hey
i think i might have bent a valve on my restoration project. so this means i get to take off my heads!!!
im just looking for some cheap performance so im wondering how much can i enlarge my valves w/o modifying the combustion chamber. i was wondering if 1.94 1.60 would work.
thanks

 

No, in order to use larger valves, seats need to be istalled...not really a combustion chamber mod, so to speak, but a bit of time/$$ at the shop.

Also, I don't know if you can run 1.6's in the exhaust either.

Bottom line, IMHO, is once you start thinking about having larger valves installed in stock heads, and working them over to get a benefit, you should start comparing cost to what you can buy aftermarket off the shelf, that already will out perform all the money you've spent.

 

thanks i might just look for aftermarket heads

 

New seats do not need to be installed. You will need a new valve job. The shop will grind a new larger seat for the new valves right on the existing hardened seats.

You want to go to 1.94 intakes and stay with 1.50" exhausts for a 305. The combustion chamber wall near the intake valve will only have to be layed back a bit just to clear the new larger valve. Since you bent a valve you'll need all new valves any ways. You will want to have the shop do a clean up cut of the head's decks to ensure a straight deck for the reinstall anyways which will restore any difference in the new chamber. Don't sweat the small stuff.
Don;t forget the porting.

 

ok that sounds good, so let me just get this right, all i need is a valvejob, but just get them worked to 1.94, 1.50.
do you have any idea of a ballpark price
thanks alot for the info

 

o and me and my brother priced a valvejob for a 305 TBI we rebuilt and i think it was like $175. do u think that resizing the valves will jack up the price

 

Well, I'd have new exhaust seats installed, maybe I've gotten a line from my shop over the years, but they tell me the hardening doesn't stand up to recuts...do a bit more searching around...if you need new exhaust seats, add another 100 or so.

Figure a set of valve or having your reground will set you back 150 or so, then add cost/labor for guides if needed, milling/surfacing at thye least...before you start the job, you'll have hottanking cost involved, maybe (should) have the heads magnafluxed.

After all the above you're into it for 300-400 bucks...add another 100 to that cost and you have a set of aftermarket iron heads that flow better than what you have.

My 13.3 cents worth.