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PostPosted: Sat Oct 18, 2014 4:01 pm 
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Joined: Mon Oct 29, 2012 1:52 pm
Posts: 383
TMeyer wrote:
My hats off to you Dave, as Brent said, showing people your human, is humbling, yet means so much in the eye of your customer.

Amazing how when you go to 3/8 push rods, SO many things start to change.

I tell you, my saving grace is snagging this Sim-test machine that a Technical college, who closed their program used to have.
It has saved out butts a few times.

Here's a video of a SBF (360) circle track engine with almost .800" lift

http://youtu.be/_WQZQoieREU?list=UUajQhjw4mpRsbvNIaWpTJmw


I just wish I would have spotted the problem before running the engine or while it was on the dyno. Here's some video of it running on the course after about 50 miles or so all is well. He had been running about 140mph (5500rpm) and he decided to take it up to his tech maximum of 165mph(hit 167mph 6500rpm) when the hood decided to pop open which was rather surprising. The engine continued to run well all the way till just about the very end of the course(90 miles) before it started to lose power.

http://youtu.be/1tWHZkLzius


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PostPosted: Sun Oct 19, 2014 1:00 pm 
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Location: Texas
at least you didnt loose the hood. Sucks about the push rod problem. You dont think milling that amount off the rocker will weaken the rocker?


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PostPosted: Mon Oct 20, 2014 8:46 am 
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My plan is to just remove a very small amount of material using the rockers that have marks from interference as reference. I don't think it'll take much to get them to totally clear the pushrod. Will it weaken the rocker? I would assume that it almost has to at least a little bit but probably not enough to make any real difference.


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PostPosted: Mon Oct 27, 2014 9:56 am 
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I ended up getting a set of the Ultra Pro Magnum rockers to see how the clearance looks with a steel rocker. I think it is going to be a lot better. I did have some aggravation with these rockers in that right out of the box two of them were missing their tru-arc retainers that go on the ends of the trunion. I had some and fixed them up but if you use them be sure to check for this problem.


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PostPosted: Mon Oct 27, 2014 2:42 pm 
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Be sure and check the new rockers for the same deal....I've had clearance issues with 1.7-1.73 rockers multiple times.

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Brent Lykins, Lykins Motorsports
www.lykinsmotorsports.com
brent@lykinsmotorsports.com


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PostPosted: Mon Oct 27, 2014 5:34 pm 
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That's a problem to do right now. The engine is 1200 miles away from me and I don't have another engine with similar valvetrain geometry to do some comparison. The chrome moly rocker has an offset trunion which moves the rocker body back towards the pushrod side relative to the stud. This should take away some of the clearance that I need on that side but it is difficult to figure out how much. I think I'm going to have to send them to the guy and have him trial fit them on the engine.


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PostPosted: Tue Dec 16, 2014 5:07 pm 
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Many people these days thin a tool box full of tools qualifies you as an engine builder. As Dave has shown even seasoned veterans miss a details once in a while. Putting the information out there keeps the rest of us from having the same problem. If Dave had checked this it would likely have "looked" ok and even HAD clearence on the engine stand!!! High Rpm open road racing could have compromised valve float or it could simply have been the result of valve inertia going beyond the "normal" lift of the cam. Certain pushrods are worse than the ones Dave used. I had an interference with Manton pieces. I was lucky and heard it "clicking" as I ran the valves on the stand. There would be no way to hear it with the pushrod Dave used.
Thanks for the insight , glad it wasn't worse.


Dave ,
I have some offset trunion rockers from Crower and they clear by .125.


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PostPosted: Thu Dec 18, 2014 9:47 am 
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As a follow up I sent the new rockers to the customer and they fit without any problems. He has it all put back together again but the weather where he lives has not been favorable for a test drive.


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PostPosted: Thu Oct 20, 2016 5:24 am 
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Joined: Mon Oct 29, 2012 9:05 am
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Dave, you may want to do a follow-up and have your customer check the pattern on the valve tip.

Just got into this exact same scenario and decided to go for the 1830 Comp rocker. The geometry is not the same and the pushrod length changed by .100". With the same pushrod, the pattern moved way out towards the exhaust side of the valve stem and got much wider.

Been fighting for an hour or two, trying different length pushrods in .050" increments. I was at a .060" pattern with the Ultra Gold rockers with .725" lift and I'm having trouble getting that back.

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www.lykinsmotorsports.com
brent@lykinsmotorsports.com


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