I am having my head rebuilt and ported and was wondering if I should go with oversized intake valves? I am currently running the stock cam (may change) and am wondering IF I will run into any issues with going to a oversized valve or not...

If everything should be A-OK going oversized then what size should I use and what kind should I get?

 

i wish i had put oversize valves in i could have got custom valves made cheap than new oe ones . yeh if you have the time go big

 

Depending on the lift and cam overlap with piston dish size you might have clearance problems. But if you have stock pistons and valve lift then bigger valves similar to the '89 2.7 heads would work fine.
Just be carefull of aftermarket pistons with large valves and high lift cams could mean interferance!

 

The car is internally all stock.

I went from "well maybe I should have it decked and hecked out"

to "well maybe I will port it while the engine is out of the car..."

to "maybe oversized is the way to go since im ALREADY porting it"

I have plenty of time and a internally stock car to work with.

for now cam WILL stay the same and so will rods/pistons. Just need to know what size valves I can go with and where I can get them. Or should I have my machinist make them? he is already doing a valve job for me...

 

Talk to Dave at Custom Engineered Performance

Link

tell him you're exact needs, he will consult and built it for you.

 

Ditto on Dave @ CEP.

 

price will br around $2000 right?

I have a guy here that does lots of machining for our shop and he can do full rebuild/valve job/port for $1200. thats about all I want to spend except for the vavles....

If anyone has info on size and places to buy larger valves then please post!!!

thanks for your help so far guys!

 

If you have someone with a solid track record, someone you "trust" to do the head for you, go for the big-valves. Replacing the valves with larger ones (48mm+) require new seats and lots of porting. Lots of tricks to make the head flow good. Again, be aware what you get yourself into, there is nothing as bad as spending lots of money on a head that does not perform or worst yet one that self destructs. When upgrading to larger valves, it makes no sense not to upgrade the cam as well!
If you stay with 9mm valve stems, the factory 2.7L valves are your only choice (expensive). You can go to custom valves (non 9mm), but then you are replacing other hardware and the price goes up.
"some" of the larger size valves are heavier than the factory valves, so you need to look into the rest of the valve train.
If you are on a budget, you will be better off keeping the stock size valves. Get a radius cut seat and mild porting.

 

ok maybe I will just stay with the stock valves and have him do the valve job and mild port (or as large as you cna SAFELY go with the stock valves.

BTW: anyone have any guesses as to what kind of power increase a mild port will give?

 

standard valves are outragously expensive if they are damaged it will cost very little more to upgrade to +1 valves in and if they are just plus 1 there are no issues at all they can be blended in with the valve seat cutting gear .there is a strait up benifit of bigger valves the ports are a good shape do the curtain area calculations .
But if your standard valves are ok your money is better spent on portjob or atmo grind cam . any how you should stop right right were you are there is a big valve ported head in the rennlist clasifieds at the moment cheaper than doing your own

 

I stayed with stock valves and regret it.

 

me too

 

I absolutely agree that larger intake valves, ported and matched heads to extrude honed intakes is a great way to make at least 40 more horsepower in our motors! And it decreases the lag time on the force fed units.