351w guys come on in...

BOWTIEKILLR · Aug 20, 2006

my motor is slowly fading...and a 351 seems to be my best option. im going carbed simply because i HATE HATE HATE dealing with computer gremlins and i know im sacraficing driveability, gas mileage, blah blah blah. ive owned 2 67 mustangs befor that were carbed and have 3 other classic stangs at my house all carbed. i know what im getting into. i have all the avilibility in the world to build the motor (gf dads shop has everything and i could get almost anything i would need)and i just need a few suggestions on what to go with as far as motor mounts, intake, distributor, tranny selection, hood clerance and selection, cam suggestions etc... im aiming at a moderately built 351/357 and around 350-400rwhp.

351 82GT · Aug 20, 2006

Here's a combo that will get you the HP you're looking for...

351w bored .030 w/ 11:1 compression
AFR 185 heads
Long tube headers
solid cam with 245/250* duration(@.050) .550/.555 lift
Victor Jr. intake
750dp Holley
4:30 gears
3500+ stall converter if running an auto

Depending on what mustang chassis you put this in, it should get you mid-high 11 second ride.

BOWTIEKILLR · Aug 20, 2006

i have a 88gt hatch and i will be running some sort of manual tranny, i know its kinda ridiculious but i might run a toploader 4speed so i can road race the fack outta it and not worry bout breaking anything. i also can get them for real cheap. i like the combo you gave me, i also think i have some world products windsor jr heads...those any good? im probably gonna run 3.55 gears because it will be daily driven and gas mileage is a small factor. my goal is 11s in street trim. basically i dont wanna loose to those damn new vette z06s.

R2D2 · Aug 20, 2006

windsor jr head is decent, a bit small. Toploaders are phenomenal manuals. Too many ways to build a stout windsor to list. Just start with the cylinder head and build it around them

351 82GT · Aug 20, 2006

The toploader is an excellent tranny. If it was ME, I would opt for a Tremec TKOII tranny so I would have overdrive and be able to run some steep gears for the track BUT....that toploader will work fine.
The windsor Jr. heads are pretty good. I have a friend that runs a very similiar setup like the one I suggested above and he runs 11.4 with them...with a C4.

BOWTIEKILLR · Aug 20, 2006

i have the windsor jr heads avaliable and im thinking of running them at least until i can afford some afrs or something similar. i agree with getting a tkoII, tko 600, or even the new gt500 tranny, but i also wont have $1600+ to drop on a tranny anytime soon. and i also heard the tkos have trouble shifting above 5k rpms. i could get a toploader for next to nothing and i think i might just run it till i get everything set up, then swap the tranny as well as a new rear end. now as far as motor mounts and hood clerance...anyone know if it could be made to fit under a stock hood with the victor jr manifold? maybe with vert motor mounts? how much cowl is needed?and should i use the oil pan listed in the ford racing catalog? or should i look for a nicer aftermarket pan?

351 82GT · Aug 20, 2006

I THINK but not POSITIVE that you will need at least a 2inch cowl hood. In fact, I'm pretty sure you will because I have an '82GT with a 351w and stealth intake and I probably have about an inch , or not much more, clearance, with a 2 inch cowl hood.
I don't know how much you would gain with vert motor mounts.

vristang · Aug 20, 2006

This is a collection of info I have put together on the 351w swap.

It is focused on EFI, but things like motor mounts, and hood clearance are the same.
Also, the year of block you select will have an impact on the roller cam/lifter setup.
If you go flat tappets it won't matter though.

http://www.freewebs.com/vristang/fox351wswapfaq.htm

good luck,
jason

302 to 351W Swap In A Fox Body Mustang

VRISTANG

Note: This FAQ was written for converting a T-5 5.0 efi Mustang to a T-5 351w efi Mustang. The conversion will be slightly different if starting with a 2.3l or carbureted Mustang OR converting to a carbureted 351w. Converting transmissions is beyond the scope of this document.

