What is the "deck height" of a stock model T block ??

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Model T Ford Forum: Forum 2018: What is the "deck height" of a stock model T block ??
Top of pagePrevious messageNext messageBottom of page Link to this message  By Donnie Brown North Central Arkansas on Monday, November 26, 2018 - 10:25 pm:

I am in the process of having the engine block for the speedster project machined. Since I know nothing about previous work done to the engine, I am hesitant to deck the block. Does anyone know the stock deck height from the oil pan gasket surface to the head gasket deck surface.??

Then next question is how much could be machined off and not cause any problems. ??

I plan on removing the least possible. But I have no way of knowing what the guy before me has done.

Thanks in advance ...


Top of pagePrevious messageNext messageBottom of page Link to this message  By Philip Thompson Graham NC on Monday, November 26, 2018 - 10:40 pm:

I will try to measure mine tomorrow my block Thai don't think has been decked has letters stamped on the block surface. Philip


Top of pagePrevious messageNext messageBottom of page Link to this message  By Mike Bender Tulsa Oklahoma on Monday, November 26, 2018 - 10:50 pm:

Most blocks will that a stamping, maybe the inspectors mark that may give you and idea of being decked in the past. 10.625" deck height I believe. If you are going to have it deck just remove enough to square.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Frank van Ekeren (Australia) on Monday, November 26, 2018 - 11:05 pm:

10.625" is right or easier 10-5/8"
but I do have a block as hi as 10-13/16"
A bit like heads, they can be all over the place.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Donnie Brown North Central Arkansas on Tuesday, November 27, 2018 - 12:40 am:

This engine has had things done to it that make me wonder if it was decked before. It has a 290 cam, was running a Bosch front plate distributor, no magneto, .040 aluminum Jahns pistons, Model B carb, intake, and exhaust, a EE crank, modern stainless valves, and the machine work on the cam, cylinder walls, and crankshaft is top notch work. Nothing real drastic, but all of it together made me wonder if the block had been decked before. My machinest wanted to know if I knew the stock deck height, so he could tell where he was, before he did anything. I just want to remove enough to know it is flat and square. Ill be installing the Rajo 4 valve on this block. They tend to be a little problematic as to blowing head gaskets. So Ill feel better knowing it is flat before I start on the Rajo. Thanks for the info. Ill get it to the machine shop tomorrow...


Top of pagePrevious messageNext messageBottom of page Link to this message  By Mark Gregush Portland Oregon on Tuesday, November 27, 2018 - 10:52 am:

If the top ring comes out of the bore you have gone too far!
Has he check it? If it is not flat, it's not flat. Unless it is really bad, the ones I have had surfaced were only a few thousands out.
To me there is a difference between decking and surfacing, decking removes a lot more material (example; I had the head decked 1/8" to increase compression), surfacing just removes enough to clean up. I think the last block I had done was under .010 to clean up.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Henry Petrino in Modesto, CA on Tuesday, November 27, 2018 - 11:08 am:

I'm far from a machinist, but a thought occurred to me. Wouldn't the overall block height, meaning the measurement from pan gasket surface to head gasket surface, actually be irrelevant? It seems to me that the critical dimension would be from the main bearing center to the head gasket surface.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Philip Thompson Graham NC on Tuesday, November 27, 2018 - 01:40 pm:

i think the bottom is the crank centerline. philip


Top of pagePrevious messageNext messageBottom of page Link to this message  By Harold Schwendeman - Sumner,WA on Tuesday, November 27, 2018 - 02:28 pm:

Seems like one look at a Ford factory drawing would answer that question Tony. The point from which the deck height is specified on the drawing would be obvious, and I'd bet that the deck height is referenced from the pan gasket surface and the crankshaft centerline which are no doubt shown on the drawing to be on exactly the same plane. The thing to remember is that that is probably only "theoretical", as the "actual" location of the crankshaft centerline on any one particular engine is determined by the final babbitt pour and final alignment boring of the main bearings, which no doubt varies at least a few thousandths from engine to engine, whereas the pan gasket surface would remain an actual "constant".

Not sure if that made sense or not, but I guess that I know what I meant by that, even if nobody else does,......(:^).....harold (:^)


Top of pagePrevious messageNext messageBottom of page Link to this message  By Donnie Brown North Central Arkansas on Tuesday, November 27, 2018 - 08:32 pm:

From a manufacturing/machining point of view, I would bet that "everything" is based from the pan gasket surface. I would also bet that it was the "first" surface that was machined. Then most everything else was "referenced" from that surface.

My KR Wilson Combination machine, uses the pan gasket surface as the point most everything bases off of.

Mark, Never really thought of it that way but I guess you are right. If the ring comes out the top then it was machined too far. and time to say "oh crap"

My machinest thought it would clean up with about .005, but for sure less than .010 . The surface was probably plenty good if I was using a stock head, or any aftermarket flat head. But the Rajo 4 valve is my driving force to make sure it is as flat and square as possible. The 4 valves have a history of blowing gaskets.

I had a discussion with the machinest. When working on model Ts the main objective is to "save iron" as much as possible.

In the last thirty years or so I have went thru three very good automotive machine shops. All because the owners retired and there was no one to take over. This machine shop has been in business since right after WW2. The owner of this shop was going to shut down 2 years ago because he was retiring. There was a young man working as a mechanic, that showed interest in taking over. So for the last two years he has been running the shop and doing all the work. I have heard nothing but good things about his work. So Im taking a chance and letting him do this job. It is pretty basic machining, but he really showed interest in doing it right, and the Model T engine fascinated him and the shop helper. He took me thru the shop and I see all kinds of tools to work on Modern engines, but I also saw lots of the "old stuff"

The other good thing is that the previous owner, still comes by the shop on a regular basis.

