Explorer coil spring swap
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8ton
- New Member
- Posts: 35
- Joined: Sun Jun 04, 2017 9:33 am
Re: Explorer coil spring swap
The gt40 heads are on mid 90s mustang cobras and v8 explorers and mercurys. The later '97 and up explorers have the gt40p heads that have a different spark plug angle, a smaller combustion chamber and exhaust valve.
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Jacksdad
- Blue Oval Fan
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- Joined: Sat Mar 30, 2013 8:52 pm
- Location: San Diego, CA
Re: Explorer coil spring swap
Sorry - didn't mean to leave you hanging there.
Yeah, '96 to early '97 are the years for GT40 heads on Explorers (or '93 to '95 F150 Lightning or Cobra Mustangs). The GT40P heads were used from '97 to '01. Less plentiful, but Mercury Mountaineers came with them too - I just pulled a pair off a '98 with a 5.0 at the wrecking yard.
F150 Lightnings ran them on a 351, but the 5.0 heads from an Explorer/Mountaineer will have to be drilled out to accept the larger Windsor head bolts. Other than that, they're pretty much a straight swap.
I did a lot of research before I settled on GT40P heads over the GT40s. One thing I discovered was that there are two groups of "experts". One has never run them, but swear that headers won't fit GT40Ps because of plug/wire interference. The other group are using them with 90 degree plug boots to get around any clearance issues, and sometimes heatproof sleeves and shorter plugs depending on the brand of headers. That's not to say they work 100% of the time and some headers definitely fit better than others, but the 90 degree wires seem to work around the problem in most cases. MAC headers are popular and BBK shorties work too, but cheap Chinese eBay headers can be a crap shoot. I got some unequal length Fox body BBKs for my build as I didn't want to deal with any long tube fitment hassles.
The "P" heads have different ports, valve sizes, plug angle/location and combustion chambers, and flow slightly more than GT40 heads.The smaller chamber gives you a nice compression bump, and should lift a stock 8.8:1 short block like mine above 9:1, which is fine for my intended use.
On the downside, the GT40P valve springs suck for high performance applications, but TFS and Alex's Parts both sell drop in kits for less than $200. If you're not going to rev it past 5500 rpm though, new stock springs should be fine on something like an RV cam with less than .500" lift. I found a few people online that did just that and didn't experience valve float until 6000+ rpm. One guy was running an Explorer motor with "P" heads and new stock springs in a Mustang, and even with an F303 cam (.512" lift) he could spin it to 6300 rpm.
Hope that helps. They're both great heads for a budget build, and can easily support well over 300hp on the right motor. Unless you already have money invested in a pair of E7s, it seems like a no brainer not to use them.
Yeah, '96 to early '97 are the years for GT40 heads on Explorers (or '93 to '95 F150 Lightning or Cobra Mustangs). The GT40P heads were used from '97 to '01. Less plentiful, but Mercury Mountaineers came with them too - I just pulled a pair off a '98 with a 5.0 at the wrecking yard.
F150 Lightnings ran them on a 351, but the 5.0 heads from an Explorer/Mountaineer will have to be drilled out to accept the larger Windsor head bolts. Other than that, they're pretty much a straight swap.
I did a lot of research before I settled on GT40P heads over the GT40s. One thing I discovered was that there are two groups of "experts". One has never run them, but swear that headers won't fit GT40Ps because of plug/wire interference. The other group are using them with 90 degree plug boots to get around any clearance issues, and sometimes heatproof sleeves and shorter plugs depending on the brand of headers. That's not to say they work 100% of the time and some headers definitely fit better than others, but the 90 degree wires seem to work around the problem in most cases. MAC headers are popular and BBK shorties work too, but cheap Chinese eBay headers can be a crap shoot. I got some unequal length Fox body BBKs for my build as I didn't want to deal with any long tube fitment hassles.
The "P" heads have different ports, valve sizes, plug angle/location and combustion chambers, and flow slightly more than GT40 heads.The smaller chamber gives you a nice compression bump, and should lift a stock 8.8:1 short block like mine above 9:1, which is fine for my intended use.
On the downside, the GT40P valve springs suck for high performance applications, but TFS and Alex's Parts both sell drop in kits for less than $200. If you're not going to rev it past 5500 rpm though, new stock springs should be fine on something like an RV cam with less than .500" lift. I found a few people online that did just that and didn't experience valve float until 6000+ rpm. One guy was running an Explorer motor with "P" heads and new stock springs in a Mustang, and even with an F303 cam (.512" lift) he could spin it to 6300 rpm.
Hope that helps. They're both great heads for a budget build, and can easily support well over 300hp on the right motor. Unless you already have money invested in a pair of E7s, it seems like a no brainer not to use them.
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