How to put together cut to length pushrods

-
D

Dusterguy

Well-Known Member
Joined
Aug 9, 2011
Messages
234
Reaction score
18
Location
finland
I got Comp Cams cut to length pushrods. How do I put the cup end on it? Sure first I need to cut tube to correct length but what then? Do I need to drill the pushrod tube before inserting the cup part? How to insert it, do I just press it? Part number for these pushrods is K8805-16. Pushrod cups are 249-5C5P-1

I have seen comp cams special drill to this job but it expensive and I dont know do I really need it.
 
I'm just going to go ahead and say that you either need the comp cutter tool, or at least a reamer size same as in the chart below.........


"A clue" is given to you right in the Comp Cams listing:

"When the cut is finished it leaves a .002--.003" press fit.........."

See page 20

http://www.compcams.com/catalog/COMP2012/pdf/COMP_Catalog_2012_292-311.pdf

pushrod1.jpg


pushrod2.jpg



You are going to pay 30--40 dollars for just about any precision reamer, at least, so the cost of that tool doesn't seem very "outlandish" to me, considering it's basically TWO separate tools Jegs shows about 80 bucks

On the other hand, you could use a no 22 drill which is .157. You'd have to face the end of the thing either in some sort of home made jig (drill press) or rustle up a friend with a lathe
 
Last edited:
I have a lathe in work and I can buy correct size drill but I cant pay 80 bucks for one drill. I bet kids in china makes them for 5 bucks.

That tools says "bore .169" What that bore means? edit: does it means that the drill is tapered? from .157" to .169"?
 
Last edited:
Dusterguy said:
I have a lathe in work and I can buy correct size drill but I cant pay 80 bucks for one drill. I bet kids in china makes them for 5 bucks.

That tools says "bore .169" What that bore means? edit: does it means that the drill is tapered? from .157" to .169"?
Click to expand...

If you have access to a lathe, then you ought to know you don't just grab a drill and use it to finish a hole to size. That is why comp sells the tool they do. Or, you REAM the hole. Never drill it.

Now that I have said that, it don't really matter in the end (no pun intended). The cup can actually just drop into the pushrod. Where is it going to go? It can't get out.

Still, there is a way to do things, and then there is the correct way. Either use the tool comp sends or use a reamer and do it correct.
 
Dusterguy said:
I have a lathe in work and I can buy correct size drill but I cant pay 80 bucks for one drill. I bet kids in china makes them for 5 bucks.

That tools says "bore .169" What that bore means? edit: does it means that the drill is tapered? from .157" to .169"?
Click to expand...


It says PILOT .157 and bore is .169 and it means exactly what it says. The tip of the cutter is sized to .157 and is NOT a cutter, it is the pilot and should be very close to the I.D. Of the tube. The actual cutter size is .169 which is .002-.003 SMALLER then the measured diameter of the pushrod cup that you will press into the tube.
 
Right, now I got it. English isnt my original language so I had difficult to understand it. I have done only some simple tasks in lathe but I think this is doable to me if I buy correct sized drill(reamer) and ream that end of the tube. Thanks for help.

edit: If I put pushrod tube into a lathe can I use just normal drill to make the hole good enough? If not why not.
 
Last edited:
Dusterguy said:
Right, now I got it. English isnt my original language so I had difficult to understand it. I have done only some simple tasks in lathe but I think this is doable to me if I buy correct sized drill(reamer) and ream that end of the tube. Thanks for help.

edit: If I put pushrod tube into a lathe can I use just normal drill to make the hole good enough? If not why not.
Click to expand...


You speak English pretty good. Better than some on here, who are from here.

Yes, you can use a drill bit to open the pushrod tube up to size. But you have to remember that a drill doesn't make a round hole. It's actually 3 sided. And, it's hard to hold size.

As long as you have .002-.003 press fit, you will be golden, even if you do it with a drill. The tip can't come out once it's installed in the pushrod, and the pushrod is installed in th engine. They can be slip fit and not fall out.

As a machinist, I just go a bit retard on procedure. Sometimes guys get lazy and once they skat by once they do it all the time.

If all you have is a drill, you can do it.
 
The Comp tool is a waste of $$ because the stems of the pushrod cups vary in size over a range of .003-.004", and you need an interference fit of around .002". You will need to get a few small drills around the nominal size and customize the holes where the cup stems press in.

Here is a thorough write up on how my son and I did this very process, with pix and ways to do it with no lathe or special tool, just a vise, hacksaw, grinder, hand drill, and drill press. Of course, with a lathe, that work even better.

Field Cut/Assemble Custom Pushrods
 
Last edited:
I use the Comp set up to ream the end of the push rod and square of the push rod tube. I always cut the tube .010-.015 long and cut it down to size with the reamer. Also if you don't have a way to hold the push rod tube straight and keep it lined up with the cup end it will bend really fast and you get to start over again. If it wasn't that I end up making so many different push rods I would just buy them premade but I also hate waiting if them to come in when I want to finish a customer engine
 
Thanks for explaining this. I have some scrap pushrods maybe I should practice this process and see how it turns out.
 
Dusterguy said:
Thanks for explaining this. I have some scrap pushrods maybe I should practice this process and see how it turns out.
Click to expand...


Yup, practice a bit. It's not hard, use the lathe. Use a back stop. Cut the pushrods .010-.015 long and trim them in the lathe with a dial indicator.

It's not hard. I just usually buy the right length so I don't have to screw with it. I have shortened a bunch of them though.
 
yellow rose said:
Yup, practice a bit. It's not hard, use the lathe. Use a back stop. Cut the pushrods .010-.015 long and trim them in the lathe with a dial indicator.

It's not hard. I just usually buy the right length so I don't have to screw with it. I have shortened a bunch of them though.
Click to expand...
I needed 0.157" longer pushrod than stock (mechanical lifter pushrod.) I couldnt find them anywhere and local part shop said this cut to length version is only option.
 
Dusterguy said:
Right, now I got it. English isnt my original language so I had difficult to understand it. I have done only some simple tasks in lathe but I think this is doable to me if I buy correct sized drill(reamer) and ream that end of the tube. Thanks for help.

edit: If I put pushrod tube into a lathe can I use just normal drill to make the hole good enough? If not why not.
Click to expand...

a drill cannot hold as tight of tolerance on the hole size as a reamer. The reamer is more accurate, which may be what you need to control the interference fit...
 
Just finished my pushrods. It took 16 hours to me. I destroyed 3 lathe cutting bits and 4 drill bits. For some reason my drill bits needed resharp after every pushrod hole. Was not easy job without real comp cams cutting tool. Not going to do it again ever!

Where you buy custom pushrods and what they cost?
 
You can get custom from Smith Bros. Also search Summit by length, they have a large selection. Go with a quality 1 piece, you won't regret it. Two piece & welded tip are prone to failure.
 
Like op have said call smith bros, but first buy a comp adjustable push rod so you can see the length you need, then call smith bros and have them make you a custom set.
 
Smith brothers, Trend and I'm sure there are several others I can't think of right now. Manton is another.

The cost depends on OD, ID and what ever you might need for ends, straight, single taper, double taper etc.
 
Jesus..... it took my son and I a total of 4 hours start to finish. No lathe.... not necessary.
 
You must log in or register to reply here.
-

Back
Top