valving question, looking for more flow

[stumpy]

searching the archives hasnt helped much, maybe i am not being specific enough-


i would like to put larger valves in a 3FE head. i saw one mention of 1.84/1.50 chevy valves being easy to get in with minor machining. i cant find a good source on these valves, or what the original application is. anyone have some more of the specifics? or anybody have a better idea? know where i can find the stock valve sizes?


TIA

 

[zebrabeefj40]

The machine shop doing the work will have several sources including good used for those valves. For best results you might go chat with your machine shop. The owner of the motor shop I used to work for did all kinds of wacky stuff like this for his customers. Find the right shop/shop owner and see what they say.

HTH,
Nick

 

[FJ40Jim]

IIRC the stock valve sizes are appx 1.48/1.81 w/ 8mm stem.
Lo-perf SBC parts are 1.50/1.84 w/ 11/32" stem.

Let the machineshop deal with it, that's why they get paid the big bucks.

 

[andrewfarmer]

i would like to put larger valves in a 3FE head. TIA

Why?

There are a lot of better things to do to it...

 

[FJ40Jim]

Why?
There are a lot of better things to do to it...

Several reasons:
- to get into new material in the guide without the hassle and expense of pressing in new Toyota guides.
- increased durability of larger diameter stems.
- to get into new seat material without the hassle & expense of pressing in new Toyota seats.
- increased durability of stainless valves
- requires new springs, so automatically comes w/ benefit of all new springs for much less $$ than OEM.
- slightly larger valve head gives slight performance/efficiency increase, without going so big that low speed torque starts to drop off.
- on the 3FE, replacing the dished OE valves w/ flatface SBC valve increases the CR about 1/2point, from 8.1 to 8.5, for a slight performance/efficiency increase.

All for now....

 

[stumpy]

Why?

There are a lot of better things to do to it...

and what other things are you thinking of? i am going to do a 2F block, balance, port and polish heads, header, and maybe HPC coatings on the pistons, chambers, and exhaust valves. anything else?

thanks for the numers jim. noted. off to the machine shop.