Wrong rocker assembly, pushrods, lifters?...

T

TucsonHooligan

Well-known member
Motor is assembled and back in the car, ready to fire up. Cranked it over, and after some troubleshooting realized I had no compression. Pull the valve cover and bring cylinder #1 up on the compression stroke. No space between rocker and top of valve so I took some quick caliper measurements from top of valve to top of head. Removed rocker assembly and could obviously see the valves come up further, and after I remeasured the depth they moved a little over .125 (1/8th). So obviously my compression problem stems from the valves being perpetually open. Question is, whats the best cure? The head is a later model square log from the 80's. I had it fully rebuilt and am using the original rocker assembly that came with it, as well as the stock pushrods. I had the block zero decked and the head milled for compression, but was told by the machinist that any pushrod issues should be cured by the play in the lifters. .125 seems like a lot to just be a result of milling. Is there a possibility that the job done on the head has the valves seating that much further in? I read some tech articles that suggested puting shims underneath the assembly mounts, but that seems kinda shadetree. Best I can figure is shorter pushrods, but how do I find the exact length I need? Buy one adjustable, bring #1 up to TDC and run a trial and error till I get the right adjustment, then order a set at that length? Any help here would be appreciated, and please feel free to ask specific questions about details I may have glossed over.
 
Adjustable rockers would also work for you. But since you have had so much milled from both your head and block, you really need to correct your geometry at this point. You need to purchase an adjustable pushrod tool and determine what length is needed to restore both your valve adjustment and pushrod geometry. Never assume that even with a stock unmachined block or head that your valve train geometry is dead on. Anytime you cut more than .030 off of either you should check it to verify you weren't right on the trailing edge of being unacceptable to start with.
 
Not sure how much it was milled, but it was CC'ed to make sure it was correct for the 9:1 compression. It was done so long ago and I don't remember what it was. I could probably go by the machine shop and they would have it saved in the computer somewhere. Now that I think about it, since it's a later style head, they probably had to take off quite a bit just to get the compression back to stock, much less up to 9:1.

I will pick up an adjustable pushrod tool this weekend and test it out. Anybody have a link or description on a step by step on how to do this? I have a rough idea, but I'd rather not forget something important.
 
Simple enough it would seem, but as my dad always told me, nothing is foolproof to a sufficient fool. Are adjustable pushrods easily found locally or is that something I'll have to order?
 
Maybe if you have a speed shop in your area or large auto parts store like a NAPA.
 
If I choose to go with adjustable rockers, where is the best place to get a used set? What models came with them? I fear that trying to sort out the length of the pushrods may prove to be difficult. When I get it set perfectly, do I then add .030 to the length to make up for the play in the lifters or what? If you haven't been able to tell by now, this is my first build on something with valves and more than one cylinder. Don't wanna do this wrong and trash the brand new motor.
 
Take the stock 200 size you have , and delete 62.5 thou. Pull one out, measure to the spec, and request one minus 62.5 thou. Ford Australia used to offer shorter pushrods for planned heads, a common practice over here.

You will be better off than you are now. Make sure you are using the right lifters, as one type requires a 125 thou shorter pushrod even before the head and block decking numbers get deleted. Use the right ball and cup arrangement for your engine.

Over here, we had funny rocker set ups, with the rocker system so I can't help you with exact pushrod lenghts, but 62.5 less will get you backon track for sure.
 
I think only the 144 engine had a solid cam stock so years would be a 1960 to 64 and models were the Falcon & the 1960 Comet. Adjustable might also have been used in the early 170 engines if so that would be the 1961 to 64’s models would be Falcons, Comets, Fairlanes and Meteors. They have and still are a popular swap on the other small sixes so you can look for a used set in any small six. You might check with C.I. to see if they have a set other places would be ebay, Craig’s list, wrecking yards, and old time auto parts stores they may still have a rebuilt set sitting on the shelf. C.I. has the checking push rod and carries push rods for non-adjustable and adjustable rockers in three lengths stock, -.125, and -.250. I set mine up a little different than most people with adjustable rockers and (hyd. lifters). I warm the engine and than set them with engine running is chance for a little oil splash. Using a setting of zero plus a ¼ turn tighter they might sometimes tick at start up until the lifters pump up most people don’t like hearing the tick and think there is something wrong if so just add another ¼ to ½ a turn. Another way is to use method below link:
http://classicinlines.com/ValveAdj.asp

As far as your worry about trashing your new motor I hear you is expensive to build a motor. The push rods need to be near the right length, though the lifters do have quite a bit of travel, but for sure you don’t want too long of push rods they could bottom out the lifter pistons. This lack of clearance will stack up to hold a valve off the seat. Your thoughts are close on length at .030 longer .060 would be better if you keep using a non adjustable rocker with lifter at full height sitting on the heel of the cam lobe. Using the adjustable rockers make sure the adjusting nut is also set so it still has at least ½ of its travel left and be able to tighten it down more.

