I'm bored so I figured I would create this thread for those who are seeking to build a stroker motor out of an early 351w block. Feel free to add any additional info.
The first two years of the 351 windsor was '69 and '70. These blocks featured a deck height of 9.48" and are considered the strongest of all factory 351 windsor blocks. I've heard that they can handle 700+rwhp. The only problem with these blocks that I've encountered is their unique 9.48" deck height compared to all later 351w blocks that feature a 9.50" deck height. This requires careful selection when choosing a stroker combination. I've added up a list of stroker combinations that add up to or .005" less than the 9.48" deck height of the 69/70 blocks and thought I would share. Keep in mind that slight lower intake milling may also be required and headers may hang a fraction lower compared to later blocks.
Also, factory 351W blocks feature a very big 3.00" main journal. High rpms can be the enemy of these. If high rpms are desired, I would recommend a Dart block with Cleveland mains.
CHP 408 Kit 12360-030-ps-f408w
This kit consists of a 2" throw, 6.200" rod, and 1.280 piston. This combination adds up to 9.48. Any milling required of the deck surface of the the 69/70 blocks may cause the pistons the stick slightly out of the hole. I would use this kit with caution. Some custom 1.275 pistons would also be an option for this combo. 10.24 C/R w/58cc head
The good: Most cubic inches and highest compression ratio
The bad: Lowest rod ratio and no room for block surface milling
Optional 408 Kit
- 2" throw/6.125 rod/1.35 piston. This combination adds up to 9.475 which will give the builder room to deck the block if needed. However, CHP recommends running no less than a 6.200" rod with the 408 (4" stroke) crankshaft.
The good: Most cubic inches and fits in 69/70 block easily
The bad: Even worse rod ratio which is probably why CHP doesn't offer this in a kit
CHP 383 Kit 10676-030-ps-f383w
1.875" throw, 6.250 rod, and 1.35 piston. This combo adds up to 9.475. Gives 9.92 C/R w/58cc head.
The good: By far the highest rod ratio. Makes cylinder wall and piston skirt life easier than the others. Lowest compression ratio would make it the best choice for a boosted application (64cc head).
The bad: Least amount of cubes :
+ a 383 is a popular Chevy 350 stroker combo
CHP 393 Kit 10676-030-ps-f393w
1.925" throw, 6.200", and 1.35 piston. The combo adds up to 9.475. Gives a 10.16 compression ratio w/58cc head. This will probably be my kit of choice when the time comes. It's a good compromise between the 383 and 408 cubic inch wise, rod ratio wise, and compression ratio wise. It gives enough room for the block to be decked without too much issue while still offering a good boost in displacement. It is also the only one of these kits able to be internally balanced, which is always preferred.
So, make sure you do your research if you happen to own one of these fairly rare blocks. You don't want to order a 351w stroker kit and find your pistons sticking 0.020 out of the bore! Especially if you don't find it :O .
This is the end of my pointless rambling lol
The first two years of the 351 windsor was '69 and '70. These blocks featured a deck height of 9.48" and are considered the strongest of all factory 351 windsor blocks. I've heard that they can handle 700+rwhp. The only problem with these blocks that I've encountered is their unique 9.48" deck height compared to all later 351w blocks that feature a 9.50" deck height. This requires careful selection when choosing a stroker combination. I've added up a list of stroker combinations that add up to or .005" less than the 9.48" deck height of the 69/70 blocks and thought I would share. Keep in mind that slight lower intake milling may also be required and headers may hang a fraction lower compared to later blocks.
Also, factory 351W blocks feature a very big 3.00" main journal. High rpms can be the enemy of these. If high rpms are desired, I would recommend a Dart block with Cleveland mains.
CHP 408 Kit 12360-030-ps-f408w
This kit consists of a 2" throw, 6.200" rod, and 1.280 piston. This combination adds up to 9.48. Any milling required of the deck surface of the the 69/70 blocks may cause the pistons the stick slightly out of the hole. I would use this kit with caution. Some custom 1.275 pistons would also be an option for this combo. 10.24 C/R w/58cc head
The good: Most cubic inches and highest compression ratio
The bad: Lowest rod ratio and no room for block surface milling
Optional 408 Kit
- 2" throw/6.125 rod/1.35 piston. This combination adds up to 9.475 which will give the builder room to deck the block if needed. However, CHP recommends running no less than a 6.200" rod with the 408 (4" stroke) crankshaft.
The good: Most cubic inches and fits in 69/70 block easily
The bad: Even worse rod ratio which is probably why CHP doesn't offer this in a kit
CHP 383 Kit 10676-030-ps-f383w
1.875" throw, 6.250 rod, and 1.35 piston. This combo adds up to 9.475. Gives 9.92 C/R w/58cc head.
The good: By far the highest rod ratio. Makes cylinder wall and piston skirt life easier than the others. Lowest compression ratio would make it the best choice for a boosted application (64cc head).
The bad: Least amount of cubes :
+ a 383 is a popular Chevy 350 stroker combo CHP 393 Kit 10676-030-ps-f393w
1.925" throw, 6.200", and 1.35 piston. The combo adds up to 9.475. Gives a 10.16 compression ratio w/58cc head. This will probably be my kit of choice when the time comes. It's a good compromise between the 383 and 408 cubic inch wise, rod ratio wise, and compression ratio wise. It gives enough room for the block to be decked without too much issue while still offering a good boost in displacement. It is also the only one of these kits able to be internally balanced, which is always preferred.
So, make sure you do your research if you happen to own one of these fairly rare blocks. You don't want to order a 351w stroker kit and find your pistons sticking 0.020 out of the bore! Especially if you don't find it :O .
This is the end of my pointless rambling lol
. My machinist is a big 351w Ford guy and I seem to remember him blocking or re-routing some oil gallery plugs to help with oiling to the mains.
