Another Mopar Off My Bucket List - Barracuda Fastback
There are a lot of fellow members that have a ton of experience with procedures like this. For me, this is new ground I'm covering. Please bear with me as I describe the process I used and don't hesitate to correct me on anything you might see that's squirrely.
I had read a few articles on configuring pushrod lengths and was fairly certain I had a grasp of what needed to be done. One article had recommended putting masking tape on the valve stem and then using a sheet of carbon paper between it and the rocker arm to leave an imprint of contact pattern. I understood the importance of centering the roller with the valve.
I was all set to do it as I had planned when I came across another article where they used a dry erase pen instead of the masking tape/carbon paper. It sounded simpler so I decided to try that instead.
The darkest color dry erase marker I had was a neon blue. I'd rather have used black but hoped it would show up well enough.
I'd already removed the valve covers and original pushrods. The cam lobe of the first valve I wanted to check was already at it's bottom. I had verified it with a dial indicator.
My next step was to paint one of the valve stems with a dry erase pen. It's difficult to see in the picture but wasn't hard to see in reality. When I went to install the test pushrod I was unable to slide it into place with the rocker adjusters backed all the way out and the checker fully compressed. It was close but it wouldn't go in place. So I removed the rocker shaft assembly, dropped the pushrod checker in place, and re-attached the shaft.
After bolting the rocker shaft back down I tightened the rocker arm's adjuster to approximately the half way point of it's adjustment travel (2&3/4 turns). Then I spread the pushrod checker until it properly seated between the lifter and the rocker arm. With no vertical play left, I went ahead and added a 1/4 turn load with the adjustable rocker arm and locked the nut on it.
Next I hooked the battery back up and rotated the motor a few revolutions with the starter. Once that was done I disconnected the battery (I've tried to be really anal about it because we'd had trouble with the last FAST ECU & one MSD control box).
When I pulled the rocker shaft back off I was pleased with the pattern left on the valve stem.
It appeared as though I was where we needed to be on the first try. The COMP CAMS 7703 adjusting rod is 7.800" long when fully compressed. I had spread it apart 9&3/4 turns. According to COMP, each turn is equal to 0.05". With my calculations we would need a pushrod 8.2875" long.
7.800 + 0.4875" (0.05" X 9.75)
I still wanted to be able to repeat the process to make certain I hadn't gotten some erroneous reading. It took awhile but I set things up two more times and came up with the same results. I know that I'd said I was going to check all of them but 69 340 GTS had said it was unnecessary and I was already feeling I wouldn't be getting any different results if I continued further.
- By the way, THANKS AGAIN 69 340 GTS!
View attachment IMG_6605.jpg
View attachment IMG_6612.jpg
View attachment IMG_6607.jpg
View attachment IMG_6622.jpg
View attachment IMG_6606.jpg
View attachment IMG_6623.jpg
View attachment IMG_6611.jpg
View attachment IMG_6615.jpg
View attachment IMG_6618.jpg
There are a lot of fellow members that have a ton of experience with procedures like this. For me, this is new ground I'm covering. Please bear with me as I describe the process I used and don't hesitate to correct me on anything you might see that's squirrely.
I had read a few articles on configuring pushrod lengths and was fairly certain I had a grasp of what needed to be done. One article had recommended putting masking tape on the valve stem and then using a sheet of carbon paper between it and the rocker arm to leave an imprint of contact pattern. I understood the importance of centering the roller with the valve.
I was all set to do it as I had planned when I came across another article where they used a dry erase pen instead of the masking tape/carbon paper. It sounded simpler so I decided to try that instead.
The darkest color dry erase marker I had was a neon blue. I'd rather have used black but hoped it would show up well enough.
I'd already removed the valve covers and original pushrods. The cam lobe of the first valve I wanted to check was already at it's bottom. I had verified it with a dial indicator.
My next step was to paint one of the valve stems with a dry erase pen. It's difficult to see in the picture but wasn't hard to see in reality. When I went to install the test pushrod I was unable to slide it into place with the rocker adjusters backed all the way out and the checker fully compressed. It was close but it wouldn't go in place. So I removed the rocker shaft assembly, dropped the pushrod checker in place, and re-attached the shaft.
After bolting the rocker shaft back down I tightened the rocker arm's adjuster to approximately the half way point of it's adjustment travel (2&3/4 turns). Then I spread the pushrod checker until it properly seated between the lifter and the rocker arm. With no vertical play left, I went ahead and added a 1/4 turn load with the adjustable rocker arm and locked the nut on it.
Next I hooked the battery back up and rotated the motor a few revolutions with the starter. Once that was done I disconnected the battery (I've tried to be really anal about it because we'd had trouble with the last FAST ECU & one MSD control box).
When I pulled the rocker shaft back off I was pleased with the pattern left on the valve stem.
It appeared as though I was where we needed to be on the first try. The COMP CAMS 7703 adjusting rod is 7.800" long when fully compressed. I had spread it apart 9&3/4 turns. According to COMP, each turn is equal to 0.05". With my calculations we would need a pushrod 8.2875" long.
7.800 + 0.4875" (0.05" X 9.75)
I still wanted to be able to repeat the process to make certain I hadn't gotten some erroneous reading. It took awhile but I set things up two more times and came up with the same results. I know that I'd said I was going to check all of them but 69 340 GTS had said it was unnecessary and I was already feeling I wouldn't be getting any different results if I continued further.
- By the way, THANKS AGAIN 69 340 GTS!
View attachment IMG_6605.jpg
View attachment IMG_6612.jpg
View attachment IMG_6607.jpg
View attachment IMG_6622.jpg
View attachment IMG_6606.jpg
View attachment IMG_6623.jpg
View attachment IMG_6611.jpg
View attachment IMG_6615.jpg
View attachment IMG_6618.jpg