Big Four/460 Crankcase Differences

[gearhead4]

For some reason I do not know the exact difference between a Big Four crankcase and 460 crankcase. I’m asking because I bought a collection and there are tons of big iron parts in it plus a couple powerbeads that were partially assembled.

Just trying to ID what I have and see what’s needed to get them back together when they move down the lineup of engines to restore. Hopefully some photos will make it on here so I can see what differences there are and possibly casting numbers as well!

Thanks in advance, look forward to seeing some photos of engines!

[jerry-ahrens]

I would suggest getting in touch with club member Jim Ross. He knows these motors well. He is on here from time to time.

[eltoquad]

The quickest way to tell what they are is the round brass plug at front with the model and serial number stamped on it…if plug isn’t missing.

[ftruntz]

The 460 case has an adapter for the carb to crankcase. The Big Four and pumper do not.

[garry-in-michigan]

After painfully typing for half an hour – the whole thing disappeared … had to go out in the yard and smash a few things in order to save my new aggravating computer. (The spell checker is still putting a space between chaps and boy in my Email address.) I usually don’t catch the other erroneous "corrections" until I print out the message in the larger formate . . . 👿

The two inch inside diameter adaptor is so that the Varturi carburetor will clear the long ignition coil that mounts across the front of the engine. The 460 has a battery ignition and a smaller flywheel. The crankcase opening is likewise a two inch inside diameter. The carburetor venturi starts out at 1-¾" ID, but is often altered. The phosphor bronze center bearing is part of the rotary valve system. Several cylinder head/piston combinations were available, but all were a higher compression ratio than the Big Four/pumper power heads.

The Big Four has a inch and a half primer adaptor which couples the 2" Vacturi carburetor to the 1-½" crankcase opening. The carburetor venturi is also 1-½" ID. The phosphor bronze center bearing has a roller bearing insert which slightly decreases the rotary valve area. The P500 pumper has slightly shorter connecting rods which puts the wrist pin hole slightly lower in the pumper piston. Wico Piston Co made a high dome Speeditwin pisten which used the pumper rode for "C" Service racing. The Big Four compression ratio is lower than the 460.

[gearhead4]

That though crossed my mind about asking Jim Ross. I’ll try and see what photos I have of crankcases/engines and post them. It seems I have lots of this stuff to make a few out of but whether they’re Big Four/P500 or 4-60 is where I’m in need of help.

I’ll post some pics later after I see what I have in the external hard drive.

[gearhead4]

Okay, finally had a few minutes to sit down and get some pics uploaded to post them. Let me know if any of you know the difference as the lot I picked up many items and I just want to know what’s what so when I do go through and start building some engines I can build them with the correct parts.

[fmanracer]

The crankcases can be identified as follows. The real 460 case has the brass freeze plug on the front of the case and above the carburetor. The big-4 and stormboat motor both have the same brass freeze plug and it’s on the front of the case but it is below the carburetor. The P500 case has no freeze plug. There are 4 crankcases possible and these are the ways to identify what they started life as.

[fmanracer]

On the first motor at top the original 460 parts include the flywheel and timer, the coil and brackets and the switch box. The lower unit may be 460 but I can’t see enough of it to ID. The crankcase looks to be P500. The stacks are aftermarket by Procter. The tank is not 460 but could be either Big 4 or stormboat motor. The driveshaft tube is either 460 or aftermarket by Hubbell for "F" racing.
The second motor has a front freeze plug on the front of the crankcase with the brass plug gone but it is in the position of a big 4 or stormboat motor. It has a magneto ignition so none of that is 460. It has a notched out Speedifour tower to be able to bolt on the "F" powerhead and the foot is either Speeditwin, Speedifour or Big 4. Stacks may be Procter also.
The last motor looks to be a P500 powerhead with a Hubbell lower main to adapt it to a Johnson S, P or V tower and early Johnson lower unit. The powerhead still has the P500 rope plate on the magneto and the plugwire guides on the heads. It does have a WISCO adapter on the vacturi carburetor for attaching the throttle cable and a large float bowl. The tower clamp handles are 1929 only and break easily so take care of them. This motor also has a Johnson S or P tank on it.

[gearhead4]

Awesome, thanks for the input on these fmanracer! I will have to dig through the rest of the collection stuff I bought to ID the rest, 90% of everything was apart and in boxes or just laying around in the shed it was all stored in for 50 years.

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