I'm working on the 69 Dart I recently picked up, decided to do a cam swap and just seem to have gone backwards on getting this thing together. The one piece of info I can't seem to find the direct answer to is will the old factory style adjustable rockers work with a hydraulic cam? I have gotten a shorter pushrod but still struggling, what am I missing
72 360 Cam Install - Mopar Engine Beating Me
- Thread starter billsdartgt
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Frank Mopar
Well-Known Member
Thats because stamped stock rocker are not very strong when using a high lift cam
To the op. The answer is yes but You just need the proper length pushrods. You need to measure for proper length. You cant just pick a shorter pushrod. Comp Cams has all lengths of 5/16 pushrods
Plenty of people use adjustable rockers with a hydraulic camshaft. If you want a more solid answer, you need to give a LOT of info. WHAT camshaft? Specs? WHAT rocker arms?
AJ/FormS
68 Formua-S fastback clone 367/A833/GVod/3.55s
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I use adjustables on my hydros because
They can take the spring pressure a .571 lift cam needs at high rpm,and
I can set the lifter preload to what I want, so that if the springs would lose control, then the lifters can't pump up and ram my valves into the piston crowns, and
I don't have to worry about the pushrods coming thru the cups, 800 miles from home.
basically catastrophe prevention insurance
They can take the spring pressure a .571 lift cam needs at high rpm,and
I can set the lifter preload to what I want, so that if the springs would lose control, then the lifters can't pump up and ram my valves into the piston crowns, and
I don't have to worry about the pushrods coming thru the cups, 800 miles from home.
basically catastrophe prevention insurance
rockers were in the engine when I got the car, no idea what they came out of, lot like the typical stock ones I've seen on the internet for my year car with the mechanical/solid cams. I swapped out the solid lifter cam for a Lunati Voodoo (220/226 @50) lift 475 in, 494 ex, hydraulic, the number I found on the old cam was 292S, the rods that were in there were 7.5" overall length. I tried the 7.33 length, (effective length 7.185) they seemed too long. I have a 5/16 X 6.8 pushrod now. The geometry seems off with both the shorter pushrods, I am going to pull the rockers back off tomorrow to see if I can see any number, will grab a pict. also The engine has a date code of march 1972. I don't have any specifics on the motor, guy I got the car from thought it had a different cam because of an old box that was in the car when he bought it.
Do You know the specs on the cam?
Bill, you can certainly run the adjustable rockers. In fact, I recommend them. They are super tough. I prefer modifying them to run the Crane adjuster screws with the locknuts, however, as long as the factory adjusters are still tight with their self locking threads, they'll certainly hold up to the mild cam you have.
Here's the trick about pushrods. You want no more than about three threads showing through the pushrod side of the rocker arm when they are adjusted correctly. Now, using a different adjuster than factory will affect this measurement, so be sure to measure for pushrods with the adjusters you want to run. I hope that helped.
Thanks for the info, I bought the Crane adjuster screws with locknuts with this last set of pushrods, need to grind a little on the top of the rockers to get them flat. Got my answer that these adjustables will work, just a little more finish adjustment sounds like I will be good.
Yes sir, that's how to do it. You can actually do that with a hand file. I like doing it that way better. Yes, it's slow and old school, but you can get that area flat, while removing the minimum amount and do a really nice job.
Also one more point with adjustable rockers on hydraulic camshafts. You can make subtle differences in engine performance by varying lifter preload. I always liked running mine loose. It adds a little RPM potential. I've run them as loose as around .010" preload. You can run zero, but don't do it with the light duty hydraulic lifters with the little wire retainer clip that holds the plunger in. You'll want to have the heavy duty hydraulic lifters with the good snap ring if you run them that loose.
Just food for thought.
Thanks all, still a little bit of hope I will be able to take this to Hot August nights in a few weeks, at least all my electrical woes are now fixed
I agree they will rev better loose I loosen them until they tick and then tighten them until the tick stops plus a quarter turn . you will find the engine will run a lot run and rev better . like said about .010 preload .
after some more effort I decided that I need to either get some custom length pushrods or just get some non adjustable rockers and maybe some standard length pushrods, either way until I get a pushrod checker tool won't be much happening to get back on the road, Hot August Nights in less than 2 weeks, gotta take care of the house before the trip, got my Challenger ready to go yesterday.
Another member on the site has a set of stock rockers from a 69 340, anyone know if they will work on my 72 360 block?
Another member on the site has a set of stock rockers from a 69 340, anyone know if they will work on my 72 360 block?
All day long.
I thought so, after one of your comments I looked harder at my adjuster screws, currently I am almost all the wat through the rocker, enough room to barely get the locknut on even after a little grinding work, just don't like the way it looks, will just take a break until I get back from Reno, Thanks for the help.
The rockers are the same as for interchangeability, but if I remember right........and I think I do, the factory 340 rockers have a thicker cross section at the shaft area and also thicker metal in the pushrod cup. Mopar Performance offered the 340 rocker arm package for a long time and that was how they described them. I have had a few sets before and noticed it myself.
PRH
Well-Known Member
Is the only issue you’re having the pushrod/adjuster relationship?
Or are you not happy with the way the rocker interacts with the valve tip as well?
I see it often where people think you can impact the rocker to valve relationship by altering the pushrod length.
On shaft mounted rockers....... you can’t.
Using the stuff you already have......
Set the adjuster screw to the desired position. Measure how far it protrudes below the rocker body.
With the cam on the base circle, install one of your current pushrods.
As long as it’s not so long the cup contacts the underside of the rocker body, it should be fine.
Turn the adjuster screw to get the desired lifter preload.
Remove the rocker and shaft. Remeasure how far the adjuster screw protrudes from the rocker body.
The difference between the desired protrusion vs the observed protrusion is how much different in length the pushrods need to be.
Or are you not happy with the way the rocker interacts with the valve tip as well?
I see it often where people think you can impact the rocker to valve relationship by altering the pushrod length.
On shaft mounted rockers....... you can’t.
Using the stuff you already have......
Set the adjuster screw to the desired position. Measure how far it protrudes below the rocker body.
With the cam on the base circle, install one of your current pushrods.
As long as it’s not so long the cup contacts the underside of the rocker body, it should be fine.
Turn the adjuster screw to get the desired lifter preload.
Remove the rocker and shaft. Remeasure how far the adjuster screw protrudes from the rocker body.
The difference between the desired protrusion vs the observed protrusion is how much different in length the pushrods need to be.
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for the off the shelf length pushrods one length the pushrod hits the rocker, on the other I have to have the adjuster screw almost fully threaded in the rocker, a set of custom length pushrods would work out just fine, I am moving forward with getting the non adjuster rockers, waiting on a few deliveries and after hot august nights to get back at it, just hoping a stock length or readily available length pushrod will work, will also have a general idea how much the motor or heads have been milled
Frank Mopar
Well-Known Member
Comp cams has pushrods in every size you might need
http://www.compcams.com/Products/CC-'Pushrods'-3.aspx
http://www.compcams.com/Products/CC-'Pushrods'-3.aspx
The TA rockers have offset intake rockers because the pushrods were mover away from the intake runners to allow for porting. The rockers you were asking about in the for sale section are not TA rockers. They are the standard heavy duty 340 rockers. Have you bought them yet? If not, I am going to go look and buy them today. I don't even have a small block, but if you're gonna keep draggin your feet, I'll snap them up myself.
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