200 and 250 cams interchange?
- Thread starter jamyers
- Start date
The 1969 250 came out, and Ford started playing with cam profiles. After 1972, all cams were similar 'scolloped' to suit. So there is no problem fitting aftermarket cams if they are made after 1972.
As for stoker 200's using a later cam, its possible if you do the measurements. There are Aussie Holden XT5 Rods 5.25" long with 1.9" crank pins, you could get a 3.35" stroke. The change in crankpin diameter is 224 thou, and if your machinist is very accurate, that's a 224 thou strok increase. The rod ratio is 1.56:1 with that combo.
With 40 thou over 1.04" deck Iapel or custom Ross pistons, you would then need a 200 thou thick steel gasket to raise the deck height to make the pistons fit in the block. That is 218 cubic inches from an engine that had 199.5 cubic inches to start with. You would have to run custom pushrods to suit, and make certain the top ring lands were 25 thou away from the top of the block.
The 200 block is the shallowest in the business, and it makes it the hardest of all engines to stroke. It has a poor rod ratio to start with, and it's only got six cylinders to increase stroke on. Just a stroke increase alone of 224 thou on a 6 gives a 7.1% capacity increase as it does on a 302, but theres a lot more cubes with a 7.1% capacity increase on a V8.
In 1968, both Australia and Argentina stroked the 200 to 221 cubes by adding 660 thou to the depth of the block. Same with the 2.3 HSC engine in the Ford Tempo...it was a cut-down 3.3 engine with a 660 thou taller deck.
As for stoker 200's using a later cam, its possible if you do the measurements. There are Aussie Holden XT5 Rods 5.25" long with 1.9" crank pins, you could get a 3.35" stroke. The change in crankpin diameter is 224 thou, and if your machinist is very accurate, that's a 224 thou strok increase. The rod ratio is 1.56:1 with that combo.
With 40 thou over 1.04" deck Iapel or custom Ross pistons, you would then need a 200 thou thick steel gasket to raise the deck height to make the pistons fit in the block. That is 218 cubic inches from an engine that had 199.5 cubic inches to start with. You would have to run custom pushrods to suit, and make certain the top ring lands were 25 thou away from the top of the block.
The 200 block is the shallowest in the business, and it makes it the hardest of all engines to stroke. It has a poor rod ratio to start with, and it's only got six cylinders to increase stroke on. Just a stroke increase alone of 224 thou on a 6 gives a 7.1% capacity increase as it does on a 302, but theres a lot more cubes with a 7.1% capacity increase on a V8.
In 1968, both Australia and Argentina stroked the 200 to 221 cubes by adding 660 thou to the depth of the block. Same with the 2.3 HSC engine in the Ford Tempo...it was a cut-down 3.3 engine with a 660 thou taller deck.
