chevyboy07 91

hey all...I've been running these heads on my Z for a few years now with great results. Digging through some old files I found the flow #'s on these after I massaged them a bit....figured I'd share. Been a while since I've contributed....Army life takes all my time. No dyno #s for the car...set-up in sig.

Anyway: I went with a 1.6 exhaust valve by the way, and "a valve job"(had specs posted but removed b/c it's secret squirrel stuff).....the valves are from a set of Systemax Holley heads if I recall. I was in college at the time and had a bunch of crap to choose from working in the I.C. engines lab. The flow bench was designed and built by the head of our dept. and myself. Ronny Crawford, Wilson Manifolds and a few other "high dollar" guys used it/us at the time for R&D...so its safe to say these #'s are damn close to "perfect."

I will post the best intake port and exhaust port #'s. My first couple of ports I took the intake runner to 195 cc and can tell you that I found no gains after 185.5 cc so....volume did not help ME at that point.

intake: here I saw some significant separation which hurt flow @ .500 and after. Now, this was my best port and was 185.5 cc. even the 195 cc ports did not yield better #'s at higher lift (surprising actually). With the cam I'm running this actually worked out just fine, but still....no good in the high lift dept. BTW: STOCK MAX flow #'s on intake was 224.5 @.450, then it dropped to 218.5@.500 and back up to 223.3 at .600...weird. Anyway:
68.3 @.100
127.5 @.200
189.7@.300
234.4@.400
252.4@.450
256.6@.475
251.4@.500


exh: now these #'s are DYNOMITE GOOD. Very surprising.....As you can see the 1.6 Holley valve yields a HUGE gain over stock #'s out on the net. I dont know where my 1st page of notes is..that had the stock flow #'s for the exhaust side.
61.1 @.100
120.0 @.200
168.9@ .300
197.3@.400
205.8@.450
211.7@ .500
217.9@.600


hope all of you are doing well and can use this info....these haeda outflow stock ETEC 200's and a whole bunch of aftermarket heads..pretty cool.

I wonder what kind of HP they can support...anybody have a guess????

Dyno Don

iTrader: (7)

I ported a set of 062's and put them on a 350 '65 Chevelle.
750 DP, Crane Sat. Night spec cam,etec. etec.
First time out the car ran 12. flat @ 115.xx

chevyboy07 91

btt..anyone else have a guess at how much HP these heads can support? And max cam profile to match it?

Orr89RocZ

iTrader: (20)

256 cfm onthe intake is great for upwards of 380whp i'd say. Exhaust numbers are incredible

for a cam, i'd look into a custom grind with lift on the intake around .480 and exhaust around .520 or more

Not sure why the intake doesnt flow more above .475 lift but any higher cam lift will hurt numbers