Briggs & Stratton Opposed Twin Engine Questions

I am building a tractor and it will have a Briggs opposed twin vertical shaft engine. This wont be an off road tractor it will be a close to factory build with some tweaks, a usable and showable tractor. I want to build the biggest and best Briggs opposed twin that I can using OEM Briggs parts, no aftermarket. Base engine will be a 46ci 460777-2277 E1 but have the sump from a 422777-1281 01 with full pressure lube, oil filter, and oil cooler. Will the sump swap without hassle or not? The 46ci is a 20 horse and the other is a 18 horse. Will also have Turbo Cool fins on the flywheel. Whats the biggest and best all adjustable carb that Briggs had for these opposed twins? Also whats the best starter? A starter is something I would be willing to go aftermarket if there is one better than Briggs. Also I have seen very few 21 horse Briggs opposed twins in Craftsman tractors, does anyone have a model number for this engine? I'd rather use it as my base, its just 1 more hp but I cant say I have built the biggest with a 20. The tractor this will go in is a Scotts by Murray GT I am building which had basically the best Briggs opposed with oil cooler and all but only 18 horse, Id like 20 horse minimum. Thanks in advance for any replies.

98Murray wrote:

I am building a tractor and it will have a Briggs opposed twin vertical shaft engine. This wont be an off road tractor it will be a close to factory build with some tweaks, a usable and showable tractor. I want to build the biggest and best Briggs opposed twin that I can using OEM Briggs parts, no aftermarket. Base engine will be a 46ci 460777-2277 E1 but have the sump from a 422777-1281 01 with full pressure lube, oil filter, and oil cooler. Will the sump swap without hassle or not? The 46ci is a 20 horse and the other is a 18 horse. Will also have Turbo Cool fins on the flywheel. Whats the biggest and best all adjustable carb that Briggs had for these opposed twins? Also whats the best starter? A starter is something I would be willing to go aftermarket if there is one better than Briggs. Also I have seen very few 21 horse Briggs opposed twins in Craftsman tractors, does anyone have a model number for this engine? I'd rather use it as my base, its just 1 more hp but I cant say I have built the biggest with a 20. The tractor this will go in is a Scotts by Murray GT I am building which had basically the best Briggs opposed with oil cooler and all but only 18 horse, Id like 20 horse minimum. Thanks in advance for any replies.

I dont see why the oil sump wouldnt go right in. Rods might bedifferent (?) But probably not. Check ECcarburetors.com for aftermarket stuff. Sounds like you have everything to make it "the best" With OEM. Starter doesnt have to be aftermarket, they only do that when compression is really bumped.

Ive looked at multiple threads, part #'s, and talked o a few people, and the only difference between the 40ci, 42ci, and the 46ci is stroke. So different crank and rods, but im not sure if the pistons wrist pin hole is placed differently, kinda doubt it.

Id put in a adjustable carb (remember not all 3 screw carbs are adjustable) And see if you can put the 20hp jet in, if that is different. And with the 20hp vs the 21hp, it could only be the carb jet, or the sticker on the shroud.

EDIT: brousing ebay for a while, i see that all the connecting rods are labled "40" "42" and "46" so they must be all the same for each of their ci classes.

For pistions, 16hp-18hp matched up to be the same i believe. But between the 20hp and 21hp pistions, the part # is different.

All the carbs 12.5-21hp seem the same. And for the most part, cranks are made for each CI family as well.

I have no clue how a pressure lub OPE engine is, but im pretty sure the block needs to be milled right for the added stuff and for the oil channels as well.

Starter you can leave stock. No point in switching it unless you are increasing compression by extending stroke or shaving the head.

Thanks guys. The 460777-2277 E1 is a full pressure lube engine and will for the most part be the base for this project. The 422777-1281 01 has an oil cooler. After more looking I think all I need to swap is the filter adapter peice, not sure tho. I dont know if the 18 horse is full pressure lube, it doesent say it is on the shroud.

98Murray wrote:

I dont know if the 18 horse is full pressure lube, it doesent say it is on the shroud.

If it has a filter, it's a PL.