302/351w weakness

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Nov 23, 2009 | 10:58 PM

#16

doug1222556

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Joined: Mar 2007

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Quote:

Originally Posted by TriumphTune

And I'm guessing that the cost of machining (as mentioned above) is close to the 250 to 300 range I've seen for I-Beam rods from Eagle or Scat (depending on the shop of course)? Are the stock bolts fine for a stock rebuild with upgrades geared to reliability and a small increase in low rpm power?

Josh

I think that that would be on the high end for sure. Remember though that you have to add the approximately $50 of the cost of the bolts in and there are some cheaper rods out there.

The stock rods should be fine with the stock bolts for a fairly large increase in HP. It just never hurts to have a little extra insurance, but you should be fine.

Nov 23, 2009 | 11:15 PM

#17

American Thunder

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Joined: Apr 2009

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From: Upstate New York

Quote:

Originally Posted by Mustang6147

Actually the Bottom ends of both engines are pretty strong, but the 302 's short comings are the Block.

I was part of a test, in a drag raceing enviroment. We built the top end of a 302 in an 88 Mustang. It included a home made plenum. Shortened rear end 35 inch slicks power glide tranny. Stock bottom end, not rebuilt, it had 86000 miles on it. we thought it would be fun to put as much HP threw it that we could, until it blows.

This engine had close to 650 HP and ran low 10's consistantly. What broke on the enigne, was the block. It cracked between the lifters.

That is 1 example. I also have pictures of more 302 block failures, even with ARP studs, holding the rotating assembly together.

The difference between the pre-1980 blocks, and the modern 5.0 blocks is quite a bit of material around the main webbing. If I recall, the older 289/302 blocks are 20-40 lbs heavier than the newer blocks. That '88 block you used is supposedly safe to about 450 hp, basically forever. The older blocks are reliable to much higher hp levels. Especially if you use a main stud girdle. The '72 302 block I used as the foundation in my 332 stroker motor has survived 8500 rpm and 530 hp for 10 years now, with no issues whatsoever as of yet. That extra .250" of stroke I'm running seems small, but the increased stress it places on the mains is quite a bit. If you're going to build anything even semi-serious, an early block + stud girdle will hold together surprisingly well.
As for the stock rods and all, I've thrown together "Grenade motors" for dirt cheap, with stock lower end, ported heads and solid cam, and screamed them up past 7k rpm, and they held strong. I even used cheapy Badger pistons once that cost me a whopping six dollars a piece,(they were heavy) and the damn 302 still wouldn't come apart. The rods are amazingly durable, even with the small stock bolts in them. Ford's metal quality is very respectable. Really the biggest weakness in a 302 is the oil pump drive shaft. That steel pencil really isn't too great.

YouTube - 1977 Mustang II 332" 530hp stroker motor throttle response
Stock 302 block, video.

Nov 24, 2009 | 09:17 PM

#18

Blurry94

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Joined: Jun 2003

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From: Calhoun GA

Quote:

Originally Posted by Country705

just a little bit above stock. basically i want to get in my truck and go. i dont want to have to worry about weither my truck will make it to my job which is 45 miles away or make it home at 5am when i get off. i just want it to purrrrrrrrrr like a kitten and take me to my mom's house which is up a steep gravel road with a huge hill. i dont tow anything just drive.

The strength of the rods should not be an issue for what you're looking to do, if anything, I'd worry more about the hardware. It doesn't hurt to have the rods checked though; in many cases you can have a machine shop check and resize them with new hardware. Inspect the crank journals and install new main bearings with new bolts and the rotating assembly should last a long time.