resurface cylinder heads

Have you ever wondered why Ford says don’t resurface these cylinder heads? Thickness of the cylinder head could be one reason, surface finish can be another and lastly, maybe they just want to sell more OE Ford cylinder heads.

I don’t think they say it to sell more Ford cylinder heads at all. That leaves thickness or surface finish.

Let’s talk about thickness. Let me also say all the specs I’m using are from Ford cylinder head specs or our measurements of Ford OE cylinder heads.

The original thickness is listed from 3.7380-3.7400” (95.00 MM). We have actually seen some that are as much as 3.7550” (95.37 MM). I sat back and said if I have a cylinder head that is max thickness and I’m only going to remove .002”, why not? It bugged me.

      1. For those of you not familiar with valve recess, there is a spec for the amount of recess from the fire deck (surface) down to the valve head fully seated. It is .013-.027” (we use .020” +/-.002”) intake and exhaust valves. If we surface .001” off the deck (bringing the valve head closer to the piston plus increasing lifter pre-load) and recess the valves in the seat a .0015” deeper (moving the valve head further away from the piston {and stay in spec}) the tip of the valve is in the same relative position to the block, and lifter, as it was to begin with. The problem with that logic is we have brought the rocker arm pivot the same .005” lower. The rocker arm ration is 1.5:1. For every .005” variation, up or down, thickness or valve recess, we affect the pre-load .0075”. It’s actually a simple calculation once we know the variables. Enough tech crap.
      2. Surface finish. Ford does not offer a spec on that obviously, because they say “DO NOT RESURFACE.” Good, I got that. All the gasket manufacturers provide a spec (albeit usually a generic) for desired finish for their gaskets. I called Dana because to the best of my knowledge as of this writing, they are OE Ford supplier. They don’t have a spec. on micro-inch finish because Ford doesn’t. The tech service rep. went on to say 5 to 40 uin (micro-inch) for MLS (multi-layer steel). We checked our glass windows and they’re 3- 5 uin. We looked at 40 cylinder heads we purchased for micro inch surface finish. Some had rust and some had been resurfaced previously so our sampling was 27 heads. What we found ranged from 23 to 41 uin.
      3. Here is an excerpt from a from a bulletin sent to me by the Tech Dept. of Mahle Clevite (Victor Reinz):

        Ford Motor Company’s Recommended Procedure for Cleaning 6.0L Diesel Cylinder
        Heads:
        Ford Motor Company’s Recommended Procedure for Cleaning 6.01, Diesel
        Cylinder Heads
        Material
        Item Specification
        Metal Brake Parts Cleaner
        PM-4-A or PM-4-B (US): CPM-4 (Canada)

        1. NOTE:
        The cylinder head cleaning and the cylinder head distortion check procedures are different than other engines. Watching the video prior to carrying out the procedure may be helpful if doing the procedure for the first time.
        2. NOTICE:
        Do not clean the cylinder heads with steel scrapers or blades, which can cause scratches or gouges that result in leak paths. Also, do not use rotary abrasive tools including: pads, disc, wire brushes, sand paper or emery cloth. These products can alter the surface finish of the head, adversely affecting the combustion chamber sealing.
        NOTICE:
        Cleaning the cylinder head employing any other method may cause a non-warrantable condition.
        NOTE:
        Use a brass scraper such as the Grainger 5LL98 brass scraper and a non-abrasive Scotch-BriteTM General Purpose Scouring Pad 96, or equivalent to clean the cylinder head. With the valves installed, clean all the cylinder head gasket surfaces with metal brake parts cleaner and a brass scraper to remove the hardened carbon deposits. Repeat the process as necessary to remove the hardened carbon deposits. Then, use the general purpose scouring pad to remove the remaining residual deposits.
        • Use only a lint-free rag to wipe the head gasket surface after cleaning
        3. NOTE:
        Staining of the metal surface is normal and does not affect sealing ability. Witness marks or indentations in the cylinder head resulting from the head gasket fire rings are normal and do not affect sealing ability. Clean all bolt holes and be sure that the gasket surfaces, oil return holes and coolant passages are clean. After rinsing thoroughly in hot water, blow the passages out using filtered compressed air.
        4. NOTE:
        The cylinder heads used on the {this} diesel engine cannot be resurfaced. Wash all bolts (except head bolts, which must be replaced) with a suitable solvent and dry thoroughly.
        Kind regards,
        Brian Mentgen
        MAHLE Clevite Inc.
        Product Coordinator 11 (Ford Gaskets)
        1240 Eisenhower Place, Ann Arbor, Michigan 48108-3282 USA

Sorry to bore you with all that but it does illustrate the only thing they talk about is surface finish.

Based on our findings previously mentioned, we decided on our own spec +/- 5 uin. We experimented with 6 different inserts all “claiming” to meet our requirements. We even surfaced one on a Blanchard Grinder (I’d prefer not to spend $65,000 if possible). We have come up with the right combination of cutter head speed; traverse speed, cutter insert and cutting fluid to achieve that spec.

I don’t have an exact count on how many 6.0 and 6.4  Ford diesel cylinder heads we have shipped in the last 4 years but as many as 7 pair a week.  What I can say is we have not had a single head gasket failure in that time. In all fairness we always recommend ARP studs, EGR delete etc.

Thanks for your time.

CategoryFord
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