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PostPosted: Wed Oct 15, 2014 1:25 pm 
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A couple of months ago I built a 385 inch Cleveland for a customer who ran it in a Pantera at the Silver State Challenge in Nevada. The engine had been run for an hour, dyno tested and then driven about 100 miles before heading to Nevada where it ran as fast as 167MPH with ease. Just before the end of the 90 mile run it started to lay down and only pull about 5500rpm. When the run was completed it sounded funny and had an obvious miss. A couple of days ago the customer stopped by here on the way back from Nevada and we pulled the covers to see what happened. It had broken one rocker on one side and two on the other side(all intakes) due to a screw up on my part.

During the build I spent quite a bit of time looking at the valvetrain geometry and making sure that there was no interference with the spring retainer but I DIDN'T happen to notice an interference between the pushrod and the back side of the rocker, d@mn! This engine was built using the Competition Cams 19045 gold colored aluminum rockers which are a very nice piece. The cam is a solid roller with .700 lift and I was using an 3/8 8.600(+.100) length pushrod which seemed to give the best overall geometry on a set of old Ford Motorsport A3 heads.

Looking at this rocker when compared to a Crane or other similar rocker it appears to have a lot more "meat" on the back (pushrod) side of the trunion area and I think that if I had used a different brand of rocker or compromised the geometry with a shorter pushrod I wouldn't have had an issue. I'm just going to get 8 new ones and relieve them very slightly to eliminate the problem but if you're using these rockers on a Cleveland build this is something to really eyeball. I didn't have any problems on the exhaust side of the engine.

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PostPosted: Wed Oct 15, 2014 3:26 pm 
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Ouch! Details, details. Dave, when you relieve the rockers, can you polish the grind marks with a very high speed grinder and a 180-220grit cartridge roll? That will take out any chipped areas prone to cracking in the future. I always try to polish aluminum so that there are no stress areas for a crack to start later. Joe-JDC


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PostPosted: Wed Oct 15, 2014 4:54 pm 
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I've ran into it before with ultra pro XD rockers. I got bit by it once myself and it's one of the first things that I check.

Shows what kind of man you are Dave to publicly confess a boo-boo...

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PostPosted: Wed Oct 15, 2014 6:08 pm 
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Thanks for sharing Dave. Good to see you didn't do the blame game thing and it was caught before any major damage.


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PostPosted: Thu Oct 16, 2014 7:54 am 
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Location: Texas
you cant just use some bad ass 5/16 pushrods? that way you dont have to grind on expensive rockers :shock:


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PostPosted: Thu Oct 16, 2014 9:30 am 
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I just thought I'd share this because of how unexpected it was given how conventional the combination. Hopefully it'll help somebody else to avoid a mishap. There was absolutely no other damage done to the engine, no parts were pounded or lost or ground up at all. It didn't bend the pushrods or anything.

In the past I've had problems with in a Cleveland where the pushrod was running out of travel at the bottom of the guide plate slot. This one had plenty of room in that area as it did around the spring and poly lock adjuster. .

If I would have used a 5/16 pushrod I would have been fine but the customer was already set up to use a 3/8. What I'm going to do is just get 8 new rockers, probably set them up in the mill and give them a very slight relief which I'll smooth with a cartridge roll.


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PostPosted: Thu Oct 16, 2014 12:45 pm 
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I'm surprised it went that long with the interference. I would think something like this would rear it's head within the first few minutes of break in.


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PostPosted: Thu Oct 16, 2014 4:23 pm 
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booyah45828 wrote:
I'm surprised it went that long with the interference. I would think something like this would rear it's head within the first few minutes of break in.


That's what I would have thought too. I did a lot of dyno work on the engine after a run in period of about an hour. I had the covers off three or four times during the dyno work and I just didn't catch the problem. It ran fine till just a few miles from the end of the 90 mile course out there in Nevada.


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PostPosted: Fri Oct 17, 2014 10:38 am 
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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

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PostPosted: Sat Oct 18, 2014 11:18 am 
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Great info and good job for putting the info out there Dave...We are all hiuman

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