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[Shawrco]

Greetings,
Haven't posted in a while, caught up w/busyness. So much so I'm taking the bike to an Indy for cam & lifter change and to get the Fullsac DX pipes put on rather than do it myself. The cams are the Crusher (Kuryakin) TC24 (w/new bearings) and Wood directional lifters. Today I was telling the Indy which parts I have for the job, including a set of Fuel Moto quick adjustable push rods. He suggested keeping the stock push rods. My understanding was that cam change meant adjustable pushrods, partly due to base circle difference affecting the valve train geometry. After some searching on the net I think he isn't totally off base. Looks like part of the deal with the adjustable PRs is purely the convenience/time saving of not taking the top end apart. The TC24 is advertised as a "drop in" cam that doesn't require changing springs, etc., so the PR length difference is probably well within the capability of the lifter to take up. Bike is '15 CVO Road Glide @ 11k miles; only thing I've done so far is change out the baffles with the Fullsac ones I got with the pipes.
So, I'm just checking here with you sage mechanics to see what you think - reuse the stock or go with adjustable? The Indy's price was certainly very reasonable, even with taking the top end off. I guess I could get him to install the Rocker Lockers that I bought many months ago and have never put in!
Thanks in advance.

[J.D.]

Generally more labor reusing stock pushrods vs adjustables but both will work fine.

[grc]

Assuming (which is a bad thing to do most of the time) the base circle diameter is the same as or at least very close to the stock cam, running the stock single piece pushrods is fine.  As noted earlier, it adds to the labor cost compared to using adjustable rods.  Find out how much extra your guy is going to charge to pull the tank and rocker covers to reuse the stock pushrods.  Compare that to the price of the adjustable rods and see if it makes economic sense.

Jerry

[Yellow09SERG]

I'll look at my install sheet from the 24D's, but I am thinking the installation sheet tell you that adjustables are required.

[J.D.]

Yep if these new camshafts have a smaller base circle, and/or the stacked height to the rocker arms changes (e.g. thinner head gaskets) then possibly the stock pushrods aren't the way to go.  But if your mechanic does go this route then it is a good idea to install the rocker lockers at the same time.

[Shawrco]

Yep if these new camshafts have a smaller base circle, and/or the stacked height to the rocker arms changes (e.g. thinner head gaskets) then possibly the stock pushrods aren't the way to go.  But if your mechanic does go this route then it is a good idea to install the rocker lockers at the same time.

I'm searching for what is stock cams in 2015 110" engine... is it SE255? If I can find specs can compare with TC24. Just changing cams & exhaust, no head gaskets, etc., so it's mainly a labor difference.

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[J.D.]

A quick Google search would suggest these Crusher cams may in fact have a smaller than stock base circle diameter, which likely means stock pushrods won't be the best option.

[Shawrco]

A quick Google search would suggest these Crusher cams may in fact have a smaller than stock base circle diameter, which likely means stock pushrods won't be the best option.

I have both spec sheets but neither one gives base circle diameter. I'm not smart enough on cam technology to figure it out. Without the diameter given how does one infer the 24 has smaller circle than 255? Thanks

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[J.D.]

There should be literature available on the camshafts from the manufacturer, or break out the precision measuring tools and do some simple math.

[Shawrco]

I have both spec sheets but neither one gives base circle diameter. I'm not smart enough on cam technology to figure it out. Without the diameter given how does one infer the 24 has smaller circle than 255? Thanks

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I guess since the 24D has higher lift @TDC, that would mean the base circle has to be smaller?

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[J.D.]

https://www.kuryakyn.com/products/4910/crusher-tc-24d-bolt-in-cams

[Yellow09SERG]

I have both spec sheets but neither one gives base circle diameter. I'm not smart enough on cam technology to figure it out. Without the diameter given how does one infer the 24 has smaller circle than 255? Thanks

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Right below the cam specs shown on the 24D instruction sheet is a disclaimer say the use of adjustables is required. Thst is saying that the base circle is smaller than stock

[grc]

There is a third option for those who aren't big fans of heavy adjustable pushrods.  Harley sells what they call Perfect Fit one piece pushrods in longer than stock sizes to compensate for higher lift cams. 

Jerry

[Shawrco]

Right below the cam specs shown on the 24D instruction sheet is a disclaimer say the use of adjustables is required. Thst is saying that the base circle is smaller than stock

Thanks, correct. I read over the instructions in the box with the cams. All the aftermarket cams probably say that. To do it properly the correct measurements should be taken. Or use an adjustable for trial fit to measure and order fixed length. I've done this before myself and used adjustable PRs.

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[Shawrco]

There is a third option for those who aren't big fans of heavy adjustable pushrods.  Harley sells what they call Perfect Fit one piece pushrods in longer than stock sizes to compensate for higher lift cams. 

