Build a Lightning Bronco?

[Carnut1]

I have a good friend who owns a 93 Bronco low miles with stock 351w and 4 speed auto 40" tires and 5:13 gears with rear posi. He got banged up when a girl t boned his pickup and the bronco sat for a while. When he fired it up it bent a pushrod and sounded terrible. No stuck valves, replaced pushrod rocker and it still sounds bad. The question is I found a 1993 lightning with high miles as a replacement engine. I would like to keep it relatively stock maybe a good porting of heads and intake and Mike Jones custom cam. He would love a roller cam but being such a mild profile I doubt there is any real gains. Before I buy the lighning I would like to ask if this is a good idea? Thanks.

[Carnut1]

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[Carnut1]

This will not be a super high horsepower buildup. The rear is a beefed up 8.8" with limited strength. I figured with some porting and a good rebuild the 240hp and 340 ftlbs. Lightning motor could put out 280hp and 380 ftlbs. The truck was fine with the stock engine but was not a road burner. I believe the lightning was mass air fi and I know the bronco is speed density.

[Carnut1]

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A bad picture of a picture. This was the last engine I built for my friend about 23 years ago. Ceramic coated e7te cut for 1.96/1.6 valves

[Carnut1]

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Forged trw .030 ceramic coated pistons and worked up stock rods.

[Carnut1]

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306 lower end. Ran 11.00 on street tires with crappy 60 ft.

[Carnut1]

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Snotty little 306. Engine still runs all these years later. It was actually sold recently.

[Carnut1]

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5.8l ford lightning engine 220,000 miles sounds very strong considering the body is trashed and very high mileage.

[91stang]

What are you worried about? The only real difference is the intake manifold.

[Carnut1]

I have read that the lightning engine has higher compression, hyper pistons, different cam profile, gt40 heads, different valve springs, factory headers, gt40 intake, different injectors, high flow fuel pump, different computer program. I thought the lightning was mass air fi but it looks like speed density.
I have had issues with speed density systems before. This needs to be easy upgrade and very budget friendly. Thanks, Charlie

[Carnut1]

And 91stang, love the picture of your mustang smoking the tires. Great photography!

[Carnut1]

Does anyone have some insight into porting the heads/lower intake and still being able to keep the speed density fi? Thanks in advance!

[Daniel Jones]

> Does anyone have some insight into porting the heads/lower intake and still being able to keep the speed density fi?

If you google "TMoss porting GT40 intakes" you'll find links like:

http://tmoss.efidynotuning.com/
http://eectuning.org/forums/viewforum.p ... a826716584

with downloads/links on porting 5.0L HO, GT40, GT40P and Cobra intakes. The F4TE casting code blocks are roller ready but the Lightnings got flat tappet cams. The 5.0L HO roller cam and Ford Motorsport/Crane 1.7:1 ratio bolt-down (pedestal mount, adjusted with shims) roller rockers were a fairly common upgrade for 1st generation Lightnings but be aware you'll need a steel distributor gear to match the roller cam. Way back when the GT40 cylinder heads were introduced, Ford engineer Brian Wolfe did a two part article on porting GT40 heads for Super Ford magazine. Might be worthwhile trying to track down a copy.

Dan Jones

[Carnut1]

Thanks for the info Dan. The part that worries me is getting some good flow numbers out of the heads and intake with a mild roller cam and having the speed density computer blow a hissy fit. Not sure how far I should go. Friends don't let friends drive stock! As I am sure you know.

[Daniel Jones]

> The part that worries me is getting some good flow numbers out of the heads and intake with a mild roller cam and having the speed density computer blow a hissy fit. Not sure how far I should go.

I don't think it will be a problem. The Mustang 5.0L HO speed density works fine with the stock cam, 1.7:1 roller rockers, and aftermarket heads and intakes, headers, etc. with nothing more than tuning via an adjustable pressure regulator and the throttle position sensor. It's the cam overlap that upsets the stock speed density computer since it relies on the MAP sensor (vacuum). I'm still running the stock cam (with 1.7:1 roller rockers) but the Mustang speed density guys have a list off-the-shelf aftermarket cams that will work. See the gif at http://www.allfordmustangs.com/forums/5 ... -cams.html.

I've not done it on a Lightning but would expect it to be similar and a quick search on the full size Bronco site shows this:

"I just got my truck back. It now has a 351 (357) with ~9.5 to 1 compression, GT40X aluminum heads, GT40 Lightning upper, lower intake and 65mm throttle body and a 5.0 HO mustang roller cam advanced 4 degrees. I have Ford Motorsport 1 5/8" headers and dual exhaust. I did install a 93 Lightning speed density computer as a precaution since it can be tuned. The truck runs, idles, and starts just fine. The cam is pretty mild compared to some aftermarket cams, but the heads are much better than any E7 and better than the GT40 irons the Lightnings come with. I haven't had a tune yet, but have zero drivability problems. Speed density can handle overbores, increased compression, and better aftermarket aluminum heads and intakes. I now KNOW this."

Dan Jones