Broke a Summit rockers
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Pro
Joined: Jun 2018
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Broke a Summit rockers
I put in a rebuilt engine last year, a .30 over 350 with all new hard parts and AFR heads. Finished it in July 2024.
I went with Summit Racing 1.6 cast rockers with roller tips and polylocks and have had quite a bit of trouble with them.
First one of the polylocks came undone on #1 Intake after about 1000 miles. Banged up the rocker. I replaced the rocker and pushrod and locktited all the polylocks.
Then last week the exhaust rocker on #7 broke. The fulcrum broke out of the bottom of it. It has about 6k miles since the rebuild.
Worst part is Summit is out of singles, so it is eaither buy 16 or wait until estimated time of January 30th when they will have single rockers in stock. :-(
Anyone else have issues with these?
I went with Summit Racing 1.6 cast rockers with roller tips and polylocks and have had quite a bit of trouble with them.
First one of the polylocks came undone on #1 Intake after about 1000 miles. Banged up the rocker. I replaced the rocker and pushrod and locktited all the polylocks.
Then last week the exhaust rocker on #7 broke. The fulcrum broke out of the bottom of it. It has about 6k miles since the rebuild.
Worst part is Summit is out of singles, so it is eaither buy 16 or wait until estimated time of January 30th when they will have single rockers in stock. :-(
Anyone else have issues with these?
Drifting
Joined: Nov 2018
Posts: 1,764
Likes: 648
From: USA
Some AFR heads have valves that are .100" longer than the traditional length, this can cause the roller-tip rocker body to interfere with the push-rod before maximum lift is achieved. AFR specifically states in the fine print on many of their heads, that roller-tip rockers are not to be used. Considering your down time, repair time and replacement parts are all adding up...my opinion is that if you would switch to full-roller-rockers this problem would be solved...provided that your push-rod length is correct now and correct again with the full-roller-rockers! Just my $0.02s worth, good luck with whatever you decide to do👍
Melting Slicks
Joined: Nov 2016
Posts: 2,256
Likes: 3,082
From: So Cal
2023 C4 of the Year Finalist - Unmodified
Do these AFR heads have pushrod guide plates?
There are 2 types of rocker arms. Self-guiding and plain (flat) as used on traditional SBC prior to aluminum heads.
Self-guiding have 2 ridges that run on each side of the valve stem to keep the rocker and push rod aligned. Self aligning rockers are for heads that don't have guide holes in the head nor guide plates.
Plain rockers are just that. Flat on their tips. These rockers must be used with guide plates or guide holes in the heads.
If the OP has guided rockers on heads with guide plates, this may be the cause of some of his recurring problems with valve gear.
There are 2 types of rocker arms. Self-guiding and plain (flat) as used on traditional SBC prior to aluminum heads.
Self-guiding have 2 ridges that run on each side of the valve stem to keep the rocker and push rod aligned. Self aligning rockers are for heads that don't have guide holes in the head nor guide plates.
Plain rockers are just that. Flat on their tips. These rockers must be used with guide plates or guide holes in the heads.
If the OP has guided rockers on heads with guide plates, this may be the cause of some of his recurring problems with valve gear.
Thread Starter
Pro
Joined: Jun 2018
Posts: 532
Likes: 104
Some AFR heads have valves that are .100" longer than the traditional length, this can cause the roller-tip rocker body to interfere with the push-rod before maximum lift is achieved. AFR specifically states in the fine print on many of their heads, that roller-tip rockers are not to be used. Considering your down time, repair time and replacement parts are all adding up...my opinion is that if you would switch to full-roller-rockers this problem would be solved...provided that your push-rod length is correct now and correct again with the full-roller-rockers! Just my $0.02s worth, good luck with whatever you decide to do👍
The cam I have is not a really high lift and I did size my pushrods prior to purchasing though so I would not think it would be a problem.
