Adjusting 351C Rocker Arms

[Ciphyx]

I decided to rebuild my first engine and have a xcouple of questions on the rocker arms. Most videos I watch deal with new lifters. My friend had an engine with a fairly clean background. I decided to take the engine apart and put new bearings and rings in it. All the videos on the rockers that I see assume new lifters. I am reusing the same lifters, push rods and rocker arms. Heads have been reworked. These are 4V closed chamber heads with non adjustable bolts. One video I saw by Clevo King talked about the EOIC method. He also stated that he keeps the preload around .020 from zero lash to 24ft/lbs of torque. When I measure from zero lash to 24ft/lbs of torque on intake #1 I am .125 over. When I physically look at the preload on the lifter it is a lot... I see that most people just tighten the bolt to spec and move on, but that's a ton of preload. I am assuming I need to order new pushrods and shims to compensate.

Would you shim .100+ or buy new push rods?
If the lifters are already pumped with oil due to it being in a running engine before, does it matter on the preload?
I wasn't able to push the lifters down by hand -even pushing back on the rocker arm. Is that because they have been soaked and pumped already?
Would you even worry about it and just move on?

Thanks for your guidance in advance,

Cip

 

[boilermaster]

Ciphyx,
Expect a ton of different answers here.
What I have been taught over the years is adjust to the manufacturers specifications or 50 % of the lifters total travel.
you will probably find that modern lifters have much less travel than they did 50 years ago.
re-grinding the valves and valve seats will alter preload and so will head gasket thickness.
Your old lifters may not like going to a place they have never been before.
I suggest using the shims to find where your happy place is.
Pretty sure Crane cams offers a kit with 0.030'' and 0.090'' shims.
try and find which one or which combination gives you the best idle vacuum
without being noisy.
with a new lifter 3/4 to 1 full turn should be good
Boilermaster

 

[Spike Morelli]

To answer your question, yes, you can shim your rockers to gain better ( less ) pre-load, if needed. Although, .100" may be too much for the depth of the slot and still hold the pivot securely. It's probably the easiest way to gain some height. Otherwise, a pushrod change would do it. Most hobbiests don't have adjustable "checking" pushrods to figure with, and aren't comfortable with the geometry check at the tip of the valve. Shortening the pushrod will move the rocker arm's contact point on the valve tip inboard (up ) from where it is now, you want contact point geometry centered when pushrods are figured. To kinda simplify the adjustment ,when you have an adjustable valvetrain, you can do some simple math to figure how much to tighten the nut after zero lash. Let's say you have a 7/16ths rocker stud, it will be a fine thread of 7/16th-20, which is 20 threads per inch. So, divide 1.00" by 20, and that will give you .050" per full turn, so if the lifter manufacturer says .020 lifter pre-load, a half a turn past zero lash will put you at .025 pre-load which is almost perfect and totally acceptable.
The same for an engine using 3/8ths screw-in rocker studs. Fine thread 3/8ths is 3/8ths-24. So, divide 1" by 24, and you get .041" per full tightening revolution. To adjust this for .020" pre-load, you can see a half a turn will do.
Of course, you do this static ( not running) with each lifter that is being adjusted, sitting on the cam's base circle. I've longtime used the method where the Intake is adjusted as it's companion Exhaust lifter/valve is beginning to open, and adjust the Exhaust after it's companion Intake lifter/valve has opened fully and is well on the closing side of it's movement.
It's not as confusing as it sounds. Too much information?

 

[Ciphyx]

Information sounds great. With my setup though I have unknown hydraulic lifters with bolt fulcrums that just torque down. Shims or push rods are my only adjustment. My dial indicator showed .125 travel, so it sounds like I just need to use the rod length checker and make sure my valve contact rides center. Sound right?

 

[c9zx]

Unless you indexed each lifter to each cam lobe, reusing them may be a bad idea as each lifter and lobe have "taken a seat" with each other. Worst case is the cam gets wiped out and you start over. Best case is you get away with it. Also new rings on a used bore may cause the rings to take a longer time to "seat". Consult the ring manufacturer for hone grit and cross hatch desired. The pushrod length pushrod will likely require low pressure checking springs to prevent damage to the checking pushrod. Check intake and exhaust lengths as they almost certainly will be different. Preload settings vary by manufacturer. Use Spike's math on the turns. Depending on the quality of the valve job, the lengths may vary significantly from hole to hole and valve to valve. A straight edge placed on the valve stem tips will give you an idea of how much they differ. The stock multi-groove vales are a known point of catastrophic failure, they break dropping the valve into the cylinder. I'm not trying to throw cold water on you plan. I'm just letting you know that there is a lot more to engine building than many people believe. Good luck with the project and keep us posted on progress.
Chuck

