Just curious if the main bearings are all one piece... How does one get the crankshaft into the engine in the first place?

 

I would think it would be pretty hard to stretch one piece mains past the counterweights.

Only time I've seen those is on a motorcycle engine where the crank is in two pieces. At least I think that's right. And they were roller bearings.

 

Could it have been something similar to a main cap girdle?

 

No no it was a one piece main bearing set up. But I dont mean one piece with the block. The mains themselves {ie: the mains you unbolt and take off} were one piece. Then you bolted the piece back on like normal main bearings except the main caps were all one piece.

I thought about the difficulties of clearing the crank counterweights too. I wonder if one of the high volume racing oil pans would allow enough clearance?

Steve

 

Hey everyone,

I saw a friend of mine taking apart some honda engine the other day. I dont know much about honda's but this piece got me thinking. The mains were all one piece. Instead of the seperate ones like on a sbc. I assume that setup would stregthen the lower end somewhat and possibly allow some higher rpms? I was just curious if anyone has done it? Is it worth a try? If I ever get some time Id attempt to make a one piece main for my test bed 305 {gotta blow it up someday LOL}. Just wondering what everyone elses thoughts were?

Steve

This again is WW II aircraft technology that has crept into production autos. Like cross bolts used in the Daimler Benz series inverted V12, the Rolls Merlin and Griffin, the Allison 1720 (the latter engines being upright V12s) and many other highly stressed aircraft engines where this is used to stiffen and strengthen the bottom end (crankcase).

This had been commonly found on Japanese engines for quite some time and has found it's way onto GM's new LS series engines. It's very useful for aluminum blocks which are softer than cast iron so it takes better engineering to keep them together to meet Federal/Ca/EU/Au/NZ/Nippon emissions regulations.

Now that last sentence got you I'm sure as one thinks of caged mains, bearing girdles, and cross bolts as something done to keep high output engines together. The driving issue was that over the decades aluminum blocked engines just didn't hold up. One of their big problems was block distortion that allowed excessive amounts of combustion gasses and lubricating oil to leak around the pistons because the the bores were pulling out of round from crank stresses reacted into the case. Since all the western democratic governments, Australia, New Zealand and Japan have stringent emissions regulations with a requirement for the new vehicle to meet these regulations for extremely long periods of time, 100,000 miles or more. Additionally, they are also required to meet ever improving fuel mileage requirements so getting weight off the vehicle is important to that end, thus aluminum becomes useful to meet those requirements. So if aluminum was to be used, engineers were driven to improve the product's strength such that case distortion was controlled so as to meet these emission and longevity requirements.

Meeting emission requirements has given us cars that are more powerful, with better handling, get substantially better fuel mileage, and last much longer than those of the "good ole days" When I was a kid getting a 100,000 miles on a car was a really big deal that didn't happen to many people. Nobody got there without at least a couple valve jobs; at least one re-ring job; 7 or 8 carb rebuilds; a couple exhaust systems; a radiator or two; 4 or 5 hose replacements; 10 to 20 sets of spark plugs, points, rotor, cap and condenser; 4 or 5 sets of spark-plug wires; 30 to 40 oil and filter changes; at least 3 or 4 full up brake jobs including the master cylinder; 10 sets or more of tires; and at least one repaint and interior recover; if you lived back east your car was a rusted rotted mess in three years and probably never lived to see the high side of 30-40 thousand miles. All this was the average guy, imagine if the car was hot rodded. One of the memories fried into my brain from my youth in San Diego was "Engine Eddie" and his $29.95 Ring and Valve Special advertised in the news paper, on radio and TV. So the next time some ignoramus goes on about how taking lead out of gasoline destroys's valve life, consider what I just glazed over.

When it comes to power, handling and braking from the "good ole days" just consider what driving a 4000 pound 1962 Chevy 409 or a Ford 406 was like with drum brakes and bias ply tires. The fact any of us survived the era alive is amazing and a lot of my buddies didn't.

Bogie

 

Thats correct Jmark. I was unaware that the LS series had adopted this technology. I just saw it on a little honda engine and thought it might be a cool thing to try on a american V8. Guess I already got beat to the chase. Good info though guys. Thanks!

Steve

 

I still didn't know what you guys were talkin' about until I went back and looked at Blazin72's photo of a girdle. I understand now. There is a full one-piece girdle with the main caps cast into it.