Engine Donor '00 Mountaineer meet '91 Fox

Delete smog/egr. Use the TB from the Mountaineer, you'll have to modify the shaft/throttle linkage. You can use the Mustang HO cam, it works great with the P heads. Definitely upgrade valve springs. Install new stock oil pump and timing set.

Upgrade to 24lb injectors. A lot of people continue to run 19's but a healthy 'P' headed combo will max out 19's. Been there, done that, I run 30lb'ers in my car.

Stock oil pump with HD shaft or ARP shaft. No need for high volume/pressure with a basic combo. Stock oil pump is fine.

Get a MAF calibrated for 24lb injectors.

TFS spring kit TFS-2500100 works great with P heads. Been abusing mine for 15+ years issue free with stock HO cam and 1.7 rockers. Sees 5500-6k A LOT.

For timing set, buy a quality set of your preference and you'll be fine. No cheap Chineseum.

I used these Beehives from Alex's parts on my P heads...

limp said:

I used these Beehives from Alex's parts on my P heads...

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Alex springs was my initial go to, at the time the ETA was the deciding factor so I went TFS. No regrets, but Alex's setup has proven to be solid.

I am assuming your 91 is a 5.0 - you didn't say specifically.

The 19 lbs injectors will work fine (use the Mountaineer ones) unless you plan on running at 5000+ rpm for extended periods - you will max them out at higher rpms. If you plan to cruise around, maybe low 4000 rpm runs, the 19s will be best as your computer already wants to run them, no tune or calibrated MAF will be needed - and you already have them.

The Mountaineer TB will be plenty and will work great. You will need to swap the throttle cable mount as described in the post above. The TPS is a different plug and the fox one may need a slight trimming to fit if I recall.

Valve springs - I agree with limp and would do the same - go to Alex's Parts and get a set of their GT40P specific spring sets.

Timing set - look for play or stretch when you pull the timing cover, replace if needed, not just because you can. It is already a double roller and they don't usually stretch like modern engine do, unless you have high mileage on them.

Stock 5.0 cam will work great and if you can, find a set of 1.7 roller rockers, otherwise just keep the stock rockers. Again the ECU likes the stock cam, so drivability should still be good.

MAF - With stock cam and 19 lbs injectors, the stock MAF will work fine. I used a C&L 73mm with tube for 19s. I also used a 76mm with a tube for 19s and currently use the 76mm with a tube of my own sizing for 24s. No tune and AFRs at 5000+ rpm are 12.x-13.x with idle from 14.5-15.8.

The 8.8 in the Mountaineer is a leaf spring rear, it will not bolt into your foxbody without mods. Width is different as well if I recall correctly. Left and right axle shafts are different lengths as well.

My set up is GT40 3-bar Explorer heads (smooth finish, mild ported), Crower cam (.527/.544 lift with 1.7rr), untouched Explorer EGR intakes, C&L 76mm MAF, 1.7rr. I started running this combo with Explorer 19s and as 86HO5.0 says, at high rpms (5500+) the duty cycle on the injectors would blip/hit 95+% briefly so I switched to 24s (pulled from a late 90's Navigator). I then math'd my own sizing for a flow tube for the 24s (actually did the 19s first with great results). I will be using the 73mm C&L and Explorer 19s on my son's 89 GT we are building - Explorer EGR intakes, 65mm TB and GT40Ps as well with the stock cam and rockers.

Good luck with the build and keep us in the loop.

KRUISR said:

I am assuming your 91 is a 5.0 - you didn't say specifically.

The 19 lbs injectors will work fine (use the Mountaineer ones) unless you plan on running at 5000+ rpm for extended periods - you will max them out at higher rpms. If you plan to cruise around, maybe low 4000 rpm runs, the 19s will be best as your computer already wants to run them, no tune or calibrated MAF will be needed - and you already have them.

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You just confirmed what I stated earlier. 19's are NOT enough. Running injectors near their limit is never a good idea.

I was seeing 100% D.C at 4900 rpm with my setup. 24lb injectors are NEEDED.

86HO5.0 said:

You just confirmed what I stated earlier. 19's are NOT enough. Running injectors near their limit is never a good idea.

I was seeing 100% D.C at 4900 rpm with my setup. 24lb injectors are NEEDED.

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I never saw 100% and I was never over 5500 more than a couple seconds. During these blips of high duty cycle my AFRs were 12-13 the entire time - so no issue. I wasn't worried but wanted the buffer for what I was doing (and I had the injectors sitting on the shelf). If you don't rev it out beyond 5500 and not for more than a second or two, you will not lean out your motor.

