351 dart block stroked to 427ci

MikeR351w · Apr 20, 2006

I have been brainstorming for quite some time about what to swap in my 93 Mustang. Recently I thought of a great idea. I could get a get a long block from CHP or somewhere else that is a 351/427 stroked engine. Could I use all my stock computer w/a spider intake with this combo if I make it EFI, AND because, it is a 351, could I re-use all my brackets and accessories??? I think that is could be possible. Would this combo be reliable and could I use my stock AOD transmission. ANY info or input would be much appreciated!

THANKS:SNSign:

86bluecobra · Apr 20, 2006

ok if you are referring to the brackets on the 302 in your car then no. since the 351 is wider because of the deck hieght you need different brackets. all the accsesory's can be used. yes you can use your automatic the question is how long will it last with all the extra power going through it. the computer will not like the stroked windsor. you will need to get it upgraded.

vristang · Apr 20, 2006

302 to 351W Swap In A Fox Body Mustang
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 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), but after that the block remained basically unchanged until it ended production. From 1994 on, all 351w blocks were equipped with roller cams/lifters.

Getting Into the Nitty Gritty

Firing Order-
See Camshaft Section

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 deck height and lifter combination, and using the stock 302 HO firing order (since you are most likely reusing the stock 302 computer). Probably the best thing you can do is ask the company you plan on purchasing the cam from, 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.
Here is some unverified info on Ford 302 & 351w 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 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 will 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 assy. 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 & stronger. 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.

Heads-
302 heads are 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 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 the 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 my 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 is 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 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. If a high volume oil pump is to be used, it is recommended that a high volume oil pan be used as well (most aftermarket pans seem to be 7qt).

Distributor-
The taller 351w does require a longer distributor. This can found from several stock Ford factory 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 351w swap. The EEC-IV will be fine until the combination gets more dramatic 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. 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. 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. Here is a link to my Fuel Injector Calculator...
http://www.freewebs.com/vristang/autocalculatorsformulas.htm

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. 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.

MikeR351w · Apr 20, 2006

Ok,

I understand that all the simple stuff will swap over. Will the distributor still work with the mustangs wiring harness'es? As far as I can understand, if I pull out the 302 and get a stroked 351 to 427, all of the stuff above should swap over. Now, what is the best intake/head combo that will allow the smallest cowl hood?? I am building a sleeper, so fitting it under the stock hood would be great. You also mentioned that my stock AOD would work. So you are saying that it should bolt up to the 351 block and work? Aside from a different flywheel. As far as my stock computer is concerned, if I tune it correctly, the computer should still work and think that the same 302 is under the hood, right? Thanks for all the info so far!

vristang · Apr 20, 2006

MikeR351w said:
Ok,

I understand that all the simple stuff will swap over. Will the distributor still work with the mustangs wiring harness'es? As far as I can understand, if I pull out the 302 and get a stroked 351 to 427, all of the stuff above should swap over. Now, what is the best intake/head combo that will allow the smallest cowl hood?? I am building a sleeper, so fitting it under the stock hood would be great. You also mentioned that my stock AOD would work. So you are saying that it should bolt up to the 351 block and work? Aside from a different flywheel. As far as my stock computer is concerned, if I tune it correctly, the computer should still work and think that the same 302 is under the hood, right? Thanks for all the info so far!

The distributor will need to be from an efi 351w. Not hard to find, just check the drive gear for compatibility with your cam.

I don't have any answers on the AOD, maybe someone else can help?
Please?

Yes a proper tune on a 427w will let the computer think that the stock 302 is still under the hood. That is exaclty the problem.
The bigger motor will want more air.
Make sure you have an appropriate MAF/MAS/Injector combo, and you should be fine, but far from ideal.

MikeR351w · Apr 21, 2006

That sounds good, thanks for all your help. I plan on digging into this project this summer, as I have nothing else to do this summer! I dont think it should be too hard though. Just a lot of $$$ for the rebuild. Thanks again! If you want to keep updated, check out my webpage at:

www.geocities.com/MikeR351w/Mikes_Mustang_Page

Thats where my car is and I will keep it updated during the swap.

Thanks all!

Rick 91GT · Apr 21, 2006

For a healthy 427ci motor I would go with a AFR225, Super Victor Spyder, so you'll need atleast a 4" cowl hood. You can modify the elbow to pint downward if you find you need extra clearance for the inlet piping.

Will this be a NA motor? Pump gas or Race gas? Depending on those answers you may need custom pistons to get the compression low enough

I'm getting ready to build a 434ci for a customer...with some boost

MikeR351w · Apr 21, 2006

I plan on making the 427 pump gas. I will also use (after talking to a machine shop) a late model 93 or so 5.8l from a truck or van and have it rebuilt to 427 specs using the CHP 427 stroker kit. I want to, but am not attached to the idea of, keeping the stock heads from the 351w that came with it and have them ported and put in a good cam and valve train. Other than that, I hop to reuse the stock intake, and bolt the beast back into the 5.0 's auto trans and hope she does not give in. If it does, then I will upgrade it. But my plan is to basically have N/A, 427ci that has great street manners and retains it's EFI and will be run off of the tuned EEV-IV computer. Will this work? You say you are going to build one, would my application work?

vristang · Apr 21, 2006

MikeR351w said:
I plan on making the 427 pump gas. I will also use (after talking to a machine shop) a late model 93 or so 5.8l from a truck or van and have it rebuilt to 427 specs using the CHP 427 stroker kit. I want to, but am not attached to the idea of, keeping the stock heads from the 351w that came with it and have them ported and put in a good cam and valve train. Other than that, I hop to reuse the stock intake, and bolt the beast back into the 5.0 's auto trans and hope she does not give in. If it does, then I will upgrade it. But my plan is to basically have N/A, 427ci that has great street manners and retains it's EFI and will be run off of the tuned EEV-IV computer. Will this work? You say you are going to build one, would my application work?