Jerry

Right, after taking all the measurements. Since the only things changing in this case are lifters and cams most folks would cut out the stock PRs and replace with the adjustable set. Indy is suggesting reusing stock PRs.

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[Yellow09SERG]

Thanks, correct. I read over the instructions in the box with the cams. All the aftermarket cams probably say that. To do it properly the correct measurements should be taken. Or use an adjustable for trial fit to measure and order fixed length. I've done this before myself and used adjustable PRs.

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Everyone has their preference, but will say I am in the 12,000 mile range with the 24d cams and SE adjustables with no issues. Now I will not argue that one piece are probably a lot more ridged, but so far no issues with adjustables over the period of several motors.

[J.D.]

Yep on auto engines an adjustable is often used to measure for custom length pushrods.

I prefer the adjustables on the Harleys regardless as they have never failed me and literally every Twin Cam engine is going to need lifters again sooner or later.

[johnsachs]

To remove any guess work, as I stock 24D cams, I just checked a set.
The base circle is: 1.226"
John
If you can't find the base circle measurement of the SE255 cams, let me know, and I'll check a set later. I have several sets for sale.

[Yellow09SERG]

To remove any guess work, as I stock 24D cams, I just checked a set.
The base circle is: 1.226"
John
If you can't find the base circle measurement of the SE255 cams, let me know, and I'll check a set later. I have several sets for sale.

Thank you John. I'll write that down with the cam card

[johnsachs]

To remove any guess work, as I stock 24D cams, I just checked a set.
The base circle is: 1.226"
John
If you can't find the base circle measurement of the SE255 cams, let me know, and I'll check a set later. I have several sets for sale.

Se255 cams. Base circle is: 1.300" 
If it were me, I'd use adjustable p/rods.
John

[Shawrco]

Se255 cams. Base circle is: 1.300" 
If it were me, I'd use adjustable p/rods.
John

Thanks John. I'm going to present this info to the Indy. Do you happen to have any good TTS maps for the 24D cams and Fullsac DX pipes w/1.75 baffles? Everything else is stock.

[longlast]

Your mechanic is right you could use your stock p/r. As the se255 cam is 1.300" and the 24d is 1.226" Base circle the lifters can make up the difference. This would mean the lifter plunger would be operating higher than center that is where they are designed to preform to their highest efficiency.
As you're going for more torque it may affect the overall performance of the lifters. One thing you know for sure by using the stock p/r the lifter plunger will not be in its designed center setting. By using adjustable they will be set at where thier designed to preform.
Go for the adjustables then you'll know everything is in its rightful place.

[J.D.]

Assuming the stock pushrods on the stock camshafts sits at nearly exactly the midpoint of the lifter plunger travel (1/2 of 0.210" = 0.105") it might just work.

1.300"-1.226"=0.074" total difference in base circles
1/2 of 0.074"=0.037" half of total difference (or difference in radius of base circles)

Lifter plunger (theoretical) depth would then be 0.105"-0.037"=0.068" preload (about 1/16")

Eeegh, I don't know.

[Shawrco]

Assuming the stock pushrods on the stock camshafts sits at nearly exactly the midpoint of the lifter plunger travel (1/2 of 0.210" = 0.105") it might just work.

1.300"-1.226"=0.074" total difference in base circles
1/2 of 0.074"=0.037" half of total difference (or difference in radius of base circles)

Lifter plunger (theoretical) depth would then be 0.105"-0.037"=0.068" preload (about 1/16")

Eeegh, I don't know.

Thanks for all the discussion. Just to let everyone know, we're going to use the adjustable pushrods I had already purchased. All we need to get is the two piece tubes.

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[johnsachs]

Thanks for all the discussion. Just to let everyone know, we're going to use the adjustable pushrods I had already purchased. All we need to get is the two piece tubes.

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If your tech removed the rocker box covers and the rocker arm saddle, you really don't need to by new p/rod tubes.
1- Just have him put the adjustables in,
2-  put the rocker arm saddle on,
3-  lengthen the p/rod to the start of adjustment point,
4- mark them,
5- remove the saddle and p/rods and set to the manufacturer's spec.(turns),
6- lock them up,
7-  re-install everything, p/rods and tubes, rocker saddle and rocker box covers like they were stock non- adjustables with the tubes, etc. 
John

[Shawrco]

If your tech removed the rocker box covers and the rocker arm saddle, you really don't need to by new p/rod tubes.
Just have him put the adjustables in, put the rocker arm saddle on, lengthen the p/rod to the start of adjustment point, mark them, remove and set to the manufacturer's spec.(turns), lock them up, re-install like they were stock non- adjustables with the tubes, etc. 
John

Thanks, he mentioned that technique as well. Not sure which way he's going with it. I'll be talking to him tomorrow cause if he's taking the rocker box tops off I need to get the rocker lockers out to him. Appreciate all the assistance.

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