Background Info-

The major disadvantage of the 302 is its lack of strength at high power levels. Most will agree that at ~500hp the factory 302 block will try to split in half. For many the solution to this is an aftermarket 302 block.
Another alternative is to swap in a 351w block. There are 2 production blocks available; the 69-70 blocks had a deck height of 9.480”, and the 71 up blocks had a deck height of 9.503.” This is compared to the 302 deck height of 8.200” The 69-70 blocks also had thicker main webs and higher nickel content, making them significantly stronger. From 70 to 74 the 351w maintained some of the higher nickel content, but lost some of the material in the main webs. Another small reduction in the main web thickness occurred in 75, along with another reduction in Nickel content (supposedly). In 1992 the lifter bores were lengthened (made taller) in order to accomodate standard roller lifters and standard base circle cams. From 1994 on, all 351w blocks were equipped with roller cams/lifters.
Note: The nickel content statements above have not been verified

Getting Into the Nitty Gritty

Camshaft-

The specs of the cam will depend mostly on what your goals are for the motor. Cam spec selection is way beyond the scope of this FAQ. What you want to watch out for is selecting the correct base circle for the lifter combination and using the stock 302 HO firing order (since you are most likely reusing the stock 302 computer).

69-91 351w blocks -
Option 1) Standard Base Circle Cam / Aftermarket Linked Bar Hydraulic Roller Lifters
Option 2) Small Base Circle Cam / 302 HO Roller Lifters

92 & Later 351w blocks -
The Standard Base Circle Cam can be used with 302 HO Roller Lifters.
A Small Base Circle Cam is not needed in these blocks.
(The 92 and later "roller" blocks will have a F4TE casted into the block near the starter)

If using solid lifters (either flat tappet or roller) then a standard base circle cam can be used on any year 351w block.

If in doubt, ask the company you plan on purchasing the cam from (or better yet a reputable engine builder) what would be appropriate for your application. They will need to know what year the block is and what lifters you plan on running. Additionally it may be helpful to have your rocker ratio available, and what piston you will be using if not stock.
NOTE: Small Base Circle Cams are known to be less than ideal, as they are weaker. Also, there are not as many cam profiles available for the Small Base Circle Cams, so your Off The Shelf Cam selection will be limited. If possible, it is recommended to avoid the Small Base Circle Cams.

Firing Orders-
Early 289 & 302 1-5-4-2-6-3-7-8
302HO & 351w 1-3-7-2-6-5-4-8 (this is all 83-93 Mustangs, and all 5.0 Explorers)

Pushrods-
Again, there are far too many options available to cover here. Check with the cam manufacturer on what length pushrod you will need. Or even better, you can use a pushrod length checker and measure them yourself.

Roller Lifters-
The stock 302 lifters can be swapped over to the 351w (see the cam discussion above) with a little machining and grinding. First the spider will require 2 holes to be drilled in the main valley. These holes will be drilled over the cam bearings, so great care should be taken not to damage the camshaft or bearings. Risk can be minimized by removing the camshaft, and drilling the holes before the cam bearing is installed. Some grinding may need to be done to allow the factory 302 dogbones to sit flush on the 351w block as well. A dremel is adequate to get the job done. Be patient and work slow; it is easier to remove material than put it back. Of course it would be best to do this work before having the block cleaned and prepped for assimbly. Ford Hydraulic Roller lifter (for both the 302 and 351w) part number is M-6500-302.
If all of this does not sound appealing to you then maybe some of the aftermarket roller lifters will be a better option. These tend to be fairly expensive however. Look for lifter pairs that have a link bar, connecting each pair of lifters.

Rocker Arms-
This will depend on the heads you select. All of the same rules that apply to selecting rockers for a 302 still apply to the 351w. Options to consider are Pedestal vs. Stud Mount, Roller vs. Non-Roller, and Brand.

