I have been a marine tech for 30 years now mostly omc and stern drive last five years honda Give me a good motor question. I will try my best to answer it I love to talk motors and fishing and its been a long winter My screen name probably should have been MOTOR HEAD
I have a 1960 Chris Craft Roamer with the original Carter WCFB (2669S) carburetors (on the small block GM engines). I would like to replace these carbs with something a little newer, or at least in better condition. I had them rebuilt about 4 years ago, but they have so many issues I don't want to deal with them anymore. Hopefully, I can find something with the same footprint so that I do not have to get into new intake manifolds, wedges, etc.
Any suggestions?
Thank you for your help.
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there are all ways a bunch of ways to do things and the rite way for you is all ways going to be your decision but i have to tell you the carburator intake manifold and distribute are all ways a matched set and a delicate balance . carburators have to be parrallel or flat to operate properly or at least real close to flat especially at lower speeds.
There is no easy bolt on fix for the carburator alone . and more often than not the carburator is blamed for performance problems caused by other components or bad fuel .
so the million dollar question what makes you want to put new carb on these motors . If the carburators where over haulled properly this problem should have been eliminated and the process or elimination needs to move on to the next probable cause
I'll start with a ten dollar response to the million dollar question. First, I hope the carbs were overhauled properly. I had trouble finding someone to do it. The shops had never heard of these carbs, but rebuild kits are available, so I bought a pair and an old motorhead I worked with at the time rebuild them for me.
Assuming he did his best, my issues now are with the chokes and idle mixture screws.
The idle mixture screws do nothing. Turn 'em in, turn 'em out, no change. The fuel splatters and dribbles from the jets at idle. From what I can glean from old manuals and the rebuild kit instructions, the seats for the idle mixture needles are not replacable.
The coil springs that operate the chokes are bad. At least one, if not both, are the wrong spring, and they do not move enough to properly open the chokes. I set them so the chokes are full open at operating temperature, but then I do not get the choke that I need for cold starts. I have not been able to find any information about these springs, or replacements.
I hope this all makes sense. Ask me some more questions.
Thanks again.
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first lets examine the obvoius > if the idle jets have no effect on the running of the motor at idle there has to be pluged pasages or the throttle plates are open past the idle ports in the throats of the carb. we need to know whitch is the case! > there are some inherent problems with small block chevy motors that should be checked just as a matter of experience
> the cam shafts have a habbit of going flat (wearing out) when you no longer get the proper lift from the cam the first thing a mechanic does is screw the idle stop screws in until the engine will stay running . meight explain this symton
> the intake manifolds rot out under the carburator (where you cant see it with out disassembly) and allow exhaust gas from the intake crossover into the intake manifold corrupting the intake mixture . when extra choke is added the sympton goes away. the idle jets will have no effect on the running of the engine if this problem is present .
there are specialty marine carb rebuiders that rebuild these carbs all the time and this is not a problem . but i suspect that there is some sort of other problem going on . first thing first we need to find out why the idle mixture screws have no effect. I used to have a 1957 bull nose criss with in line flat head herk motors now those where a pain in the butt to work on and find parts for your small block chevy motos should be a piece of cake if you want to see it through
Ok. Now I will have to do some studying and investigation.
I'm reasonably sure that the intake manifolds are not rotted out. I have had the carbs and manifolds off, and I assume I would have been able to spot any rot during the cleanup.
I'll let you know what I find out. (Don't hold your breath. It may be spring before I can do anything.)
Thanks again.
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You forced me to hit the books a little to learn about carbs so I can communicate with you better. This is a good thing?
This is what I learned from the books: Starting at the bottom of the throat, you first have the idle port. This will always be below the throttle plate. A little further up is the low speed port, which should be above the throttle plate at idle.
I went to the boat yesterday and pulled a carb to bring home. Assuming that I learned correctly from the books, here is what I see:
The idle stop screw is in far enough to hold the throttle plates open to about the middle of the low speed port (a vertical slot).
I’m not liking where this is going.
From the drawings in the book, it appears that the same passage feeds both the idle port and the low speed port. On my carb, the two ports are not lined up vertically in the throat, so I am wondering if they are fed by the same passage. Also, one throat has a third hole—a horizontal slot at the same level as the low speed port. Do you know what that slot is?
One other little piece of information: I discovered a couple of years after I bought the boat that the original 283 blocks had been replaced with 350 four-bolt main truck blocks of early 1970s vintage. As near as I can tell from the casting numbers, they hung the original heads, intake manifolds, etc. on the replacement blocks. (This boat has been a real treasure hunt from the day I got it.)
Now what, doctor? (And please don’t tell me you are a proctologist.)
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what do you mean you dont like where this is going? We are going to fix this thing! First if you are correct and the original heads where put on a 350 block you have a bunch of mis matched parts . this will drasticaly limit hp out put and waste a bunch of fuel but will not or should not effect idle and idle should be addressed before we go to the next step the intermediate fuel circuit in your carbuerators at idle should become a emulshion inlet for air into the idle circuit and if they are uncovered at idle this would explain the lack of effect the idle mixture screws have. Your carburators may not have any thing wrong with them except may be the wrong high speed jets from the block change we touched on earlyer . You need to do some comprehensive testing to find out more hard information its looking more and more that the carbs are geting blamed for other problems as is often the case there are two test that i would perform before we go any further these thest will drastically elimante the diagnostic time required to fix it rite the first time cylinder leakage test. to do this you need a good portable compressor and a leacage tester . allthough a compreshion test will tell you if there is a problem the leacage tester tells you exactly where the problem is . this test puts air presure in the clylider from the compressor and tells you what percentage is leaking out. if it is leaking your ear will tell you where the problem is if you have a ring problem the compreshion will be heard leaking out the vale cover if a intake valve is bad the sound will come out the carb or exhaust valve it will be the exhaut . also the distrubuter should have the advace curve checked to make sure it is advancing the timing at the proper time and speed . if all is well with the leakage thest the motor ill have to be run to check the distributer . I am going to guess here and say you probably have either a flat cam or some bad valves . the good news it the small block chevy is the easyest and the cheapest engine ot find good used parts for if the heads have to come off they should be checked they should have the 1.94 intake valves this is the measurement across the face of the intake valve and is the stock size intake deminsion to suport a 350 cid motor with a four barrel carb the cam should also be taken out and measured to mke sure the lobes are all intact if you end up going this far i would recomend a new can and lifters .
Going to add a Simrad Auto Pilot as soon as the weather breaks here. Requires a new steering cable, how difficult is this on an OMC Cobra 3.0L engine? Thanks. -Alan
How great is this... and OMC tech on the board, not easy to find these days!
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not bad on most boats it can be a problem if other things have been tied to the cable like wires and transducer cables . they should only be attached at each end take the old cable in to you dealer to get the correct replacement the first time it should not take more than 3 hours if you decide to take it in and have it done
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