PAGE 1: "THE SKUNK"
PAGE 2: ABOUT TUNNEL RAMS
PAGE 3: HOW & WHY
PAGE 4: BUILD NOTES -- 302/5.0 SWAP, C4/5.0 NOTES, MII ENGINE MOUNT FABRICATION
BUILD NOTES (AKA: "Things I Wish I'd Known Before I Tried This")
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SWAPPING IN A 5.0L H.O. FOR AN EARLIER-MODEL (PRE-1985) 302 V8:
The 5.0. H.O. serpentine belt system will not fit in a Mustang II; at least, not with the stock fan assembly. You can, however, use an aftermarket, electric clutch-type fan mounted in front of the radiator.
However, the 5.0 oilpan will not fit in a Mustang II, nor the 5.0 H.O. dipstick, which is located at a different point on the 5.0 H.O. block. Also, there is no eccentric on a 5.0 to drive a fuel pump, so you'll need to use the eccentric on the 302 timing cover -- and hence the 302 timing cover and accessories assembly -- to run a mechanical fuel pump. If you want to keep the serpentine belt assembly, you will need to use an electric fuel pump.
This is not a straight swap. It can be done; it only took 12 hours and I only broke one finger. Some notes:
1.) The 302 timing cover won't fit without first removing the locator pins on the front of the block. They're a bitch to get out, and once you get them out, it makes lining up the holes a royal PITA.
1a.) The 302 timing cover won't accomodate a gear drive timing set. I had to grind the hell out of it to get clearance fore and aft, remove the internal flange, and cut one of the bolt holes in half (it's still oiltight.) Had I a timing chain set, I would've swapped that #$%^&*er in a heartbeat. But I spent good money on the gears and I think they sound cool. So it was worth it.
2.) 5.0 heads are NOT REPEAT NOT ambidextrous, the way 289 & 302 heads are. Blockoff plates (unthreaded holes) go on the BACK, otherwise your 302 accessories won't fit.
3.) Blockoff plates are a PITA to fabricate. Buy them. You can also get threaded inserts for $18 each from a Ford dealer.
4.) The 5.0L H.O. uses the 351W firing order.
4a.) You cannot use your 302 cam.
5.) The fan and water pump on the 5.0 assembly run in reverse from the 302 fan and water pump.
6.) This may be specific to my personal hell, but the Pertronix "Flamethrower" ignition module for the 5.0 (I used this to replace my Duraspark) WILL NOT WORK with the MSD BLASTER 2 COIL. The coil will eventually waste the ignition module. There is a specific Pertronix ignition module for the MSD Blaster 2; you have to get the part # from Pertronix or -- as I learned from Pertronix over the phone -- you can either use the stock coil, or install a ballast resistor.
7.) When getting a 28-oz. Mustang II flexplate rebalanced to 50 oz. (mandatory), make sure that the machinist leaves enough room for those eccentric nuts on the back of the torque converter. Leaving the hole clear is not enough. Give him one of the nuts to work with. Otherwise, you'll be grinding down the flared skirts at the edges of the nuts.
8.) And finally, a reminder: always double-check your attachment points when hoisting the engine, even if just lifting it a couple of inches; I dropped the sonofabitch on my hand and fractured my finger. Hairline fracture, mashed it good. (In my best Bugs Bunny voice, "Of course you realize, this means war.")
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MATING A 5.0 H.O. TO A MUSTANG II C4 TRANSMISSION
The Mustang II uses a specific transmission bellhousing that is smaller than the stock C4 bellhousing. The spacer ring between the tranny and block, which worked fine on the 1978 302, was preventing the 5.0 H.O. motor from turning. Put the engine in, tried to rotate it to TDC by hand, wouldn't turn.
Tried a breaker bar.
Tried jumping the starter: ***BZZZT-WHANK***
Took the engine out.
Took the tranny off. Engine rotated easy.
Put the tranny back on. Engine didn't turn.
Off.
Put the spacer ring on. Turned fine. 1/4" clearance.
Put the tranny on. Discovered that the spacer ring interfered with the flexplate weights.
Off. Spacer ring seemed to not interfere with the flexplate weights. (Flexplate was rebalanced from 28 oz. to 50 oz.)
On. Discovered that the spacer ring interfered with the flexplate weights, but only when the transmission was bolted to the engine.
Off.
You get the idea. This took most of the day.
I finally hollowed out the inside of the spacer ring with a cutting torch (it's now basically an inverted "U" shape) and fabbed an aluminum skirt to keep road grime from coming in the bottom of the bellhousing. FYI.
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REBUILDING MUSTANG II ENGINE MOUNTS
This is a quick "How To" for MII owners who are searching for V8 engine mounts.
The Mustang II won't use stock Mustang motor mounts; most of you know this.
