1964-1966 Mustang Engine Swaps FYI ---------------------------------- Below, I've put together some information relative to 351W and 351C engine swaps into 64-66 Mustangs. Since the shock towers of these Mustangs are quite narrow, engine swap choices are restricted to the mid-sized 351's. You can forget about big blocks, modular motors, or even a 351M/400, unless you are willing to do major surgery (i.e. shock tower removal). Of the Ford 351's, the 351W is the most popular. Less popular, but still possible with special headers and maybe little tower massaging, are 351C swaps. Essentially a taller deck version of the 289/302, the 351W is the most straightforward of the mid-size blocks to swap in. The 351W is taller and wider, but fits within the general V envelope of the 289/302 engine. The 351W (and 351C) share the 289/302 motor mounts and bellhousing bolt patterns (64-65 5 bolt 260/289 blocks excluded). Unfortunately, there isn't enough clearance between the heads and the shock towers to fit the stock 351W exhaust manifolds. The shock towers could be notched to provide the necessary clearance, but the usual approach is to replace the cast iron exhaust manifolds with a set of steel tubing headers, preferably ones made specifically for the swap. In some cases, the companies listed below have a specific swap header for 64-66 Mustangs with 351W's. In other cases, they show a generic header for 64-73 Mustangs with 289/302/351W engines. Your best bet is to stick with the specific swap headers. There's an outside chance the generic headers will fit but most likely they will require mods to the shock towers and/or header tubes. A long while ago, I did some checking into 64-66 Mustang 351W swap headers for one of the list members who suffered sticker shock over the JBA swap header price ($699 for his case). I was surprised to see so few places making headers 64-66 Mustang 351W swap headers. This is a fairly common swap, so I expected to see a wide variety of vendors supplying these headers. I actually ran across more places with Pinto 351W swap headers. Hedmann has recently stepped in to fill the void with 351W swap headers but make sure they are compatible with your heads. Some aftermarket Windsor heads have raised exhaust ports and may not quite fit. 1. Mustangs Unlimited (from their 1995 catalog) 800-243-7278 order 203-647-1965 tech and local MU carries a specific 64-66 Mustang 351W header (1 1/2" primaries with 3 1/2" collectors). Part number is ES9. They also list the JBA 1606 header for $699.95 (1 3/4" primaries, 3 1/2" collector) but note that it will not fit power steering cars and the equalizer bar from a 1967 standard 289 engine must be used. Their catalog claims that power steering brackets are required for any 64-70 Mustang using any style header and power steering. Mustangs Unlimited also lists 64-66 Mustang 351C swap headers in their 1995 catalog. For the 2V heads, they have part number ES7 (1 3/4" primaries with 3 1/2" collectors). For the 4V heads, they have part number ES7A (1 7/8" primaries with 3 1/2" collectors). 2. Sacramento Mustangs order 800-442-8333 info 916 334-0190 Note: This info is from an old (1989) performance catalog supplement. They list a custom header for 64-66 Mustang, Comet, Falcon, and 70-76 Maverick and Comet applications. They might be sourcing the headers from Total Performance (or their supplier) since they show several other swap headers that TP sell (like the 64-66 351C headers). They also have a generic listing for 64-70 289/302/351W Tri-Y headers and list a power steering adapter. 3. Total Performance 44050 N. Groesbeck Hwy. Clinton Township, MI 48036-1108 313-468-3673 313-468-7434 fax Note: This is from a 1989 price sheet. Part number 8009 is listed as fitting 60-66 Mustang, Comet, Falcon, 70-78 Maverick and Comet applications with 351W's, 1 1/2' primaries. Also list 64-66 351C Mustang swap headers in 2V or 4V flange. 4. Tubular Automotive PO Box 279 248 Weymouth St Rockland MA 02370 617-878-9875 Lots of swap headers for Fords, including 351C into '65-'66. Darkhorse Performance carries Tubular Automotive headers. Darkhorse Performance 16617 SE 134th Renton, WA 98059 425-227-7778 425-277-3893 fax 5. Pro Mustang Performance 2070 Del Amo Blvd Torrance, CA 90501 310-781-1441 Custom 351C into '65-'66 Mustang swap headers. 