Cam, Lifters, Headers In An Inline Six

[usmcchevy]

The only break in your springs need is a few heat cycles. Your cam on the other hand, I'd call comp and do as they say.

[Jbesotes]

FInally statred the project have the motor torn down here are the pictures.

[Jbesotes]

here are some more picts

[Jbesotes]

I have a question in this picture I have the harmonic balancer that has a crack in it and it is the third one that I have gone through and I do not know why it keeps doing this. It is causing me to have an oil leak at the seal on the timing chain cover.

If anyone has any ideas on what could be causing this please let me know.

[68Stepbed]

Probably vibration. It may be time to have the bottom end checked and maybe balanced.

[Shaky]

Originally Posted by 68Stepbed

Probably vibration. It may be time to have the bottom end checked and maybe balanced.

This. You've got an imbalance in your crank-rods-pistons-flywheel system.

[slomotion]

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[RichardJ]

Am I looking at a crack through the key slot? I would inspect the end of the crank to make sure there isn't any damage or peened oversize. I would check the key to make sure it isn't sitting too high. How do you install the dampener? Not that I am able to say I have never hammered one on, but the best way is with a threaded shaft. Thread the shaft into the crank and pull the dampener on with a nut and some oiled washers.

Long before an out of balance condition could do that damage, the crank would surely break.
How about a 98 cubic inch two cylinder engine?

[Jbesotes]

The only thing that I can think is that the key is too big because When I rebuilt this engine three years ago I had the Crank ground and turned.

[Shaky]

Originally Posted by RichardJ

Am I looking at a crack through the key slot? I would inspect the end of the crank to make sure there isn't any damage or peened oversize. I would check the key to make sure it isn't sitting too high. How do you install the dampener? Not that I am able to say I have never hammered one on, but the best way is with a threaded shaft. Thread the shaft into the crank and pull the dampener on with a nut and some oiled washers.

Long before an out of balance condition could do that damage, the crank would surely break.
How about a 98 cubic inch two cylinder engine?

Good point. It's either a crank geometry issue where the damper goes on or an imbalance.

['68OrangeSunshine]

Over-revving can blow out an HB, one way or the other. Sometimes they just go "off-clock" and other times they blow up, blasting their way thru the radiator on the way to chaotic entropy.
If you're getting a new Harmonic Balancer, anyway, why not get the 3-groove 292 part? The heavier operating mass can only smoothe things out that much more. GM p/n: 10141202.

[RichardJ]

You are not going to damage a HB by over-reving a 292. If you had an outer ring break apart, it was because it hit something when it flew off. Oil and old age destroys the bond between the rubber and the outer ring or the rubber and the hub or both. Most engines only have inertia trying to move the outer ring around the hub on their HB's. The Chevy inline six has the drive belts, fan, water pump, alternator and power steering pump, all trying to twist that outer ring off the HB. Everytime you start the engine, all of those accessories give the HB ring a nice big tug.
I had one outer ring fly off my 292 while I was driving down the freeway. Another dropped to the ground when I started the engine.
It wasn't till I had one come loose on a 350 that I realized I would be smart to add a hub mounted pulley on my 292 to trap the outer ring should it come loose again. I knew I would eventually be adding AC so I mounted the AC pulley just as a guard. I put new white paint on the HB timing mark and a mark on the new pulley. As long as those easy to see marks line up the HB is still good.

[Shaky]

Yeah - my 292 spun the outer ring. In this case, however, it's a 250 and he cracked the inner ring where the seal rides and he did it twice before!

[slomotion]

I would measure the width of the key slot in the HB, then measure the crank key width to be sure the key isn't too small allowing the HB to "rock" back and forth against the key creating shock loads on the damper. It wouldn't take but a few thousands to allow the damper to move back and forth too much.

[Jbesotes]

I did find out why the harmonic balancer cracked in the key way I think. I was told by a machine man that it could have been from the motor back firing. As I did have quite a few backfires with my old setup.


I have the new cam that I got back today with the gear presses onto and the head back with all of the springs put on and head cleaned.

All gaskets are cleaned off the motor and covers and I am ready to start putting the motor back together hopefully tomorrow. Will post picts as I work on it.

Thank You everyone for all of your imput, help and sugestions.

[Jbesotes]

hello everyone sorry I havent had any replys latley my computer crashed on me and i just got it back from service. I am working on putting the headers on and I am running into a problem where my header on the rear of the motor is titting the bracket off the motor for the clutch linkage. Does anyone have any ideas of what to do or if there is a part out there that can replace the bracket, or if i should just fabricate something myself.

[dnorris009]

Is your linkage touching the header tube like mine?
http://67-72chevytrucks.com/vboard/s...d.php?t=406127

[Jbesotes]

No, I actually have the short headers I will get a picture soon, it would be hitting the bracket that attaches to the motor but I had to take it off so that the headers would bolt up. I am having to fabricate a new bracket to hold the clutch bar that attaches the clutch linkage from the cab to the linkage that goae to the bell housing.

[OJ1988]

I just pulled the 250 out of my truck.
I ran a Clifford intake 450cfm holley 4 barrel, pacesetter long tube headers with bullet mufflers that exited out the driverside in front of the rear tire.
I also added an hei dist. I drove if daily in mostly city driving with a 3pm the tree. Had it tuned very lean an was able to average 12 miles to the gallon.

[OJ1988]

I just pulled the 250 out of my truck.
I ran a Clifford intake 450cfm holley 4 barrel, pacesetter long tube headers with bullet mufflers that exited out the driverside in front of the rear tire.
I also added an hei dist. I drove if daily in mostly city driving with a 3pm the tree. Had it tuned very lean an was able to average 12 miles to the gallon.

[Jimmy S.]

Jbesotes,what method was used to install the aluminum timing gear on the camshaft?

Jimmy

[Jbesotes]

Jimmy: I have a machine shop that is near by to my work and I had them press the timing gear onto the cam for me.

[Jbesotes]

Almost finished got the motor put back together and it looks like a whole new machine. The headers, intake and carbuerator are on, and I am waiting on a new clutch fan. I ended up putting all new ARP Black annodized bolts on the motor holding every external part on the block.

[Jimmy S.]

Before you try to start and run the engine.Ask the machine shop if the aluminum timing gear was heated to exspand the aluminum gear.Before it was pressed on to the camshaft.

Also check the clearance between the timing gear and thrust plate.
Clearance no less than .001, no more than .005

I just went through a spun timing gear on my inline 250 camshaft.
The person who rebuilt the engine, hammered the gear on to the camshaft.

Just a little over 3000 miles since rebuild.

Jimmy S.

[Jbesotes]

Here is the problem that I am running into The clutch linkage is running into the header on the rear of the motor. I am debating on cutting the tube on the cluch back a bit and making a bracket to hold it coming off of the frame, to the clutch tube and back to the frame so that it wont hit the header.