I was thinking about stroking my block to 393 or 408 as a winter project. And getting a kit with forged parts for more strength on the bottom. Id like to use my stock block but I was looking on coasthigh.com whos kits were recommended by people on stangnet. They say 69-70 block extra care must be taken when machining/notching to make the kit fit. Should I be worried about this? Is it risky enuf to make it worth just getting a new block? If so will my old heads, headers, flywheel, waterpump, pulleys, balancer, etc. all be reusable on a newer 351w block??
The concern is with the lower end of the cylinders. On some of the '69-70 blocks the cylinders are a little extra long. So you may have to notch them a bit more than expected to clear the con rods. It's the same amount of clearance all blocks need, but it just looks like more. I wouldn't hesitate to use your block if it's in good conditions. Your current flywheel and balancer may or may not work. Some kits use a
28oz balance, and some kits use a 50oz balance. I forget what the stock '69 balance is, though. Ask the kit maker if it will work. If they don't, you'll just need to replace the flywheel and balancer to match. All the other components will work just fine. The external dimensions won't change. You really need to reconsider using the stock heads. The stock '69 4V heads are pretty good - by '69 standards. By today's standards, they stink. Add another
55 cubic inches, and they get a lot worse.
I'd get the 393 since you'll save money. The only non-stock part is the crank. You use stock 351W rods and dished 302 pistons.
They are who I bought my crank from. Check this out...
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Well there are 3 different deck heights for the 351 (not counting the Cleveland) 9.48" for '69, 9.503" for '70+, and 9.20" for the SVO blocks. AFAIK, regarding the 69-70 Windsor the blocks are different, but the heads were the same. It's up to you if you want to worry about the .023" difference between the 69 block and the more numerous 70+ blocks. It could matter when it comes to assembled height of the crank/rod/piston and clearance to the valves and how wild a cam you run and rocker ratio.
The other thing that had to be done to the bottom end was some slight notching, but also a few strategically placed outward "dents" in the oil pan for clearance. Make sure you mock it up before final assembly to make sure everything clears.
Yes! I'm using a D9 block with C0OE heads. Everything else that bolted onto the original '69 block will bolt on. In fact I swapped a few parts off the C6 289 that was in my Ranchero onto the D9 block. They didn't stay there long, but they all worked fine. You will HAVE to have it balanced or the engine WILL scatter itself in short order. You should have seen the flywheel before we dropped the motor in. I've never seen so much weight on one side of a flywheel before. sheesh!
The CHP kits he's talking about will work. '69 351 was 28oz balance, just like the 302 and 289. Everything will HAVE to be balanced (balancer, flywheel, pistons, rods, crankshaft) since the stroker throws everything out of whack. My flywheel had so much weight on it it was scary.
I'm running D0 cast iron heads and getting 372 lb/ft torque and 288hp with them, and that's at 5280' in Denver. Those peak numbers are separated by only 350rpm and both below 4500rpm. Not bad for 35 year old iron technology at a mile high. Although I'm bolting on a set of GT-40X heads ASAP. At sea level I'll be looking at the 450 range for both HP and torque, though the RPM's climb a bit ;)
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