We recently built a '76 Pontiac 350 for my son's '79 Trans Am.
I selected a Summit Hydraulic Cam and Lifters. The cam has nearly exact spec's as the Edelbrock Performer Cam designed for idle-5000RPM with smooth idle. We did the usual valve adjustment as on other Pontiac V8's (1/2 turn past 0-lash) We use Penzoil 10W40 with a bottle of STP to compensate for the lost Zinc additives in the oil.
The engine ran fine the first 800 miles, but it would occasionally have lifter tick for a few seconds after startup which immediately went away as oil pressure came up. We double-checked the lash and found no problems so I passed it off as a characteristic of the Summit lifters.
We had just stopped by a sub shop for lunch and started the car only to hear a loud pop, then a very rough miss in the engine... we also had a large stream of oil pouring out the oil pan! After towing it home, we discovered a pushrod stuck through the oil pan. Pulling the valve covers, we discovered the 1/2 of the #7 intake pushrod laying in the lifter valley. It had come off and fell through the cam area and was snapped in half by the crank!
Thankfully, no other damage. We ordered a new pushrod, removed and welded and reinstalled the oilpan. Adjusted the the valve and sealed it back up and we were good to go... for another 80 miles.
Again after startup the engine made a pop, then began running rough... at least no hole in the oil pan. This time, we found the #3 Exhaust pushrod had popped off and had again got flung into the oilpan. One piece was laying in the lifter valley and the other half was laying in the oil pan. Again, no other engine damage. We did find the adjustment nut on that rocker arm had slightly backed off but only a bit. Again we ordered and installed a new pushrod, re-adjusted, but this time there was considerable torque required to turn the adjusting nut the 1/2 turn past 0-lash. On closer inspection, what I discovered was that the lifter plunger was not going down at all, but rather the valve was being pushed open! The lifter would not compress at all!
I checked the others and found 6 others with plungers stuck completely in the fully extended position. We had changed oil at 500 miles and again at 800 when we fixed the oil pan, so the engine was very clean. I pulled the affected lifters and all of them looked fine with no visible contamination, dirt, sludge or unusual wear pattern on the face. After reassembly, they now compressed like normal!!!
We pulled all the lifters and installed a set of Comp Cams hydraulic lifters and have since driven 200 miles with no issues and no ticking during engine starts.
My question is if anyone else has had issues with Summit lifters or should I be wary that some other problem is lurking?
Our Pontiac 350 is a mild performance build with 6X-4 heads, a 0-decked block, and a set of headers with a good dual exhaust and 60PSI Melling oil pump. When the heads were rebuilt, we upgraded to Comp Cams 7/16 Rocker studs and Roller tip 1.5:1 Rocker arms. We also double checked that the pushrods had adequate clearance and that the valvetrain geometry was good.
Thanks!
Kevin
I selected a Summit Hydraulic Cam and Lifters. The cam has nearly exact spec's as the Edelbrock Performer Cam designed for idle-5000RPM with smooth idle. We did the usual valve adjustment as on other Pontiac V8's (1/2 turn past 0-lash) We use Penzoil 10W40 with a bottle of STP to compensate for the lost Zinc additives in the oil.
The engine ran fine the first 800 miles, but it would occasionally have lifter tick for a few seconds after startup which immediately went away as oil pressure came up. We double-checked the lash and found no problems so I passed it off as a characteristic of the Summit lifters.
We had just stopped by a sub shop for lunch and started the car only to hear a loud pop, then a very rough miss in the engine... we also had a large stream of oil pouring out the oil pan! After towing it home, we discovered a pushrod stuck through the oil pan. Pulling the valve covers, we discovered the 1/2 of the #7 intake pushrod laying in the lifter valley. It had come off and fell through the cam area and was snapped in half by the crank!
Thankfully, no other damage. We ordered a new pushrod, removed and welded and reinstalled the oilpan. Adjusted the the valve and sealed it back up and we were good to go... for another 80 miles.
Again after startup the engine made a pop, then began running rough... at least no hole in the oil pan. This time, we found the #3 Exhaust pushrod had popped off and had again got flung into the oilpan. One piece was laying in the lifter valley and the other half was laying in the oil pan. Again, no other engine damage. We did find the adjustment nut on that rocker arm had slightly backed off but only a bit. Again we ordered and installed a new pushrod, re-adjusted, but this time there was considerable torque required to turn the adjusting nut the 1/2 turn past 0-lash. On closer inspection, what I discovered was that the lifter plunger was not going down at all, but rather the valve was being pushed open! The lifter would not compress at all!
I checked the others and found 6 others with plungers stuck completely in the fully extended position. We had changed oil at 500 miles and again at 800 when we fixed the oil pan, so the engine was very clean. I pulled the affected lifters and all of them looked fine with no visible contamination, dirt, sludge or unusual wear pattern on the face. After reassembly, they now compressed like normal!!!
We pulled all the lifters and installed a set of Comp Cams hydraulic lifters and have since driven 200 miles with no issues and no ticking during engine starts.
My question is if anyone else has had issues with Summit lifters or should I be wary that some other problem is lurking?
Our Pontiac 350 is a mild performance build with 6X-4 heads, a 0-decked block, and a set of headers with a good dual exhaust and 60PSI Melling oil pump. When the heads were rebuilt, we upgraded to Comp Cams 7/16 Rocker studs and Roller tip 1.5:1 Rocker arms. We also double checked that the pushrods had adequate clearance and that the valvetrain geometry was good.
Thanks!
Kevin