ok let me have it, along with wat is on sig. i am going to upgrade to a 13.5:1 piston and was considering doing the valves while everything is apart. +1 over kibble's, is it worth it? Both intake and exhaust? this will be my final upgrade to this ride and i would like some input on the valve situation.

thanx

Yes it would be worth to do +1 intakes for the build you have now.

So what's the benefit of the +1 intakes anyway?

Builds more cylinder pressure..

So if you want lower compression, don't use 'em?

so after a couple of hours searching, i never really come up with an answer to weather i should just do the intake (+1) or both intake and exhaust..

let me know some thoughts.

heres the pro's:
- supposed to offer more airflow than the sock size valves
- umm thats about it
heres the con's:
- valve is heavier
- cost more to cut seat to fit
- does not flow more if the valve is not unshouded
- may cause piston to valve clearance issues if the piston is not flycut (only if needed...check clearances!)

do i think they are worth doing? not really. only way they are worth it is if it is done correctly...and most people dont know any better. the valve throat needs to be opened also.

hmm i c. so i may have to consider clearance problems if i go ahead and put my 13.5:1 piston in while i have it apart.

Yes, you'll need to clay check the piston to valve clearance...paying special attention to the outer edge of the valve.

Soooo, both intake and exhaust valves or just replace the intake?

you should be claying this process anyways. its not that big of issue. cp pistons have no problems with +1s that ive experienced or heard of. makeing sure its done right is key

some just went up for sale on the for sale board today..........

what i am asking is, performance wise, do i get both the intake and exhaust or just the intake?

If you are going to do one, then I would think that it would only make sense to do them both. If you do the intake only, and not the exhaust, you won't benefit any from the potential of getting that extra amount of air in there, if you can't get it out as well.
That is just my 2 cents though.

+1s all around, or even just one set, isn't gonna help you that much on a 434 engine. You'd be better off having the cylinderhead ported for a 434.

+1

That motor isnt big enough to benefit from both +1 int and +1 ex.

Port it. Forget the valve for now. 470s can use +1s all around pretty well. Some 450 combinations work well with +1s. Not worth it on the 434/440 combos.

The +1mm valves are going to flow more than stock. It's my understanding they better match (% wise) the IN port configuration. Whether your engine combo can utilize them is the question but I think not.
Larger displacement engines like a 470 big bore stroker like Normal pointed out will realise their benefit. Also if your always in the higher rpm with your 434 they may help.
The exhaust port needs more help in porting than the intake so if your considering larger valves, I'd do both IN & EX. My choice for valves would be ferrea due to their shape under the head. Of course the valve seat, transition blending and bowl area needs to be reworked correctly to take advantage of that.

+1's have valve shrouding issues since the combustion chamber is tight.
With a good port on stock valves and getting rid of the valve shrouding it will flow better than +1 valves.

On these motors you wouldnt see much if any gains unless its a massive engine build.
As said above the oversized valves will have issues with shrouding because of the combustion chamber, unless you cut a ton out of that head.

If you need an explanation on shrouding so you understand the flow problem, I can explain or you can just search "valve shrouding"