Before you try to start your new engine you should try to get everything as close as you can on the tune and pre oil it. Once you start it you need to do as the cam manufacture advise on the break method too. I would also use good oil with ZDDP or add it to your oil. Hope to helps you some and nothing beats hearing an engine run again after doing a build up. Good Luck
 
Xctasy,

Why only .0625 instead of a full .125? Wouldn't the indication be that I'm fully bottomed out on the lifter, and that bringing it up .0625 will still have my valves open? It seems to me I would have to come up a full .125 and then another .0625 to put me somewhere in the middle of the play in the lifter. Or is my thinking on this wrong?

Bubba,

The real kick in the teeth on this one is that I had a set of adjustable rockers when I pulled the 170 out, but my mechanic buddy told me they were of no use on the new head I would be using. Of course now it turns out he was wrong, but it's too late as they've gone off to the scrap yard months ago. Gonna have to stick with the solid rockers to save time/money. Plus I remember having to adjust the 170 every 6 months when a clicker popped up, too much of a PITA for a daily driver. I figure the checking pushrod is still my best bet as trying to calculate and hope may just cost me more time.
 
The real kick in the teeth on this one is that I had a set of adjustable rockers when I pulled the 170 out, but my mechanic buddy told me they were of no use on the new head I would be using. Of course now it turns out he was wrong, but it's too late as they've gone off to the scrap yard months ago.
Click to expand...
:shock: Bummer! It's getting hard to find them. :unsure: Sounds like the -.125 would be quite close.

If you had a way to do some machining (lathe) you could make a checking push rod out of an old push rod and some all thread, a nut, tubing for a sleeve and bit of welding if not would likely be cheaper to buy one.
 
The other bit of sweet irony being I'm currently at work, sitting less than a foot from the lathe (CNC) I run, but am unable to do personal work due to the security level of the plant I work at. Last shop I was in I could do whatever I wanted. Here, not so much.

What do you think about Xctasy's post about getting a .0625 shorter rod? The rocker is 1.5:1 ratio, meaning for every 1 inch of lift from the pushrod, the valve opens 1.5 inches. Or do I have that backwards? If i get a .0625 shorter rod, will that open the valve .125 less? I found pushrods that are .0625 shorter, but is that enough?

EDIT: a .0625 shorter rod will open the valve .09375 less. Doesn't seem like enough considering it seems like the lifter play was bottomed out. I think I'm going to just have to get an adjustable to be sure and not guess at it.
 
a .0625 shorter rod will open the valve .09375 less. Doesn't seem like enough considering it seems like the lifter play was bottomed out. I think I'm going to just have to get an adjustable to be sure and not guess at it.
Click to expand...

Yes I would say your right if your valve is all ready open .125 at TDC than it would take about -.0835 just to close it and as you said the lifter piston is still bottomed out. I wish I could remember the length piston travel in the lifter I am guessing it is around .180 to .250. You would want the piston near the center of its travel for longest life compensating for wear of parts over time. So now if you can find specs for your lifter divide the travel by ½ and add .0835 and subtract total from your stock push rod and you should have your answer.
 
:unsure: Hi TH.Hope that I`m not creating a problem here,as I`m not real swift at math.However,
Xctasy said 62.5 thousands.You said.0625.IIRC .0625=10 thousandths measurment.WAY smaller than what Xctasy said.
If I`m wrong,please correct me.Thanks.
Good luck.Have fun.Be safe.
Leo
 
Woodbutcher,

I believe he's using machinist terms. 62 and a half thousandths is written as .0625. A thousandth is .001. Unless I misunderstood him.
 
Hehe, no problem Mr. Woodbutcher!

Ok, so I got ahold of an adjustable pushrod and am ready to determine the length I need. I know the lifter has to be on the low-end (back side) of the cam, so I put cylinder #1 on the compression stroke. This should have the cam on the low. Question is, where does this put the play in the lifter? Without oil pressure, is the lifter fully bottomed out or at its peak? When I find the length of the rod, do I need to add or subtract .0625? Since the motor doesn't run, I cant really "pump up" the lifters, can I? This is the last key to the puzzle, and I should be able to get this taken care of over the weekend.

Thanks!
-T
 
I think you need to use a solid lifter for the measurement. I could be wrong though, haven't had to do it myself.
 
Check out this link.
http://www.carcraft.com/techarticles/11 ... ewall.html
If you already have the head on the engine, you can install a very weak valve spring so the lifter will not collapse when you get the valve halfway open.
Otherwise install a solid lifter & when at midlift adjust the adjustable pushrod so the rocker arm foot print is centered on the valve stem contact surface.
Simple check when you do it right. Bill
 
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