Rocker assembly and head milling

[Sedanman]

Up until re-joining the forum a few weeks back, all available info (other people, Ford Six Performance Handbook) over the past few years was telling me that if I mill my head, you need to install an adjustable rocker assembly. I do have one, but it will involve disassembly and cleaning, and require new cupped pushrods.

As discussed in other threads about my project, my '68200/'69 head (with about 8k on it) have been rebuilt at least once, so a milling of .050 was suggested. So can I keep my non adjustable assembly, or do I need to install the adjustable one from my old 170?

Thor

 

[CZLN6]

Howdy Thor:

The question is what head gasket will you be using and what is in there now? The stock range of hydraulic lifters is about .125". Assuming that the rockers was about in a half way position from the factory you would have about .0625" to play with. .050" is safely within that limit.

The adjustible rocker gives you the opportunity to adjust the range of the lifter to minimize lifter pump up and to get all of your cams potential. If you've got the rockers already you're half way home. Go for it.

Adios, David

 

[Lazy JW]

Adjustable rockers are a fine thing but having the correct length pushrod is better. Having both is the best plan.
Joe

 

[JackFish]

So can I keep my non adjustable assembly, or do I need to install the adjustable one from my old 170?
Thor

Yes you can use it.
I have both, and couldn't be bothered with trying to fiddle with the lash on hydraulic lifters, so I will be using my non-adjustables as well.
If you're concerned about head bolt length, in lieu of using washers as shims under the bolts you may be able to just grind the end off a bit and chase the threads to make sure they're clean.

 

[CZLN6]

Howdy Back:

Hey Jack- Not need to adjust for lash with hydraulic lifters. Just tighten the rocker down until all play is gone then add another 1/4 to 12/ turn more and it is unlikely that you'll every have to adjust again. And you're just gained all of the potential of the cam and lessened the chance of valve float due to a pumped up lifter. Those are the real advantages of adjustible rockers with hydraulic lifters.

Adios, David

 

[Sedanman]

Hi David,

The engine has/had a Fel Pro steel head gasket when I tore it down; I have a collection of gaskets somebody gave me, and believe it's a "standard" style gasket. I do have the adjustable assembly, but being my 170 had 120k and 40 years of use, it probably needs thorough cleaning. The non adjustable one on the engine now looks to be nice and clean (only 8k on it) so it's basically a time saver to bolt it right back on...

Jack - would milling .050 really cause a head bolt length problem? I'm not a mathematician, but overall that sounds like a tiny amount of material in the real (non-compression related) world of nuts and bolts (?)

Lazy J - I thought the shorter rods weren't available any more? This is another reason I'd like to wait to put on an adjustable shaft assembly - if I decide to step up to the 1.6 ratio I'd have to buy new cupped rods again since you're not supposed to mix old and rockers/pushrods, or so I've been told....

 

[CZLN6]

Howdy Back All:

The Fel Pro gasket measures about .055" thick compressed. The stock, OEM steel shim type head gasket measure .025". So you lost compression and increased the distance from cam to rocker shaft by about .030". Which gasket will you be using on reassembly? Gasket thickness is a part of the total measurement.

I doubt that there will be anything wrong with using your newer non-adjustible rockers, but I wouldn't assume that they are clean and ready to go. Even though they only have 8k of road miles on them the gunk is forming while they are just sitting too. If the engine is of an eighties vintage they have been sitting for almost 30 years. I'd give either a good cleaning and inspection before deciding and using. Incidently, the non-adjustible rockers have bigger 1/8" oil holes on both sides of the shaft. Your 170 rockers can be drilled out to 1/8" too.

With your question to Jack, it's not that .050" is tiny or a bunch. It's that FoMoCo was not into precision casting and machining with these lopo engine. It is cheap insurance to, at least, check the bolt holes depth before assembly. If a bolt bottoms out, you'll get correct torque wrench readings, but not be tightening the head. Washer also make the process of torquing easier and more accurate.

With your question for Lazy J, both longer and shorter pushrods were available and may still be in some sources with New Old Stock (NOS). Anyway, neither are needed with hydraulic lifters and adjustible rockers. I used a set of 170 adjustible rocker pushrods on my 200 with no problems. I had to get custom ones for using the 170 rockers on my 250. And, I think the same length pushrods are used for the 1.6:1 rockers too. New and old are all over the place in my engine. When we put that engine together there were very few sources of small ford six parts. Cleaned, inspected,and in good serviceable shape, I see no reason to not use old parts.

FYI- rocker and pushrod wear occur due to lack of oil circulating from the back of the rocker shaft to each rocker and down the pushrod. Check the ball ends of the rockers and the cups of of both the rockers and the pushrods for any wear other then round and shiny. Round and shiny is good. On start up leave the valve cover off and watch the oil seep out of the rockers from back to front. If it doesn't you've got a blockage.

Adios, David

 

[Sedanman]

I'm not quite clear how I tell if the head bolts are too long; I torque them down without the head on, but then how to I mark them so I can tell when the head is on?

