Fox T-Bird/Cougar Forums

Technical => Engine Tech => Topic started by: GDawg148 on September 09, 2014, 01:51:09 PM

Title: GT40P/Aftermarket valve springs
Post by: GDawg148 on September 09, 2014, 01:51:09 PM
Hey guys, been doing some reading online about the HO swap and precautions before doing so (I have no previous knowledge in this kind of stuff, so bear with me). 
I am planning on installing the GT40P heads in my bird.  I've read that the stock valve springs on the GT40Ps are trash, and that I should buy aftermarket.  People say the Trickflow kit is a good buy, but they can also act up.  Others mentioned the Alex parts springs that are a great buy and good for the price, and also Crane cams have a reliable set.  Someone lead me in the right direction..

In addition to that, is there a way to avoid the spark plug clearance issue when you use stock mustang headers with the GT40Ps? (smaller spark plugs, different boot, i dunno, etc).  Thanks guys.
Title: GT40P/Aftermarket valve springs
Post by: TheFoeYouKnow on September 09, 2014, 06:38:05 PM
Ford Racing makes Mustang (or other Fox platform) swap headers just for P heads.  You can also run shorty plugs, but the ones that fit P heads are expensive.  For my P heads, I just sent them to my machine shop and told them to hook me up with springs and retainers to suit the cam I picked.
Title: GT40P/Aftermarket valve springs
Post by: GDawg148 on September 09, 2014, 09:35:03 PM
Quote from: TheFoeYouKnow;437840
Ford Racing makes Mustang (or other Fox platform) swap headers just for P heads.  You can also run shorty plugs, but the ones that fit P heads are expensive.  For my P heads, I just sent them to my machine shop and told them to hook me up with springs and retainers to suit the cam I picked.

Thanks for the info!  Do standard brands like NGK and Accel sell shorty plugs?
Title: GT40P/Aftermarket valve springs
Post by: thunderjet302 on September 09, 2014, 11:36:51 PM
Quote from: TheFoeYouKnow;437840
Ford Racing makes Mustang (or other Fox platform) swap headers just for P heads.  You can also run shorty plugs, but the ones that fit P heads are expensive.  For my P heads, I just sent them to my machine shop and told them to hook me up with springs and retainers to suit the cam I picked.

I used (and still use) FRPP GT40P headers when I ran GT40P heads. As far as springs I used the springs Comp recommended with my cam. The machine shop made the Comp springs fit.
Title: GT40P/Aftermarket valve springs
Post by: Aerocoupe on September 10, 2014, 08:59:05 AM
I have heard good things about the Comp and Twisted Wedge springs both.  If you have a good machinist (read shop that builds engines with an in house machine shop) local to you then they can set the heads up to the cam you pick.  With the GT40 and GT40P heads being pedestal mount type I would think that they would be limited to how aggressive you can get with open/close pressure on the springs.

As far as headers go for the GT40P heads a lot of the guys running these heads (including the Mustang crowd) run the BBK 1515 unequal length shorty headers and report that the #7 plug is the difficult one to access.  One guy suggests the following:

[COLOR="#0000FF"]I use the bbk headers with p heads, you only need a 90* plug on the #7 cylinder. To change the plugs on the # 7 you can cut about a 1/2" off of a spark plug socket. then cut a narrow slice down the middle of the socket so it will slip over the end of the plug. the slice doesn't have to extend all the way down the plug, just enough for the plug to be able to slide through. then you can use use a open end wrench to tighten or loosen the plug. the rest of the plugs you can get in and out with a standard spark plug socket and open end wrench. you will definitely need boot protectors.[/COLOR]

Darren
Title: GT40P/Aftermarket valve springs
Post by: TheFoeYouKnow on September 10, 2014, 09:04:08 AM
Quote from: Aerocoupe;437859
As far as headers go for the GT40P heads a lot of the guys running these heads (including the Mustang crowd) run the BBK 1515 unequal length shorty headers and report that the #7 plug is the difficult one to access.  One guy suggests the following:

I use the bbk headers with p heads, you only need a 90* plug on the #7 cylinder. To change the plugs on the # 7 you can cut about a 1/2" off of a spark plug socket. then cut a narrow slice down the middle of the socket so it will slip over the end of the plug. the slice doesn't have to extend all the way down the plug, just enough for the plug to be able to slide through. then you can use use a open end wrench to tighten or loosen the plug. the rest of the plugs you can get in and out with a standard spark plug socket and open end wrench. you will definitely need boot protectors.

Darren
And you had better believe it.  My BBK's work, but when I had to pull #7, I took the header off.