81 Bronco 351w donor block for 69 mustang?

[69shocktower]

Would this make a good donor block for building a stroker kit for a mustang? Dont know if theres differences in the block between, car and trucks. Dont think there are. Only differences are in the rotation assemblies and heads and what not. But the blocks are the same right?

Thanks,

 

[rbohm]

for the most part all the parts are the same. the later heads have smaller valves and ports, but other wise you can use the block with no issues. build away.

 

[109jb]

The 81 block will work fine, but you may want to consider a newer roller block. Depends on if you want to run a roller cam or not. The non-roller block can run the expensive linked roller lifters and a standard base circle cam, but the price is pretty high for those. You can also install the factory style roller lifters in a non-roller block, but you have to use a small base circle cam. With a factory roller block you can run the factory roller lifters and standard base circle cam. Its already set up. This would allow a cam profile that has faster opening and closing ramps which will let the engine breathe good for power, but still have streetable manners. The roller blocks came in about 1993 and can be identified by a "F4TE" stamped into the block casting. I think this is near the starter. The roller blocks are plentiful in pickups and should be able to be found pretty easily in salvage yards. If you are planning flat tappet camshaft then the 81 block will be fine. I myself plan on building up a 351W based stroker later and will be getting a factory roller block.

 

[69shocktower]

81 bronco 351w

Well Id rather have a roller block but this one is in an auction coming up and if it was cheap enough, Ive been asking around to find a block for awhile now and havent had any luck.

 

[brianj5600]

Get an F4TE and you will not be sorry. They are in pick ups and vans. Look for a white panel vans at the junkyard.

 

[countryboy116]

either the newer roller blocks are very nice or at older block i think tis about 69 or so 351w block is the strongest factory production block, the main webbings are thicker and are the strongest blocks to buy, that 81 block will be able to handle decent power though, it just depends on how radical of a motor you want to build

 

[Edster]

I'd rather have a Cleveland

 

[brianj5600]

It is not likely you will hurt 351W blocks with less 800hp. I have only heard of 2 351w's cracking. One a nitrous motor making over 700 to the wheels and the other would be classicboost on here. Classicboost's car ran 140mph in the 1/4 which would take 800ish.

 

[68stang351]

One thing to consider that I haven't seen mentioned is the clutch linkage (assuming you have a manual trans). There is no place on the later block for you to hook the Z bar to.

If you run an auto, then nevermind.

 

[dennis112]

One thing to consider that I haven't seen mentioned is the clutch linkage (assuming you have a manual trans). There is no place on the later block for you to hook the Z bar to.

If you run an auto, then nevermind.

Unlike the 302, Ford continued to cast the boss for the Z-bar pivot on the 351w block through at least 1990. I flattened the boss of my 90' block out with an angle grinder and then drilled/tapped the boss for the pivot (using my old 70' block as a dimensional pattern.) If that method doesn't sound feasible, the aftermarket 302 adapter will also work just fine.

 

[countryboy116]

It is not likely you will hurt 351W blocks with less 800hp. I have only heard of 2 351w's cracking. One a nitrous motor making over 700 to the wheels and the other would be classicboost on here. Classicboost's car ran 140mph in the 1/4 which would take 800ish.

I'm going to have to disagree with you, while it may be ok an 800hp windsor is seriously, i repeat SERIOUSLY pushing it, there are too many variables involved to say exactly what hp the block will hold such as what rpms you will spinnning when you make that 800 hp, ive always gone by and been told by some of the best sbf builders around that 600 is a good assumption to build it to and still be reliable and safe, again it depends what parts the motor is built with and what rpms the motor is turning, just my .02 cents

 

[brianj5600]

Have you ever seen a cracked Windsor block? I would not try 800 on a stock block if I was going circle track or road racing. Street/strip I am not too scared.

I know not all blocks are created equal, but there is a car on the turbo forums that has about 150 1/8 mile passes on an F4TE at over 800hp. At 3000 pounds it has gone 5.45 at 128mph. If you believe calculators that would take over 850RWHP and around 1000hp at the crank. 600hp seems very conservative to me.

 

[countryboy116]

Yes as a a matter of fact I have, I have seen a few windsor blocks crack, and one was pushing around 700hp, a factory production block is only good for around 600hp give or take, it really depends on the parts that the motor is built with and what rpms the motor is turning, 800hp even on the street will be still be pushing it the max, regardless 800hp on a 351w is not streetable so i doubt the op will be driving a 800hp car on the street, so more than likely if someone is building a 800hp motor it is for some sort of racing application. Regardless, with 800hp theres a very high chance that the block will not hold up, do your research if your going to be building a motor that powerful and do it right, dont half ass it using a factory block, a 69 block may hold up to the abuse but I'd still rather be safe than sorry.

 

[brianj5600]

I'll hope to be testing mine soon to 800hp. I hope it works out. It is very streetable and will not be revved past 6000rpm.

 

[countryboy116]

whats the specs on the motor, sounds like a badass little motor, keeping it under 6000rpm will help but im still gunna say youll need to be very careful with that much power on a stock block, and what you consider streetable may not be what i consider streetable, stree legal and able to drive on the street sure, but driving it on the street a couple days a week reliably and easily, not so much, id still love to hear specs on the motor though soudns cool

 

[brianj5600]

It is a 9:1, .030" over 351w with stock crank, eagle rods, dished pistons, AFR 185s, 228* .512" 112lca 111icl, 750dp, torkerII intake, S475 turbo. With the cam advanced to 107icl it idled fine in gear at 650rpm and 700 in park. Turbo cams usually are set at 110-112icl. The car went 6.90's in the 1/8 last summer with a smaller turbo, 3.08 gear and 3200 converter. I tried a 2.73 gear, but at 10psi it slowed to 7.0's. I am going to try the 2.73 with 6 or 8 more psi and see if it will work. The extra boost should make about 200 more HP.

This is with stock rear suspension with only an added main leaf to the 40 year old stock 6cyl leafs, worn out shocks and no traction devices of any kind. The car is driven to the track and everywhere else. The car is quiet and exhaust goes all the way to the bumper. I have owned an unstreetable street car. This one does not attract any attention until it spools up. This was 65 miles from home on the same tires I drove in on and pump gas.

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[68stang351]

Unlike the 302, Ford continued to cast the boss for the Z-bar pivot on the 351w block through at least 1990. I flattened the boss of my 90' block out with an angle grinder and then drilled/tapped the boss for the pivot (using my old 70' block as a dimensional pattern.) If that method doesn't sound feasible, the aftermarket 302 adapter will also work just fine.

Thanks for the info! I didn't know that, I have an 85 351w I'm building but I just never noticed it before.