40H carbs?

[Schiada]

Cleaning up the carbs on my 40H . Found a drilled hole on the port side,after the throttle plat,about 1/2" behind the last progression hole.Carbs are AJ33A.
It is on both carbs. The amount of dirt on the carbs I never saw it.
This is a direct leak in atmosphere? Is this a "H" thing?or does this need a plug?
Thanks of the help! Can't find anything in the manual!
Randy

Added a photo. Hole is just ahead of the mounting flange.
http://i916.photobucket.com/albums/ad5/schiadab85/DSC05218.jpg

[Fastjeff57]

Seen that before. I believe its purpose is to raise the idle speed/ air flow rate at closed throttle.

On Merc triples, I've found that enlarging the three, existing holes in the butterfly to 1/8 " makes a HUGE difference in eliminating bogging. The enlargement is not that much, but the effect is impressive! Perhaps that's another reason for that hole?

Jeff

[Schiada]

Thanks Jeff. That is what I was thinking . May have something to do with the H lower unit? Can't seem to find a idle RPS in the manual. Not mush info in the manual for the 40H

[Mark75H]

Doesn't have anything to do with the lower unit.

[Schiada]

I was thinking that Q lower mite need a higher idle? That's all.

[Mark75H]

Nope, generally doesn't. A few years later all racing motors were altered to stop at low idle rather than idle well as a safety measure. I have no idea what the holes are really for or if they would be found on all

[Ron Hill]

My dad probably rebuilt every Mark 40-H in SoCal.....Like maybe 6-8 total. I used to take things like the carbs off, port covers off, and the belt on the mag off. At 10 years of age or so, I saw almost everything on a motor. Had the Mark 40-H had holes drilled in the carbs, I would have seen them. I never saw holes like this.

Around, 1958, we had a Mark 40, "Club Foot" that we ran on an old C Runabout (Morehouse) that Ken Scoville had owned. We threw a rod through the block at Blythe one New Years, that motor didn't have this hole in the carbs, I know for sure.

[Aeroliner]

I will look at the two 40-H engines I have. I beleive that was a normal feature. I will also check my 40-H parts manual.

Alan

[Schiada]

Thanks Ron. I would say it looks to have been their from new,but???
Carbs are missing the long low speed valve? Has shorts now?
Now sure if you are the same person that built props for my Schiada Sea's B85,but best props I had till they hit a shark. Oh well!:eek:

Alan,thanks for taking a looking . I guess I will know what they do when I get the power head running.:)

[Ron Hill]

Maybe, at ten years of age, I over looked the hole.

Did KG-4-7 carbs have this hole???

Fun thread here, anyway!

[curbman]

My 40H carbs never had any holes drilled into them, and it ran great.

[Trident]

Should have no holes and should have full butterflies. Contact Aeroliner for butterflies and be carful to align with the beveled edges contacting the venturi wall correctly. LocTite 271 on the screws.

Contrary to popular belief, butterflies are NOT round. They are elliptical and cut on an angled fixture to get the beveled edge and correct shape.

The 40H came OEM with partial butterflies that allowed it to idle, but later APBA Safety rules require full buuterflies.

Later yet, a lanyard a kill switch was required by the Safety rules, belt and suspenders. Even for classic demo running, I recommend a kill switch in the boat. Simple hook-up, one wire to mag terminal post, other wire to ground on mag or engine block.

Jerry.
Trident racing

[Trident]

Apparently I need to put my glasses on typing this stuff. Sorry about the typos.

Getting old IS great, It beats the alternative. And, you can get away with stuff...

Jerry

[Schiada]

Can the float with the spring be used in this carb ? Don't think I have seen the float with just a rubbing plare?:confused: And if yes what needs to be changed?
http://i916.photobucket.com/albums/ad5/schiadab85/DSC05233.jpg
http://i916.photobucket.com/albums/ad5/schiadab85/DSC05232.jpg

Thanks,Randy

[Krazy Karl]

It is my understanding that some of the early KE7's had this hole also, to help with idle quality. Seems like a half a#$ed way to fix a carburetor design issue. I think my KE7 had it too but I put a 8 petal reed cage and larger carb on it years ago. Might have been some kind of clandestine dealer or home remedy upgrade. Who knows?

kk

[Aeroliner]

I have looked at the carbs on both my 40-H engines. They are AJ33's and they all have the bleed hole. Attached is a copy of the parts manual I have also. Note the hole in the small boss right next to the carb mounting hole.

