Rebuilding my Flathead random questions
 

I am rebuilding my first Flathead. Please don’t tell me to leave it up to the pros. That's boring and there are none around me. Anyway, below are the specs and my first question as I start to put this together. I will use this thread for the random questions I have along the way rather than starting a new thread every time.

Car
40 coupe, stock drivetrain, upgraded brakes and suspension.

Engine Specs
40 block
4” crank
3 3/16 pistons (stroked crank taken into account)
8ba rods
Isky max 1 cam
Adjustable lifters with holes drilled for adjusting
Edelbrock aluminum heads
Dual 97’s on an edmunds intake

My first question is, is it ok to use the steel crank gear up against an aluminum cam gear? Somewhere I read this was not ok? Please confirm.

Re: Rebuilding my Flathead random questions
 

French motors use steel crank gear and aluminium cam wheels. So I would say it is ok.

Re: Rebuilding my Flathead random questions
 

Regarding the gears. yes it is absolutely OK to use. Unless you want to get a specially made gear set, your choices are steel crank and aluminum or fiber cam gear.

If you haven't already, I would strongly urge you to get the block completely checked out by you or someone who knows what to look for before you proceed.

By checked out, I mean:

1) Completely cleaned and the water jackets cleaned off all crud
2) Pressure tested. If it passes pressure testing, move to set three.
3) Magnifluxed

Until you do these three things to the block, there is no guarantee the block is good and you could be spending a lot of time, effort and money for naught.

Re: Rebuilding my Flathead random questions
 

Yep. I did these things. There is a trusted machine shop around me that did all of the machine work and testing. They just don’t assemble them. Only machine work.

Re: Rebuilding my Flathead random questions
 

drill for adjustable lifter, use them. check for clearance on the crank to block-area outside block rails-sometimes you will need a little relief there

Re: Rebuilding my Flathead random questions
 

First, I'd like to know the application of the engine and car. Why the cam. why the carbs. And the factory used the aluminum cam gear on the cast iron crank gear. Do you have all these parts now?? Youmight be better off with a 59 block. You;ll have many more questions befor you finish.
Gramps

Re: Rebuilding my Flathead random questions
 

Ford used fiber cam gears with steel crank gears without any problems.
My 1953 Ford V-8 still uses them both.

Re: Rebuilding my Flathead random questions
 

Yep. Did that too (drilled for lifter).

Re: Rebuilding my Flathead random questions
 

40 coupe. I used this block because I believe it to be original to car. Came up with that combo after lots of research after I randomly happened upon a non ground mercury crank (for basically free) so decided to build something a little peppier than stock.

I’ll have hundreds of questions. Most which will be answered by searching internet. The ones I can’t find I’ll come here. I’m not afraid to ask!

Re: Rebuilding my Flathead random questions
 

OK, good news.

Re: Rebuilding my Flathead random questions
 

If using the 4" merc crank, I would also use some 8ba rods since you have 2 oil holes per journal, and the bearings are cheaper and easier to deal with. Merc crank needs merc pistons too, if you didn't know that.

Re: Rebuilding my Flathead random questions
 

Also, be aware that some 8BA rods have squirt holes and some do not. The early 8BA's used the splash system of oiling and didn't have the holes. Later 8BA's did.

Re: Rebuilding my Flathead random questions
 

Oh yeah, I’m using 8ba rods. I updated my original post (and will do so as people mention things I forgot to say).

Also using correct pistons as recommended by van pelt. When I ordered months ago we actually had to correct that before shipping so I know we discussed it. Will post photos of rods later today.

I should also note that my machine shop would not do any machine work until I had all parts ordered and in their hands, including bearings, rods, pistons, etc. They wanted to have them on hand to make sure they would work with the machine work they were doing. They told me what sizes to buy after initial inspection then I bought from van pelt then the machine shop did the work.

Re: Rebuilding my Flathead random questions
 

Just an FYI...Before beginning assembly, check to make sure the rear cam bearing is lined up so the fuel pump pushrod will go by it and not hang up on the edge. Happens a lot!


Terry

Re: Rebuilding my Flathead random questions
 

Good point. Do you mean the hole of the bearing not being centered over the hole in the block? The bearing was centered perfect over the hole as far as I remember. I remember looking at it because someone else mentioned that to me recently. There was no bearing overhanging the hole but I will verify next time I unwrap the plastic that keeps it clean between sessions.

Re: Rebuilding my Flathead random questions
 

The hole through the rear cam bearing that the fuel pump push rod drops down through. I got that off just a bit on a recent assembly (it looked ok, but push rod wouldn't assemble). Didn't want to disassemble everything, got lucky and my friends were able to use an old cam bearing and a small port-a-power between the engine stand and the rear of the motor to ease the cam bearing forward on the assembled engine. I don't recommend going through all that.

Re: Rebuilding my Flathead random questions
 

Clever, but nerve-wracking :)

Re: Rebuilding my Flathead random questions
 

It sounds like you're gonna do a real good job. Fun, ain't it?

Re: Rebuilding my Flathead random questions
 

Do you have the more modern rear seal plates? Your engine probably came with what are known as labyrinth seals in the rear mains. You'll want to replace the stock seals with the later seal plates and rope or graphite seals. You can chat with VanPelt about this. I'd run the GraphTite gasket kit - with the composite head gaskets (not the copper ones). Also, pay particular attention to the instructions for the rear main seal - and the installation of the "roll-pin" to keep their seals from potentially spinning.

Also, make sure that when you test fit the replacement seal plates that they DO NOT stick up above the deck or ream main surface. I've had to trim some of them on my mill - to make sure the rear main cap would seat all the way down.

I'd replace the 1940 oil pump with the later 49-53 pump and buy the special bolt-on pickup from Speedway. Also, stretch the front oil-pressure relief spring about 1/4 to 3/8" so that the new pump's pressure relief spring/plunger becomes the "boss".

Best of luck!

Re: Rebuilding my Flathead random questions
 

Here is an example of a conversion kit for the mains - from Reds. VanPelt will probably have the same thing - at a better price:

https://reds-vintage-parts.com/store...e-1936-to-1942