6. Hedman Hedders 16410 Manning Way Cerritos, CA 90703 310-921-0404 310-921-7515 fax Hedman has recently introduced two sets of 351W headers specifically designed for swaps into 64-73 Mustangs: P/N 88660 - Full Length - 1 5/8" primaries with 3" collectors P/N 88650 - shorty Note: a couple of guys have had real trouble swaping in aftermaket headed (Dart, TW) 351W's. Here's what one said: * Unless you are a masochist, DO NOT put Dart heads on your early Mustang, particularly the '65-66. They are great heads BUT the plugs are seriously relocated, enough for you to go to "custom headers" which are more aggravating than I'd care to discuss. Fox Mustang owners will gladly take your Darts if you're reading this a little late in the game; they can use 'em all day long.I recommend Edelbrock Performer RPMs or GT-40 Aluminums for early car folks. They go right on there, pretty as you please. I did talk to Bill Mitchell, maker of the Dart heads, recently, and he admitted that the relocated plugs were giving people problems. He said my circa 1995 heads were "old" and that the new batch of heads has the stock locations for the plugs again. So, get the *new* Darts. One list member was able to make a set of generic Hedman Hedders work in his '66 fastback ('69 351W with C4). He notched the shock towers in 3 places and modified the end of the headers where they exit. The job was time consuming as it involved several iterations of dropping the engine in (without tranny), putting the headers on, marking where they touched the shock towers, pulling the engine out, heating up the area with a torch, and notching it in with a round buck and a hammer. He reported the end result was very professional looking. A member in the local (St. Louis) Ford club had good luck with the 351W swap headers from Total Performance (much better than my own experience with TP's 351C swap headers). His swap consisted of a 351W with T5 manual transmission and air conditioning into a 1966 Shelby GT350. Hooker may also make a header that will fit the early Mustang chassis. Here's what one individual (David Cole) on the web had to say. "On the headers: Hooker Super Comps. Part #6208. These are 1 3/4" headers with 32" tubes. I have well over 400 rwhp in my 383-W and they are plenty big enough. These are engine swap headers to let you put the 351-W in an early Mustang. They fit 65-70 Mustangs. I have them in my 69, but they are designed to fit the earlier cars also. Before I bought them I called Hooker. They told me that these headers were designed to be able to fit a 65 Mustang with a 351W and C-6. Anything else is cake. I have seen them installed in a 65 and a 66 and they fit well. True, plugs are a little tight to get to, but it is workable. These headers are available mailorder for around $360. Hedman also makes a set. I had some but refused to install them due to poor quality." In all cases, you'll need to verify fit for your specific combination of transmission (automatic or manual), power steering, air conditioning, etc. In most cases, early Mustangs with power steering will need to have the power steering slave cylinder relocated using a swap bracket. One list member reported the bracket is inadequate to take the load from the power steering system. His fix was to weld the bracket to the frame with a pair of 1/4" plate gussets behind it. Many times headers for Fords are listed as being incompatible with automatic transmissions but often this applies only to the large bellhousing C4, C6, and FMX. In those cases, switching to a small bellhousing C4 (and matching blockplate) and a 157 tooth flywheel (28.2 oz-in balance factor) will provide the required clearance. When doing this, you may need to roll the lip of the oil pan back a bit to get proper starter placement. With a 64-66 Mustang, the C4 (or an AOD if you want overdrive) is definitely the way to go if you want an automatic transmission. The C6 is much larger and will require transmission tunnel work to fit. You may also want to consider switching to the small diameter, late model, permanent magnet starter that came on some Lincolns. Once your headers are in place, you may find it impossible to remove or install the starter (I did), without removing the headers or disassembling part of the suspension. The lightweight starter is much smaller and slipped right into place. SVO sells them new with a wiring harness and instructions. These can be had for less than $150. My favorite approach is to find a core and get it rebuilt with a lifetime warranty. If you go this route, remember these starters are wired differently. I should have a copy of the wiring diagram (it's very simple), if you need it.
Aftermarket bellhousings and heads, suspension modifications, steering modifications (like the Shelby quick-steer kit with longer idler and pitman arms) can complicate matters as well. In many cases, oil filter relocation (using a 90 degree elbow or remote filter), will be required or will make things easier. My swap headers fit with only a little clearancing on my Lakewood scattershield. Another tip is to install a torque strap to limit engine rock under acceleration. This can keep the headers and air filter case from making contact with inner fenders or hood. I also suggest you wait until you've made a trial fit and any needed modifications before you have any sort of coating applied to the headers. Over the years, the shock towers on early Mustangs tend to sag towards each other. This can complicate a 351W or 351C engine swap. The proper dimension for 64-70 Mustangs is 40" from inner fender to inner fender (at the Monte Carlo bar mounting points). You may need to use a port-a-power to spread them apart. Once you have the engine in, install a Monte Carlo bar to keep the shock towers from flexing under load and causing clearance