273 Pushrod length

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Jarmo72

Jarmo72

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Hello there, I have had some progress, but now I face out next problem.

I have comp cam CL20-221-3 with hydraulic lifters.
Original rods are little pit too long ( measured legth at the rod is 7.497")(without ball at the top) just rod length.
It seams that I dont have enough adjustemt on my rocker and lifter assembly.

I know that some of You have more experience and I need to know will Comp 7821-16 rods fit my needs. (lenght 7.389") cause I believe that the way how they (Comp) is introducing to measure correct lenght for the rods, don't fit for the Pushrod specs what they are giving.
 

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With several (not sure how many is ideal, 1.5?? or 3, wait for others to advise) threads showing underneath the rocker, on base circle of course how much preload do you have?
 
Fast reply, I would like to get one round preload, what is around 1,0 mm ->0.04".
 
Get an adjustable pushrod, set the length where it needs to be, then measure it and order a custom length set. That's the best way to go about this IMO. If nothing else then you would at least know what length to look for.

I've got a set of custom length Smith Bros chromoly pushrods in my 340, they have good products and good customer service.
 
hi, try comp cams pushrod 7821-16. it's for adjustable rockers and hyd cam. length is 7 .234.
 
Or you could shim the rocker stands.Mancini has shim sets in different thickness. Just a thought.
 
Perfacar, I was thinking those Comp 7821-16 rods, but I wasn't sure. What that length 7.234" indicate. Rod legth between ball and top of the cup, or between ball and top of the ball- ball diameter?

I will need rods with length 7.389" ( between the ball and on the top of the cup).
 
perfacar said:
hi, try comp cams pushrod 7821-16. it's for adjustable rockers and hyd cam. length is 7 .234.
Click to expand...
This is where the confusion arises with the Comp Cams 7821-16. Their catalog lists 7.389" length, and they say that they specify them as gauge length, which would be tip of ball to bottom of cup for an AC (5/16" ball-cup) pushrod. These would be the same length as what the OP has now or even a bit longer. I am curious if this 7.234" is an actual measurement..... perfacar?? (Just checking to be sure as it does not agree with what Comp Cams states.)

Jarmo, I would email to Comp Cams directly ans give them your pushrod length needed.

And, you can make a checking pushrod from one of your stock 273 pushrods; it would be good to use a spare one for that.
 
7.49 pushrods are for solid cams with adjustable rockers....

7.33 or so are for hydraulic cams with adjustable rockers...

the seat where the pushrod rides on the solid and hydraulic lifters are at different height in the lifter.
 
DesertRat said:
See below, these are what you want.

http://www.summitracing.com/parts/sum-g6420
Click to expand...
Interesting... are these 7.234" overall length, ball tip to top of cup? Or 7.234" effective or gauge length (ball tip to bottom of cup)? (Which would match what the OP says he needs....) I would not trust the Summit description of 'overall length' without an actual measurement or some confirmation. (Maybe you have these DR, and can verify?)

A lot of numbers are being given without being 100% clear as the exact point on the cup where they are measured. There typically is .175" from the top of the cup to the bottom of the cup for the Comp Cams and stock 273 pushrod cups (which, yes, I have actually measured....) Not bustin' on anyone, but trying to make sure the OP gets what he needs.
 
Thanks all of YOU, We have here ( In FINLAND) mid night now so I will take a nap, but once I open my eyes I am back.
This is not so clear for me.... But I know what I need.
You are very helpfull there!!!!! Thanks a lot.
 
ok, did some measuring. for hyd cam and adjustable rocker, they list 7.234. solid cam lists 7.342. on page 307 in older book, tells how to measure pushrods correctly. they use a .3125 ball in cups, this is how pushrods are measured correctly. you subtract .3125 from measurement, this gives you their measurements listed. so, 7. 234+ .3125 = 7.5465. solid cam pushrod is 7.655- .3125 =7.342 the 7821 rod will fit with hyd cam and adjustable rockers. also, mopar hyd lifter cups sit way up in lifter. the comp hyd cup sits lot farther down. closer to solid cup height. so the pushrod they list is correct length. BTW, smith bros measure all their cup pushrods this way. I use their calipers to measure with.
just food for thought
 
nm9stheham said:
Interesting... are these 7.234" overall length, ball tip to top of cup? Or 7.234" effective or gauge length (ball tip to bottom of cup)? (Which would match what the OP says he needs....) I would not trust the Summit description of 'overall length' without an actual measurement or some confirmation. (Maybe you have these DR, and can verify?)

A lot of numbers are being given without being 100% clear as the exact point on the cup where they are measured. There typically is .175" from the top of the cup to the bottom of the cup for the Comp Cams and stock 273 pushrod cups (which, yes, I have actually measured....) Not bustin' on anyone, but trying to make sure the OP gets what he needs.
Click to expand...
Another member put me on to these. I ordered them and on my bench put my old solid lifter and pushrod combo side by side with my Lunati hydraulic and the summit pushrod listed. When I added a little preload on the empty Lunati lifter, the overall lengths were exactly the same. If my cam degrees out I will have photos to post soon.
DR:coffee2:
 
I hope the above good info helps Jarmo..... I assume he has to order from the USA, pay the shipping, and wait maybe 1-2 weeks for it to arrive in Finland. It would not be good to get the wrong part!
 
That is correct, Order from USA, shipping + tax+ custom clearance, price is normally about 3 times , compared what You get there.

Anyway I am happy with my hoppy and I get enough info, so I will order pushrods.
By the way, my driving season is over now, today we got first snow here....

Thanks all of YOU, I will add some pictures later on.
 
Completed with com 7821-16 rods, seems to be correct length.
And ready for Dyno test/tuning.
 

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