Stroking a 302

[1975Bronco]

I have the 302 from my '69 completely apart, crank and all removed.

I am thinking about putting a 347 stroker together using the factory heads.

Am I clearly not of the right frame of mind?

 

[nirvana]

heads

the factory heads are a poor performance choice and would be very restrictive ...now i'm no engine guru...but i know for sure that those heads are not gonna work for you without extensive machine work. you would be better off skipping the stroking and getting a good set of aftermarket heads..in my opinion..good luck!

 

[Hozr]

I did a forged 347 stoker kit (SCAT) and used a set of P heads i happened to have lying around. Love it!

 

[DJs74]

Thumbs up on the stroker but thumbs down on using the factory heads in conjunction. You will increase your cubic inches and power potential with the stroker kit but if it cannot breathe, well... then it just won't perform very well. If you are considering spending the money and have a budget, I would do the stroker deal and top it off with a good set of aftermarket cylinder heads (AFR or Edelbrock, etc). If it were me (and funds were tight) and I had to choose one or the other, I would go with the cylinder upgrade over the stroker kit.

IMO, you can achieve better performance with the factory stroke & bore with good flowing cylinder heads versus a stroker kit with restrictive factory heads.

Cylinder heads + camshaft + carb + good ignition fire = a great cake. Add the stroker kit on top for the perfect icing. I can enjoy a good piece of cake without icing - give me a bowl of icing without cake - I'll pass



Good luck & let us know what you decide. These are just my opinions but I've tried & test many combinations so my offering comes with experience, not just theory.

DJs74

 

[1975Bronco]

Cylinder heads + camshaft + carb + good ignition fire = a great cake. Add the stroker kit on top for the perfect icing. I can enjoy a good piece of cake without icing - give me a bowl of icing without cake - I'll pass DJs74

This is the kind of anaolgy that make sense to me.

Thanks for everyones input, I think I will opt out on the stroker kit.

 

[eastbaybronco]

what about a stroked 347 and lightning heads?

 

[Mountain Ram]

Stock heads really won't allow you to get what you need with the stroked motor. It would be similar to a stock 351 in overall displacement and be just as choked. Heads need to be a part of the equation...

 

[Broncobowsher]

Just do a 351. Way more thought went into making a good durable mid-300 inch displacement engine. The added weight is not noticed in a Bronco as it would be in a light weight racer. Once you open a 351 and look at the parts and see how much beefier they are compared to a 302. Stock heads (any of the stock heads) will run like a stock engine. A 347 is just an expensive way to get a lightweight almost a 351.

 

[73azbronco]

More goes into a 347 than 347 cubes. Cam, heads, pistons, intake, exhaust, etc. If you want cheapest bang for buck, stay 302, or go 351. BUT, even a 351 is not a plug and play drop in as some try to make you think. If you want a 347, you need to read up on lots of stuff to make it right, and it won't be as cheap and easy as dropping in a crank and pistons. However, I have had a 170, 200, 302, 5.0, 351 and a 347, I prefer the 347.

Unless you really want more cubes, stay 302/5.0.

 

[Ourobos]

302 parts make 302 power..

Even a 351w with 302 parts makes 302 power.. I agree that a good set of heads, a proper cam, and a good intake will benefit you more immediately. THEN you can build the engine of your choice and bolt your parts on when you're ready.

 

[Broncobowsher]

302 parts make 302 power..

Even a 351w with 302 parts makes 302 power...

It just does it 500 RPM lower.

 

[jckkys]

I don't see why a longer stroke equates to an attempt to get more horse power. The logical reason to put in a 347 crank in a TRUCK engine is to have more torque. A 351 does this in an easier, more effective, and less expensive way. High flow heads, cam, intake, and exhaust hurt the low RPM part throttle efficiency, that is more valuable in a TRUCK engine. In a hot rod Mustang, it makes a little more sense to build a race engine.

 

[73azbronco]

Longer stroke does not get you more HP, it gets you more TQ. RPM gets you HP.

You are right on two out of three, easier and less expensive. It is just as effective to use a 347 as a 351.

