Please tell me what would happen in terms of street drivability and horsepower by replacing the stock size intake 2.04" and exaust 1.71" valves in my 2V heads with 4V valves (2.19" intake) (1.71" exaust)

Would it be worth doing? or just a waste of time/money?

Building up my 400M a little.......

Bored .040 over
Silvolite reverse dome pistons
Block decked .010
High energy 268 CompCam kit
Weiand Action Plus 4-BBL manifold
650 CFM Holly 4-BBL

 

Bigger valves are going to give you the ability to pull more A/F in to combustion chamber and produce more horsepower without the disadvantage of the bigger intake ports which can rob you of low end torque. Here's a link with the specs for a stock 2V (M) head and one with the bigger valves.
[link:www.waldens.com/waldens/351heads.htm|Waldens]

I haven't run the numbers on DD2K with the bigger valves but I would anticipate a larger torque number as well as higher horsepower.

 

Just a suggestion; if you aren't going to do any mods on the ports when you install the valves, use the 2.09" big-block intakes and the 4V 1.71" exhaust valves. Those heads need more help on the exhaust side than the intake.

 

 

depending on the year of your heads,it might help or it might be a waste of time. 75 and later the exhaust side is so restricted i'm suprised they run. here's a link-see what you think
http://users.abilene.com/~dkelly/hotrod/newmotor2.html
if yours are 75 or later, just swapping to earlier heads will be a big improvement, then if you do the valves, woooee. by the way, how does that cam run for you?

 

ok some quick play testing with my stock config setup


stock

227hp@ 4000 361tq@ 2000, but had 298tq@ 4000

exhaust to 1.71

229hp@ 4000 362tq@ 2000, but had 301tq@ 4000

intake to 2.09, exhaust at 1.71

231hp@ 4000 362tq@ 2000, but had 304tq@ 4000

intake to 2.19, exhaust at 1.71

235hp@ 4000 361tq@ 2-3k, but had 308tq@ 4000

got silly 2.25 (boss 302 intake, 1.75 429-460 exhaust)

239hp@ 4000 364tq@ 3000, but had 314tq@ 4000

 

I haven't fired her up yet.....From what I have read, should be great as long as I keep the static compression ratio under 9.2 Any higher would work against the cam.

I'll let you know in a couple of months