Servicing a Mercarb 2bbl

[Capn Jack]

First time ever my 4.3 V6 started popping at over 3,000rpm. Not surprisingly I had serviced a lot of other engine bits but not the fuel delivery system.

Ed said that I should get a Carb service kit, one look at the plugs and he said it was running lean and diagnosed the problem....(he's a genius), so I ordered it via Keypart plus a fuel pump filter and a Water Seperator.

Ed said he would help with the strip down but we have had a difficult time this month so it's been slow.

Anyhow, I managed to get down to the boat today for an hour and whipped off the carb.

Removed the Air Horn (thats the top bit....) and un screwed the Venturis

Here they are............

This is the bottom bit.....float chamber etc.

Service kit arrives tomorrow......next bit is to arrange with Ed to get over to him and play with the Carb.....MOT and Dentist tomorrow, London on Tuesday...long story, Wednesday free.....

[Gazjen]

Looking good, I tried to rebuild mine on the Maxum but it was so badly corroded it wouldn't come to pieces without breaking so I ended up buying a new one

[Capn Jack]

Talking about corrosion Gaz, when I looked at the carb to try to find a serial number I thought it odd that the carb body had been painted in black. First thoughts were corrosion and how bad could it be.

Then reading the manuals, Mercarbs are painted Mercury Phantom Black and it looks like there is no corrosion to be seen.......yet!!

However....look what arrived this morning, ordered Friday morning at 08:00 arrived Monday at 10:10 and seasonal free postage, well done Keypart. You know, I don't normally buy from them because they are usually quite expensive compared to MPD or Repower Marine, but on the odd occasion they are there or thereabouts. These bits are slightly dearer but they offer a better website selection than the others, it was difficult to find what I wanted quickly, no explanations, but Keypart selects under the engine type/serial numbers or Stern drive type so much easier.

This paperwork was in the Carb kit, very comprehensive measurements and weights etc.

[Ed]

looks good to me

[Capn Jack]

Having taken apart the Air Horn...thats the top bit of the carb, I thought I may have lost the accelerator pump return spring, plus there was a tiny ball bearing in the chamber which is actually a check ball. I was also unsure about the way in which the inlet strainer spring went in. Ed had previously offered to help with the service so I arranged with him to pop over to his workshops near Chobham......terribly posh over there, don't you know!!
I arrived at his premises which turn out to be on the grounds of a very large Film Studios which had made films like Clash of the Titans and Warhorse....
Here I am parked outside but it doesn't quite show the scale of his workshop, there were at least 5 cars in there and did I mention that the owners were asking for some sort of incredible horsepower from their engines?...

I had already arranged all the parts in a tray............

Ed had cleared a space for us to work.......

I arranged the paperwork I had printed off on top of what looked like a neuclear reactor rod mover, it was actually a sandblaster.....

Ed began by cleaning a lot of the airways in the carb and cleaing it with carb cleaner, he also multi tasked quite a bit advising customers on how to make a 1,000cc engine into 600hp....

Then once all the parts were clean we had some lunch at the film studio cafe....mmmmm bacon and chicken pannini!! With muffin and some caramel shortbread to follow......

There was a shiney new idle valve which Ed said wouldn't do much but he liked the fact that it was shiney, so we fitted it!

Yeah come over and I'll make your 400hp Supra into 600hp

Then a new power needle went in....

Fitting the float chamber to the base. The base turned out to be made from steel but the rest of the carb is an alloy.

After this I spotted Eds latest engine purchase.......without the power head....

He had fitted a new power trim....

Then the venturi's....

Now because I couldn't find an accelerator pump spring, Ed looked on the internet for something similar and came up with a Machine Mart spring selection box, so his apprentice who was already wizzing around trying to get some parts for Ed, called in to Machine Mart and bought the spring kit. We had to modify one but it worked well....

We had to check float drop as the needle spring was less.....

Ed was very careful when fitting parts which required a little accuracy.

Then all the bits had been fitted and the job was done....

Thanks for all your help Ed, I'll be fitting it next week... And by the end of all this.....he was serious......he wanted to fit a turbo to my boat, so instead of what 180bhp we would be talking about 400bhp, thats serious!!!

[Ed]

Great stuff!!! :) I notice how in every pic I'm on the phone.. It didn't stop that day!

[Capn Jack]

I notice how in every pic I'm on the phone..

Not quite every pic Ed...... ....... but when I was there I agree the phone was non stop, but I'm not surprised you are so busy and it wasn't the film producers wanting you for the next Fast and Furious either!

I hope this is of help to those of you wishing to rebuild or service a carb. The next stage for me is to re-fit and to change the fuel pump filter. Then test to see if it all works.

[Capn Jack]

One thing I didn't say was that whoever rebuilt my carb in the past had overtightened one of the Air Horn screws. As Ed was re assembling this part he put a very small amount of torque on the screw and it and it just span. They only bite into a small amount of thread and have a 7/8" thread length. Ed measured the screw with a very wizzy digital readout gauge (it's a 10-32 UNF machine screw with an outside dia of 3/16") which he later revealed was a cheapy from somewhere but it looked like the muts nuts.

It was this one.......

What we actually wanted was a screw with a 1" thread length.

Ed did a bit of internet wizzy searching stuff and found a company called Westfield Fasteners who had 10 of the screws for £10.24 but with a hex head instead of a Philips/Slotted round head. I found a company called Stig Fasteners alias a2stainless.com who supplied a closer version with a 1" thread but with a Philips only head plus I got 4 Stainless Triton jubilee clips for a total of only £7.45 including postage......bargain, arrived this morning, screw fitted perfectly and tightened down well.

Again thanks for all your help Ed, keep a note of http://www.a2stainless.com , Mark Pinkney Sales Manager, quick delivery and he pops a card in too.

[Ed]

Ahh cool top stuff. Westfields was the only place I knew, and in some respects their range is a bit limited

[Capn Jack]

Nice morning this morning so I got the boat from the barn and finished off the carb refit and then went on to fitting the fuel filter in the pump. What a bar***rd it was to fit too, why on earth they could make it a canister or something like that. The pump is tucked away under the engine and the filter housing has a retaining strap. Inside the housing is the filter, held down by a spring, but its all loose nothing clips together so when you put it back together it all falls apart again. A five minute job which took an hour...

The fuel in the tank was a tad old so on Ed's suggestion I wanted to get as much of it out as I could. I had to decide how to get it out, the bilge drain was an ideal exit for a pipe, nice and safe and below the tank level. I found a piece of fuel pipe in the garage which went over the tank connection and it also was a perfect fit straight into a piece of hosepipe.

Then I took the pipe out of the bilge drain

I had an old drill pump which I had used once in about 20 yrs, so I connected it to my cordless drill, no sparks from the commutator.
It all worked perfectly even when it was dry it sucked out the fuel so no syphoning and I got nearly all of it out.

What a difference between the old and new fuel. Here is some of the old fuel in a bucket, fresh fuel is almost clear.

This bottle is almost clear when empty....

Hear is a little fresh fuel in a Whisky bottle.....10 points for guessing which make the Whisky is?.
What a difference........

So I turned the engine over.....and over to suck up fuel into the carb and she fired, so I warmed her up then took a video of her starting again, she has a much better throttle pesponse, but the throttle cable sticks and wont return to idle revs without help....another job for tomorrow.