347 stroker in 1st gen Bronco

[Grey owl]

Anyone have an opinion about the drivability of a 347 stroker with a C4 behind it. Would likely use a little milder cam. Thoughts

 

[badandy73]

Drivability is great, more torque the better. Running one in front of a 4R. but the C4 will be fine depending on your gearing.

 

[Broncobowsher]

Way too many unknowns. Tire size, axle gearing are a couple of the big ones. A stock 302 with the right gearing for the tire size will run rings around a built 347 with the wrong gearing for the tires size. Not to mention sending the transmission up in smoke signals.

Done right, yes a 347 will run fine. A C4 can work, even in stock form. But if going that far, they make stroker kits for the 351 to run them up into the 400" range. At which point a good set of heads and a mild cam will be a lot of fun and very drivable, providing the axle gearing is correct for the tire size.

 

[Grey owl]

3:55 gear ratio, 235X70 15s

 

[gnpenning]

Just remember to include down stream drive train components in the cost as you increase torque and hp.

For some reason it gets neglected until the chasing your tail begins.

Whatever you decide make sure it matches your use and have fun.

 

[Speedrdr]

Just remember to include down stream drive train components in the cost as you increase torque and hp.

Where was that piece of sage advice when I had the PREVIOUS bronco? It only had around 320 HP but there was an abundance of “downstream” parts…and most all were pricey! Lol

 

[73azbronco]

Is the 347 built for 4500lb truck or 2000lb mustang?

 

[Grey owl]

Just remember to include down stream drive train components in the cost as you increase torque and hp.

For some reason it gets neglected until the chasing your tail begins.

Whatever you decide make sure it matches your use and have fun.

Seems to me the C4 can easily handle all a 347 can make and a 9 inch diff most certainly can. I guess that leaves the D20. They are pretty rugged and it won't be driven hard. Just looking to add another 150 hp but maintain the drive ability.

 

[AZ73]

Is the 347 built for 4500lb truck or 2000lb mustang?

This is key. I gave my complete vehicle specs to Jim at FordStrokers and he built my 347 to produce almost full torque from 1000 rpm through about 5500. I'm running 4.11's and 35" tires (although when it was built I spec'd 33") through a 5 speed, but I've beefed up the rest of the drivetrain to handle it. While your C4 can handle it and your rear differential housing can, your stock differential might not be able to take it, and your axles might be too weak (I think factory is 28 spline?) I replaced mine with 31 spline. Your D20 isn't a problem.

I did some basic math for your 3.55's and 235X70 15s compared to my 4.11 and 35x12.50R17 tires. I removed the transmission from the calculation to just look at torque to the ground through your differential compared to mine.

You come in at 0.254 torque to the ground while I'm at 0.235. Basically very close with a slight advantage to you in a direct comparison. To be an even match if I'd have to run 4.56 (which I should have) or even 4.88. So your set up using my cam would have a little better pull not accounting for the transmission

FYI
My cam is based on the 347, TEA prepped TF heads, 4:11, 33s, 4500 lbs. It's similar to a Comp Cam XE256H but the duration isn't as long. If you don't want to go custom cam, I would recommend the XE256H. You'll lose a little power at the bottom end, but since you're running an automatic with a torque converter, your motor has to spool up anyway and you'll gain a little power on the top end.

 

[Grey owl]

Thanks for this important detailed information. Should I proceed with this modification I will be in touch with you.
Thanks agsin

 

[Madgyver]

it is my plan. 347/C4

 

[Grey owl]

I did the C4 conversion last winter, I would now just like to wake it up with some more HP.

 

[73azbronco]

you want to wake the torque...

 

[Grey owl]

I am not using mine for off roading, the stock 302 is sluggish. Just want to make some more power

 

[73azbronco]

camshaft, intake. Headers. Way less than 347. And I would suggest a 351 vs 347 if you want bigger, it's far cheaper. I have 347, because I built it..

 

[pcf_mark]

This is key. I gave my complete vehicle specs to Jim at FordStrokers and he built my 347 to produce almost full torque from 1000 rpm through about 5500. I'm running 4.11's and 35" tires (although when it was built I spec'd 33") through a 5 speed, but I've beefed up the rest of the drivetrain to handle it. While your C4 can handle it and your rear differential housing can, your stock differential might not be able to take it, and your axles might be too weak (I think factory is 28 spline?) I replaced mine with 31 spline. Your D20 isn't a problem.

I did some basic math for your 3.55's and 235X70 15s compared to my 4.22 and 35x12.50R17 tires. I removed the transmission from the calculation to just look at torque to the ground through your differential compared to mine.

You come in at 0.254 torque to the ground while I'm at 0.235. Basically very close with a slight advantage to you in a direct comparison. To be an even match if I'd have to run 4.56 (which I should have) or even 4.88. So your set up using my cam would have a little better pull not accounting for the transmission

FYI
My cam is based on the 347, TEA prepped TF heads, 4:11, 33s, 4500 lbs. It's similar to a Comp Cam XE256H but the duration isn't as long. If you don't want to go custom cam, I would recommend the XE256H. You'll lose a little power at the bottom end, but since you're running an automatic with a torque converter, your motor has to spool up anyway and you'll gain a little power on the top end.

How does this cam idle and what is the low end performance characteristics? I asked because that is a pretty stout cam on paper.

 

[Grey owl]

camshaft, intake. Headers. Way less than 347. And I would suggest a 351 vs 347 if you want bigger, it's far cheaper. I have 347, because I built it..

I have had several 351 Windsors, built a dozen different engines from a 11 second 300 six 66 mustang to a stroked 351 in a rear engine dragster. Boss 302's, several Clevlands. So I know the options, bigger is not always better plus I want to maintain stock air filter and stock appearance.

 

[AZ73]

How does this cam idle and what is the low end performance characteristics? I asked because that is a pretty stout cam on paper.

 

[Broncobowsher]

Stock air filter will work on a 351W.
A really mild 351 build, add a bump in compression to the low 9s, and they run good.
Broncos are fun to drive when there is ample torque. HP doesn't make them fun, just scary. The kick in the pants from good torque is more enjoyable then being able to do 130 and still pulling hard.

 

[pcf_mark]

That is a pretty high idle what is it like at 850 rpm? I was thinking lumpy and soft. Nice build i bet it is a hoot.