problems. Hood clearance will be tight. If I remember correctly, the '65 motor mounts lower the engine farther than the '66 mounts. They are better for hood clearance, but worse for ground clearance. Low profile intake manifolds and air cleaners are generally required if you don't use a hood scoop. Remember to leave enough clearance to account for the engine rocking in its mounts. I use an Edelbrock F-351 intake and 14"x3" drop base K&N air cleaner on my 351C with room to spare. A local club member with the 351W in his Shelby GT350 used both Performer and Torker II intakes with a low profile Mopar open element air cleaner. In many cases, sparkplug access can be tight, so some general sparkplug tips are in order. The first tip is obvious but easy to overlook. Many sparkplug sockets have flats on them so they can be used with an open end wrench, instead of a ratchet handle. Sometimes the wrench will need to be bent to get the proper clearance. The second tip is handy when it's difficult to get a socket on the plug. Cut a U-shaped opening into the side of the socket. This opening can be aligned with the plug to gain clearance. Since the opening will weaken the socket, try to remove the minimum amount required for clearance. In some cases, you can also trim the overall length of the socket for additional clearance. Also, Accel makes plugs that are approximately 3/8" shorter than standard plugs. If you still can't get a socket on, try heating and bending a box-end wrench to fit. The final tip can help get the plug started in tight spaces. Push a piece of rubber hose over the end of the sparkplug and use it to position the sparkplug at the hole. Simply spin the hose to start the plug. Specially modified tools can also come in handy elsewhere. I bent and trimmed some box wrenches to make it easier to do home alignments. If you're still running points, you may want to switch over to a high energy electronic ignition to extend spark plug life. However, I'd stay away from platinum plugs. Under the right circumstances, platinum plugs can have remarkably long service lives, but they seem to be susceptible to rich mixtures and can foul easily. The 351W is approximately 65 to 75 lbs heavier than a comparable 289/302. A 351C is another 25 lbs more (see the engine weights and dimensions chart below). You can compensate for the increased front end weight by installing stiffer and/or taller springs in front. You may also want to increase rear spring rate or add a traction device to handle the increased torque. See the Early Mustang Suspension FYI for details. Of course, you can also lighten the load by using aluminum heads, an aluminum water pump, a lightweight starter, tube headers, a fiberglass hood, relocated battery or by deleting heavy accessories like air conditioning and power steering. On the 351C in my '66 fastback, I have no power accessories, an aluminum intake, tube headers, a lightweight starter, and a relocated battery (trunk mounted). I expect my front end weight isn't that much different than a '66 289 Mustang with cast iron intake and exhaust manifolds and maybe a few accessories. The magazines have featured 351W swaps a number of times: 1. "Windsor of Change", Mustang and Fords, September 1993. This article details a 351W swap performed by Dyno Don Nicholson into a friend's 1966 GT fastback. JBA swap headers were used. The shock towers on this car had sagged and had to be port-a-powered apart. The 351W was dyno tested with both Torker II and Performer intake manifolds. The Torker II, with a one inch spacer, made the most power but would not fit under the hood so the Performer intake was used instead. The car was fitted with power steering and a C4 automatic, both of which are not supposed to work with the JBA headers. Power steering bracket lengthening was required. A four core radiator was used. 2. "Old Favorite", Super Ford, November 1991. This article covers a 351W swap into a 1966 fastback using JBA headers and a T-5 transmission. 3. "'Stang With Sting", Hot Rod, date unknown. Another 1966 fastback with 351W, this time with Doug Nash 5 speed tranny. The 351W swap is, for the most part, straightforward. The 351C swap, on the other hand, is more involved. The Cleveland heads are wider than their Windsor counterparts, making the shock tower clearance problem more difficult. Special swap headers or shock tower modifications are required. Sparkplug access will be tight. The swap headers will have a 90 degree bend coming out of the port so exhaust flow will be hurt some. On the plus side, the 351C has a lower deck height, so hood clearance will be a bit better. The 351C also has better flowing factory heads and strong crank, rods, and main caps. It will take more work than a 351W swap, but the results can be impressive. Three list members have voiced their experience with 351C into 64-66 Mustang swaps. Here's what Darius Rudis had to say: "My best friend stuffed a 351C (yes Cleveland 4V) into his 1966 coupe. This I would say physically fits, but not really. By the time the shock towers were sledge hammered