Head porters whats the difference between Manley pro-flo valves and Manley street-flo valves. The description is the same except for material. Street-flo's are lighter. Frank95z

They are the same shape and will flow equally. The Racemaster valves (which include the Pro Flo) are stronger and more heat resistant. As Manley's catalog says "Designed for the enthusiast preparing a stock or mildly modified street engine, or a bracket
racer seeking maximum value for his dollar, the Manley Street Master valves are the perfect choice." The Race Master series is "is targeted at the bracket, drag and oval track racers operating below 8,000rpm".

If you have mild mods, go with the Street Master", if it's highly modified, the Race Master.

Rich Krause

I went with the Racemaster proflo's because I may be using high valve spring pressure and thought they may be stronger. Does that sound out of line to you. Frank95z

Stronger springs probably don't have much to do with needing a better valve. It's high output/high rpm use that does. But I wouldn't use the Street Master except as a stock replacement. The Race Master is the way to go.

Rich Krause

Frank, are you still using "stock castings" with a stock style 2 angle valve job? That 10 second barrier is getting oh - so - close to you now! Your times are astounding! Those heads are not decked either right?

Everyone I talked to said to get the pro-flo's because they're stronger, even if they are a bit heavier.

I do believe that I have the Race Flos and that they are necked down to decrease the weight and improve flow. I believe they are a step down from the Severe Duty valves which are not necked down.

I'd advise going with the Flos. JMHO

97SS, H/C 227, shorties. 410s.

chrism I ran 11.16 with my stockheads and valves not decked. I set up a set of ported heads with proflow valves(Sat in attic for 2 yrs ) but just put them on 3 weeks ago. No tuning yet still running with stock head tune but with fuel pressure turned up. In warm weather ran 11.20's at right at 120. This combo will run 10.70's are so by the end of this year. Needs tune,looser converter,and more gear. Frank95z

Most likely they just have more margin which is the thickness of the head from the bottom of the seat angle to the face, probably less dish in the head too.

Bret

hey frank havent seen u posting in a lil while... nice to see the fastest bolt on cam only stock heads guy posting! lol Frank is def an inspiration to alot of us here who would like to run good times NA.... so i see ur porting ur heads? break into the 10's thats sweet...can't wait to hear about the results