GT40P headed 306

MiracleMax · 03-21-2004, 05:46 PM

I'm screwing together a GT40P headed 306 so we can put it in my brothers 86 four banger.

I've got a few questions about the heads.

They are unported P heads with the stock valve size. I'm using Manley SS race flow valves but i'm not sure about what type of valve job needs to be done? I've heard that a 3 angle valve job might actually hurt low-lift flow?

Anyways here is the combo

Holley 670 CFM Avenger carb
Edelbrock Air Gap RPM
GT40P Heads
Comp Cams Extreme Energy 274 (302 firing order flat tappet cam)
9.5:1 comp
Stock length rods
1-5/8 Long tubes with 2-1/2 X-pipe and bullet mufflers.

The engine is gonna be backed by a C4 and a 3.55 gear

88workcar · 03-24-2004, 05:29 AM

Max that is good planning. It will be just fine. A good valve and a three angle job will do great.

MiracleMax · 03-24-2004, 06:11 PM

Yeah, we wanted to put something together reasonably cheap with enough power to have some fun.

So far it hasn't been to terribly expensive. Picked up a engine for 100 bucks, and a set of bare new GT40P's for 230 bucks. My brother has a set of chevy wheels he sold for 500.00 so that will cover the rods and he picked up a back-halved RX-7 for free. We figure we can dump the RX-7 for enough easy money to get some good pistons.

I've been pondering the headers though, might make a switch to 1-1/2 long tubes? It sounds crazy, but with the dinky exhaust valve and the theory behind it (hot high velocity gas) 1-1/2 primaries might work pretty well, in any event. we'll see when we get there.

Ron1 · 03-25-2004, 12:01 AM

If you need ANY info on the GT40P's, this site might be of some help. It is a very good resource.

http://www.stangpro.com/html/article...les/gt40p1.htm

Ron

MiracleMax · 03-25-2004, 10:33 PM

Yeah I checked the page out earlier this week, it was a pretty good site, also there is a guy named mouse that had another very informative site.

tmoss · 03-26-2004, 08:18 AM

Anyone ver notice how the exhaust cross sectioned head in that site is missing part of the exhaust wall? Take a look - someone tampered with the picture - you can tell if you look close enough.

Quote:

Originally posted by Ron1
If you need ANY info on the GT40P's, this site might be of some help. It is a very good resource.

http://www.stangpro.com/html/article...les/gt40p1.htm

Ron

88workcar · 03-28-2004, 08:43 AM

1 1/2 long tubes is the wat to go.

03-21-2004, 05:46 PM	#1
MiracleMax Registered Member Join Date: Apr 1999 Location: Hayes, Va, USA Posts: 798	GT40P headed 306 I'm screwing together a GT40P headed 306 so we can put it in my brothers 86 four banger. I've got a few questions about the heads. They are unported P heads with the stock valve size. I'm using Manley SS race flow valves but i'm not sure about what type of valve job needs to be done? I've heard that a 3 angle valve job might actually hurt low-lift flow? Anyways here is the combo Holley 670 CFM Avenger carb Edelbrock Air Gap RPM GT40P Heads Comp Cams Extreme Energy 274 (302 firing order flat tappet cam) 9.5:1 comp Stock length rods 1-5/8 Long tubes with 2-1/2 X-pipe and bullet mufflers. The engine is gonna be backed by a C4 and a 3.55 gear __________________ 2002 5M GT (99% stock) 1991 5M LX (30% stock) patiently awaiting my satin silver 07 Mach 1, and don't forget the shaker

03-24-2004, 05:29 AM	#2
88workcar Registered Member Join Date: Oct 1999 Location: Pierre Part, La. U.S.A. Posts: 1,850	Max that is good planning. It will be just fine. A good valve and a three angle job will do great. __________________ 88workcar 1988 Mustang LX 342. 417rwhp @ 6800. 28 X 10 ET Drag, 4.30s, 10.69 @ 126.43 1.42 60ft. 11.13 @ 127.7 on BFGs 1.72 60ft Rice Hater # 42 To be old and wise, You must first be young and stupid I'm somewhere in tthe middle.

03-24-2004, 06:11 PM	#3
MiracleMax Registered Member Join Date: Apr 1999 Location: Hayes, Va, USA Posts: 798	Yeah, we wanted to put something together reasonably cheap with enough power to have some fun. So far it hasn't been to terribly expensive. Picked up a engine for 100 bucks, and a set of bare new GT40P's for 230 bucks. My brother has a set of chevy wheels he sold for 500.00 so that will cover the rods and he picked up a back-halved RX-7 for free. We figure we can dump the RX-7 for enough easy money to get some good pistons. I've been pondering the headers though, might make a switch to 1-1/2 long tubes? It sounds crazy, but with the dinky exhaust valve and the theory behind it (hot high velocity gas) 1-1/2 primaries might work pretty well, in any event. we'll see when we get there. __________________ 2002 5M GT (99% stock) 1991 5M LX (30% stock) patiently awaiting my satin silver 07 Mach 1, and don't forget the shaker

03-25-2004, 12:01 AM	#4
Ron1 Registered Member Join Date: Sep 1999 Location: Vancouver, WA USA Posts: 439	If you need ANY info on the GT40P's, this site might be of some help. It is a very good resource. http://www.stangpro.com/html/article...les/gt40p1.htm Ron __________________ 65 Mustang Fastback 347 Stroker, C4 with 4.56 10.68 @ 122 N/A 9.74 @ 137 w/ N2O www.fastspecialties.com

03-25-2004, 10:33 PM	#5
MiracleMax Registered Member Join Date: Apr 1999 Location: Hayes, Va, USA Posts: 798	Yeah I checked the page out earlier this week, it was a pretty good site, also there is a guy named mouse that had another very informative site. __________________ 2002 5M GT (99% stock) 1991 5M LX (30% stock) patiently awaiting my satin silver 07 Mach 1, and don't forget the shaker

03-28-2004, 08:43 AM	#7
88workcar Registered Member Join Date: Oct 1999 Location: Pierre Part, La. U.S.A. Posts: 1,850	1 1/2 long tubes is the wat to go. __________________ 88workcar 1988 Mustang LX 342. 417rwhp @ 6800. 28 X 10 ET Drag, 4.30s, 10.69 @ 126.43 1.42 60ft. 11.13 @ 127.7 on BFGs 1.72 60ft Rice Hater # 42 To be old and wise, You must first be young and stupid I'm somewhere in tthe middle.

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