Y Block Heads Oversize Intake Valves

noswal

here's pic of my late C1TE stock head.

putting 1.92's over 1.84's in adds another .040" of RADIUS!

in plain language 40 thousandths all the way around.

that's 2 matchbook covers thick.

yep! looks like it'll be tight!:)

i'll get a 1.92 valve and stick a plug in later and see how it works.

to test it it's not necessary to machine valve seat.

that's job #2023 with this y block!

have a nice day!
 

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When your valve head grows and comes up close to an obstruction like the spark plug boss, that area of the open valve is " shrouded ", meaning the flow through that area of valve opening is compromised by the obstruction, basically negating any advantage you've gained by the bigger valve.
 
street dreams

that area next to the plug boss is

1/16th of the total around the valve.

the flow overall will improve.

the thing to do is dummy fit the 1.92 in there

to check if it will fit without grinding boss too much.

if it does need a little grinding hopefully

it won't effect strength of boss.

have a nice day!
 
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Put a plug in there and open the valve up to make sure it don't hit the end of the plug before you spend any money having those things hogged out for 1.92 valves. Been there. Older heads will take the 1.92, but C0 and C1 heads won't unless you use a plug that is recessed into the boss.
 
master cylinder

sounds like you're flat subtracting that,

that would be off, some air will get through that section.

that little bit of valve 'circumference'

being 'shrouded' by the spark plug boss

will be made up for by larger 1.92" valve.

that's a pretty big gain going from 1.64" to

1.92" intake valve!:)

will give a report about valve bonking into spark plug.

have a nice day!
 
noswal

here's pic of my late C1TE stock head.

putting 1.92's over 1.84's in adds another .040" of RADIUS!

that's a pretty big gain going from 1.64" to

1.92" intake valve!

You were comparing it to a 1.84, not 1.64. Besides I did state I figured the circumference MATHMATICALLY, using your numbers, not actual flow.

I doubt you would see too much gain on your so called "Racing Engine" without hogging out the ports and milling the heads and block to raise compression also.
 
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noswal

since you say a 1.92" intake valve will hit

i'm not going to spend $10 on a new valve

to test this, i'll wait until i run across a used one. :)

anyhow, looked at the F11YC Champions that

were in this thing and looks like the only thing

that sticks out is electrode, but i believe you.

looked up CO heads and they are '60s 292 & 312, are you

saying these two, CT & CO, have the spark plug boss?

have a nice day!
 
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