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1970 amx new timing covers

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DHACKING View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote DHACKING Quote  Post ReplyReply Direct Link To This Post Posted: Apr/24/2018 at 10:37pm
thanx to all for the replies.....greatly appreciated....
ESPECIALLY WANT TO THANK SC/397 FOR YOUR DETAILED TIPS....I FOUND THEM THE OTHER NIGHT ON THE WEB AND THINGS LIKE THIS ARE GOLD TO US ESPECAILLY AFTER BEING OUT OF THE HOBBY FOR 3 DECADES!
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Post Options Post Options   Thanks (1) Thanks(1)   Quote SC397 Quote  Post ReplyReply Direct Link To This Post Posted: Apr/25/2018 at 6:22am
Glad it was helpfull!
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Post Options Post Options   Thanks (0) Thanks(0)   Quote amcenthusiast Quote  Post ReplyReply Direct Link To This Post Posted: Apr/25/2018 at 7:15am
Since all '66-'91 AMV8s use no cam thrust plate to control camshaft end play, you gotta get the cam snout assembly 'stack height' correct & use the correct grooved head cam snout bolt.

-The stock AMV8 cam bolt doubles as the 'cam button'. The grooves are there in the head of the bolt for lubrication as the 'button' butts up against the machined surface there inside the timing cover.

*The stock cam bolt is actually a component of the engine's oil system, where the grooves are there to lubricate the 'button location'.

IMO, the best way to measure cam bolt to timing cover clearance is to place a small lump of modeling clay on the grooved head bolt and 'dummy' the assembly together.

-too much clearance and you're sure to have distributor gear problems.

-too little clearance (or none at all) and the cam bolt (wrong type of bolt?) will gouge into the underside of the cover (I've seen this on junkyard engines back in the seventies where the mechanic used an ordinary hardware store type of bolt and the cam chewed a hole through the cover into the water pump cavity)



 


Edited by amcenthusiast - Apr/25/2018 at 7:26am
443 XRV8 Gremlin YouTube video: https://www.youtube.com/watch?reload=9&v=2DmFOKRuzUc
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Post Options Post Options   Thanks (2) Thanks(2)   Quote 69 ambassador 390 Quote  Post ReplyReply Direct Link To This Post Posted: Apr/25/2018 at 10:01am
The grooves are there to denote grade eight fastener. They are just marked that way instead of just lines to denote a special thin head fastener. The bolt DOES NOT act as a cam button and should never contact the inside of the cover. The grooves in the head of the bolt actually will destroy the cover if they make good contact with it. They act like a cutting tool. I have taken many engines apart that have had the cover almost cut all the way through by those "lubrication slots". A few have even destroyed the engine when they grab the cover and jack themselves through the water pump or push the cam out the back of the engine. You are correct in saying that you must have the correct stack height though. I often polish and thin the head of a grade 8 bolt to prevent this. The oil pump drive gears and cam lobe provide rearward thrust to hold the cam sprocket against the block. The bolt should never touch the housing unless the chain is shot or the stack height is wrong. Just saying. I do this for a living and exclusively have done AMC for the last eight years. Did three this week.

Edited by 69 ambassador 390 - Apr/25/2018 at 10:04am
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 69 ambassador 390 Quote  Post ReplyReply Direct Link To This Post Posted: Apr/25/2018 at 10:12am
By the way, we have had good luck with the Omix/Ada covers but the ProForm covers are crap. The ProForms look to be a much nicer casting but the machine work was done by six year olds. Don't use the ProForm covers. Always check any cover for gear mesh pattern and backlash with lead past or blue paste. Just like any hypoid gearset. Also check pump cavity fitment and distributor to pump gear fit. Test fit gears and dizzy off engine and then on.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Steve_P Quote  Post ReplyReply Direct Link To This Post Posted: Apr/25/2018 at 12:47pm
The screw that holds on the cam timing gear is called a place screw. The head is slotted so that it deflects and helps to lock the fastener in place. It's not for lubrication purposes and as said it acts as a cutter and saws thru the timing cover on higher mileage engines when the timing chain wears out.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 304-dude Quote  Post ReplyReply Direct Link To This Post Posted: Apr/25/2018 at 2:41pm
My high milage (120,000 miles) engine that was rebuilt with over 95,000, still has its original timing cover. It does not show much wear at all. Since it never was high performanced I think chain stretch plays into how far the cam can walk or abruptly kick into the cover.

I also have a scrap oem timing cover of unknown history, that has pump wear (scoring) and the infamous circular gouges from cam walk. Unknown milage, but from the wear patern in the pump, i assume most of the damage is from lack of lubrication. Could be also be from running the engine hard, jeeping or strip use.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 6PakBee Quote  Post ReplyReply Direct Link To This Post Posted: Apr/26/2018 at 9:11am
Originally posted by Steve_P Steve_P wrote:

The screw that holds on the cam timing gear is called a place screw. The head is slotted so that it deflects and helps to lock the fastener in place. It's not for lubrication purposes and as said it acts as a cutter and saws thru the timing cover on higher mileage engines when the timing chain wears out.


An absolutely correct answer.  You find the same type of fastener on some flywheel/flex plate bolts for the same reason.
Roger Gazur
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