the plugs and inspect for damage.
do a wet and dry compression check to see if you damaged a valve and/or piston, or maybe just a pushrod, or even just the sparkplug.

since you didnt hear awful metal banging sounds, hopefully you didn't do much damage. possibly even just jumped the timing chain. in fact, check the timing first, and see where your rotor is pointing at tdc#1.

yup. i'm goin with the chain. least damage, least work, most likely culprit. please tell me it was old.
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post #4 of 26 (permalink) Old Oct 6th, 03, 08:54 PM
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If it's not just a fouled plug, loose plug wire, pitted points or arcing under the distributer cap, then I'm betting the timing chain (if loose and worn) may have jumped a tooth.

A bent valve would give you other more audible indications.

Meanchicken
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post #5 of 26 (permalink) Old Oct 6th, 03, 09:11 PM
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A couple basic checks I always do for peace of mind when I think I broke something

Check the oil for water and the water for oil - any mixing indicates a blown head gasket or maybe a crack in the block.

Check the oil for anything small and shiny. Little flakes of metal in the oil is bad . . . like a spun bearing or something.

Put a vacuum gauge on the engine and watch it while the engine idles and revs. If the needle stays steady your cam is OK, if it has a spike to it then there is an intake valve or cam lobe problem.

Check the spark plugs for damage, like a bent electrode or tiny black spots on the ceramic under the electrode. That would indicate detonation was present or that a piece of something went through the motor (like a piece of piston).

While the plugs are out do a cranking compression test. All the cylinders should read about the same +/- 10%. A cylinder that is off might have a bent valve - if you squirt a little oil into a cylinder that reads low and the pressure comes up it is a ring or piston problem, if it doesn't come back up its a valve problem. If all the cylinder read real low maybe the timing chain jumped a tooth like the others suggested.

Hope that helps - I'd also be suprised if its anything serious at only 6500 RPM. Shoot, I shifted to neutral once and passed 7 grand by a bunch

Hope its nothing serious.

E85 racer and E85 carb builder

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68 Camaro, E85 powered 427" small block. 9.96 @ 133 MPH, 1.319 sixty foot on motor. 5.92 eighth @ 116 with a 1.42 sixty breaking beams with back tire on the bottle
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post #6 of 26 (permalink) Old Oct 6th, 03, 10:05 PM
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If your still running a points type distributor, look there. Mine would get fubar after about 5k on my old motor, and start doing what you describe. I used to have to pull over to the side of the road pull dist-cap and rotor and file down the points just to get home [img]graemlins/clonk.gif[/img]
The MSD pro-billet distributor is great- never worried about that again. [img]graemlins/beers.gif[/img]

67 Camaro<br />383-SRP Pistons, Manley Rods, Cola Crank, Edelbrock Performer RPM package, Speed Demon 750 dp, MSD Ignition, 9" rear
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post #7 of 26 (permalink) Old Oct 7th, 03, 11:42 AM Thread Starter
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Thanks to everyone for your help! [img]graemlins/thumbsup.gif[/img]

(68rs406) The motor was rebuilt before I bought the car so I'm not 100% certain on some of the details. This is the information passed on to me:

original 327 motor (rebuilt)
76 cc heads (350?)
1.94" valves
Crane Hydraulic Cam WG996 (327/350hp &gt;&gt; GM# cam 3863151?)
Edlebrock Performer intake
Holley 600 cfm

Doug
'69 SS clone w/numbers matching 327, M-20 & 8.5 rear swap (3:73 posi)
'65 327/300hp Corvette Coupe (regrettably sold years ago)
M-92 Bultaco Sherpa-T {326cc}
M-115 Bultaco Alpina {250cc}
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post #8 of 26 (permalink) Old Oct 7th, 03, 12:02 PM
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crazy. i'm sure the motor is not seriously hurt, but you'll have to look into it. there are a lot of good ideas given, so try some of them. i still would try a compression test first, after inspecting the plugs. if its just a miss, not running like crap, i'd doubt it was the timing chain. its not impossible by any means though. i think the ignition idea is a good one, if you are still running points. don't count out a valve though, thats why i reccomend a compression test. all it takes is slight contact with a piston to bend a valve, just enough to cause a miss. weak stock spring will easily float at 6500. check the plugs, check compression (that will eliminate a bent valve if its good) its just going to take some searching now. i like the list eric gave you for trouble shooting. at any rate, good luck with it!