We took a set of Pinto V8 mounts (the II, of course, was built off the Pinto chassis) with broken center bushings, and replaced the bushings with 1950 Ford V8 "donut" engine mounts using Grade 8 hardware.
At this point, I ground off the ends of the thru-bolts and bashed the bolt heads down flush. I don't have pics, but you'll see what I mean when you get there.
Simple, nasty, cheap, and functional. It beats the hell out of paying through the nose for a set of "remanufactured" MII mounts from a specialty shop.
This is also a microcosm of the way this car has gone together.
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UPDATE September, 2006.
DIFFERENCES IN 302 vs. 5.0L H.O. DISTRIBUTORS
Wow. Where do I start?
'86 5.0L H.O. with a 1978 302 timing cover -- the serpentine belts wouldn't fit in my engine bay. When I assembled the engine I didn't mark a timing mark; just put her at TDC and tuned it by ear.
Yeah, I know.
Fast-forward one year.
Put the car in gear one morning, and it dies. It had idled great. Fired it up, dies again as soon as I put it into reverse. I took off the scoop and air cleaners (dual quads) and fired it up again. This time it died -- and backfired, blowing flames about 12" above the carbs. Tunnel ram intake = LOTS of gas to catch fire. Looked cool as hell.
Started at the beginning. Took the carbs off, checked everything. Replaced power valves.
Tried again. BOOM! More flames.
Eventually I got to the distributor, took off the ignitor module and plate. . . .
Shrapnel.
The entire mechanical advance unit had come apart. Weights, pins, retaining clips, the whole thing. For reasons I don't understand, the shaft had developed about 1/2" of vertical play, and had pushed the weights off the pins and then beaten the bejeezus out of them.
I don't even want to go into details about how many different distributors I tried; turns out the 302 and 351W distributors are NOT interchangeable, and the diameter of the distributor shaft varies -- the 1987 and up 5.0, and 351W, shafts are .51" diameter, and the pre-1987 5.0 and 302 shafts are .49" diameter. Plus, the diameter of the hex driver for the oil pump varies from year to year, as well. Because of the sump location in the 1978 pan -- I had to use the '78 oil pan because of tranny clearance issues -- I had to use the 1978 oil pump, which uses a 1/4" drive shaft, not the 5/16" shaft on the 1987-up blocks. Mallory et al do not appear to make a small-shaft 5.0 distributor; much less one that fits the 1/4" oil pump driver. At least, not that I'm aware of.
I ended up BUILDING a new distributor. I took a 302 distributor from a 302 E150 van, disassembled it, went over it with 600-grit sandpaper inside the housing (on a 29/64" drill bit) and over the shaft until it shone, hammered and pinned a steel drive gear on it -- had a bastard of a time finding a steel drive gear for the smaller-shaft distributor, BTW -- and soaked it with Tri-Flow until it moved like sex on ice.
This older distributor came with a 10- and 13-degree advance. I'd been running a 15-degree in my other dizzy and I had a hunch that she'd run better with more advance, so I did some careful math and some scribing with a protractor, and opened the 10-degree side into a 21-degree advance curve with a rat-tail file. Took about three hours. I used slightly heavier springs on reassembly to give it more of a logarithmic advance curve over the power band, and secured the weights with one-way seat spring washers, the ones with the little teeth that only bend one way.
Dropping it in was a laugh a minute. I hadn't indexed the worm drive gear when I put the steel gear on. I had just drilled a hole in the gear, heated and hammered it onto the shaft, and then through-drilled the other side.
Which meant that my rotor would not, for love or money, line up with #1. At least, not with the registration marks that I'd laid down on the block.
Easy, no? Just advance the distributor housing. . .
Except that, with no timing mark on the balancer. . . .
. . . see where this is going?
Welcome to my personal hell.
Eight hours, today. Finding TDC by hot-wiring the starter. REALLY finding it. Down to the nano-millimeter. Painting on a new timing mark. Shuffling the plug wires around so that I could rotate the dizzy to get the advance I wanted. Then the fun part -- running it up and down the street at redline to get the dwell just right. Even built a homemade dwell meter. :) Then, moved on to the carbs. Lots of screwdriver time, splitting hairs each direction. Burned up half a tank of gas laying rubber this afternoon.
The good news is, the car runs better than ever, now. The hesitation at launch is gone. The weird little periodic shudder at idle is gone. It idles at 800 without dying -- it used to have to idle at about 1100 in gear. It rolls with much less effort and with 21 degrees of advance curve, it pulls way past what my tach will show (6K.) She's much more civilized at idle and she jumps out of her skin when I goose it. I had always thought that my 5.0 ran rough, and attributed it being "overcarbed" and on a tunnel-ram; frankly, I didn't care that much, as it made the car sound nasty. She just wasn't tuned. Really, really, tuned. She purrs, now. I'm very, very happy.
