Briggs opposed twin heads??

[Arkie]

I need a right bank USED head for a Briggs opposed twin. On the head flange it's stamped 42-1. Right bank head is termed #1 cylinder by Briggs for the oppose3d twin.

I'm not sure that the air cowling model and code match the engine block. model 461707 0145F3

I see on flea bay heads stamped as 40-1, 42-1, 46-1 and all these heads use the same head gasket for the right bank.

I see that Briggs part# for a 461707 head is 69112.

For some other opposed twins such as a model 400707 and 42A707 is 493457.

Anyone know why the heads have different part number or stamping?

Should I stay with the stamped 42-1 head?

Both of my engines heads are stamped 42-1 for Right side, 42-2 for the left side

[Walt 2002]

The shape of the combustion chamber is different, depth. It has been too long since I have worked on 42 & 46 series engines and I can't answer the rest of your question.

Walt Conner

[Walt 2002]

Sounds like someone has cobbled together an engine out of misc, parts. I can send you a Service Manual that will have the cylinder bore which you can use to tell if you have a 42 or 46 Series and use which ever head(s) called for for that series. Address below, put in proper format and remind me what you want.

Walt Conner
wconner5 at frontier dot com

[Arkie]

The shape of the combustion chamber is different, depth. It has been too long since I have worked on 42 & 46 series engines and I can't answer the rest of your question.

Walt Conner

I suspected that is why I need to stay with a 42-1 stamped head is the difference in the size of the CC of the other heads that are stamped differnt.

Check your PM.

[Arkie]

I got off on another project and finally got a chance to review WHY the heads are probably stamped on a Briggs opposed twin engine.

It appears as though it's probably directly relates to the CC of the opposed twin engine per the first two digits of the model number and I checked heads stamped on some engines in use and some heads that are stamped on flea bay with models numbers listed.

stamped numbers 42-1 is right bank head for #1 cylinder and is for a model 42xxxx engine and close to 42cc engine. 17.5-19.5 engines

46-1 for a model 46XXXX 20Hp engine

40-1 for a model 40XXXX approx. 12.5HP engine

Walt
This confirms that the air cowling model # for my engine is wrong one. (someone has changed the air cowling)
AND I need to stay with a 42-1 head as a replacement to keep the cylinder CC balanced.
Thanks for the tip.

[KE4AVB]

Curious, What is the CC of the 42-1 head?; as I got a pair of 46-1(2) heads that came off a 42A707 here. I hadn't even looked at them until now and they been in storage for 5 yrs after the customer ran their engine without oil. They would need cleaning of the carbon so I could measure the CC of them.

Customer just couldn't figure why it was out of oil even though the mower was turned upside down in a storm for a week, just uprighted and started mowing his lawn. The engine only spin after he stopped for a cola drink. Snapped both rods. He was lucky that I had brought a mower with the same engine size for the Dana 6 speed transaxle for another project.

[Arkie]

KE4AVB

I do not know the CC of a 42-1 series head.
After I seen that it appeared that the 40, 42, 46 series stamped heads related to the first two digits of the model number on the air cowling I assumed that a 40, 42, 46 related to the CC of the engine, of the engines I looked at the 40 was around 12hp, 42 several different HP's up to 19.5 and the 46 I seen was on a 20hp and up

After I found out that it appears that I should stay with a 42-1 head I found one on flea bay.
When I first started looking I did not even realize them being stamped and then when I went searching I begin to see the difference and appears that some of the heads for the opposed twins are not even stamped.

Are you sure that your 46 heads are from a 42A707 model series engine?
Reason I ask is the 46 series heads on a engine I have are on a mower is 461707.

If I had any of the 40, 42, 46 Briggs heads in hand I would check the liquid CC just out of curiosity.

Anyway thanks for the notice.

[Skywatcher]

Greetings All

On virtually any multi-cylinder engine, the cylinders are always numbered starting with # 1 being closest to the flywheel. The 42-1 indicates it's the #1 cylinder head on a 42 cubic inch (688 cc) displacement engine. From what I understand, the differences between the #1 and the #2 heads are the clearances for intake and exhaust valves and the curve of the cooling fins on the head. As for the engine information, on a horizontal shaft twin the numbers are usually stamped into the top cylinder baffle of the left cylinder as viewed from the flywheel. On vertical shaft twins, it's usually on the main cowling. Hope this hasn't confused you too much,

Sky

[Arkie]

[quote="Skywatcher"]Greetings All

On virtually any multi-cylinder engine, the cylinders are always numbered starting with # 1 being closest to the flywheel. The 42-1 indicates it's the #1 cylinder head on a 42 cubic inch (688 cc) displacement engine. From what I understand, the differences between the #1 and the #2 heads are the clearances for intake and exhaust valves and the curve of the cooling fins on the head. As for the engine information, on a horizontal shaft twin the numbers are usually stamped into the top cylinder baffle of the left cylinder as viewed from the flywheel. On vertical shaft twins, it's usually on the main cowling.

So if a 42 stamped head is seen on a model 46 vertical opposed twin engine it's has wrong model air cowling and vice/versa.

It's always nice when a guy finds that the model stamped on the air cowling does not match the engine, especially after parts are bought going by the model number. (due to Bubba switching air cowlings)

[KE4AVB]

I agree it is a pain when Joe shade tree does the engine shroud swap and doesn't transfer the old numbers...

As for the opposed engine I have seen the same model and type number have at least three hp ratings 18.5, 19.5, and 20.5 on Craftsman mowers. I actually had all three at the same time on the service yard which had me double checking the numbers. All three were the exact same engine down to the factory code. This is what Briggs got in to trouble about on the hp ratings.

The 42 and 46 had the same bore so they must have been stroked differently to make up the extra 4 cubic inches on the 46.