Time for rebuild

[falcongeorge]

i think its a bb mopar problem.i have a bracket buddy rebuilding a 440 right now and he decided not to stroke it because of this

built tons of bbm’s never cracked a main cap. More problems with rod big ends, but you really gotta be winging the sh*t out of them. Bbm bottom ends are very robust in my experience.

My buddy that owns the dyno I use is hardcore Mopar.....he puts aluminum main caps on all his high-end BBM engines because of cracked main caps.  The aluminum caps absorb some of the bad harmonics.

All the mopars I built were iron heads, 500-575 hp range (Same power levels we are talking about here, anything will break if you push beyond its intended envelope) stock stroke, not only did I never crack a cap, I never saw any evidence of brinneling at the cap/main web interface, which I have seen on other makes at similar power/rpm levels. I HAVE had some experience with rb rods pinching in at the parting lines at the upper end of the engines I was building. As far as that goes, I have used aluminum rods to absorb the harmonics that otherwise eventually end up in the main webs, but I wasn’t doing that in B.B. mopars, and it was at much higher power levels than we are discussing here.
Clearly, I am rocking the Ford blue boat here, I’ll shut up now, back to your regularly scheduled programming.

[fryedaddy]

i think its a bb mopar problem.i have a bracket buddy rebuilding a 440 right now and he decided not to stroke it because of this

built tons of bbm’s never cracked a main cap. More problems with rod big ends, but you really gotta be winging the sh*t out of them. Bbm bottom ends are very robust in my experience.

My buddy that owns the dyno I use is hardcore Mopar.....he puts aluminum main caps on all his high-end BBM engines because of cracked main caps.  The aluminum caps absorb some of the bad harmonics.

thanks for the help Brent.thats what my buddy was concerned with -too much hp with the long stroke crank.worried about his main caps, beating on them too much

[69Shakar]

I forget that when I’m looking at the various dyno charts for 390’s and 445 builds that the ratings are at the flywheel.... with that being said why isn’t there a bigger difference in power and torque between the two especially with some of the fine flowing heads being offered now.

[My427stang]

First, the difference in power will be dramatic with a 445.  However, with your combo, I think HP goals and examples are not the right indicator.  Build to the use, and just wait and see, it'll feel like a monster.  I think if you dig around, you will find the torque numbers between these 390s and the 445s are night and day.   Look at those and look at average torque.  That being said, you can build a heck of a 390 to replace your tired one, but 28 inch tall tires and 3.25s will be happier with a 445

Second, I have never seen an FE main cap break, and I have certainly read and seen pictures of main saddles breaking, but have never had one come through here.  Especially at the power level and use you are talking, I wouldn't think twice, even with stock main bolts. 

I would build a hyd roller 445 for a 5700-5800 rpm peak, TFS heads look good for that with a small fast port that flows a lot of air, although Barry's heads will work great too, do a little professional rubbing on an RPM, and carefully assemble a zero deck shortblock at the right compression to match the cam choice.  It'll feel like a monster compared to your current engine.

[69Shakar]

Shortly after getting car had to rebuild rear end at that point had never drove the car at highway speed... so I kept the stock ratio but added limited slip.. it was open before.. found out on the highway with stock tires rpm was 3100 with the tire change it dropped it to 2700 and the car felt better...as I have been working on the car it is being based around the goal of a monster engine under the hood..and now getting sticker shock now that I’m trying to put together everything for the build.. 5 yrs ago when I had the on a dyno we were able to tune it to 290 hp and 385 tq.

[69Shakar]

Other than port matching what rubbing would you recommend?? also what is considered to be streetable manners?  I’ve heard the term but not sure of meaning.. i understand that with stroking and larger cam it will idle alittle higher than stock but how much is unsuitable for low speed manners?