Richie's Mk1 Restoration

[Lynn Eades]

Your motor is 3 3/16 (Merc 3 3/16 = 3.1875") and about .030" os. You can get os pistons out to about .080" os. state side. apparently they will normally go out to about this oversize.

[RichardT10829]

cheers so with this being an early one (with the drain holes in the base where it bolts to the sump) does that mean its the 100hp unit ?

[ajmac]

Going by your bore dimensions it's the post 1939 24 stud '100hp' that's the 239CI 3.9Litre also known as the 'Merc'. According to the parts books Ford US and possibly Canada manufactured the 24 stud as an 85Bhp (3.6Litre) and also as the 100Bhp (3.9Litre), the 3.9 being introduced in 1939 for the Mercury car range hence the 'Merc' tag. From what I gather there was a tweek on the CR at some point which had the names changed from 85Bhp to 90Bhp and the 95Bhp to 100Bhp. That was for US, I'm not sure what happened in the UK or Canada. I've got a nice period engineering journal report on the 'all new' 24 stud of 1939 which I picked up in the US, I'll get is scanned in and posted.

[RichardT10829]

Thanks Alistair it is appreciated..... got the block totally stripped out now but iam going to need 3 helicoils done for snapped studs i cannot beleive the studs go through the deck into the water jacket !!! i highly recomend folks replace the head studs on a rebuild unless it is known that the ones in the block are ok.... the threads were pulled on most of mine and i know i keep saying this, but the studs themselves are like toffee !!!!

[George McKenzie]

If you have the Mecury engine you won't be disapointed .The extra horse power makes it a different carrier to drive .Jim DeBock told me that the way to tell if it is a Murcury is that there is a small knob on the crank through . I have the factory parts manual for these engines if you need some pictures . Trivia ?? How many carriers can you restore in a liftime ? It would be interesting to keep a record of the time one spends doing one .

[RichardT10829]

George if you could post up pics it would be appreciated... looking at other Merc blocks of the era they seem to have a triangle hole and two circle holes in the block where as mine is a triangle, a circle, and a trapezoid.... this is so confusing ! is it possible to use a merc crank and rods in a ford block and vise versa ?

[Lynn Eades]

Yes you can use the Mercury crank in the ford block. The Merc. has a 4.0" throw, so the piston height is different. If you have one you are lucky. Ford throw is 3 3/4"
The water holes at the centre of the blocks changed shape at times and is a way of identifying the year of production.
Alistair, I have heard (not substantiated) that the "increase in the H.p. was to do more with the increased octane rating of the available fuel, than any particular improvement of any engine component.
The merc crank has a circle cast into the front counterweight, and has a larger gallery plug in the front big end drilling ( Merc=5/8" plug. Ford= 3/8" plug)
There is a lot of info available on the web.