NEED HELP WITH ACCELERATOR DIAPHRAGMS

I need to replace the accelerator pump diaphragms on my 40 DCNF carbs. I've done this many times on some V 12 Ferraris, but this will be my first experience on a 308 and it does look intimidating. Instead of the access of being right in front of you, they're off to the side without the expanse of room I'd like. It seems to me that somewhere,somebody recommended replacing the 4 mm screws that hold the pump to the carb body,with either a hex machine bolt or some other faster that would be easier to access. Maybe a fastener that accepts an Allen key or a socket? Any thoughts on this process? thanx steve

 

Well, I don't have any strength, desire, balls or assistance to remove the hood. I've got the air cleaner off, as well as crossover pipe. Maybe the job won't be as bad as I think. We'll find out Saturday morning. Thanks Brian. Steve.

 

HMMMM....." Other than the play, Mrs. Lincoln, how was your evening?"

 

THANX!! steve

 

As luck would have it, I did not have to remove any of the accelerator pump diaphragms. I cleaned the nozzles and all the other internal parts like the emmulsion tubes and pump jets within an inch of their lives; now they could go in an operating room. For cleaning, I used my new HF (about $156 with 15% off coupon)ultrasonic cleaner...has worked great so far. With all that done, the squirters work great, at least in situ. I did make one modification to the forward most knurled hold down nut by using an M8 Rivnut. Pictures below.

I used lots of towels around the carburetors to protect me from my own clumsiness and dropping important parts into the valleys of death. I was also very meticulous about stuffing the Venturi's with tissue paper to prevent a similar catastrophe. Among the things I did learn is that I affixeded the little collars that are inserted into the rubber gaskets, with the single drop of superglue. It seems nearly impossible to hold all 16 of those collars in their respective gasket openings while trying to wrestle with the oil bypass hose.

 

As luck would have it, I did not have to remove any of the accelerator pump diaphragms. I cleaned the nozzles and all the other internal parts, like the emulsion tubes and pump jets within an inch of their lives; now they could go in an operating room. For cleaning, I used my new HF (about $156 with 15% off coupon) ultrasonic cleaner...has worked great so far. With all that done, the squirters work great, at least in situ. I did make one modification to the forward most knurled hold down nut by installing an M6 Rivnut in the “A” bracket of the housing itself. Then I used “red loctite" to affix the stud to the knurled nut itself. Pictures attached.

I used lots of towels around the carburetors to protect me from my own clumsiness, and dropping anything into the “valleys of death”. I was also very meticulous about stuffing the Venturi's with tissue paper to prevent a similar catastrophe. Among the things I did learn was to affix the little collars/sleeves that are inserted into the rubber gaskets, with a single drop of superglue. It seems nearly impossible to hold all 16 of those collars in their respective gasket openings while trying to wrestle with the oil vapor hose. It occurred to me, that perhaps you're supposed to slide those sleeves down the carburetor studs and then press the base of the air cleaner housing onto them. However, I was concerned that it was going to be really difficult to get them all well seated in their insert orifices.

There are four things you can do to make the fight with the damn bypass hose a bit easier A.) Put a bit of white lithium, grease or silicone on the end that goes into the air cleaner housing 2.) Loosen the far end of the hose that goes into the canister. You needn’t remove it, just loosen the clamp so that it moves easier. iii.) Having two people definitely makes it easier, as does IV.) removing the oil filter. (don't forget to reinstall it!)

This was my first experience with the removal of the air cleaner, the stacks, and the tops of the DCNFs. Obviously, removing the rear bonnet would have made life much simpler, but it was not in the cards for me. A few tools were most helpful…an 8mm nut driver, the shortest 8mm socket you can find (grinding one down X’d my mind), and an 8mm spanner with a flexible box end. Oh yeah….lots and lots of patience.

My meager knowledge of physics tells me that the air flow across the stacks is critical to the engine’s performance (or so says Bernoulli!), so I would not run the engine without the stacks and preferably, for safety’s sake, the flame resistant air filter as well.
Ya’ never know.

steve




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Sorry for my post #7, which was sent in error before I finished what I wanted to read about. Steve

 

Thanks for your input Andiy. II I ever have to do this again, I will certainly grind down an 8 mm socket. That would make a huge difference and it's a great idea. One cannot tell from the photo. but we struggled and struggled with that new forward most stud to which we had attached the knurled hold down nut. My problem was that the stud created, was too short to reach the "rivnut" below but I believe we have it now. Still have one more battle and that's with the Copiglia clamp on the air clenaer bellows. They look great but are a bear to deal with. Thanks again, steve

 

I bought the Harbor Freight 6 L cleaner. When I looked at the reviews on Amazon and eBay, and not one of those cleaners had reviews as stellar as Harbor Freight's. Generally, as a rule, I like to see 90% of scores at four or five. I don't believe a single unit that I looked at on Amazon came close to that arbitrary number, whereas HF's ratings were vastly better, approaching 97 or 98%, as I recall. I believe the 6 L is big enough to do a single carburetor, but as noted, I just did the tops and the guts. I did not do the bodies, nor did I take out the idle mixture screws. All other screws and jets were removed.

I used several different cleaning agents, as I only did one carburetor's guts at a time. I found that powdered dish washing detergent did not dissolve well, and ended up on some of the threads. It is astounding how many different things people have used as their cleaning agents. My bath itself was always water from the tap, and cleaning agents were sequestered with the parts I was cleaning. For this, I used Ziplock bags or sorbet jars. I just ordered some kerosene from Home Depot as I'd like to see how that works. I was disappointed with Dawn, but maybe I need to try it again, though I don't see anything for the unit on the horizon. However, I may do the power windows on my 308, if my balls get bigger. You are correct, in my opinion: the good chemical cleaner you used to buy in 5 gallon cans is now worthless and expensive. Steve.

 

Lee, thanx for the evening laugh! s