One thing we are now lacking in this area is someone who can turn Model T crankshafts properly. I plan on taking a couple diamond web crankshafts to him at a later date, and let him turn them for me. Then if he does a good job, Ill take the EE cranks to him :-). But he has to prove himself to me before he gets to touch my stash of EE cranks. Thanks for all the input ...


Top of pagePrevious messageNext messageBottom of page Link to this message  By Lyndon Moore on Wednesday, November 28, 2018 - 10:51 am:

Donnie, you have me curious. I have owned and run a machine shop for over 43 years. I have ground thousands of crankshafts in my life. From Ts, As, race cars, diesel cranks. Large and small. Your diesel and race car cranks all have a pretty good radius on them. I just take a radius gauge to see what they were cut at and set my radius dresser at that setting and dress the stone to shape. I am getting ready to grind a T crank for myself and I am curious if I am doing it correctly on my own engines. Is there something I need to know. I always cut my radius to match the original on any crankshaft. Is there something that you T guys prefer other than this? The last Model T crank I ground for one of my own, I cut at an 1/8th inch radius. I just got done offset grinding a 413 Chrysler crank cut down to Big Block Chevy journal with a 3/32 radius. This week, I just received a new Scat stroker T crank that just came off backorder. It shows to be cut with a 1/8th inch radius.
I guess you can say that Model Ts. Model As, and Flat head engines is what put me in business. Because when I was just a kid, it was just so complicated to get a valve job done on flat head engines that I traded a junk car for a valve grinder. Not knowing what I was doing, I just jumped into it. Then the boring bar was next. And then, as I started realizing that the big equipment. The crank grinder and balancer was going to be so much money that the only way to pay for it was to go into business for myself. I never really advertised for antique car work. Because modern engines were better money makers. But I still do one every now and then. I still do more flat head V-8 engines just because of the 8-n tractors. I grew tremendously in the 80s and 90s. I even put in a dyno room. Because sprint cars and late model race cars was thriving until the bottom fell out of everything. I sold the dyno about 10 years ago to some boys around eureka springs AR. Glad I did sell it when I did. No race tracks left up here.
I will remain in business as long as I maintain my health. I plan on playing with Model Ts and As a whole lot.
One more question. Did you know Leland Gibson from Piggott AR. He was one my best Model T and Model A friends. I really miss him. I used to go to Petit Jean every year with him when I was just a kid. I see his brother quite often. His brother says his wife still has all his stuff.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Terry Woods, Cibolo, Texas on Wednesday, November 28, 2018 - 11:24 am:

Donnie, Does that 4 valve Rajo, have that small of combustion chambers? I may have forgotten, but they looked nearly as big as a stock T head if I remember, correctly. If so, even using pop up high compression pistons that the vendors sell, should not cause you to have to run racing fuel in the engine. Maybe my mind id slipping.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Terry Woods, Cibolo, Texas on Wednesday, November 28, 2018 - 11:30 am:

" is slipping "


Top of pagePrevious messageNext messageBottom of page Link to this message  By Donnie Brown North Central Arkansas on Wednesday, November 28, 2018 - 08:19 pm:

Terry the combustion chamber is pretty big. Its intake valve is also very large. I do not think Ill have any issue with any interference. The combustion also should be low enough to run pump gas. Im not going for the "power" build. Im going for the "bling" build. So I want to keep things as close to stock compression as possible so it will last longer. here is a pic of the combustion chamber. The head gasket is a stock T gasket and not a proper Rajo 4 valve gasket.

1


Top of pagePrevious messageNext messageBottom of page Link to this message  By Seth in Alabama on Thursday, November 29, 2018 - 11:39 pm:

I think it'd get way too hard to hand crank long before you'd ever have to worry about running higher octane gas.

As for the head gasket - go to Olson's Gaskets. They supply all of the head gaskets for the Model T parts people. When they heard I had blown one of their head gaskets in my 4 valve Rajo, they supplied me with a new one that was improved over the older design AT NO COST TO ME. Won my business forever. They also upgraded and now make a fully copper clad head gasket for the 4 valve Rajo. I have one of those on my engine now and have had the head off and reinstalled it and still have had zero problems.

Next time I have it apart I'm gonna probably deck the head to help bump the compression up a little more. I already run the domed pistons. I figure some is good, more is better, and too much is just right.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Donnie Brown North Central Arkansas on Friday, November 30, 2018 - 12:28 am:

Seth, we are at opposite ends of the scale :-) You want more "zoom, zoom", and Im more "bling, bling". Good to hear about Olsons gaskets. I already have two original style head gaskets (with fire rings), and also a solid copper gasket. So I hope, Im good to go as to gaskets.

I will be e-mailing you soon. When I get the engine back together, you are my "go to" man as to Rajo 4 valves and also for my Columbo cross drive Bosch magneto. You may end up changing you e-mail address before I get the engine running. :-)


Top of pagePrevious messageNext messageBottom of page Link to this message  By Seth in Alabama on Sunday, December 02, 2018 - 12:01 pm:

Haha no way, I'm always happy to help. I'm excited for you to get that speedster up and running.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Wayne Sheldon, Grass Valley, CA on Sunday, December 02, 2018 - 04:48 pm:

The two of you could almost run down the road as a "before and after"!


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