Engine Mounts-
Stock 5.0 mounts will bolt up to the 351w. Aftermarket alternatives include solid mounts and polyurethane mounts. Convertible Engine mounts are supposedly reinforced & shorter. Another alternative is lowering engine mounts from HP Motorsports. These are solid and lower the motor ~¾”. Lowering engine mounts are useful for gaining hood clearance, but will also reduce clearance between the oil pan and stock k-member. This presents clearance issues with some aftermarket pans and stock k-members, but should be ok for the FRPP pan. The use of an aftermarket tubular k-member may help improve clearance with aftermarket oil pans.

Heads-
302 heads are basically the same as the 351w heads with the exception of the head bolt diameter. 302 heads have a 7/16” head bolt hole and the 351w has a ½” head bolt. Opening the holes can be done by hand, if done with care. It would be best to send this work to a machine shop however.

Exhaust Headers-
Stock 302 headers will bolt up to the head of a 351w (since the heads are basically the same), but will not mate up to the factory 302 mid-pipe due to the extra width of the 351w. There are many aftermarket suppliers of 351w Fox Body headers including MAC, FRPP, Kooks, Hooker, and Hedman. The Ford shorty headers are p/n M-9430-A58.

Intake Manifold-
Since the lifter valley of the taller 351w is wider than the 302, a new lower intake is required. Aftermarket suppliers of 351w intakes are numerous. Most of these companies offer a 351w lower intake that will bolt up to their 302 upper intakes, which many Mustang owners may already have. Being able to reuse your current upper intake can present a significant $ savings.
Be cautious with intake height if you are trying to clear a stock hood. If the above mentioned drop motor mounts are not used then, another option is to cut down the upper intake. This is easier on the plastic box upper from Comp Cams, as the aluminum intakes will require cutting/welding followed by machining to square up the mating surface.
Shortening the upper intake will cause clearance issues between the TB and valve cover if the upper is trimmed more than ~¾”. Keep in mind that TrickFlow and many other aftermarket head companies have raised the valve cover flange up to .300” which will limit how much you can trim from the upper intake. Of course the use of tall aftermarket valve covers will be somewhat restricted as well. If you do plan on cutting the upper intake, be sure to do a full mock up with all parts that will be installed later. The part numbers for the Ford 351w Cobra manifold are as follows; Upper M-9424-D50 / Lower M-9461-D58.

Oil Pan-
The 351w oil rails are wider so a new oil pan is required. The lowest cost option is probably the FRPP 351w pan for Fox Body applications (M-6675-A58). Aftermarket companies have standard volume, high volume, drag race, and road race pans available. A pan specific pickup tube and dipstick will also be necessary. If using a main girdle and/or windage tray, be sure to select an oil pan that will clear these added components. If you can find them, the 351w equipped Crown

Victoria and Grand Marquis had an oil pan that will fit in your Fox Body Mustang.

Oil pump-
The 351w oil pump is different from the 302 (mostly external). These are readily available in standard volume, high volume, and high pressure models.

Distributor-
The taller 351w does require a longer distributor. This can found from several stock Ford factory efi applications, mostly pickup trucks/vans. Some aftermarket suppliers do have electronic/TFI distributors available, such as MSD and Accel. Be sure that the cam drive gear is appropriate for your application. Roller cams require a steel dist. gear.

Engine Management-
Any stock 302 computer will handle a mild to moderate 351w swap. The EEC-IV will be fine with larger injectors, heads, intake, and cam. Aftermarket plug in style chips are not going to offer ideal performance. The best solution is to invest in a chassis dyno tune or an EEC-IV computer tuning system, such as a TwEECer.

Flywheel/Flexplate & Starter
The counter weight of the 5.0 is 50oz. The 351w counterweight is 28oz. You can reuse your 5.0 flywheel if you have it rebalanced at a machine shop. This is probably the easiest and most cost effective alternative, but may affect durability. If purchasing new parts just make sure that the flywheel weight and starter tooth count are correct for the other components you already have. Ford flywheel M-6375-A302.

