When building heads that have been fully ported what are the advantages of going with 2.00 intake and 1.56 Exhaust over the stock 1.94-1.50 set-up?

Is the $100 in valves and $50 to cut for larger valves money well spent? Or would the $150 be better spent somewhere else?

 

It is only worth it if you pay to have extra porting done to take advantage of the larger valves. I had the larger size valves put in my older stock castings (Which were well ported already) a while back and the before/after flow results with minor porting and a nice valve job were very minimal.

Not work the $500 I paid!

DaveW

 

I was told by a couple of porters that the gain is pretty minimal...maybe 10hp.

I have decided not to go that route.

 

My heads were ported for 2.02/1.56 valves but the moron put in 2.02/1.60 valves and forgot to grind the exhaust vaqlve down to 1.56.

When I got my stroker built, my engine builder experimented with different valve sizes and found the best combination to be 2.02/1.515 for my heads. This combo had the least amount of turbulence and the highest velocity.

CFM numbers were where they should be for ported heads. Just the velocity was higher and the airflow smoother.

I'm not saying this setup is for everyone but it worked great on my heads.

He also said he saw a negligble gain going to bigger valves and didn't think it was worth it.

 

What about if your buying valves anyway? Can it be a bad idea to g ith the 2.00s or 1.55 in that case?

 

Depends on whether you're talking about an aftermarket valve that just happens to be stock size, or a stock valve.

Stock valves are garbage, we won't even work with them. If you're going to pay to have work done, you might as well put something decent in them.

 

I was looking to put Manley 2.00-1.56 Race Flo valves in. Have a competition 5 angle valve job done along with cutting for the valves. Price was qouted at $150 for the machine work. Along with another $40 to mill the heads and $50 for bench flow. Plus the $170 for the valves. Just this is going to put me at $480 for the heads plus the above = $990. Then if I need new guides, bronze will be $72. Plus another $400 for springs, ARP screw in Studs, and guide plates and 1.6 RR's. Puts me at a grand total of $1462.00. And if the heads flow 280+ and 190 + is this a deal?

 

Well i have a question too? i had my heads P/P and had 2.00 int/1.56 exh installed and better springs . This getting installed on a car with a blower producing anywhere from 6.5 to 7.5 psi will i notice a big diffrence in performance and rwhp with ths change...

 

Still undecided here...I'd like to hear more. Some say yay, some call me a moron for spending the money.

I'm going with a 383, larger cam (Specs unsure att), Ported heads, and long tubes.

Whatcha think?

Combinationmotorsports has www.sivalves.com Silverline's for $9.90 each.

Scoggin Dickey has Manley Race Flo's for $9.34 ea.

or, just keep 'em stock?

Shooting for ~450 ish fwhp.

 

We decided to go with stock size REV valves to maximize the velocity on stock bottom end. I was skeptical at first, but am now very happy.

 

I have never used after market valves that were stock diameter but as far as stock 1.94/1.50 valves and after market 2.00/1.56 valves (SI, REV, Manley, Ferrea, etc), there is about 10 cfm difference at .500 and .600 lift.

If you are gonna buy ANY aftermarket valves, I would get the 2.00/1.56's. If the $$$ is a concern, I would use the stock ones. Phil has used aftermarket stock diameter valves and has some GOOD flow #'s and HP #'s with them so they "might" flow "closer" to the 2.00/1.56 valve flow #'s. I have never got the same flow #'s but like I mentioned, all of the 1.94/1.50 valves that I have used have been stock GM valves and not aftermarket.

You can make GOOD power with stock valves so if you are on a budget, the $$$ saved here could probably be spent on better headers, better cam, TB, Dyno Tune, etc and give you more of an increase in performance for that $$$.

NightTrain66

 

SO whic SI are the ones to run in terms of budget perfomance and whats their best? Looking for a necked down valvestem.

 

I am not sure of the part # or 'series" but I have had alot of people buy the $10 ones from Combination Motorsports and they work fine. I would give them a call for more details at 702-798-8504

NightTrain66