I don't have a brand name, but the gasket I have is not a steel gasket...

 

[drag-200stang]

Sedanman,

Please, whatever you do, do not torque the bolts down without the head on. Especially the weak one by the water pump. It will act like a wedge and crack the block. One method I 've used when I couldn't get measuring tools to work, put something flat against one of the bolt holes of the head (not the block) and drop a piece of welding rod or something like that, mark it the best you can, cut it off with some cutters. Just keep working it - maybe with a file so that it is flush with the top of the head's bolt hole. Now take that measuring tool over to your block with the bolt that you lightly screwed in with a wrench and see how much longer your measuring stick is than the bottom face of the bolt head. It should probably be at least .060 longer depending on how thick your head gasket is. It will take up additional space. If you don't have any overlap, grind the bolt shorter. It wouldn't hurt to check all bolts and head holes.

When I put my engines together, I want the most strength I can get. I won't willy-nilly throw washers under the head without checking to see that I need them. And I won't lose extra threads when I can have them. Just make sure to check to see that they don't bottom out. That is my way.

 

[CZLN6]

Howdy Back:

Q- I'm not quite clear how I tell if the head bolts are too long?

A- Stick a smaller stick, like a pencil into the bolt hole to measure from the bottom of the hole to the deck surface. Note that measurement. Measure the thickness of the head for that bolt. Measure the thickness of the gasket you intend to use. Add these three measurement together. Call this "A". It is easier to use a decimal system in adding. Compare that measurement to the length of the shank of the head bolt for that hole. Call the length of the bolt's shank "B". "A" should be at least .100" greater than "B". Drag Stang uses .060", which is fine, if you know the compressed thickness of the head gasket and you know that the hole is chased and clean, and no assembly oil gets in the hole on assembly. Bottoming out a head bolt is many head aches. Losing a thread, more or less will not change the strength of the seal that much with a composite gasket and 9:1 CR or less. Ideally, you want both- a good, true torque seal and all the strength of the bolt and hole.

Q- I don't have a brand name, but the gasket I have is not a steel gasket...

A- You will need to measure the thickness of the gasket to be able to figure dimensions for the above comparison and, later, for estimating the compression ratio. Most manufactures give both a thickness and compressed thickness specification on their gaskets. Can you describe the gasket. Does it have a metal surface? Asbestos fabric? Does it have any sealing ridges? FYI- a stock, OEM, steel shim type gasket measures .025" thick. An aftermarket composite type head gasket measures .045" to .055".

Adios, David

 

[Sedanman]

David,

Here's a photo I just took of the gasket; I don't know that it's an ROL as it came in a larger box with a bunch of other gaskets, and was not attached to that piece of cardboard...

http://www.flickr.com/photos/sedanman/3 ... otostream/

 

[CZLN6]

Howdy Back:

At first glance I thought it might be the Ford Service replacement for the steel shim gaskets, but on a closer look and comparison it is probably not. The FoMoCo service gaskets were made by McCord and were stamped with an "MC" along one side. They almost always had a Ford part # stamped into them at the front/top- C9DZ-6051-C. They had a bore of 3.81", as shipped thickness of .037", and a compressed thickness of .035". Your gasket could be a close copy of this one. Look it over carefully for any marks of any kind and measure the bore diameter and thickness. Those two dimensions will tell you alot.

And, here I am saying it again- I've never seen a ROL gasket for a small Ford six. If it is, thanks for sharing.

Adios, David

 

[Sedanman]

Bore diameter is just a hair under 98mm, thickness approx. 1.75 mm. I'm just using a ruler, though - don't have access to anything more accurate. I have purchased ROL gaskets for my sixes in the past, but don't recall if it was a head gasket or not...

 

[Lazy JW]

Howdy Back:

Q- I'm not quite clear how I tell if the head bolts are too long?

A- Stick a smaller stick, like a pencil into the bolt hole to measure from the bottom of the hole to the deck surface. Note that measurement....

Ummm...... this all assumes that the threads actually go all the way to the bottom. I would be buying a bottoming tap and make CERTAIN that they do.
Joe

 

[CZLN6]

Howdy Back:

The bore measurement at 98 mm is roughly equal to 3.80". Thor, machining dimensions are almost always in decimals of inches. You may need to find a 1" micrometer to accurately measure the thickness of the head gasket. 1,75 mm thick seems way too thick. 1,5 mm is close to .050". Did you inspect the gasket closely for any markings?

Joe's mention of a 7/16" bottoming tap is also a good idea. They are a little hard to find and somewhat expensive for a one time build but, it would be the very best to know, for sure, what is down that hole and how far. A bottoming tap will clean, re-establish and determine the depth of the threaded part of the hole.

Adios, David

 

[Sedanman]

Yeah, I looked it over closely, David - no markings that I can see. That thickness measurement was done with a plastic ruler, not the most accurate but all I have, so I may be way off the mark.