 

[Spike Morelli]

The More I think about your situation, it makes me wonder. To have .100" of lifter piston colapse, on an engine which proportedly was a running engine, doesn't ssem like it should be, how could it have run before? Perhaps the previous owner has has the heads milled a lot for more compression, or the block and heads milled a lot, and didn't tell you. But if performance was in the back of the other owners mind, and the reason for severe milling, why didn't he have the heads machined for adjustable screw-in studs? Also, why now, does lifter pre-load become an issue if that cam / lifter/ pushrod /block /cyl head combibation was formerly a running unit? Am I simply assuming that your engine project was a complete running unit?
I'll offer this thought as well...perhaps you are checking lifter pre-load, with the cam's lobe still slightly under the lifter, and not completely placed the lifter on the base circle of the cam. It would be interesting to know what the issue is.......and why it is occuring,...because it shouldn't be. I mean, .125" of travel on the hyd lifter plunger? I guess I've never checked to see if any lifter even had that much compressive travel. In any case, I would check it again, with the intake manifold off ( it always is when I adjust valves for the first time when assembling ) double check that you are on the base circle for sure. Take an air hose, if you have access, and blow the oil out of one lifter through the top and side oil holes until you've purged it of any oil that may resist compressing the plunger. Verify lifter plunger travel by pushing the cup down, it should have a light spring tension and return each time. Check travel compressed from the top edge of the cup to the retaining wire clip to verify the .125" movement, just to know, " OK, It IS over compressing by that amount", if the lifter doesn't have .125" of cup travel, you are holding valves open , also you know you're on the right track, or there's an error in checking/assembling somewhere.
In any case, when it comes to adjusting hydraulic lifters, I always do it with the intake off.....it allows better visual movement as to where each lifter is as you go down the line adjusting, and....you can get a better feel spinning each pushrod in the valley area with your fingertips as to just when "Zero lash" occurs, as opposed to doing this by reaching under the rocker arm fully assembled .

 

[Hemikiller]

If you're working with a stock, or near stock camshaft, the factory shop manual has a clearance checking procedure for the non-adjustable pedestal rockers. Essentially, you're putting the lifter on the heel of the cam and compressing the lifter plunger. Factory spec is .100" ~ .200" rocker tip to valve stem clearance.

If you're running a performance cam, then this goes out the window and you should follow the cam & lifter manufacturer's preload specs. I've used the Ford Motorsport rocker shims in the past, but my preference would be to get the pushrod length that gives you the best tip pattern and proper preload.

 

[Spike Morelli]

Interesting Hemikiller. Truthfully, I have never checked any references as to total lifter plunger travel. I don't think I've ever required more than a full turn on an adjustable, usually a half, so bottoming out the travel has never been on my plate. Most performance recommendations will call out a minimal lifter pre-load. As you report, if the shop manual is giving that window, then there it is.

 

[mrgmhale]

Speaking of camshafts, and assuming this is a First Generation Mustang and an engine from the same era, especially since you are using the valve train that was in the engine previously, there is something you need to know. Those old school flat tappet cams new Zinc, actually Zinc Phosphate, in the engine oil. Otherwise you will too soon find yourself with a cam with its lobes worn down to little nubs, and lifters that have the face ground deeply in a concaved manner. Ugly and costly. What I suggest is you look at the ingredients of the engine oil you are using or planning to use. If it does not say it has Zinc, it doesn't. The Zinc fouls catalytic converters, so engines began to use roller lifters, which do not need Zinc. If it does not state clearly it has Zinc you either need to use an oil with Zinc in it, or use a Zinc additive in the engine oil. I would suggest the first option, find a good oil with Zinc in it.

There are a few really high quality engine oils, both petroleum and synthetic based, that have Zinc. But you will have to hunt for them. Personally, I use AmsOil Z-Rod 10/30. Once my older engines begin to use oil with the 10/30 I will move to their Z-Rod 20/40. I order my AmsOil on line at their web site. And I use either Motorcraft FL-1A oil filters, NAPA Gold or Platinum, or Wix XP filters. There are some other really good filters (Purolator comes to mind). But, I suggest you avoid using Fram oil filters. If you wonder why go to YouTube and search on "best oil filter," then watch in horror as folks cut open the various brands of filters and show how they are made, how much filter medium there is inside, etc. I have always liked the Motorcraft FL-1A, and these various videos show time after time that they are well made (I think by Puroloator). But, if ever I am n a pinch and can't find Motorcraft filters I am fine with the other brands I mentioned as being good as well.

I hope you already knew about Zinc in the oil of older engines, or you have not run the engine on non-Zinc oil yet. I have read about a few too many horror stories for my comfort when it comes to oil selection on these older engines.