I've done a bunch of reading over the weekend about what I found Friday evening. I was taking the generator off my '35 so I could get it tested and have a regulator matched to it. Anyways, I was cleaning the engine up a bit and I found what looks and feels like a fair amount of OIL on the bottom of the primary carbs which are 97's. The oil seems to be coming from where the Jet plugs are mostly on those two carbs. Now what I found there was some indication that improper venting could cause issues like this or perhaps the rings not being seated properly. I'd think if I had real ring seating issues though I would be able to see it in the form of blue smoke out of the tail pipe which is why I have been focusing on the venting. The engine is a '56 so I have an oil filler tube with breather AND a factory oil draft tube near the distributer. That should be enough I think but can anyone think of something that might be improperly working? Anybody come across this issue especially with 4 carbs? Is it more common to have access pressure when you have more carbs? Does my engine need breathers? How can you check if you're getting the right amount of venting? This also might be partially the case why I was having problems with my engine "sputtering" after driving it on the thru-way for more then 50 miles at a time correct? Any info would be great. Not looking to run a PCV, just looking to fix what I have with what they had. Thanks, JJ
PVC would probably be a better fix. You can get a fitting that replaces the road draft tube and the PVC valve goes in there with a short hose to the manifold. The breather on the oil fill tube should be good enough for suction. Are you sure the can baffle under the intake manifold is not plugged up?
Well the engine doesn't have 1000 miles on it since the rebuild and it was completely gone thru HOWEVER I might have to pull the intake and check that out just to make sure. PCV would be a last resort. I really don't want to go that route but if it means not driving or running one, then I'll do it. Thanks, JJ
Are you sure the carbs arent leaking my does the same thing its fuel as im a little high on fuel pressure.
It's really thick like oil, sticks to the finger like oil and doesn't smell like gas at all. My pressure is kept around 2.5 so it should be fine. And if they were being overrun by the fuel pump I would think all 4 carbs would show that. I'm gonna have to clean the carbs so I'll get pics asap.
I have to say holmes that Dave50 is on the money. My 94's will get a thick, sticky, gluey residue all over the base of the carbs. It's leaky fuel. Which rules on my white engine.
I get the same thing. Kinda oozes out of the three plugs. Im sure that the road draft tube is fine. I like them more than the pcv.
That looks like the gas that gathers at the base of my carbs. How it got in your **** is a mystery to me...
Let me ask this. Say that is gasoline and it doesn't have anything to do with my venting. HOW DO YOU TEST THAT YOU ARE VENTING PROPERLY? What test can be done to check you have optimal venting or is it something where you just wait for signs to tell you it's NOT venting right?
That's what I thought when I read it. Leaky 97's, the fuel is just turning into varnish and looks like oil. Drat tube and breather should vent it fine.
"HOW DO YOU TEST THAT YOU ARE VENTING PROPERLY?" Very interesting and astute question, I think! Since ventilation (slightly different concept from just venting) is pulled through by road draft, you need to have road draft from motion before you can test it...and with car moving the airflow up top would make simple tests to see if there's a flow in through the vent cap very difficult. Chaining an apprentice or graduate student to the radiator rods to blow cigarette smoke at the stack isn't going to work with all the flow from movement and fan. My thought for test is an attempt to measure the slight negative pressure that should exist there when car is moving. My first flying guess at an experiment capable of measuring slight pressure drop would be about so: Remove filler/filter cap. Plug the hole with something rubbery with a small hole through it. Shove a length of clear plastic tubing into the hole, run it through firewall into the still air of the ****pit. Be thankful at this point that you couldn't find a roadster...bend tubing into a U inside the car, add some water so you can see a level in both sides of U, loose end pointing up. Go for a drive. If my theory that this simple manometer is sensitive enough is correct, water in engine side of the U should move uphill a bit. If no movement, though, nothing is shown because my design may be faulty. I'm thinking here that a water manometer like you would use to synch carbs is probably considerably more sensitive than a normal automotive vac gauge.
Getting back to your comment in your first post, I can't see how excessive crank case pressure is going to make your car sputter after driving it 50 miles. And I don't see how you could get a crank-case pressure build up with your setup anyway. Even if there is a blockage in the road draft tube that prevents air flowing through the engine there is still a breather on the front and that is going to prevent crank-case pressure building up. With your setup, the worst I would expect would be some condenstation build-up in the valve covers if there isn't enough air-flow through the engine.
I just took this pic of my intake stuck my finger in it IT DOESN'T SMELL LIKE FUEL BUT IT IS ik it's hard to believe but I am pretty sure that's your leak, take your finger and feel bottom of carbs instead of your bum bum.. Posted using the Full Custom H.A.M.B. App!
No worries....I've had that stuff on my fingers before..... but it came from 3 leaky rochesters. No real answer on how to test for proper venting, but if you had to much pressure, it's gotta come out somewhere...rear main, front .... cutting out and the other problems sound carb related...
Why are my secondaries not doing it? Just by chance that it's the primaries are the ones with the substance seeping at the bottom? These carbs were rebuilt by Uncle Max who's know for building leak proof 97's. Just want to make sure it's not something on my end.
If your road draft tube is oily, it's probably working. I have an OT bike that makes brown gooey stuff on the bottom of the carbs at the drain and jet plugs...looks just like the stuff on your finger. +1 for fuel seepage.
Yup...looks like the goo I've seen too. I had some of this form on the outside of the intake in the grooves from a slightly leaky main jet housing. I have those adjustable ones with the tap-looking piece and the outer piece can weep a little if a fiddle to much with them (sounds familiar). It doesn't smell like petrol and has the oily feel. It would turn to varnish if I left it I'm sure. So blame the ol' 97's.....
According to your finger picture.....it came from your end. Ok seriously, you can temporarily swap a valve cover or covers for one with a breather and drive it to confirm its not crankcase pressure. My Rochester 4gc leaks the same ooze though, it's not oil but evaporated fuel residue. Take some of your gas and put it in a dish and leave it in the sun/heat for a few days. You'll end up with that stuff in the dish.
In olde car usage... Vented just means there are holes for the pressure to get out. As noted above, probably the filler pipe is enough to accomplish this. Think '32-24 Ford. Ventilated, as in most engines from then into the 60's, meant using a draft tube (or other means, as on '36 Fords) to try to generate some actual through flow, needed to clear out all the fumes in an engine that cause sludge and acid. This was helped along in the '60's by adding a PCV to make the flow somewhat more positive and less dependent on car speed. Some sort of flow is important, or you will get sludge and corrosion in there.
subscribed, I have the same issue on my fresh built 265 with two 48's, running stock draft tube and fill neck on a 56 gm dual quad intake, I had my fuel press reg at 3psi. I have a oozing issue at the shaft (****erfly shaft that is), I ***umed gas and turned is to 2.5psi, but I still see it, and it seems oily.
I think they're right it's just gas and these strombergs suffer from leakage. The shaft's are a common place to leak unless you send them to Uncle Max and have his rebush them properly.
This sounds serious............. Why don't you pack up that 4x2 setup and send it to me? I'll do some investigating and get back to you.
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