Valve train adjustment
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Valve train adjustment
I have a E-150 Econoline with a 302. I put the engine back together and am now in the process of adjusting the valves. I completely disassembled the heads and rebuilt them with the original valves and new valve guide seals. I have the rocker nuts tightened down all the way ( to the bottom of the threads) and yet some of the rocker arms are still loose. I didn't remove the cam or lifters from the engine and have the original pushrods put in in the original order. Why are the rockers loose even though all of the rocker nuts are tightened down all the way? I can't do an accurate feeler guage check on it with the way it is.
Cheers
Brendan in Nelson BC
Cheers
Brendan in Nelson BC
Post Fiend
Joined: Nov 2001
Posts: 14,947
Likes: 6
From: Topsfield, MA
Did you have any milling done on the bottom surface of the heads?
Any change in deck height of the motor, size of head gasket, and/or change in height of that lower surface on the head, will alter the pushrod length.
If you removed material from the bottom of the head, that means the head will sit lower on the motor and require a shorter pushrod. A thicker gasket will raise the head off the motor, requiring a longer pushrod.
But it sounds like your pushrods are too short, or your rockers arn't mounted correctly. When I was using my adjustable pushrod checker, if I made the pushrod too long, the rocker would still bolt down tight, it would just also compress the valve spring too. If I made the pushrod too short, it would bolt the rocker down fine but the pushrod would be loose. It's kind of sounding to me like the rockers arn't on right...do you have confirmation that they're perfectly on there?
Explain to us what has changed with the work you've done (in regards to machining or changes to the motor that may affect pushrod length).
Any change in deck height of the motor, size of head gasket, and/or change in height of that lower surface on the head, will alter the pushrod length.
If you removed material from the bottom of the head, that means the head will sit lower on the motor and require a shorter pushrod. A thicker gasket will raise the head off the motor, requiring a longer pushrod.
But it sounds like your pushrods are too short, or your rockers arn't mounted correctly. When I was using my adjustable pushrod checker, if I made the pushrod too long, the rocker would still bolt down tight, it would just also compress the valve spring too. If I made the pushrod too short, it would bolt the rocker down fine but the pushrod would be loose. It's kind of sounding to me like the rockers arn't on right...do you have confirmation that they're perfectly on there?
Explain to us what has changed with the work you've done (in regards to machining or changes to the motor that may affect pushrod length).
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I think I have it figured out. I didn't remove the cam or lifters from the engine. The pushrods are the same and I did'nt take the rocker completely off the heads( I just swung them out of the way to get the pushsrods out. Following the directions in the Haynes manual I have marked the vibration damper at TDC and 180 and 90 degrees. When I set the valves in the order mentioned I can still compress the rod into the lifter. The neighbour next door told me that when I start the engine the oil pressure in the lifters will stiffen up the slack. I've only rebuilt a 1968 BSA 650 Lightning motor before so I have never dealt with hydraulic lifters before.
Cheers
Brendan in Nelson BC
www.bcdc.ca
Cheers
Brendan in Nelson BC
www.bcdc.ca
Post Fiend
Joined: Nov 2001
Posts: 14,947
Likes: 6
From: Topsfield, MA
Yeah, when the whole valvetrain is set correctly, the pushrod will be pushing down the hydraulic lifter probably 1/2 way between it's bottoming point and top point. It's more precise then that but I don't know what the spec is. The lifter seat should not be pressed all the way down. Also, make sure the rocker contacts the valve stem correctly. It needs to roll/slide accross the middle of the stem, and not roll off the front or back of the stem surface. I used a marker and rolled it over a few times to check the contact patch until it was right.
