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Topic Review (Newest First)
01-23-2013 02:01 PM
FabioV8 Ok thank you very much, I order these....
01-23-2013 12:41 PM
cobalt327
Quote:
Originally Posted by FabioV8 View Post
Yes, those would be safer than the unknown wall thickness of the $27 set. I tried to ask Summit for my own curiosity from the eBay site showing those p-rods, was told they don't answer questions like that. The other info I saw was saying this was all the info available, so finding out the wall thickness w/o sawing one in half prollably ain't happening.
01-23-2013 04:28 AM
FabioV8 I take these to be safe, okay?

Crane Chromoly Pushrods 36622-16 - SummitRacing.com
01-22-2013 09:22 PM
cobalt327 You should be good to go, but I cannot find the wall thickness of them. I thought they were at least 0.065", but they might not be. Keep your eye on them, if you have unexplained valve float it could be from them flexing and making a pole vault effect.
01-22-2013 01:45 PM
FabioV8 I use a 390 stroker kit
original head
rocker arms original
cam
COMP Cams Xtreme Energy Camshafts 20-745-9 - SummitRacing.com
valve spring
Mopar Performance Valve Springs P5249464 - SummitRacing.com
01-22-2013 01:25 PM
cobalt327
Quote:
Originally Posted by FabioV8 View Post
the average is 6.81 they told me to add .060 ,so I should take 6.87
these might be okay?

Summit Racing® Pushrods SUM-G6413 - SummitRacing.com
I wasn't paying close enough attention to the decimal places, the difference between the two is negligible.

I'm guessing they say to add 0.060" to make up for the oil holes. If that's the case I agree that the pushrod length you linked to will be almost perfect. The only thing is if the cam requires a stiff valve spring, these economy p-rods might not have the wall thickness you need. But for a street engine, no prob.
01-22-2013 12:59 PM
FabioV8 the average is 6.81 they told me to add .060 ,so I should take 6.87
these might be okay?

Summit Racing® Pushrods SUM-G6413 - SummitRacing.com
01-22-2013 11:55 AM
cobalt327
Quote:
Originally Posted by FabioV8 View Post
Hello guys, are the friend of jeepers creepers,finally I managed to make the measurement:
6.8140 intake
6.8170 exhaust
I enclose a photo

pushrod which do you recommend?

Thanks
If you're asking what brand, there are several very good pushrods available (Manton, Smith, Trend), but if you're asking what length, both if that's what it takes to get the right geometry.
01-22-2013 10:47 AM
FabioV8 Hello guys, are the friend of jeepers creepers,finally I managed to make the measurement:
6.8140 intake
6.8170 exhaust
I enclose a photo

pushrod which do you recommend?

Thanks
12-17-2012 05:50 AM
engineczar Like I said in an earlier post the equivalent of 3/4 of a turn is not enough on a Magnum Mopar.

I had a 360 Magnum in the shop this past summer for the same symptoms. In his case the heads were already converted to an adjustable rocker. I set them up at 2 full turns. On a Chevy I generally go a half turn or less but for some reason Magnums require more.

Read through this post, specifically page 2

small block mopar issues • Speed Talk
12-17-2012 05:09 AM
cobalt327
Quote:
Originally Posted by techinspector1 View Post
The studs are likely 3/8"-16, meaning that there are 16 threads per inch. If you divide 1 by 16, you get 0.0625". That equals one full turn of the rocker nut. If you turn the nut 1/2 turn, you get 0.03125", right where Comp told you to put the preload.
TI, a whole ago I posted basically the same thing regarding using the stud's TPI to figure how much preload was being applied to a hydraulic lifter (in my case it was a 3/8-24 stud, not 3/8-16).

In any event, someone said the rocker ratio had to be accounted for. So using your example above, it would then look like:

1/2 turn = .03125" x 1.5 (or whatever the rocker ratio is) = 0.047" (rounded off).

