MTFCA Forum

On a forum on Facebook, someone questioned how much a block can be decked (milled). I offered my two cents and said that a block deck should be milled as little as necessary to remove pits or square up, and that I have been told by a knowledgeable rebuilder that up to .150 or slightly more can be removed from the head, but to do so to try to increase compression, produces minimum results. Two people liked my answer, but one said he totally disagreed. What is eveyone's thought here on this subject?

You're right regarding surfacing the block to make it flat as you don't have to remove much. Just enough to enable the surface flat.
The cylinder head it doesn't make sense to remove that much better off to get a Z head or change pistons.
Model A guys think they can do the same thing. The heads aren't designed to machine off .150 and you increase the compression to 10-1 doesn't work that way.

You'll never win an argument on the internet as some expert that has never seen an engine will know more than all of us combined.

Less is better and also cheaper. The shape of combustion chamber is also very important. 50 years ago i used a Model B head and water pump on a Model A Doodle Bug and it made a difference in power! Bud.

J and M Machine wrote: ↑

Tue Jan 19, 2021 9:43 am

. . . You'll never win an argument on the internet as some expert . . . will know more than all of us combined.

So true ! So often contradictory opinions seem to prevent posts from actually providing good answers to the questions posed.

As for re-surfacing heads and blocks, my question is whether there's a reliable way to gauge how much material is left ? At this late date, it could be difficult to determine if parts have been re-machined, or how many times it may have been done.

The Facebook poster who didn't agree with my answer, referred me to the Montana 500 website regarding engine modifications. My answer to him, was that I thought the original question was involving an engine in a Model T that wasn't going to be raced or that the engine builder wasn't seeking ultimate performance. I, further stated, that if performance was the objective, much more can be done to a T engine other than decking the block or milling a head

ModelTWoods wrote: ↑

Tue Jan 19, 2021 11:38 am

The Facebook poster who didn't agree with my answer, referred me to the Montana 500 website regarding engine modifications. My answer to him, was that I thought the original question was involving an engine in a Model T that wasn't going to be raced or that the engine builder wasn't seeking ultimate performance. I, further stated, that if performance was the objective, much more can be done to a T engine other than decking the block or milling a head

I could wrong in my knowledge of Montana 500 rules, but I would guess that if a Z head were allowed on the MT500, nobody would bother decking the block or head for the want of compression.

Before milling the block deck, determine first, whether or not you need new valve seats. If you do need them, mill the deck after the new seats have been installed.

I have had Model T A and B heads trued up in the past and usually a good machinist knows best! Bud.

In an effort to mill off as little material as possible from the head and block, would it be okay to leave minor imperfections, as long as they could be sealed with Permatex Copper Spray gasket? Jim Patrick

Jim, your suggestion is quite reasonable, unless the imperfections are in the lip on the outboard side of the two large water galleries at each end of the block. These need to be spot on, just as they do on the cylinder head.

Allan from down under.

jiminbartow wrote: ↑

Wed Jan 20, 2021 1:35 am

In an effort to mill off as little material as possible from the head and block, would it be okay to leave minor imperfections, as long as they could be sealed with Permatex Copper Spray gasket? Jim Patrick


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With an engine out of the car and being resurfaced anyway, an imperfection that still requires "sealing" by any other means than the head gasket, needs to be addressed, (i.e. removed). Besides, if you're decking a block or head, and you have a "minor imperfection", chances are, taking another .005" off will get rid of it and be no big deal. Copper coating is no replacement for a good head gasket and two good seal faces. Not to say that Copper Coat isn't worth using however. I always use it.

Rich Bingham wrote: ↑

Tue Jan 19, 2021 11:09 am

J and M Machine wrote: ↑

Tue Jan 19, 2021 9:43 am

. . . You'll never win an argument on the internet as some expert . . . will know more than all of us combined.

So true ! So often contradictory opinions seem to prevent posts from actually providing good answers to the questions posed.

As for re-surfacing heads and blocks, my question is whether there's a reliable way to gauge how much material is left ? At this late date, it could be difficult to determine if parts have been re-machined, or how many times it may have been done.

Only way to know for sure how much has been machined off the block is to know exact block spec from Ford or measure a known unmolested one.