What parts are available for the old 25ss merc

[dndsam]

ZUL8TR,

I still have a full box of new L3G plugs with the electrode still intact. The ones in the motor have them clipped off. From the research I found, these plugs preceeded the L78V's.

Why did you switch to the L61Y plugs over the permagap L78V? Are there advantages with one over the other?

I have found NGK BP8HS, BP8HS-10 and BP8HS-15 plugs. What might the differences be?

Doug

[ZUL8TR]

25ss plugs

ZUL8TR,

I still have a full box of new L3G plugs with the electrode still intact. The ones in the motor have them clipped off. From the research I found, these plugs preceeded the L78V's.

Why did you switch to the L61Y plugs over the permagap L78V? Are there advantages with one over the other?

I have found NGK BP8HS, BP8HS-10 and BP8HS-15 plugs. What might the differences be?

Doug

Doug

The L3G plugs are not the required 1/2" reach of the L78V, they are 0.472" reach which will result in a retracted plug in the cylindere head. I would not use the L3G plugs. The L78V are 1/2" reach and they are still manufactured by Champion. The NGK racing equivelent is BUHW and available as PN 2622 at Discount Auto.

When I was active in racing (73 to 80 in APBA) in the 25SSH class most of the drivers experienced fouling and hard start with the L78V, I never did? Hewever we switched to the Champ L61Y for improved anti fouling, better power due to the projecting electrode and it was easy to read the plug for correct fuel mix. The NGK equivelent is BPH8S (PN 2630) which is there standard electrode design. The -10 and -15 designation at the end of the the number refers to larger gap design of 0.040" and 0.060" respectively. Here is the NGK table to decipher the plug numbers:

http://www.ngksparkplugs.com/docs/te...tnumberkey.pdf

As a side note I tried an adjustable jet in the carb but found the 0.061" fixed jet worked the best for me for all seasons in Region 5.

[dndsam]

Awesome information! Thank you! One more for you.

When you ran with the .061 fixed jet, you no longer used the high speed adjustment that comes with the KC16A carb, as with most fixed jet carbs, correct?

Do you know who might have a KC16A carb and 25ss flywheel/ignition for sale? I thought I had the correct stuff in the box of parts I got with the powerhead but does not appear to be correct. I am building another motor and am missing those parts.

Doug

[ZUL8TR]

25ss questions

Awesome information! Thank you! One more for you.

When you ran with the .061 fixed jet, you no longer used the high speed adjustment that comes with the KA16A carb, as with most fixed jet carbs, correct?

Do you know who might have a KA16A carb and 25ss flywheel/ignition for sale? I thought I had the correct stuff in the box of parts I got with the powerhead but does not appear to be correct. I am building another motor and am missing those parts.

Doug

Doug

My 25ss came with a fixed jet. For an adjustable jet set up I took it from a 20H. The carb on my 1973 25ss is a KC16A not a KA16A. The KA16A was used on the Merc 850 and others.

I presently do not know who might have the parts you need. It might be easier but more costly to pick up a complete 25ss. I know where those can be had. Let me know if a complete 25ss is what you want I will get you in touch with the owner of such. There is an AOMCI meet on Nov 19 and 20 down here in Fla and I will ask around for these parts.

[dndsam]

You are correct on the carb. I made a typo as I have messed with the KA5A's on the old 22ci motors, I had KA on on the brain. Let me know if you run across one or any parts for one. Thanks for all the information you have shared! You have been very helpful.

Doug

[Heliarc]

I still have my 1973 25ss and use the Champ L 61Y the coldest Y gap in that gap series with 14 mm 1/2" reach. The L78V is a surface gap plug that came standard on my engine. When I was racing this engine it was determined that the V series plug being a very cold design was prone to fouling and also was impossible to read for fuel mixture control. Better performance was obtained with the L 61Y with its deep reach spark. Here is a link that cross references the Champion to NGK plugs. You will find X refs for the L61Y and the L78V among others.

http://www.spark-plugs.co.uk/pages/t...on860-n288.htm

BTW I also experimented on the L61Y indexing and increased gap for better fuel flame advance and combustion that increased engine rpms therefore was able to reduce the static timing somewhat and compensate the power with the increased plug gap thus reducing the effect of excessive piston crown heating that excessive static timing would create.

The NGK equivalent spark plug to the Champion L61Y is BP8HS. Has anyone actually run the NGK BP8HS in a Merc 25ss? If so, how did they run compared to the L61Y and what gap setting did you use? Before I try them myself, I would appreciate someone's input. I do not want to find out the hard way that I should have looked harder for some NLA L61Ys instead. Thanks in advance.

