Measuring for Correct Pushrod Length
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Junior User
Joined: Apr 2018
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Measuring for Correct Pushrod Length
Info:
66 f100, 352fe, reworked stock heads, RV cam, factory non adjustable rocker arms
Best procedure for measuring for the correct length pushrods? I have this tool: Click
ive searched forums and recommendations seem to be all over the place and I’ve looked in Section 8, page 9 (8-9) in the 66 Shop Manual and I don’t believe the manual holds true for my situation (cam, heads, etc) because it uses a step tool to measure for stock length pushrods or .060 longer or shorter than stock.
I ordered the book by Steve Christ to see if it has any info on the matter, and as a reference for other things, but if anyone has a step by step in the mean time I’d appreciate it.
66 f100, 352fe, reworked stock heads, RV cam, factory non adjustable rocker arms
Best procedure for measuring for the correct length pushrods? I have this tool: Click
ive searched forums and recommendations seem to be all over the place and I’ve looked in Section 8, page 9 (8-9) in the 66 Shop Manual and I don’t believe the manual holds true for my situation (cam, heads, etc) because it uses a step tool to measure for stock length pushrods or .060 longer or shorter than stock.
I ordered the book by Steve Christ to see if it has any info on the matter, and as a reference for other things, but if anyone has a step by step in the mean time I’d appreciate it.
Hotshot
Joined: May 2003
Posts: 11,141
Likes: 25
From: south louisiana
Paint the tip of the valve with a magic marker, then cycle the engine through the full valve travel with zero lash (if a hyd lifter) then remove the rocker arm and see where the marker ink has been removed from the tip of the valve. The wear area should be centered on the tip. All the valve tips should be the same elevation, check this by laying a straight edge across them all with the rockers removed. If they're not, then you may need custom length pushrods to compensate for the shorter valves. Be better to take the heads back to the machine shop and tell em to fix their messy work.
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Junior User
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Valve tips are all level. I don’t think using zero lash as a mesurment is attainable as all the rocker arms are mounted on a single shaft... rather than what I’m used to (one rocker arm/bolt per valve). Shaft has to be torqued in a specific sequence or else you risk damage to the entire assembly
Hotshot
Joined: May 2003
Posts: 11,141
Likes: 25
From: south louisiana
Valve tips are all level. I don’t think using zero lash as a mesurment is attainable as all the rocker arms are mounted on a single shaft... rather than what I’m used to (one rocker arm/bolt per valve). Shaft has to be torqued in a specific sequence or else you risk damage to the entire assembly
Laughing Gas
Joined: Jul 2010
Posts: 1,113
Likes: 113
From: Chico, Ca.
That is the correct tool. A digital caliper will help with accurate measurements. There is a range for valve lash, and this information is in Steve Christ’s book. With the lifter at the bottom of it’s travel and fully collapsed, measure the valve lash until in specs, then remove the pushrod checker and measure its length. Repeat 15 more times. Make certain that the engine is in the proper position, so that the lifters aren’t on a cam lobe. Do a search on this site, and you can find more detailed information. Good luck.
Lead Driver
Joined: Mar 2004
Posts: 8,922
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Paint the tip of the valve with a magic marker, then cycle the engine through the full valve travel with zero lash (if a hyd lifter) then remove the rocker arm and see where the marker ink has been removed from the tip of the valve. The wear area should be centered on the tip. All the valve tips should be the same elevation, check this by laying a straight edge across them all with the rockers removed. If they're not, then you may need custom length pushrods to compensate for the shorter valves. Be better to take the heads back to the machine shop and tell em to fix their messy work.
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Hotshot
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Lead Driver
Joined: Mar 2004
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The easiest way to deal with the rocker shaft is to disable it by removing all the push rods. If the head is already on and torqued, Put #1 on tdc, put light checking spring on the valve, smear marking compound on valve tip, put adjustable push rod in and the rocker shaft. Set it at zero lash. Turn the crank through a cycle all the while watching that the lifters plunger doesn't compress. Take the shaft off and look at the pattern on the valve tip. Adjust the push rod accordingly and try again till you get a even pattern sweep across the tip. It should start in a little high of center and finish a little low of center. Once you get it adjusted right, remove pushrod and measure it with a 12" dial caliper, then add your lifters preload figure ( I always use .030) to the length you got and your done.
Lead Driver
Joined: Mar 2004
Posts: 8,922
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You have to replace them with checking springs. Otherwise the valve spring will collapse the lifters plunger leaving you with messed up false readings. It is very important that the lifters plunger does not move when you turn the crank.
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Junior User
Joined: Apr 2018
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Just an update... Per Steve Christ's book, acceptable space between the valve tip and rocker arm WITH THE LIFTER FULLY DEPRESSED/BLED AND THE PUSH ROD THAT YOU'RE CHECKING ON BASE CIRCLE: .100-.200. This is with non adjustable rocker arms and hydraulic lifters. A different method is used with solid lifters and/or adjustable rockers.
Cargo Master
Joined: Mar 2002
Posts: 3,132
Likes: 217
From: W (BY GOD) V
Info:
66 f100, 352fe, reworked stock heads, RV cam, factory non adjustable rocker arms
Best procedure for measuring for the correct length pushrods? I have this tool: Click
ive searched forums and recommendations seem to be all over the place and I’ve looked in Section 8, page 9 (8-9) in the 66 Shop Manual and I don’t believe the manual holds true for my situation (cam, heads, etc) because it uses a step tool to measure for stock length pushrods or .060 longer or shorter than stock.
I ordered the book by Steve Christ to see if it has any info on the matter, and as a reference for other things, but if anyone has a step by step in the mean time I’d appreciate it.
66 f100, 352fe, reworked stock heads, RV cam, factory non adjustable rocker arms
Best procedure for measuring for the correct length pushrods? I have this tool: Click
ive searched forums and recommendations seem to be all over the place and I’ve looked in Section 8, page 9 (8-9) in the 66 Shop Manual and I don’t believe the manual holds true for my situation (cam, heads, etc) because it uses a step tool to measure for stock length pushrods or .060 longer or shorter than stock.
I ordered the book by Steve Christ to see if it has any info on the matter, and as a reference for other things, but if anyone has a step by step in the mean time I’d appreciate it.
The differing push-rod lengths form FORD are for adjusting valve lash on a hydraulic engine.
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