Harmonic Damper-
Again this must be matched to the 28oz. counterweight of the 351w. Another consideration here is getting the crank pulley to line up with the rest of the serpentine belt system. Many aftermarket dampers will come with an appropriate spacer for this application. FRPP does have a damper available specifically for this application (Damper M-6316-C351, and spacer M-8510-B351)

Fuel Injector Rails-
The stock 302 rails will not be wide enough to fit the wider 351w lower intake. However, if the flex line in the front and rear of the stock rails is removed and replaced with longer sections of high pressure fuel line the stock rails will work just fine. Simply cut out the stock flex line and replace it with high pressure fuel line, available from any parts store. A couple of hose clamps will secure the hose in place. It is also important to make sure the hose does not rub on anything.

Fuel Injectors-
Proper injector size will depend on the application. A mostly stock 351w will be ok with 19lb injectors, but with the addition of an intake & Throttle Body (with stock heads/cam) will most likely require 24lb injectors.

Fuel Pump-
A 190lph pump is recommended for mildly modified Mustangs. If an all stock 351w is being swapped in, then the stock fuel pump may be adequate. It should be noted that due to the re-circulating nature of the Mustang fuel system, installing a pump that is too large is not an issue. If in doubt, go with a larger fuel pump.

Heater Core Hoses-
The stock 302 routed the heater core coolant through metal tubes on the passenger side of the lower intake manifold. These metal tubes may or may not bolt up to the 351w lower intake. Either the tubes can be replaced with tubes from another application (junkyard parts), or heater hose can be used to replace the metal tubing. Just be careful that the hose will not bind or rub anywhere, especially the throttle linkage.

AC/PS-
This is the only stock 5.0 accessory bracket that requires modification. The original AC pump and Power Steering pump can be reused if an FRPP bracket is used. If using Power Steering only (without A/C), the FRPP part number is M-8511-A351. For both AC and PS applications the FRPP number is M-8511-B351.

Emissions-
Most emissions equipment can be swapped over, and will be required if the car is to pass emissions testing. The smog pump will present few challenges; mostly just routing of the hoses.
The EGR setup will depend on the application. The stock 302 routed the EGR gasses through the lower/upper intake. With some creativity the AIR passages on smog legal heads can be used for EGR, in fact several factory applications used a crossover pipe, which routed the exhaust gasses from the heads up to the EGR valve. These crossover pipes can be found on 351w equipped trucks and vans.

Hood-
The easy way to do it is get a taller cowl hood to replace the stock hood. This offers the aggressive look that many are looking for. If desired though, the 351w can clear the stock hood. Clearance will depend on engine mounts and intake manifold selection/modification. If necessary some of the bracing on the underside of the hood can be cut away, and the insulation mat can be removed. In general at least 3/4" will probably need to be trimmed off the height of the new 351w motor, but this will vary greatly with each combination. The reduced height can be achieved with lowering engine mounts (as mentioned under the engine mount section), or by shortening the intake manifold (as mentioned in the intake manifold section). There will be some mock-up needed for each application.

Miscellaneous-
Spark Plug Wires
Some Vacuum hoses may need to be lengthened or shortened
Accessory drive belt length will most likely change

Items Not Affected By the Conversion-

Transmission - Be sure to use the correct input shaft bearing in the crank
Bellhousing
Valve Covers
Belt Tensioner
Water Pump
Alternator
Clutch
Timing Cover
Radiator and hoses
Timing Chain
Oil Filter (the 351w uses the same part number)
Head Gaskets (same part numbers apply)

Desirable Upgrades-
3 core Radiator and Electric fan
Subframe Connectors
Tubular K-member (if clearance issues are feared)
Z-spec T-5 (or other high power upgrade)
Torque box Reinforcements
2.5” or larger exhaust
1 5/8 headers should be considered a minimum with 1 ¾ being ideal.

BOWTIEKILLR · Aug 21, 2006

thanks for all the help guys. vristang...you have any numbers or times?

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