580hp 4.0 NHRA dragster motor 8000 RPM!

[John]

The wearing of sandals and the casting of molten metal never worked well anywhere.
John

[gradon]

Maybe funny fuzzy bunny slippers would be better.

[SIXPAK]

4.0 main caps have metal that has been "removed" between the two main cap bolts effectively making the area supporting the crank have less material. 258 main caps are solid from one side to the other.

[John]

Maybe funny fuzzy bunny slippers would be better.

I can loan you a pair.. My point being that the metals industries for quality castings of that time line was awful spotty in quality. Get er done produced many local manufactured castings around the world, most of which were not what we would want in a performance builds. Many were done in ways and with materials that would be deemed impossible by established manufacturers. The Mexican motor was produced to be capable of running on gasoline of dubious quality and higher altitudes, A low compression motor for the design, they were up to the end use. With the demise of most of the casting operations here, Oilgear sourced their castings for their huge DX series hydraulic pumps to Korea and the reject rate of finished castings was staggering to the corp. Not a comment on anybody, but a strong comment on emerging technologies. By the way at my retirement from primary metals manufacturing I was the third generation of my family to do so.
John

[1bolt]

Personally I read it as either 258 or Mexican main caps... Of course as always I could be wrong. I have a lot of 258 caps I can compare everything from 88 back to a early 70's should be easy to tell if they are stronger... That said my initial reaction is that the 258 main caps I've seen over the years have all had the same sort of cavity's (one longer and one shorter presumed to be for weight relieving and iron saving)... but I can't remember how old the 258's I've torn down so far were... I can say this for sure, they were all 4 CW cranks. And I have at least one 12 CW crank sitting inside a long block awaiting tear down. So if older 258 caps have substantially more iron I'll know as soon as I pop the pan on it tomorrow.

One thing that leads me to believe he meant 258 AND Mex'can caps, was the fact that he said "4.0 caps" are junk... I think he would have specified "American caps are junk" if he meant 258 and 4.0 or at least said something like most 258 and 4.0 caps are junk...

Personally I think the billet steel bar across the top of the cap trick would be plenty of added strength. Remember we got more mains than your average V engine design.

Last but not least... Come on lifting up on the engine to get a cam in due to the block flexing? That lack of stiffness has to play a role in the Cam harmonic... Solid front and rear mounting plates (race car style) instead of traditional motors mounts sounds like a worth while mod.

[Mgardiner1]

I have never in my entire engine building career, ever heard of a block this short and small, "drooping".