aatkinsonalexdatkinson

Hi Chaps

Wonder if you can help with another novice questions.

I have fitted my new edelbrock rpm heads and performer plus cam to my otherwise stock 440 (includes stock rockers / pushrods). So far so good.

Next thing has been to check lifter preload and just want to make sure I’m going it right.

The procedure I’ve been following is:

1. Fit the stock rockers, rods and lifters and torque down the rocker shaft.

2. After picking a cylinder to check I then turn the crank until as best as I can make out I have the inlet valve lifter on the heel of the cam (I did this by looking directly at the cam in the valley)

3. Using a steel rule on the rocker cover edge and a fine marker I then marked a line on the inlet pushrod.

4. Next I unbolt the rocker shaft until the rods are loose (can easily turn using my finger) and then scribe another line.

5. I then tighten the rockers up,* turn the crank until the exhaust valve lifter is on the heel and follow the same procedure.

6. I then remove the rods and measure the distance between two lines on each of the rods – thus giving me the lifter preload / valve

Does this sound right? Is there some trick to ensure I have the lifter on the heel of the cam?

After doing this a couple of times on a couple of cylinders on each bank I have been getting 0.08 – 0.1 on right bank and 0.06 – 0.08 on the left.

I’m going to have another go this weekend but if they come out the same I figure I’m going to need longer pushrods?? I did read somewhere that you can put shims under the rockers shaft but someone over here in the UK said that that was a big no no and that you should always go for new rods (couldn’t really understand why this might be the case)

Lastly I appreciate that I really should be using adjustable rockers but 1. I don’t have the dollar, 2. I’d really like to fit once and not have to worry adjusting again and 3. I only intend to have a relatively mild street motor – no super high reving RPM.

Grateful for any thoughts you might have.

Thanks Alex

TVLynn

Best way is to use an adjustable pushrod. Adjust for 0 clearance then add .040 - .060 for pre load.Compare to the stock pushrod and order custom length. From Smith Brothers
or ??

bremereric

Never heard of doing it that way but instead with a dial indicator. Typically the say .020 preload. On a steel block with aluminum heads I have been told .030-.040. An ajustable pushrod will help you find the correct length rod you will need.

TVLynn

It makes it simple Adjust it for 0 Sent it to mfg and say this length + .040 for preload
No special tools needed.

440roadrunner

You don't need to BUY an adjustable pushrod for this test, MAKE one

Take an extra pushrod, or just go buy one, measure it, saw it in half and cut, say, 2-3" out of it. Now take a FINE thread piece of threaded rod, roughly grind a "dome" on the end and fit it down into the ends of the pushrod so it's, maybe, 1" or so short. Now just take 4 nuts (so you can lock them), lock two in place to form a permanent lock for one side, and then you can adjust the length on the other two against the other "half" of the cut pushrod.

The method you outlined sounds AFU to me.

bremereric

AFU?

PK1

The way you are doing is correct. You have a good handle on what you are doing and will get it. The good news is once you figure this out its super easy.

I have found easier ways to do it over the years because i am not as diligent with those fine measurements..

http://www.carcraft.com/techarticles/116_0401_setting_pushrod_length/viewall.html

Commando

I agree with the whole measurement of the push rod part, myself I got the adjustable rod, was just easier for me. But I have the same heads and believe they do not recommend reusing the stock rockers and remember a bunch of warning statements to that affect. I used the adjustable rockers from 440 Source, very easy to use and allows for quick adjustments.

440roadrunner

Let's just say I agree with your method!!!


For some reason I could not get that link to work until I......

http://www.carcraft.com/techarticles...h/viewall.html

PK1

If you want to master it the way you started to do it follow this link.

Hope it helps.

http://www.rlengines.com/Web_Pages/valvelashmech.html

bremereric

This link doesn't work either.

PK1

http://www.rlengines.com/Web_Pages/valvelashmech.html

One more time, well maybe 2

www.rlengines.com/Web_Pages/valvelashmech.html

Thanks for your patience!!

440roadrunner

Ya, we got it the first time.

What I'm saying is, this method may bot be the best for accuracy. Unless you use a straightedge clear across the head (valve springs in the way) how are you going to make an accurate mark, and unless you have that straightedge RIGHT up against the pushrod, you can get parallax errors, and unless you use something like a thin knife or razor, even that can be inaccurate.

For me, the decision was easy. Made two test adjustable pushrods. Installed in most front and most rear cylinders. Torque down rockers. Set for zero lash, and can easily see movement of lifter and feel with your fingers. Pull rocker back off, remove and measure pushrods, add the desired preload, and average out the difference between the two, which was minimal. Check opposite bank. I don't think I burned and hour all told.

Next engine I did, scored set of adjustable rockers, problem solved.

My Dart? Why IT has mechanical lifters. Sounds like a REAL engine!!!