Just wanted to get your thoughts on this.
12-17-2012 03:19 AM
jeepers creepers Thank you for your time guys, well, the picture i posted is not the engine my buddy is working on wich is a '96 Magnum, i already made a tool to measure up pushrod lenght, i will post a picture of it but is very similar to the Cobalt's one except i'm using two nuts on each rod side to get them solid and prevent the two parts from moving.
We tried to measure the lenght but as i told you in the first post we had difficult because of the lifters were extending and we actually got a shorter measure wich is about the stock pushrod lenght minus the preload of about .060.
Using a solid lifter would be great but i guess we have to take apart the intake manifold and i guess he doesn't want to of course but we will if there's no other way to do that.

About the noise; that was coming out from all of them, honestly it wasn't to bad, i would say that if you have a loud exhaust that is quite hard to notice but noise increases proportionally with the engine RPM.
My friend has been through lot of issue with that engine, the builder mad a lot of mistakes and they probably machined the heads may be more than once so i'm thinking about too much preload on the lifters due to the shorter height of the heads and may be as well the block, i have to ask him.
Talk soon.
12-16-2012 10:08 AM
cobalt327
Quote:
Originally Posted by jeepers creepers View Post
Thank you for the answer, they're so much apprecciated.

This is the valvetrain we are talking about:

Chrysler 318 Engine Rocker Arms Photo 14

As you can see on the picture they are different from chevy's wich have a locknut with a taper underneath that matches the rocker so you set up the preload just by add one extra turn or so, Chrysler ones have a simple bolt on top to tight at 22 lbs ft, what we probably can do is to put a spacer on the stud so the rocker will seat higher if needed or machine it on the lathe in the case longer pushrods are needed but i think get longer pushrods is easier.

What is hard to believe is that when you buy a specific camshaft to put on a stock engine the company doesn't tell you pushrod lenght.

Thank you
You'd be miles ahead of the game w/an adjustable valve train.

If that's not happening, you might find you need several lengths of p-rods to get the exact same preload- this is because of differing wear and differing seat heights if the heads were rebuilt and the seats were not done all the same. Fortunately the preload need not all be the exact same.

Make an adjustable push rod and use it to determine the p-rod length you need. You need to check ALL the valves then hopefully there'll be a single length that'll put the preload somewhere within the range of preload available from the lifters you're using.

You will need to make a solid lifter by stacking a hydraulic lifter full of washers or filling it w/grease so it will not compress while you do the checking. If you use a lifter from the engine be sure to not mix the lifters up- the lifters HAVE to go back onto the same lobes they came from. If you use a solid lifter, be sure the p-rod seat height is the same as the hydraulic lifters you are using (or you account for the difference in your measurements), else the p-rod lengths will be off.

Click on image for details on making an adjustable push rod:

12-16-2012 04:35 AM
engineczar That's a LA small block. You really don't want to cut the stands or do anything to the shafts themselves. Have you isolated the noisy rocker or is it all of them?

A couple of things to look out for. Depending on the mileage those rockers wear quite a bit where they rub against the shaft. If you're able to isolate the noisy rocker observe it while you're tightening the shaft to see if you're getting any preload at all while that lobe is on its base circle.

Also there are left and right offset rockers. Make sure you have them in the right position. If not the pushrod will act like it's short because it will be at an angle and not straight.
12-16-2012 03:37 AM
jeepers creepers Thank you for the answer, they're so much apprecciated.

This is the valvetrain we are talking about:

Chrysler 318 Engine Rocker Arms Photo 14

As you can see on the picture they are different from chevy's wich have a locknut with a taper underneath that matches the rocker so you set up the preload just by add one extra turn or so, Chrysler ones have a simple bolt on top to tight at 22 lbs ft, what we probably can do is to put a spacer on the stud so the rocker will seat higher if needed or machine it on the lathe in the case longer pushrods are needed but i think get longer pushrods is easier.

What is hard to believe is that when you buy a specific camshaft to put on a stock engine the company doesn't tell you pushrod lenght.

Thank you
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