67 Dart, 360 with a noisy tick....

Kern Dog

I like girls that wiggle
FABO Gold Member
Joined
May 23, 2010
Messages
7,576
Reaction score
19,932
Location
Granite Bay CA
My 67 is a beater. It has always been a rough looking cars the entire time that I have owned it.
I'm okay with that. I have fun with it
I have a '78 360 in it. Standard bore but with '308 heads. It has a cam with specs I don't recall, it is something a bit bigger than a stock 340 cam.
Awhile back, the timing chain snapped when it was idling. Once I replaced it, I found it had 3 or 4 bent pushrods. I replaced those but a small tick-tick-tick remained.
Today I figured I'd look into it.

IMG_5047.JPG


I tracked the tick to the left side. I pulled the valve cover and pressed on all the rocker arms looking for any slack. In the past when I have had a cam lobe going away, the rocker arm on that lobe had slack and the pushrod could be pressed in because the bottom of the lifter had worn enough to expose a hole, allowing oil to leak out. I saw nothing like that here but the # 7 exhaust rocker felt a bit loose. I could rock it side to side on the shaft and there was some slack between the tip and the valve stem.
I grabbed a new rocker arm and a good used pushrod and compared them. The rocker felt tighter on the shaft as compared to the other one and the replacement pushrod was clearly 1/16" longer. The shorter pushrod looks fine on each end, no galling, no mushrooming.
With it back together, it is back to normal. No ticking, no tapping. Simple fix.
I've found that in high mileage engines or neglected ones, the rocker arm hole diameter can be several thousandths of an inch oversize, sometimes in an oval shape.
Does anyone have the spec for the pushrod length for hydraulic cams?
 

RustyRatRod

I was born on a Monday. Not last Monday.
FABO Gold Member
Joined
Jun 7, 2010
Messages
91,975
Reaction score
79,566
Location
Georgia
It's possible it was bent just enough to make it that much shorter to give the tick. Glad you got it fixed.
 

dartfreak75

Restore it, Dont part it!
FABO Gold Member
Joined
Aug 10, 2011
Messages
11,440
Reaction score
9,194
Location
Virginia
My 67 is a beater. It has always been a rough looking cars the entire time that I have owned it.
I'm okay with that. I have fun with it
I have a '78 360 in it. Standard bore but with '308 heads. It has a cam with specs I don't recall, it is something a bit bigger than a stock 340 cam.
Awhile back, the timing chain snapped when it was idling. Once I replaced it, I found it had 3 or 4 bent pushrods. I replaced those but a small tick-tick-tick remained.
Today I figured I'd look into it.

View attachment 1715620837

I tracked the tick to the left side. I pulled the valve cover and pressed on all the rocker arms looking for any slack. In the past when I have had a cam lobe going away, the rocker arm on that lobe had slack and the pushrod could be pressed in because the bottom of the lifter had worn enough to expose a hole, allowing oil to leak out. I saw nothing like that here but the # 7 exhaust rocker felt a bit loose. I could rock it side to side on the shaft and there was some slack between the tip and the valve stem.
I grabbed a new rocker arm and a good used pushrod and compared them. The rocker felt tighter on the shaft as compared to the other one and the replacement pushrod was clearly 1/16" longer. The shorter pushrod looks fine on each end, no galling, no mushrooming.
With it back together, it is back to normal. No ticking, no tapping. Simple fix.
I've found that in high mileage engines or neglected ones, the rocker arm hole diameter can be several thousandths of an inch oversize, sometimes in an oval shape.
Does anyone have the spec for the pushrod length for hydraulic cams?
I believe the spec is 7.5-7.53 of course that length will change if other stuff in the engine had changed milled heads decked block rockers, lifter preload etc.
 
Top