[ZUL8TR]

NGK Sparkies vs Champ L61Y

The NGK equivalent spark plug to the Champion L61Y is BP8HS. Has anyone actually run the NGK BP8HS in a Merc 25ss? If so, how did they run compared to the L61Y and what gap setting did you use? Before I try them myself, I would appreciate someone's input. I do not want to find out the hard way that I should have looked harder for some NLA L61Ys instead. Thanks in advance.

I recently restored a 1981 Karelsen 25ss pickel hydro and ran my 1973 25ss on it with the L61Y equiv NGK BP8HS at 0.040". First time out with no testing, just guessed at a conservative set up on this hydro and ran 60.5 mph (GPS) at 6950 rpm (need 7100 rpm but that is doable with set up and prop). No addiltional testing done that day just had fun with it since it was a succesful long time in a hydro. Next time out I will try a set of L61Y's with all else the same on the set up. I suspect the plugs to be very equivelent.

Note the NGK BP8HS is the standard gap projecting electrode at 0.028" gap that I opened to 0.040" with no noticable real problem. I could not easily locate the BP8HS-10 plug which has a standard gap of 0.040". If you can get those they would be preferred.

Do the plug indexing I suggest to get the tip of the ground electrode to point to the general direction of the intake ports such that the back side of welded ground to the plug circumference is facing the exhaust port direction. This puts the intake charge at a clear unobstructed open gap of the plug. With 2 plugs purchased your at the luck of a coin flip as to how this will work out. If you want to get very specific there are various thickness shims that can be used get the indexing closer.

One thing I found on the 25ss after sitting in my garage since I quit racing in 1980 with being started just a couple of time since then. I did have problems to get this engine back in shape due to coil issues and grounds to the coils plus carb gaskets. So look into your ignition and get all the connections clean and replace ground wires as needed. Look for cracks in the coils underneath the rubber covers and the taped ground wire on each coil that easly corrode. These CD ignitions need excellent wiring and good coils to run right.

If you need coils the original OEM numbers have changed. Let me know and I will give you the latest number that is available.

[Team 12R]

"New" un-fired 25ss

a friend oif mine was a mercury dealer in the 70's and 80's. he has a new powerhead, tuner plate and driveshaft along with gasket set. he lives in northern michigan and has the motor at his place still for sale. pm me if you want his name and number.

[Heliarc]

I recently restored a 1981 Karelsen 25ss pickel hydro and ran my 1973 25ss on it with the L61Y equiv NGK BP8HS at 0.040". First time out with no testing, just guessed at a conservative set up on this hydro and ran 60.5 mph (GPS) at 6950 rpm (need 7100 rpm but that is doable with set up and prop). No addiltional testing done that day just had fun with it since it was a succesful long time in a hydro. Next time out I will try a set of L61Y's with all else the same on the set up. I suspect the plugs to be very equivelent.

Note the NGK BP8HS is the standard gap projecting electrode at 0.028" gap that I opened to 0.040" with no noticable real problem. I could not easily locate the BP8HS-10 plug which has a standard gap of 0.040". If you can get those they would be preferred.

Do the plug indexing I suggest to get the tip of the ground electrode to point to the general direction of the intake ports such that the back side of welded ground to the plug circumference is facing the exhaust port direction. This puts the intake charge at a clear unobstructed open gap of the plug. With 2 plugs purchased your at the luck of a coin flip as to how this will work out. If you want to get very specific there are various thickness shims that can be used get the indexing closer.

One thing I found on the 25ss after sitting in my garage since I quit racing in 1980 with being started just a couple of time since then. I did have problems to get this engine back in shape due to coil issues and grounds to the coils plus carb gaskets. So look into your ignition and get all the connections clean and replace ground wires as needed. Look for cracks in the coils underneath the rubber covers and the taped ground wire on each coil that easly corrode. These CD ignitions need excellent wiring and good coils to run right.

If you need coils the original OEM numbers have changed. Let me know and I will give you the latest number that is available.

Thanks very much for the input. I greatly appreciate it. I have access to BP8HS-10 plugs, but haven't bought any yet. Now with your input I feel comfortable buying them. I ran this particular 25ss engine in 2008 and 2009 a few times as a borrowed engine. When I ran it, the engine started and ran without any problems of any kind. At that time, I was using the L78V plugs. I now own the engine. It has been two years since it was run and I plan on looking everything over carefully.

I would appreciate the latest numbers for the 25ss OEM coils. Thanks again.

