Pushrod Length

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sledger46

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Hello all,

I am trying to determine the correct pushrod length for my special application. I have an LA short block with a hydraulic roller cam and special hydraulic roller lifters I got from Hughes. I am running EQ magnum heads with thin .028" thick head gaskets. The heads use the 1.6 ratio, stud mount rockers from magnum heads.

I used an adjustable pushrod and got a zero lash measurement of 6.804. I like to run the lifter preload on the light side so I added .020" for preload and came up with 6.824". The closest length I could readily find was 6.821", so I ordered those to get the engine running.

The engine does run, but I think I have some excessive valve train noise. I retorqued the header bolts to eliminate any exhaust ticks. I recorded a quick video with my cellphone but after I uploaded it to YouTube I noticed the sound was monkeyed with. You can hear me move inside the car, but you can now barely hear the engine.

[ame]http://www.youtube.com/watch?v=T4DHJzEkMBg&feature=youtu.be[/ame]
 
If measured correctly .003 isnt gonna make a differences. On a side note can i ask about the 3 gauge pod you have that lights up blue? Remember where ya got it?
 
Sometimes certain valvetrain components are just noisey.
 
Did you measure several valves, AKA exhaust / intake at 4 corners

Did you check the measured PR against the new ones?

At what point in the cam rotation did you check lash?

hint---EOIC or 90* rotation chart
 
67Dart273 said:
Did you measure several valves, AKA exhaust / intake at 4 corners

Did you check the measured PR against the new ones?

At what point in the cam rotation did you check lash?

hint---EOIC or 90* rotation chart
Click to expand...

I had the intake off and could see the cam itself, so I checked on the heel of the cam for both intake and exhaust. I checked opposite corners #1 and #8. I guess there could also be variations in the pedestal stand height and the rockers themselves.
 
Roller rockers can be a bit noisy sometimes. Honestly, your valve train sounds just like mine....like a sewing machine on steroids.:D
 
It's the sound of performance, you're not complaining are you lol
 
If you want to be dead sure, why not give Dave at Hughes a call? They are very sharp and they give great customer service. Dave has a kinda "flat" personality and some people take that as him being difficult, but he's really a nice guy.
 
flyfish said:
Roller rockers can be a bit noisy sometimes. Honestly, your valve train sounds just like mine....like a sewing machine on steroids.:D
Click to expand...


I wish they were roller rockers, but in reality they are the stock, stamped steel, rockers with cast aluminum pedestals that came off some stock Magnum heads (with cracks between the valves).

Even if it really isn't a 273 Commando engine with a solid flat tappet cam, I guesss it can sound like it.

motorfront.jpg
 
How about valve stem height? They the same across the heads?
 
Mine ,did the same cold. Warmed up,went away. Magnum,stock valvetrain.,stock heads. Remember,high lift cams,ground on a smaller base circle.This means,longer push rods,are needed. Mind you,this isn't a flat tappet mill. .020" works there.I would shoot .030"-.050" pre load. These do not RPM,unless you spend bucks The video ,sounded like mine,until warmed up.
 
I found a set of Wolverine pushrods that are 6.845" long I am gonna try. They were on closeout at a racer supply house for $.46 each or $7.36 for a set of 16. They cost more to ship ($10).
 
Let us know how the push rods work out.
I have a fresh 360 mag with eddy heads and comp rollers and for some reason it sounds horrible in the valve train.
I am thinking that I mis-measured the push rods, it is like I do not have enough pre-load on the lifters.
 
You don;t have enough preload. Hughes has recommended much more preload before. Get longer pushrods and reset the preload to .060. Or - call hughes. They can be jerks to deal with - but you might get the answer.
 
The new pushrods will put me at .041" preload. I always read the allowable preload range is .020" to .060".
 
There isn't a max really if the plunger still has travel in it. You just want the least that will keep it quiet and let the lifter's plunger do it's job. If the lifter bores are a little loose, or the lifters' internals are a little worn or loose more preload might fix the noise.
 
OK, as I wrote these numbers earlier in the thread I kept thinking that they didn't seem right. I pulled up my sheet where I recorded the numbers and here is what I got:

Low: 6.775
High: 6.7825

My notes show I used .040 for lifter preload and used the higher number for push rod length.

6.7825+.040 = 6.8225"

I found a Comp Cams pushrod at Summit that was 6.821" on the shelf and when with that.

The new push rods I ordered were 6.845", so the new preload should be 6.845 - 6.7825 = .0625"

I hope it is not too much.
 
lifter preload should be zero lash + 1/2 turn on the rocker for stud mount rockers- there is no "light" setting on them
 
There are no studs, these are pedestal mount rockers with no adjustment other then shims.
 
sledger46 said:
There are no studs, these are pedestal mount rockers with no adjustment other then shims.
Click to expand...
oh you said stud mount above I thought (must have mis-read)

The push rod length IS the lifter preload so you need to choose them wisely - shims do nothing but cover a large gap in case you have the heads milled or order the wrong length pushrods- my advise- go stud mount with chevy rockers MUCH easier to deal with.
 
I received the new push rods last night and managed to get all the push rods on the driver's side replaced. What was amazing was when I fired up the engine I was expecting to still have a bunch or noise on the passenger side, but I would have to say 90% of the valve train noise was gone. It made me happy. Here is a picture of the new Wolverine push rod ($.46 ea) and the Comp Cams high Energy push rod ($2.00 ea)

pushrods01.jpg


The Comp Cams is on the left and the Wolverine is on the right. Push rod length checker is in the middle.
 
Where did you actually end up buying your push rods from?
 
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