After deciding to stick with the Y block for my custom 300 hot rod build I meet with my engine builder to see what we could come up for a stroker. Here is what he came up and I want to run it past you Y block guys and see what you think. I have a complete 40 over 312 or a std bore 59' 292 to start with. Here is the rotating assembly forged 283 SBC std piston 3.875, eagle rods 6.125" with SBC pin dia and Honda 1.889 rod journal, offset grind the 312 crank to 3.727 stroke grind the rod journals to 1.889 (grind the 312 mains to std 292 if we use the 292 block).Compression height based on the 283 pin location should yield slightly over 10.1 with Mummerts 60cc aluminum head. From everything I have read this combination should work. The bore size of 3.875 (125 over 292) has me a bit worried. What do you Y block guys think, can a 351 Y block be built with these off the shelf parts?
Ted Eaton's 375ci Y-block in the Engine Masters used a 3.84" bore. 536.6HP and 507.7 lb-ft of torque These old girls are now coming into their own with advances and are definitely worthy of $$ injection
I'd be more concerned with the small rod journals on the stock cast crank; the Y-block cranks were known for breaking occasionally on stock motors (I had one break into five pieces while cruising at 50 mph with no warning). Maybe with a steel or billet crank.... although I'd ask before committing. Ted Eaton used a moldex billet steel crank. At to the bore size, .125 over shouldn't be a stretch, although it wouldn't hurt to sonic check it beforehand to make sure there's no core shift. I heard of these being punched as much .160 over 'back in the day'...
Question? Why wouldn't you use an FE? From what little I know it should fit the car you have. With a couple of carbs and some chrome look just as good or better. And be a lot more reliable for a lot less money. And if you ever wanted to go to the big FE race and show at Beaver Springs Drag-way, you could.
To answer the question of why I didn't use an FE motor. I went with the Y block for a few reasons. One, the Y block engine is what the car came with from the factory and I like that. Two, I think the Y block is a great engine when built properly and it has a exhaust tune like no other. Third, I didn't want my car to be like everyone else's car with an FE sitting in the frame rails, when is the last time you heard a big inch lopey camed up Y block? Yes the FE will make more torque/hp all day long but it will never be a Y block.
i would just build the 312.....at .040 it will be around 320" - are the extra 30 cubes really worth the expense on this build? think of the difference between a 327 and 350 chevy......not much difference perf wise when built the same way. also, will the valve reliefs be right on the chevy pistons?
As I remember, 344 was the biggest that Y blocks got to in the old days. Mostly guys started with a 292 block and ground the 312 mains to fit. 312 engines seemed to crack between the main bolts and main bearing bores. 292 had more iron there.
Grinding the rod journal size to 1.889 is a concern I have with the cast crankshaft especially spinning it over 5000 rpm. Most of the cams that will work best with this build and give me the lopey idle that I want are 280-292 duration which puts the rpm past 5k. I did check with SCAT yesterday on there upcoming y block crankshafts. They have moved it back yet another year. Their custom crank is $3000-$3500 right now. Moldex quoted me a billet crank $2750-$3000 and a much shorter lead time. In the grand scheme of things the billet crankshaft may be worth it just for piece of mind alone. Does anyone know where the common failure point is on the Y block crank?
Weren't those y-block strokers using some oddball connecting rods like from a Honda civic or something along that line?
They run a 1.889 Honda rod journal size, not an actual Honda rod, to clear the cam lobes if I understand it correctly. I think the y block runs a 2.100 rod journal in stock form.
When you offset grind any crank, you move the oil holes away from the center of the journal. Watch that the oil hole wouldn't be clear out by the cheek with that much offset grinding. I would just turn the 312 crank down to fit in the 292 block and add the heads and a good intake. On a street car you won't know the difference anyway.
Having built 2 stoker y blocks, a 292/312 offset ground crank for 320 CID, and a 312 offset ground for 340 CID, a couple thoughts. Sonic check the block. My 292 wouldn't go as far over as I wished, and the 312 block got one bore a little off center to pick up some wall thickness on one cylinder. It's a never turned/not scratched 312 crank with 2" rod bearings. Had to clearance the cam. This was the kit J Mummert was using in 2006 or so. Doing it again, I'd use a 292 rather than a 312 block. Easier to find one with no core shift, and better rear main seal options. You need to look close at the piston tops with the aluminum heads. It's easy to not allow enough quench area when you start into 10:1 territory. Made that mistake myself.
Good info, can you divulge a bit deeper on the quench area. Are you saying not to zero deck the block?
I typically do not offset grind the factory cast Y cranks any smaller than a 2" journal and even then I keep the journal widths to no more than 1.810". I then narrow the aftermarket rods accordingly and use the readily available narrowed rod bearings. Pushing the journal widths wider or the journal diameters smaller gets you into the oil holes at the filets of the crankshaft journals. As a general rule, 3.600" stroke on the 312 cranks with 2" journals and 3.480" stroke on the 292 cranks with the same 2" journals assuming you're starting off with standard sized cranks. As far as boring the blocks ..... Sonic test, sonic test, sonic test!!!! I've had some early 272 blocks that will bore out to a usable 4" bore and 312 blocks that were dangerously thin at standard bore. Core shift in the cylinder areas must be checked for and this pertains to all engines, not just Ford Y's. Ted Eaton.
I looks like the consensus is: even though the 351 Y is mathematically (physically) possible with a factory 312 crank. The method to get there could add up to a weak crankshaft with oiling issues at the rod end. I am glad that I posted this thread to get some real world opinions and confirm some of my worries. I think I am money ahead to purchase the 334" kit for a 292 block from Mummert.
Late 292s benefited from better casting less core shift. The blocks that had the road draft location cast over are the ones to look for. In the late 60s I ran a 292 bored to 3.9062 and used 301 Plymouth pistons with a 239 crank for many miles. Now I would sonic test to go that far.
49club, you'd be better off asking Ted or John, (among others) as my knowledge about proper quench is limited. But based on the looks of the piston tops, which are 0 deck and flat, I had pretty poor flame travel on the upper part of the piston. At 320 CID and 0 deck, John's heads put me over 10:1, close to 10.5. Ignition advance gets to be a problem. Starting from scratch, I'd talk to the experts, and probably end up with a dome piston down in the hole some. As it was, we used a heat coating on the piston tops, and a custom ground cam to get the dynamic ratio down to 8.5. Runs good, but probably gave up some hp.
Ted Eaton has been kind enough to give up some of his time this week and speak with me on the phone a few times about what I would like to build, what works, and what doesn't work. Grinding a stock 312 crank to 1.889 Honda rod journals defenitly isn't going to work, unless I want to build a bomb out of my motor. I have read and re-read every article that he has on his site regarding Y blocks. If you are interested in learning what makes a Y block tick it's a must read. He has built numerous 330" Y blocks that run extremely hard. I was especially impressed with the 318" he built that pulled 429hp and 388 ft/lb all on pump gas. After listening while taking notes as fast as I could. The 330" rotating assembly with his recommended 242/242 @ .50 cam and all the other go fast parts sounds like a much better plan than the 351 my local guy came up with. Ted is booked up for quite some time but I am really debating on just having him build the motor when and if he has time down the road. Who better to build a stroker Y block than the master himself! It's a 2800 round trip for me but I think it's worth the extra expense just to know it's done right and shake the hand of the man himself.
49club, you've just made the right choice. I've never met Ted, only spoken with him, but he was kind enough to run my FPA headers on the dyno motor and post the results, and gave me great information on selecting a cam in the situation I mentioned above. Not to mention his proven building skills.
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