High flow heads, cam designed for stroker to make TQ, not RPM, intake and exhaust systems all help a stroker make torque at the low end if properly designed.

To each his own, I chose a 347. Valid reasons for each though, and like I agreed, a 347 is not easier and not cheaper, but it is just as effective.

 

[Hozr]

I beg to differ on the factory heads. The P head (which everyone hates) is one of the best flowing Torque heads ever made for the SBF - for $1000 less than aftermarket.

You can make good power with stock parts and they can be very reliable.

Don't discount Ford parts.

 

[rguest3]

In the past 2 years I have had 2 broncos with identical engine builds. Same heads, same cam, same compression, same intake and carb. Both engines were balanced, both engines are Roller blocks.

The performance of the two seem to be identical as well. However, one is a 5.0/347 the other is a 351w

5.0/347 is about $500 more expensive to build but has No clearance issues.

351w has some hood clearance issues. May need 1" body lift.

Both are great motors in an Early Bronco.

 

[jckkys]

The 351 is more effective because less connecting rod angularity gives more torque and less wear. It's more cost effective because you can buy it cheap as used. The clearance problems are usually a result of intake choice. Edelbrock's Performer is too tall to easily fit under the hood. The '69-'70 Mustang-Cougar 4bbl intake works much better. No high flow racing parts are good for low end torque so early 351 or GT40 heads would be a better choice. Parts made to produce high RPM horse power are only good for racing. If a 351 won't make enough torque, stroke that to 383-390. Still no reason for racing parts.

 

[73azbronco]

Why the hate brother? My stroker doesn't have racing parts... It has a lot of custom parts for sure, none I would chose to run a 1/4 with. Nothing in my motor is made to produce rpm's, it all comes in at 1200 rpm and stops at 5000 rpm, is that low enough for you?

Your strokers are bad point is only valid if someone builds a high RPM stroker and puts it in a Bronco. Give us a little credit OK?

A 351 is not more effective due to angularity, that difference is minimal. The wear problems are minimal and unless you race the motor, strokers can last just as long as a stocker 351.

Thinking a stroker is an inferior engine is just wrong with what is known today about strokers. What you mention is old news. If strokers are less effective, why does Ford sell a crate one? Why

The clearance problem is driver side head/valve cover to body interference. Also intake, but as you noted, a good mid 70's low rise 4 barrel intake works fine. I had a 351 with this combo and it fit with no BL, however, the engine sitting closer to the body in back was an issue.

I guess if you hate strokers, you'll be hating 400's, 460's, 4BT's next?

 

[Broncobowsher]

If strokers are less effective, why does Ford sell a crate one? Why

Because there is a market to make money. They can slap that "Ford Motorsport" brand on it to make a few more bucks.

Not a hater of displacement. But when there are two different ways to get to the same basic level, then look at the minor differences. Which engine was built to last in a production setting? The 302 block was in production for years befor the 351 came out, why did Ford do all that work to make the 351? If the 347 is so good why was all that work put into making a 351? There had to be some really good reasons to spend all that budget to retool an engine with bigger bearings, bigger main cap bolts, even larger diameter head bolts.

 

[backpain]

The 351 is more effective because less connecting rod angularity gives more torque and less wear.

Agree the two are different ways of getting at HP and TQ with the same CIs. However, the typical Ford 347 kit produces a closer rod ratio to a Chevy 350 than Windsor . . . so, all Chevy 350's are worse for wear than Ford 351s? Of course not. It's a little more complex than only the rod ratio. Notwithstanding other good points, I wanted to highlight that one a bit.

Extending the concept . . . .stroked 351Ws make exceptionally good (and FUN) motors

 

[Mountain Ram]

The 302 block was in production for years befor the 351 came out, why did Ford do all that work to make the 351? If the 347 is so good why was all that work put into making a 351? There had to be some really good reasons to spend all that budget to retool an engine with bigger bearings, bigger main cap bolts, even larger diameter head bolts.

Why did ford make a 351C or the 351M/400???