Sean

1968 rs with an old school 354" SB2.2 pump gas motor.

Repetition does not transform a lie into a truth.

Franklin D. Roosevelt
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post #9 of 26 (permalink) Old Oct 8th, 03, 06:06 AM
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I'll throw my .02 worth in. Pull the valve cover on the side that you think the miss is on. Look for a bent pushrod. Mine did this, more than once, with the stock valve springs. They would bind up at high rpm's. Same symptoms as you describe. Wind it up, and limp home with a 'miss'.

Mark
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post #10 of 26 (permalink) Old Oct 8th, 03, 06:22 AM
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Start the bugger up. If it is still dropping a cylinder, remove ONE plug wire at a time until that wire does not change the running of the engine. The problem is in that cylinder. Remove that plug and look for damage. Check for spark at that plug. If all is well, remove the valve cover and check for a broken spring, rocker, etc. One thing is certain, you are on the right cylinder. If every removed wire affects the way teh engine runs, it is more "common" to all cylinders, like cap, rotor, points, etc. Good luck.

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post #11 of 26 (permalink) Old Oct 8th, 03, 10:14 AM
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i had the same thing happen once and it turned out to be a twisted up rotor spring(where it makes contact with the cap)!i was freakin!
really hope it's something simple like that!if its an hei make sure your positive wire to the cap was plugged all the way in.
Good luck!
Eric

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post #12 of 26 (permalink) Old Oct 8th, 03, 10:20 AM
 
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Quote:
Originally posted by mbrekke:
I'll throw my .02 worth in. Pull the valve cover on the side that you think the miss is on. Look for a bent pushrod. Mine did this, more than once, with the stock valve springs.
Mark
I'll put my money on it being a bent pushrod(s). That has happened to several people on the Corvetteforum. Now the SBC and LS1 are totally different motors but, never the less, bent pushrods are a common result of an over revved motor. It is probably just as easy to pull the valve covers and remove the pushrods as it is to do a compression test and the odds are higher that it is a bent rod. I would do that first. If that is the culptit, no big deal. They are cheap.

Question: Does anyone actually know of a case of a timing chain "jumping" a tooth. I've heard people suggest it as a possibility but never heard of it actually happening. Just broken timing chains.
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post #13 of 26 (permalink) Old Oct 8th, 03, 10:33 AM
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[quote]Originally posted by need-for-speed:
Quote:
Question: Does anyone actually know of a case of a timing chain "jumping" a tooth. I've heard people suggest it as a possibility but never heard of it actually happening. Just broken timing chains.
Yup. It was real common with mid-late 70's small blocks that hit the 80,000 mile mark. the teeth on the cam sprocket were nylon - the nylon would get brittle and teeth would break off. If enough teeth broke off and the chain was sloppy, the chain could easily jump a tooth.

E85 racer and E85 carb builder

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68 Camaro, E85 powered 427" small block. 9.96 @ 133 MPH, 1.319 sixty foot on motor. 5.92 eighth @ 116 with a 1.42 sixty breaking beams with back tire on the bottle
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post #14 of 26 (permalink) Old Oct 8th, 03, 05:42 PM Thread Starter
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Great ideas! I'll have to wait until next week to check my motor out as were're moving my Mom and Dad into their retirement home this weekend.

I'll report back with my findings. Thanks again to all! [img]graemlins/waving.gif[/img]

Doug
'69 SS clone w/numbers matching 327, M-20 & 8.5 rear swap (3:73 posi)
'65 327/300hp Corvette Coupe (regrettably sold years ago)
M-92 Bultaco Sherpa-T {326cc}
M-115 Bultaco Alpina {250cc}
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post #15 of 26 (permalink) Old Oct 9th, 03, 03:23 PM
 
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Good luck and be sure to let us know. Case history helps us improve our diagnostic skills [img]graemlins/thumbsup.gif[/img]
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