Technical All exhaust pushrods bent?!

^^yes!! A leak down will tell you where the compression is going!!


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It also has to run for at least a few minutes for the stale gas to create the heavy carbon on the exhaust valves. I've got one outside waiting to have the heads pulled that has exactly that issue. I thought the tank was bone dry, dumped in a couple of gallons of fresh gas to fire it up and found out that it had several gallons of very old gas in it.
Side note, exposure to air seems to be a lot more of an issue than heat. I've got another rig that has sat out here for over two years and the gas hasn't gone bad. Fi car with a sealed fuel tank system with no venting to the air.
I'm thinking on this that just as others thought the timing is just enough teeth off to case the valves to hit the pistons.

 

Good luck, Joe. Remember, no good deed goes unpunished.

 

I've seen that in a SBC were the timing gear on crankshaft was put on backwards , the owner tried shorter push rods and they still bent until I looked at the timing gear and didn't see any timing mark because the mark was in toward the block !

 

Nobody ask if they used a multi keyed cam gear it is easy to line op the wrong sets of marks I double check you turning the engine to TDC exhaust and lay a straight edge across the lifters they better be close the same height

 

the last time I loaned my shop out and left for the weekend . My tools were stolen and I was out of business for over 2 years. Just saying.
The incompetence that put into screwing up one of the easiest V-8's ever to work on . I would be afraid to let someone use my shop while I was gone. You may come home and find the engine on top of one of your friends and then you end up in a lawsuit by one of the family members.

 

I would also check to make sure the valve springs are not binding. Just a thought. Also if the valve guide were replaced ( new guides installed in place of the cast in ones) they may be hitting the valve spring retainers.

 

Alright alright! Got back from Canada on Sunday, managed about 1000 miles this weekend in the 61 without breaking too much. Had a lifter collapse on me somewhere in PA and kept it moving, had a great time at the Jalopy Jam Up, and got home safe and without a tow. A great success!



Today we tore down the front of this 318, and we have a verdict; timing chain installed improperly. To his credit, it was an honest mistake, he used the wrong set of marks, those being the ones on the edge of the gear rather than the one on the keyway. Here you can see the dot on the cam gear at the top of the picture, and you can see the "0" on the crank gear are lined up at the 6:00 and 12:00 position. But you can also see that the "0" on the key slot is like 3 teeth off to the side. Nevertheless, the cam is installed WAY off, and that's the culprit.

This is the timing chain they used:
https://www.summitracing.com/parts/sum-g6603r-9/

Downloading the instructions, I can see that it's a bit confusing as to which mark to use. I joked with him that he had a 50/50 chance of getting it right and that he should give up on roulette and switch to blackjack or something.

Unfortunately, the key on the cam gear is mushroomed from the tension of pushing on the pushrods and valves, so we have our work cut out for us getting the sprocket off without destroying the cam and thrust plate. I'd honestly rather it have sheared off.

Next we'll do a leak down test to see if the valves bent or whether we can catch a break and just do a quick timing chain and new pushrods and go.

Thanks again for all of the replies!

 

Well, who woulda thunk it?

 

Keep us in the loop please

 

It had to be something like that... good work!

 

I think forgetting the key as you mentioned earlier and if I’m understanding the dynamics of that situation - might have been the cause and doomed it.

 

That picture shows the gears timed correctly.
The key in the crank should always be pointed to #1 deck at tdc.
The gears are exactly correct, but the crank key should be in the zero slot. I don’t even see a key way.

 

Exactly ^^^^

There’s a set of markings on the teeth and a set of markings on the key way. With #1 at TDC Select the Advanced/retard or Zero on crank gear key way markings Then line up the corresponding timing marks at the teeth. R4, R2, O A2 A4 etc

That BIG red line should be where the crank key way is and corresponding with the clear “0” zero mark on the crank gear.

 

Love that 61. GM got it right in 61 on every marque that year.

 

I’d like to see where the crank key is with those gear markings lined up.

 

So ???
We get to see or not?

 

Probably got the crank turned to 6 and 12,,,,,can’t see the key way.

Just kidding Vick,,,,Lol!!!

Tommy

 

Lmao !!
Well let’s say he’s got that key in R4 maybe.
He’s just 4 teeth off on that crank then- or 60* crank degrees off.

 

Yeah,,,,60 would just about do it!

Tommy

 

I didn't get a shot of it before it got pulled off but it was on R4, out of sight of the picture. At that point we can just say it was wayyyy TF off and start over. I'm going to do a leak down test tonight to see if these exhaust valves are bent, which I'm fairly certain they are, but one can always hope.

When I was talking to my friend about how he screwed this up, he admitted he never set the engine to TDC before installing a cam before. He probably got away with it because a standard timing set only has one set of keys and for the dots to line up at 12 and 6, the crank would have to be in the right position. But with the 9 position sprocket, it added variables where old habits wouldn't work any longer.

 

Tell your friend not to beat himself up too bad,,,mistakes happen sometimes.
Where many of us have done this so much it is old hat to us,,,,seems elementary.
But to some guys that are a little less experienced,,,,especially with a multi key sprocket like that ,,,it could happen.
Always,,always,,,,gently cycle it through the motions and feel for any binding.
The best way if you plan to use a multi key sprocket is to take a paint marker and mark the key you intend to use,,,,the key slot and the corresponding O mark for that slot.
I am getting older and it is easier to do while I have it up close in my hands before I put it on the crank.

Tommy

 

Yeah man, totally agreed. Plus I give him credit for rolling his sleeves up and getting in there. The effort deserves some credit. I'm sure he won't make the same mistake next time.

We did a leak down test today and even though the harbor freight tester is a piece of shit, I was able to hear a bit of whistling past the valve. We pulled the heads and will put new exhaust valves in. For ~$60, it's cheap insurance.

That's sage advice about using the paint marker and preemptively marking the sprocket. I keep a couple silver and gold sharpies in my tool box for just such jobs.

We ordered some new valves from Rockauto.com, and they should be here in a few days. We'll pick up from there.

 

The problem isn't in making mistakes, it's in repeating them. The only people who don't make mistakes are the ones who don't do anything and that is the biggest mistake of them all.

 

I never understood why anyone would want to take a chance at lining up at 12/6.
If you aren’t actually going to degree the cam into the correct position, just go dot to dot. Much harder to be off time that way. I cant think of any reason to do otherwise.

 

Hopefully those new valves have a good grind on them and a little lapping will give you 360º contact on the face.

 

Crank for at 12 , cam for at 6 IS dot to dot .....

 

I have learned over the years that a large part of learning how to do something is learning what to not do.

 

Ha! Guess you’re right!!!
Maybe that’s why i never understood it!!!!

 

No that puts it 180 out