The one thing about this engine combo that most will dislike is the use of stock heads. The 351w heads are basically the same as the 302 heads, which can barely keep up with a healthy 302 (even with a great port work). Add 125ci, an intake, and a cam, and things will be far from ideal. You can make it work, but it won't be as good as bolting on a set of aftermarket heads, even if they are as cast.

Other than that, just be conservative with the cam, and the EEC-IV will be ok

jason

MikeR351w · Apr 22, 2006

The reason that I want to reuse the heads in because I am kind of on a budget. However, would porting the head on the 351, adding larger valves, and a better valve train do the job of a good aftermarket head? Also, what cam would you recommend, since the car will mostly only see the street with the occasional 1/4 mile run. Here is my budget so far,

427 stroker kit from CHP perfomance-$1799

Rebuild-$2000-$3000

Misc. Swap items-$1000

I dont want to spend more than $5000 if I dont have to. Also, do you know of any reputable 427-428 storker kits that high quality?

Rick 91GT · Apr 22, 2006

I hate to burst your bubble but a $5000 budget will not build the motor you want, let alone give you enough money to upgrade the tranny and the rest of the supporting parts you'll need.

I would want to see a AFR205 or 225 on that motor, with a Super Vic Spyder, 50# inj, PMS or other tuner, 75-90mm TB, and a 80mm MAF your looking at 500RWHP+ even with a mild hyd roller cam.

I wouldn't build a late model block, they DO NOT hold the power and will break with that kind of HP the motor will be capable of, seen it first hand.

I do this for a living www.rnhperformance.net and have seen a lot of this stuff.. Everybody wants a 400+ci motor that make 600HP but has no idea what it takes to maintain that type of motor or the rest of the chassis and drivetrain.

You would be very dissapointed with a 427 stroker, stock heads (no matter how ported, your wasting money), stock intake. Since this is a street car why no go 347ci, a box stock set of Vic Jrs, and all of the supporting parts, you would be able to come in closer to your budget, still over but closer... You could even go with a 347 with the TFS Track Heat kit, I've built a few of them and the results are great, still enough power to break the block in half....

As far as internals go what do you want to know, I can give you the run down on all the brands Rick91GT@suscom.net

MikeR351w · May 2, 2006

Ok, I am not too terribely concerned with the car making in excess of 500RWHP. I am more interested in having a big block car, as it will be unique and more than I will ever need. If it makes more than 400 at the flywheel, I will be happy. I plan on buying the kit from CHP performance. Is this a reputable company?

Heres the link http://www.coasthigh.com/Assemblies/Ford/ford_427w.htm

I can get the short block, preassemled and a stronger block, as you have said that the newer ones may crack for about $3500. This should save me a lot of money on the machine work. Also, after purchasing such a short block, what heads would you recommend? If Ford is an option, I would prefer since my dad can get 10% off.

This should bolt up to my 93 AOD, right? If this is too much trouble, as you have stated, would you reccomend one of the Ford crate engines as this would pretty much be a direct bolt on?

86bluecobra · May 3, 2006

yeas it bolts up to the tranny. as rick stated though the amount of hp and torque that this thing will make will eat your tranny and rear end. as for heads those afr 205 or 225's are the way to go. for ford heads i don't know. nothing they make flows like those afr heads. i guess get the heads that come on the 393 stroker long block from ford if you want ford heads.

MikeR351w · May 3, 2006

What kind of lower intake and upper should I get in order for the car to still hook up to the wiring harness and vaccum lines? I have heard that I can get a lower Victor Junior intake and then have a GT-40 on top. This would allow me to retain, the throttle body, egr and mounting hardware for the intake. What pound injectors do you think I should go with and since I must go with AFR heads, where will the fuel rails bolt to? Keep in mind, I want to have the whole setup run under the stock 93 computer, tuned of course. Major HP numbers is not my primary goal. Reliability, a/c, and emissions are where I want the overall end product to be. In essence, open the hood and have the engine look like a slightly modified 5.0.

Rick 91GT · May 5, 2006

I wouldn't be a good business man to recommend a company/shop other then mine..lol

The block from CHP is a stock 351W block, various years I am not sure if you can pick what year you want. I think you get what you get...

As far as an intake, you can not do a Vic Jr/GT-40 combo, imposssible.

Look at the 351W TFS-R if you want to retain everthing, rails will bolt up like stock as well. Injector size depends on what you final combo will be but most will use atleast a 42# inj.

86bluecobra · May 5, 2006

i was searching for intakes for fuel injected 351w. It looks like trick flow make the most. they operate between 2000-7000 rpm. which seems perfect to me. look em up on summit. quite a few there.

351 dart block stroked to 427ci

MikeR351w

86bluecobra

Advanced Member

vristang

MikeR351w

vristang

MikeR351w

Rick 91GT

Mustang Master

MikeR351w

vristang

MikeR351w

Rick 91GT

Mustang Master

MikeR351w

86bluecobra

Advanced Member

MikeR351w

Rick 91GT

Mustang Master

86bluecobra

Advanced Member

Similar threads

351 dart block stroked to 427ci

Advanced Member

Mustang Master

Mustang Master

Advanced Member

Mustang Master

Advanced Member

Similar threads

Privacy & Transparency

Privacy & Transparency