E7 cylinder heads

89LXNB · 01-02-2001, 05:02 PM

Has anyone taken a before and after bech flow test to find out what exactly cfm is to be gained from removing the thermactor air bump from the exahust port of these heads. Not a full on port and polish job, I realize that is going to increase cfm. But moreover, I would like to see the numbers before and after this bump is removed so I can isolate which operations provide proven enhancement and which ones are a lot of hype and opinion.

thanks

88workcar · 01-02-2001, 11:29 PM

I can not give you the info that you want. But I will say this. My car ran 12.60 @ 108 with E7s. I have 1.94/1.60 swirl polished race flow chevy valves in them, and they have been shaved .020. I ported them my self. The first work I ever did was gasket match them and remove the bump. This alone gave me 3 tenths and 3 mph. Later I put the big valves and a B cam. Now that I know a little more. I have unshrouded the valves and bowl hogged and polished them. I have also changed to an E cam. I had a set of Edelbrocs but they are gone and I WILL go faster with my old irons. I would say that the POWER HEADS in calf. have to better than the ones I have. For the price they are hard to beat.

------------------
Jason B Johnson 88LX,speed density,edel heads,4.30s,B-303,cobra,tremac,
12.38 @ 111.28 1.80 60ft 28X10 street tires
12.17 @ 112 26 X 10 slicks

NO SLO PK · 01-02-2001, 11:41 PM

My friend the head porter said 3-5 cfm increase, if memory serves.

------------------
'91 LX
Procharger, 3 row intercooler, extrude honed Cobra intake, Mac full Length Headers, 30# inj., 73mm C&L, 75mm tb, E303 cam, 289 rods, ported E7 heads, MSD, T-Rex w/255 lph Walbro, 5 lug conversion, Cobra R wheels, 3.27 gears and Moser Axles.

01-02-2001, 05:02 PM	#1
89LXNB Registered Member Join Date: Jul 2000 Location: San Jose CA Posts: 149	E7 cylinder heads Has anyone taken a before and after bech flow test to find out what exactly cfm is to be gained from removing the thermactor air bump from the exahust port of these heads. Not a full on port and polish job, I realize that is going to increase cfm. But moreover, I would like to see the numbers before and after this bump is removed so I can isolate which operations provide proven enhancement and which ones are a lot of hype and opinion. thanks

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01-02-2001, 11:29 PM	#2
88workcar Registered Member Join Date: Oct 1999 Location: Pierre Part, La. U.S.A. Posts: 1,850	I can not give you the info that you want. But I will say this. My car ran 12.60 @ 108 with E7s. I have 1.94/1.60 swirl polished race flow chevy valves in them, and they have been shaved .020. I ported them my self. The first work I ever did was gasket match them and remove the bump. This alone gave me 3 tenths and 3 mph. Later I put the big valves and a B cam. Now that I know a little more. I have unshrouded the valves and bowl hogged and polished them. I have also changed to an E cam. I had a set of Edelbrocs but they are gone and I WILL go faster with my old irons. I would say that the POWER HEADS in calf. have to better than the ones I have. For the price they are hard to beat. ------------------ Jason B Johnson 88LX,speed density,edel heads,4.30s,B-303,cobra,tremac, 12.38 @ 111.28 1.80 60ft 28X10 street tires 12.17 @ 112 26 X 10 slicks

01-02-2001, 11:41 PM	#3
NO SLO PK Registered Member Join Date: Mar 1999 Location: Arcadia, CA, USA Posts: 731	My friend the head porter said 3-5 cfm increase, if memory serves. ------------------ '91 LX Procharger, 3 row intercooler, extrude honed Cobra intake, Mac full Length Headers, 30# inj., 73mm C&L, 75mm tb, E303 cam, 289 rods, ported E7 heads, MSD, T-Rex w/255 lph Walbro, 5 lug conversion, Cobra R wheels, 3.27 gears and Moser Axles.