[Heliarc]

a friend oif mine was a mercury dealer in the 70's and 80's. he has a new powerhead, tuner plate and driveshaft along with gasket set. he lives in northern michigan and has the motor at his place still for sale. pm me if you want his name and number.

I sent you a PM, Bill.

[ZUL8TR]

25ss coils

Thanks very much for the input. I greatly appreciate it. I have access to BP8HS-10 plugs, but haven't bought any yet. Now with your input I feel comfortable buying them. I ran this particular 25ss engine in 2008 and 2009 a few times as a borrowed engine. When I ran it, the engine started and ran without any problems of any kind. At that time, I was using the L78V plugs. I now own the engine. It has been two years since it was run and I plan on looking everything over carefully.

I would appreciate the latest numbers for the 25ss OEM coils. Thanks again.

The coils that I used for 25ss replacement are:

Mercury Marine Quicksilver 339- 832757A4 and are black

The OEM Merc coils in my 1973 25ss were 338-4995A1 are red and NLA

If you replace the coils with the ones noted there is an improved ground strap that is taped on to the ferrite. The ferrite comes in 2 pieces that wrap around the coil with a cylindere that passes thru the coil. The require silicone only on the outside of the cylinder that passes thru the coil. Additionally one thing I did that is not noted in the directions, I completly glued the ferrite halves to the coil body with silicone. This guarantees a solid vibration free connection of the halves to the coil. As noted in the directions no silicone was used on the contact joints of the ferrite halves to alow for a complete uninsulated connection at these joints that is required.

[Heliarc]

The coils that I used for 25ss replacement are:

Mercury Marine Quicksilver 339- 832757A4 and are black

The OEM Merc coils in my 1973 25ss were 338-4995A1 are red and NLA

If you replace the coils with the ones noted there is an improved ground strap that is taped on to the ferrite. The ferrite comes in 2 pieces that wrap around the coil with a cylindere that passes thru the coil. The require silicone only on the outside of the cylinder that passes thru the coil. Additionally one thing I did that is not noted in the directions, I completly glued the ferrite halves to the coil body with silicone. This guarantees a solid vibration free connection of the halves to the coil. As noted in the directions no silicone was used on the contact joints of the ferrite halves to alow for a complete uninsulated connection at these joints that is required.

Thanks very much for the new coil number and the ignition tips that you have suggested. My experience is mostly with magnetos. The ignition on the Merc 25ss is new territory for me. So, I very much appreciate the input.

[Heliarc]

Is the CDI Switch Box 114-4911 on the Merc 25ss prone to fail at times or is it fairly reliable? I was just wondering if I should have one on hand? The reason I ask is because that part shows as NLA, but I do know where a couple new ones are. Thanks.

[ZUL8TR]

25ss CD box

Is the CDI Switch Box 114-4911 on the Merc 25ss prone to fail at times or is it fairly reliable? I was just wondering if I should have one on hand? The reason I ask is because that part shows as NLA, but I do know where a couple new ones are. Thanks.

I have the same CD box from new and have dumped the engine at least half dozen times. Plus it sat in the garage from 80 to 2010 with no issues.

So you be the judge but with parts getting scarce and if you have extra $$ .....? BTW when you get electric parts you have a choice with Merc Quicksilver, Sierra or others. I prefer the Merc stuff even if it is NOS. Note some of the CD replacements do not even look like the original box so mounting might need a mod on the plastic mounting board on the 25ss.

Any electric device can go bad at the wink of an eye but the Merc CD box on my 1973 is a solid unit so far. The ignition issues are with the ground wires, coils, electric connections and plug wires and the cap connections at the plug. I replaced both coils with upgraded models (see previous post) due to cracks in the red case. Do not know why but quess internal corrosion? So pull apart all connections and clean them bright, look at the common ground wire for the coils and the taped ground to the coil ferrite as these will go bad. The new coils do not use braided wire for the ferrite ground but instead a flat steel strap that is taped to the ferrite and bolted to the ground connection stud on the coil - far superior to early attachment. I lock all connections with a dab of silicone after they are secured for vibration security. You could use Locktite but I prefer the silicone for these electric connections. Also look at the plug boots at both ends and the plug wire + look for corrosion inside the coil plug terminal.

[Heliarc]

NGK BP8HS-10 spark plugs

Thank you for the feedback on the CDI switch box.

I bought some BP8HS-10 plugs. Can these be run full depth using only the supplied compression washer? I ask because those plugs will go noticeably farther into the cylinder than the L78V plugs do. Should thicker washers be used so that they don't go into the cylinder any farther than the 1/2 depth L78Vs?