out it looked pretty sad. The car is fast as hell, and a real sleeper. The hardest part of driving it is not switching lanes as you shift the toploader cause of all the torque and tire spin it is difficult to drive hard. The 351W, I am not sure how hard it would be to stick that in, but I know it is a lot less difficult than the 351C. Plus there are companies who sell headers for the swap." Here's how Dave Williams responded: "-> My best friend stuffed a 351C (yes Cleveland 4V) into his 1966 coupe. -> This I would say physically fits, but not really. By the time the -> shock towers were sludge hammered out it looked pretty sad. When the front end finally gave out in my '70 Torino I yanked the 11.2:1 351CJ and put it in a 1966 notchback. It was *not* a happy swap. I had to sledgehammer the shock towers, grind the A-arm bolts, and grind on the manifolds. A couple of places sell headers which are supposed to work with that swap, but I don't know how they'd run them. The engine had about 1/16 inch clearance on each side, and I got rid of it before I had to worry about changing spark plugs. The only practical way (short of pulling the motor) would have been to cut holes through the fenderwells. -> > exhaust system. I've been told that the only headers available are -> custom > made by JBA and have a list price of $899. Cyclone used to sell some, Hooker still does. They're substantially cheaper too. If you really, *really* want the Cleveland in there, check into the Crites big block conversion. They sell modified A-arms and shock tower plates. You carve out the stock towers and weld in new suspension pickups, a'la the Fairlane Thunderbolts. The Crites kit was, as I remember, in the neigborhood of $300 a couple of years ago. It would give you plenty of working room around the engine." My results were much better than either of these. I used special swap headers (from Total Performance) which ended up requiring a lot of re-work, but the final product is very strong. The headers are individually flanged and slip-fit into the header collectors, with two of the tubes passing under the engine and into the opposite side collector. The swap headers are a bit big (1 7/8" diameter primaries, 3 1/2" collectors) but they are the only size available for the 4V heads (1 3/4" primaries are available for the 2V heads). The approach is sound but the fit quality was pathetic. Initially the headers were bolted to a spare block for a trial assembly. Bolted to the engine, the primaries were not even close to fitting into the collectors. There was steering linkage and oil pan interference, as well. After several trial fits, all the tubes were re-bent and a couple of sections grafted on. Still, the shock towers had to be slightly massaged (heated with a torch and tapped with a body hammer, repainted and undetectable) to get everything to fit. When I called Total Performance to express my displeasure, I was informed that 5 out 10 people get them to go together without too much trouble, 3 out 10 have trouble but eventually get them to fit, while the last 2 just give up! Besides Total Performance, others have swap headers that will do the job. Their telephone numbers are listed above. A re-located oil filter was necessary, as was a larger radiator. I used a larger 3 core unit from a V8 Maverick with A/C. This radiator has different mounting points so I had to move the pick-up points. This set-up provided adequate cooling for a previous 351W powered '66, but has proven to be inadequate for my 351C. It worked okay when I had the stock converter, but when I installed a high stall speed converter, it was immediately apparent the heat load had increased. I added an auxiliary tranny cooler but it hasn't helped much. It sits in front of the radiator and just seems to super-heat the air flowing past the radiator, reducing its effectiveness. There are several manufacturers of replacement 3 and 4 core radiators for 64-66 Mustangs, but they are all constrained by the physical size of the radiator support opening. One of the vendors also makes a late model style cross flow unit which requires cutting the radiator support opening to match the (much larger) radiator dimensions. I've not pursued this much since I plan to switch to a Tremec 5 speed manual, which should reduce the heat load considerably. If, after the tranny swap, I still have cooling problems, I plan on opening up the radiator support and fitting a late model style cross flow radiator. Wrapping the headers with Thermo-Tec might also help, but they can turn the headers brittle over time. One other radiator note. The stock 289 radiator has both the inlet and the outlet on the same (passenger) side. 351C, 351W, and late model 5.0 engines all have water pumps inlets that require the bottom hose to be on the driver's side. Any competent radiator shop can move the lower radiator hose neck to the driver's side to match the water pump inlet. One other problem I ran into is the steering box. The '65-'66 Mustangs have an integral shaft steering box and there's no way to remove it