If I was running a road coarse and going to sustain 5000+ rpm for extended periods I would 100% say you must go with 24s or more. But for "playing" on the street, stop light to stop light, you will have no problem with 19s. If you roll race on the interstate for long runs, then yes 24s or better are needed. Not everyone runs that hard. This is why we always ask "how you plan to run your car". It makes a difference.

I understand your point, well stated. I like to err on the side of safety. It's better to have the safety 'buffer' with safe injectors and tune than run on the ragged edge. Never know when bad fuel or density altitude might bite you in the cornhole.

86HO5.0 said:

Never know when bad fuel or density altitude might bite you in the cornhole.

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This is true. But if just driving around and never seeing above 4500, you will not have an issue. How you plan to use the car matters.

OP was talking a simple build. Nothing bugs me more than when newer members are told they MUST spend the world for a simple build, a slight improvement over stock, because "your better to spend once and do it right" - how about not spend at all on most of those things. Some like the near stock and can do upgrades for little money.

KRUISR said:

This is true. But if just driving around and never seeing above 4500, you will not have an issue. How you plan to use the car matters.

OP was talking a simple build. Nothing bugs me more than when newer members are told they MUST spend the world for a simple build, a slight improvement over stock, because "your better to spend once and do it right" - how about not spend at all on most of those things. Some like the near stock and can do upgrades for little money.

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With all due respect, I'm not a newer member. Been a FoxBody owner for 25+ years, been on Stangnet for nearly 20 years. Initially under a different name. I'm simply trying to give safe advice that I would recommend to a friend or perform on my own car. My advice is based on how I would treat my own car.

Have a good day sir!! No disrespect intended..

No offense taken and I don't consider you or your advice as a new member. My advice to you would have been to "recommend that 24s be used to be safe", not imply that 24s MUST be used and 19s will NEVER work.

I see in many threads (not this one) that advice is you MUST get a tune, MUST change the ECU, MUST get brand new this or that from this vendor or that vendor, when yes those things are good recommendations and can accomplish the goal - but there are other ways to accomplish the same outcome that doesn't require deep pockets. I'll get off my soapbox now.

91firecracker said:

How do you know what spring set from Alex's if I run the stock cam? So many diff lift and seat. Probably won't, but if I ever decide to cam later I just need to be sure don't exceed lift?

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Well, stock cam is 0.444 lift at valve. If you use 1.7 roller rockers that goes up to 0.472 (almost a B cam lift). Pick a spring set that is greater than those. Its been a while since I looked but I think they have a set for around 0.520 lift and one for up to 0.550/0.560 range. Either will work with a stock cam. Read the descriptions as they describe the lift and head type intended for. They have sets specifically for GT40P heads.

Alex's wanted to know what cam I was using ( TF stage 1) and guided me on what springs to use...

91firecracker said:

Yes, no 4cyl for me!

I had heard the 19's from the Mountaineer would be an improvement to the Fox's. I don't plan on doing runs of 5000+ at all. Just cruiser with some stoplight pulls every now and then

How do you know what spring set from Alex's if I run the stock cam? So many diff lift and seat. Probably won't, but if I ever decide to cam later I just need to be sure don't exceed lift?

Sorry should've clarified I'm pulling the 8.8 for my stepfather who builds rat rods.

I was thinking the rest of the Mountaineer motor I'll tear down, see if it's salvageable and maybe throw the old E7s on it adn have a runner for the stepdad's projects.

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“I had heard the 19's from the Mountaineer would be an improvement to the Fox's. I don't plan on doing runs of 5000+ at all. Just cruiser with some stoplight pulls every now and then ”

I regularly exceed 5,500 on my ‘86 with a 3:55 when I’m accelerating from a light (with open road ahead.)

Bill

Most 302’s with GT40 heads, Explorer upper & lower, and a decent cam will make 300+ hp at the crank. Ran three different injector size calculators and at 85% duty cycle you need 24’s or larger.

Can 19’s be used? Sho nuff but you can wipe your butt with 200 grit vs toilet paper too.

If it’s all you have send it but why would a person go too all the trouble of doing a HCI swap and then not put the correct supporting parts on it? It’s the old saying of 302 parts on a 351 make 302 power.

AeroCoupe said:

Sho nuff but you can wipe your butt with 200 grit vs toilet paper too.

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I gotta think Dude Wipes are much better.....