Alan

[Schiada]

Thanks,Alan! Good to know.

Just found this carb in my "old Stuff".

The little one is a AJ32A from a KG7?, the other is a N 2150S for a 20H.
Man is it big?
http://i916.photobucket.com/albums/ad5/schiadab85/DSC05281.jpg
http://i916.photobucket.com/albums/ad5/schiadab85/DSC05282.jpg

[Aeroliner]

The AJ-32 could be used on the KG-4H and the KG-7H. Have a number of the engines with them. The Carter is a very good example of the early 20-H carb which was later replaced by the KA-7A in the conversion days. I have Mercury data going back to 1948 and was a Mercury dealer for 35 years.

Alan

[Ron Hill]

AJ-32 A carb, replaced the AJ 29 A's on KG-4 and 7's as I recall...

Great picture of the Mark 40 carbs, does the picture show that bleed hole? The AJ 32A's don't have a bleed hole, right???

The Carb were much faster than the KA-7A carbs...in smooth water or if you used a neoprene needle and seat (Which was illegal in APBA Stock)..

[Aeroliner]

The manual page I posted shows the bleed hole. I think you might be right on the carbs for early A and B. Back to the manual to check.

Alan

[Aeroliner]

I have reviewed my parts catalogue dated 1961 and it shows that the KG-4 had an AJ-36 while the KG-7 had an AL-32. When Mercury introduced the Mark 20-H they also introduced a block kit to convert the KG-7 to a KG-4. At this point the AJ-32 became legal for the KG-4.

Alan

[Ron Hill]

AJ 29 A might have been a KE-7 or even a KE-4 carb. By the time I started racing "A" in 1955, no one used the AJ 29 A carbs.

The 32 you say is in the 1961 catalog, is that the same as the 30-H????Or was that a Mark 15-Mark 20 carb.

I still didn't see the bleed hole on the Mark 40 carb picture......

Cool stuff anyway.....

[Ron Hill]

Couldn't find that thread. However, I confirmed my belief by looking at my parts books that the AJ29A was on KF7's which were the Super 10's. AJ36A were the carbs on the KG4's. The KG4H's even came with the 36A but eventually the 32A which was on KG7's were allowed.



The 32A's were allowed when the 20H came out which obsoleted the KG7H, so Merc came out with a kit comprised of block & pistons to convert KG7H's to KG4's for racing. Perhaps the confusion on the thread is a result of the KG7 to KG4 kit was actually installed on a KF7 with the 29A carb.



John


http://www.hydroracer.net/forums/images/smilies/boat.gif
John Schubert

[Aeroliner]

Hi Ron,
If you look at the -15 plug and where it goes you will see about a 1/8 in hole in the boss just right of the plug boss. It is a real small hole, might be .090 inches.

Alan

[Ron Hill]

But only on the Mark 40's???

[Aeroliner]

I will have to check the other engines tomorrow. This was the first place I found it when we were restoring the engines. My first thought was that someone had messed with the carbs but the parts book showed that it was a standard feature.

Alan

[Ron Hill]

The legal carbs for the KG4 were AJ29A, AJ32A, AJ40A. The AJ32A was popular for the KG4. I don't have any records on the KG7, but think it also used the AJ32A.

I asked Dick O'Dea what he remembered....I never heard of an AJ 40....

[Ron Hill]

Ron, They were both Tilitson (Sp) but I don't remember the numbers and letters. The KG-7 had a much bigger venturi than the KG-4. Doug Lund at Alexandria Marine in Alexandria, VA has the manuals on most of the old motors. They would give the correct numbers and letters. So they would be under KG-4H, and KG-7H, I think.

FYI:

Major Bob had a higher ranking than Major, but we always called him "Major Bob". He grew up in Ohio and raced with Jon Culver and Dean Chenowith.
I figurd he might remember carbs as he remembers when Culver ran the first 8 reed reed block...

[Schiada]

How about this??
http://i257.photobucket.com/albums/hh232/schiada/carb.jpg

[Schiada]

http://i257.photobucket.com/albums/hh232/schiada/Capture.png
Red aero.

[Fastjeff57]

Good man! There's that silly hole.

Jeff