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Discussion Starter #1 (Edited)
This is a friend's motor not mine.
406 sbc solid roller

New build and had it at the track. He came to me sat and said his timing was retarding alot as he increased rpms. I went and checked and it will retard about 22 degrees starting at around 2400 rpms. I double checked with 3 timing lights. We pulled his msd pro billet and I seen it wasn't using a brass gear on it and it was chewed up pretty good. Installed a brass gold one and the issue was still there. So we swapped in another pro billet that I know is good and the problem was still there. So I took his 6al box out and wired in a 7al3 box and it still retards the timing about 22 degrees. Any ideas on this?
I'm not a engine builder and I'm clueless since I have never see this issue before. Both Distributors are locked so no issues there. Checked timing chain today and it's tight. To much cam endplay????
Could the gear on cam be bad now that he wasn't running the brass gear on the distributor before?
Just trying to get some info for him.
 

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Roller cam - retro setup? Yup, sounds like cam walk.
 

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Wrong distributor gear material usually ruins both distributor gear and cam drive gear....doesn't matter if its steel cam/iron gear or iron cam/steel gear.

Cam end play and distributor shaft end play can both be an issue.
 

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Pulled the cam out and it's bent. Not sure how that happened but it's junk. Cam bearings look good still but the cam is bent bad. How it even went in and out of the block when they put it together is a puzzle to me.
Was the cam a cast or steel core?
 

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Pulled the cam out and it's bent. Not sure how that happened but it's junk. Cam bearings look good still but the cam is bent bad. How it even went in and out of the block when they put it together is a puzzle to me.

Bent? How much run out? Bent at dist gear? Did it tear up the dist gear? I'm interested in seeing pics on V blocks, with a indicator.
 

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Discussion Starter #11
I have a video of it spinning with a indicator if I can send it to you somehow. It's definitely bent
Gear is not tore up. I don't think that is the reason it is making the timing retard though. In the video the dial indicator moves back and forth. Wouldn't the timing move back and forth with the bend if that was the issue?
The cam is junk but I still think he has to much cam endplay. Won't listen to me though. Just that old timer that puts his stuff together. If it don't come from him then my buddy won't listen. I'm done with the deal honestly.
 

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Check wires for distributor pickup. If they're reversed the timing will do what you're saying.
Yep. Got a mis wired pick up cord from MSD once. Even though plugs were "idiot proof" the wires were inserted backwards.

Same thing, as RPM increased, timing retarded. IIRC, timing jumped around several degrees at idle as well. With wires in proper order, timing is rock solid.
 

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Yep. Got a mis wired pick up cord from MSD once. Even though plugs were "idiot proof" the wires were inserted backwards.

Same thing, as RPM increased, timing retarded. IIRC, timing jumped around several degrees at idle as well. With wires in proper order, timing is rock solid.
I bought one that was backwards too. Switched the wires and it worked fine.
 

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The Phantom Machinist
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I check and correct bent cams all the time. Brand new out of the box at that.

Timing that’s “power-retarding” is generally the cam pushing out the front of the block due to cam tunnel misalignment with the crank datum line. Even with a button, it will flex the cover. It’s trying to corkscrew out the front. That may be one of the biggest "power gains" I’ve seen where you’ve done nothing else except correct the blueprint locations on an engine during freshen. Lifter bores are right there too.
 
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