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Reverse Rotation Cam Thrust Washer
Posted by: CairoManx ()
Date: November 03, 2017 12:13PM

Where is the trust washer located on a reverse rotation cam? Instead of pulling the cam gear toward the cam in standard rotation, rotating the crankshaft in reverse pushes the cam gear away from the cam.

Is there a functioning "thrust washer". Do the lobes carry the thrust?

I'm talking about the cam thrust washer, not the distributor

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Re: Reverse Rotation Cam Thrust Washer
Posted by: Wagon Master ()
Date: November 03, 2017 01:03PM

In it's stock location and configuration, I'm thinking our standard rotation cam thrust washers will control movement in either direction.

'29 Ford Model A Tudor
'61 700 Lakewood 110 4 speed
'69 Monza Convert. 140 Auto.
'70 Dodge Challenger R/T 440 4 speed

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Re: Reverse Rotation Cam Thrust Washer
Posted by: CairoManx ()
Date: November 03, 2017 03:54PM

In standard rotation, the thrust on the cam gear is inwards toward the engine. The thrust washer lays against inner face of the cam gear on one side and on the other, presses against the case web around the rear cam bearing.

In reverse rotation the cam gear is pushed away from the engine so the thrush washer probably isn't in contact with the case.

The only point which I can see where the cam gear would be "stopped" from being thrust outward is the backside of the crankshaft flywheel flange.

Is that what "stops" the outward movement of the reverse rotation cam?

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Re: Reverse Rotation Cam Thrust Washer
Posted by: MattNall ()
Date: November 03, 2017 04:24PM

I believe it's just a "non -problem" Over 50 years and have never heard of a problem.... Ex Socal Duner.... been around 100's of them....and a few street driven.





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Re: Reverse Rotation Cam Thrust Washer
Posted by: CairoManx ()
Date: November 03, 2017 05:25PM

Wondering whether its worth the money to pay for a fail safe cam gear(which I've heard are a good idea on a reverse rotation engine) if the cam gear is going to rubbing against the crank flywheel flange

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Re: Reverse Rotation Cam Thrust Washer
Posted by: MattNall ()
Date: November 03, 2017 05:45PM

I've never seen any evidence of rubbing.... But the FailSafe Gear is still considered a good product IIRC!





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Sea Mountain, between Charleston Harbor and Coos Bay! SW Oregon Coast
Click HERE for My Website...Click HERE for My TechPages!
..............................110-PG.................................................Webered-Turbo

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Re: Reverse Rotation Cam Thrust Washer
Posted by: davemotohead ()
Date: November 03, 2017 05:51PM

Cam thrust washer fits in a slot in the engine case and limits cam movement in either direction.





Email me at: Dave Motohead

1960 4dr sedan caveman car
1961 Rampside (Chetside)
1962 Rampside (Barnside)
1962 Short Rampside (Shortside)
1962 Monza 700 Wagon
1963 Monza 900 coup (General Nader)

-----------------------------------
Rust Free Lancaster Ca

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Re: Reverse Rotation Cam Thrust Washer
Posted by: CairoManx ()
Date: November 03, 2017 07:24PM

The thrust washer is trapped on the camshaft between the gear and the bearing journal when the cam gear is installed. Recently people ensure the gear is pressed tightly enough against the washer so its trapped and can't spin on the shaft. Only the forward side of the washer faces the engine case so it will only support a thrust load if the gear is being pushed forward. If the gear is being pushed aft, the thrust washer is being pulled away from the case and so supports no thrust load

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Re: Reverse Rotation Cam Thrust Washer
Posted by: davemotohead ()
Date: November 03, 2017 07:29PM

The thrust washer fits in a grove in the engine case and controls the thrust in both directions.





Email me at: Dave Motohead

1960 4dr sedan caveman car
1961 Rampside (Chetside)
1962 Rampside (Barnside)
1962 Short Rampside (Shortside)
1962 Monza 700 Wagon
1963 Monza 900 coup (General Nader)

-----------------------------------
Rust Free Lancaster Ca

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Re: Reverse Rotation Cam Thrust Washer
Posted by: CairoManx ()
Date: November 03, 2017 07:56PM

Yes, it definitely is

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Re: Reverse Rotation Cam Thrust Washer
Posted by: Richard ()
Date: November 03, 2017 08:41PM

You could always look in the shop manual.

For '65 manual, it's on page Engine Mechanical 6-33, #7 provides End Play specs at .002" to .007"

It doesn't matter if thrust washer is loose and spinning as long as it doesn't add too and allow End Play greater than .007". Any concern about excessive End Play would be the cam walking back and forth across the lifter faces.

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Re: Reverse Rotation Cam Thrust Washer
Posted by: CairoManx ()
Date: November 05, 2017 03:39PM

If the washer isn't captured tightly between the gear and the cam it will increase endplay, especially in a reverse rotation engine. Its also more likely for the washer to spin on the shaft vs. rotate with the cam in the slot in the case, which changes the wear surface from the outer faces of the washer against the case to the washer's inside diameter on the shaft.

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Re: Reverse Rotation Cam Thrust Washer
Posted by: MattNall ()
Date: November 05, 2017 04:14PM

You are worried about nothing... imo





MODERATOR
Sea Mountain, between Charleston Harbor and Coos Bay! SW Oregon Coast
Click HERE for My Website...Click HERE for My TechPages!
..............................110-PG.................................................Webered-Turbo

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Re: Reverse Rotation Cam Thrust Washer
Posted by: davemotohead ()
Date: November 05, 2017 04:49PM

I have built Rev rotation engines, and taken apart 100's of regular rotation engines built by GM, most time's the washer does spin on the cam shaft as clearance is created when running, its really no concern as these engines still run fine and have ran for 100,000's of miles with no failures,as Matt says, you are worrying about nothing, every Rev rotation engine has the same washer pressed onto the cam the same as stock, and they run fine.





Email me at: Dave Motohead

1960 4dr sedan caveman car
1961 Rampside (Chetside)
1962 Rampside (Barnside)
1962 Short Rampside (Shortside)
1962 Monza 700 Wagon
1963 Monza 900 coup (General Nader)

-----------------------------------
Rust Free Lancaster Ca

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