briggs opposed twin carb

[38racing]

our church was given a murray hydrostatic for scrap or redtore/resale. been sitting a long time with gas in it. as expected very gummed up 4 bolt carb. engine cranks and starts on carb cleaner. so I pulled carb and have in usc. but the pump body is bad. spring is broke on one check valve. so oem carb is $450. no way. oem pump body $53 cdn. so on amazon.ca pump body 43 and whole carb 47. from my supplier pump kit alone 12 and full kit 29. so I guess I roll the dice on a chinese carb.

[bluemower]

is that a model 42 or model 46?

about 5 years ago, a local shop installed a new clone. Unfortunately, the float was warped and would not close the needle valve. The oem float would not fit.

[38racing]

is that a model 42 or model 46?

about 5 years ago, a local shop installed a new clone. Unfortunately, the float was warped and would not close the needle valve. The oem float would not fit.

42a707. the reviews indicate that it will be hit or miss.

[KE4AVB]

Then at least the vendor is allowing honest reviews. I got a vendor from eBay that is requesting me not to leave a neutral or negative review. I consider this dishonest so I will buy from that vendor again as I did have a problem with the item I brought for an ATV.

In order to get the part to fit I had to modify it using a die grinder. Now the vendor wants pictures of the problem which I can not provide as it is already modified and the ATV is no longer in my shop.

[Arkie]

Just couple hints about doing a bypass on the pump type 3 and 4 screw Briggs carb so as to check/test the engine.
If I have never seen the engine run or it's been at rest long time I do a leak down test first to see if I'm whipping on a dead horse.

The 4 screw kits and pump parts are not as easily found as the 3 screw. If I were looking to replace the carb I would think about the 3 screw replacement.

Also sometimes when I run into one of them 4 screw or 3 screw Briggs carbs with a bad pump on a new to me engine I can rig the pump section so as I get gravity or pulse type fuel through the pump into the carb bowl so as to test run the engine without having to repair the pump. I now try to keep a good spare carb set back to test them old twin engines to make sure I'm not having to be working on a carb to install on a dead horse. (throwing good money at bad engine)I've also found that when changing carbs I usually get a good run test more often if the carb has at least a adjustable idle jet. (some of them Briggs type are critical of the L jet adjustment to get both High and low rpm engine response when the carb is the fixed H jet type. The type with non adjustable L and H fixed jet types are just rolling the dice for smooth engine performance..

Carb parts for them old Briggs fuel pump type especially the 4 screw type getting pricy and hard to find, especially the plastic block spacers.

I also have a small gravity feed gas tank rigged with fuel filter and gas petcock and when I see a new to me old Briggs 3 or 4 that is not pumping through I can quite often (with little bit of luck) get gravity feed through the old pump before taking it apart so as to get a carb test run on a new to me old engine. (gas will gravity feed through the carb's pump to the float bowl sometimes W/O first taking the pump section apart.

[KE4AVB]

Now that an idea. Just remove the carburetor fuel pump check valves and install a vacuum operated fuel pump. I have seen done on one engine here that came into the shop.

And the subject of carburetor repair prices they are getting ridiculously over priced. It seems every OEM is now price gouging us. Here lately there is no point for me update my system using price files as they are changing weekly now. And it takes a whole day to import them as they gotten to be modified for my system to import them. All I need is the PN, description, the supersede PN if any, Retail, Cost, weight, and Barcode; everything has to be deleted along with delimiters within text strings. So everytime do work order items has to be reprice before entry into the work order. Heaven forbid an item get B/O as the distributor use new pricing when they do ship the item.

I still do the imports every couple months just to update the supersedes.

[38racing]

now that reminds me that I've read before about bypassing the pump. so far I've only seen the inlet needle available in a kit for 29$ cdn. be interesting to know if it's the same as used in any other briggs engine

[Arkie]

Couple more hints:
Yes if your plastic blocks on the 4 screw or 3 screw pump are sealed good just fix the front pump area so as a cheap Briggs type pulse pump can be installed using the existing pulse hose, let it pump through the old pump body. I usually just do the gravity flow run test mentioned previously to see if a unknown engine is any good.
Also when you first start testing you can either just remove the large carb bowl drain plug to see it pumping and spilling gas past the inlet needle and float and if not seeing gas you can lift the top of the carb off with the gasket at same time and see the gas inlet BEFORE the needle. I use a light grease on the top carb gasket (both sides) when going back so as to get a easy release next time the top of the carb is removed.
You really have to be careful with them old plastic pump blocks, especially the 4 screw. If you crack the plastic body you are sol.

I've never paid any attention to drilling a tapping the front of the 3 or 4 screw carb body for installing a hose barb so as to completely bypass the carb's pump input direct to the needle inlet, because I have a bucket full of old 3 screw carb's that I've saved over the years but my 4 screw carb's and pumps are weak.

On same subject of bypassing the carb fuel pump on the front of the carb's, Kinda costly but some of the old Onan B43/B48 carbs have a obselete pump on their front and guys rig them for bypass/pump through and use a $40-60, 1/2 lb psi 12v fuel pump for their cherished little tractors. They like 12v pump because they can just switch on the 12v at first without cranking the engine and get a direct prime to the carb vs a long crank time for a pulse pump if the tractor has been at rest for long time. Them replacement onan engine carbs are very costly if found and usually VINTAGE. (junk)
and about 3 different types carbs for the B43's with different bolt patterns and require a different air filter.

Kits and things getting out of sight on prices and prices changing daily/weekly and China made.
I'm starting to watch the fuel mileage little bit closer on my lawn mowers nowdays.

I'm suspecting somone is sending us a hint and wants us to convert to the non-polluting battery only equipment.

[38racing]

just heard from a friend. he has same model rider and says it started running poor and has gas in the oil. must have flooded while cutting sice he uses shutoff valve when not using.

[Arkie]

Very unusual for the old 3 and 4 screw carbs to get lots of gas in the oil while running and the engine stay smooth enough to operate without the operator immediately noticing it flooding. If the float/needle stuck open the engine should have flooded immediately as a heads up.

I would think about looking close AT THAT ONE at the gas MAYBE getting into the pulse hose pump side to getting into the crankcase while running since seems to indicate he sees lot of gas in the oil before it got to running rough.
I use the finer white fuel filter on my old pump carbs.


Did you get your new to you 4 screw carb and engine going????