valves

Also my CID keeps going up each time I talk with them which in turn so does the cost. Originally was suppose to be a 4.155x5.5 and has turned into 4.31x5.56 which I'm not really crying about. How is the 5.56 stroke going to clear in an old 201 block? Am I going to have to pick that up also to do a little clearance work to save money? Lol

I'm just running farmall H rods

The 201 blocks are narrow, a few of the later 201 blocks were wide but they were marked #40 and maybe #38 but I can't rember right now.  Anyways the common blocks are going to be narrow above the mains.

Will a 5.56" stroke clear in them?  Depends on your rods and work to the rods.  I've used heavily cut Farmall H and 350 rods at 5.4" stroke and it doesn't fit.  With some block work it may fit but it's going to be marginal amount of cast left. 

I've used straight cap rods like the Buda rods to get there and wound up with about the same clearance issue. 

2" crankpin with the Buda rods and 2.29" with the offset cap Farmall rods.  I had one engine come through at 5.125" stroke and stock 226 Ac rods in the narrow 201 block and it just plain didn't fit well and the fella who built it ended up grinding through the side of the block.

With the later 201 blocks this won't be an issue but it is with the earlier ones.

Next thing to adress is the valves.  You're probably going to put a carbuerator on that flows little air and a manifold that moves slightly more then very little air.  So you're going to open a valve and give it enough "curtain area" that the air speed past the valve is very slow. 

Most guys I set up with an intake valve somewhere between 1.8 and 1.85" diameter.....this still moves more air than the carb and manifold is capeable of.  The reasonably stock and smaller engines I use a 1.7-1.75" intake valve.

Lets look at how the cylinder signal gets transfered to the carbuerator.  It goes past the intake valve through the head, manifold, throttle shaft and venturi to the inlet of the carb.  Despite what you may think, air is pushed into the engine from atmoshperic pressure and not "sucked" in by cylinder depression.  Sorry, that's the facts no matter what some hot rod nitwit thinks.  If you still don't beleve me explain why an engine makes more power at sea level than at 10,000 feet in relationship to air density and oxygen content.

We need to figure out what you are running for a carb, engine size and speed before we worry about the intake valve.  But I can tell you that to shoehorn a large valve in there there just isn't room to cut the bowl to proper angle so the bowl to seat transition is very efficient.  By the time the valve opens any amount there won't be any air speed past it.

It's all about getting your airflow matched to your engine, and at the right time.  It's not going to do much good to have a huge curtain area when the piston stops at the bottom and turns to come back up, you need air speed to charge that cylinder.  Think about the camshaft duration, lets just say 210* @ .050 on the intake lobe.  Timed at 105 ATDC intake centerline means that the intake valve is at half duration at 105 ATDC.  Well 105 ATDC timing with a duration of 210* means that there's only 75* of crank rotation left before BDC where things stop and go the other way.  There's 105* left on the cam...... so you are 30* ABDC coming back up on compression before that valve stops moving air.

Now of course these numbers are rough and for reference but pretty close to real world numbers for one of these engines.  You have a siamesed port meaning that there's some overlap of induction cycles on half the induction cycles of the engine.

Bottom line is air speed past the valve is your friend and big valves are not your friend.