with the 351C in place. Instead of pulling the engine, I just used a cutoff wheel and cut the firewall area above the steering shaft. Pulled and replaced the box then Mig welded the piece back. The trickiest part was keeping the interior from catching fire (used a helper with wet towels to keep things cool). Before swapping the engine in, you may want to rebuild your steering box or, better yet, swap to the non-integral shaft set up of the '67-'70 Mustangs. I've re-worked the suspension to match the increased power of the 351C-4V, so I didn't have any of the traction problems Darius Rudis described . Subframe connectors, Monte Carlo brace, and export brace are highly recommended. The 351C really fills the engine bay, but the layout is quite clean. There are no messy emissions hoses or accessories to clutter up the bay. With a few customized spar kplug wrenches, the sparkplugs can be changed *without* loosening the motor mounts and jacking up the engine (unlike my Dad's 428CJ). I can also remove and install the starter without removing the headers or disturbing the suspension. Engine Weight and Dimension Comparison -------------------------------------- The following numbers come from an early Ford SVO catalog and are for "typical" engines. The dimensions include such things as air cleaners, oil filters, water pump fan, etc., but not bellhousings. Engine Width Length Height Weight 289-302W 24.0 29.0 27.5 460 302 Boss 24.5 29.0 28.5 500 351W 25.0 29.0 29.0 525 351C 25.5 29.0 29.0 550 351M-400 26.0 29.0 29.0 575 This is consistent with my experience (and other published numbers). As a check, I weighed several sets of heads and got the following weights: 50.0 lbs 289/302 - complete including rockers 56.5 lbs 351C 2bbl open chamber - bare 58.0 lbs 351C 2bbl open chamber - complete except for rockers 60.0 lbs 351C 4bbl closed chamber - bare Adding 2 to 3 lbs for valvetrain weight to the 4bbl closed chamber heads, yields 12 to 13 lbs more per head than a smallblock Windsor. For the pair of heads, figure on 25 lbs extra for Cleveland heads. A Cleveland block may actually be a bit lighter than a Windsor block, since they have a lower deck and thinner cylinder walls. Thus a 351C should be about 25 lbs more than a 351W (525 lbs vs 550 lbs). The 302 Boss weight estimate seems high compared to a 302W, especially considering it's aluminum intake. --------------------------------------------------------------------------- >Dave told me that he tried to get a 351C into a pre-'67 Mustang and >that you could even jump up and down on the thing and it wouldn't go >into the engine bay. Now as I'm wanting to put a Clevor in said space, I >have to wonder if it won't be the same brand of fun. If I remember correctly, Dave tried to put the engine in with the factory iron manifolds. You'd have to hack the hell out of the shock towers to make it fit that way. With the swap headers, it will slide in, assuming your shock towers haven't sagged towards each other. I saw one 351W swap where they had to port-a-power the towers apart for clearance. The biggest drawback with the swap is the headers have to make an abrupt 90 degree bend at the exhaust port. It's got to kill exhaust flow but it's the same with 351W swaps I've seen. I've also heard that guys with aftermarket Windsor heads on 351W's have trouble with the commonly available swap headers. You'll need a big radiator to keep 430 cubes cool. The stock radiator is tall and narrow but the grill opening is short and wide. Dump the stock radiator and cut the radiator support out to the width of the grill and mount up a Howe or Griffin circle track radiator. The extra deck height *and* the wider Cleveland heads may make for trouble. I bet you'd be looking at some re-work of the headers. Things are tight to begin with. --------------------------------------------------------------------------- >Dan, there's always a lot of questions about this swap. I think your >personal experiences would be quite helpful posted here. I know that I >would be interested. I've never attempted this swap, but get a lot of >questions about it. Okay, I've posted my swap info below. It includes notes about both 351C's and 351W's. Some of the info is outdated now and I've put in notes to myself to update it here and there where I need to add updates but you should be able to follow it. >One misconception is that the Cleveland doesn't fit without cutting the >shock towers. I've seen at least two of these swaps, using stock exhaust >manifolds, that required no cutting. The only ones I've seen that did not require notching the shock towers were the ones that used custom headers. No way mine would have gone in with stock manifolds. One big variable is shock tower sag. I've seen one 351W swap that needed the towers porta-powered back apart before the engine would go in. The Mustang Illustrated article that I mentioned earlier mentions they will be swapping the 351C into a '65 or '66 Mustang using swap headers and a swap kit from Pro Mustang Performance. It will be interesting to follow that story. Dan Jones