Fuel in My oil pan

[350runner]

What size base gasket do you have under the carb?

Sent from the dust in front of you!

 

[MadOgre]

took the old fuel pump apart today, diaphragm is in one piece. So either way at this point the fuel pump isn't the problem. I don't want to ruin an oil change if the fuel pump wasn't the problem.

Diagnostically what else can I check before I fire it back up?

See I knew it wasn't the pump. I have never seen a mechanical fuel pump dump fuel into the block. I would rebuild your carb or get a new one.

I would change your oil again real soon regardless. $25 for an oil change $1500 for a new motor.

 

[350runner]

X2 on the oil change. Is your carb new?

Sent from the dust in front of you!

 

[rich weyand]

Are the tanks vented? If you don't have a vent line, the cap needs to be vented.

If it is vented, there should be no whoosh of air either way when you take the gas cap off.

 

[ryan.johnson]

What size base gasket do you have under the carb?

I have the tv made easy kit on it, so its the two gaskets that came with that kit

See I knew it wasn't the pump. I have never seen a mechanical fuel pump dump fuel into the block. I would rebuild your carb or get a new one.

I would change your oil again real soon regardless. $25 for an oil change $1500 for a new motor.

As soon as I buy a real rubber strap wrench I'm going to change it again.

X2 on the oil change. Is your carb new?

I replaced the carb this year, march or april probably

Are the tanks vented? If you don't have a vent line, the cap needs to be vented.

If it is vented, there should be no whoosh of air either way when you take the gas cap off.

The gas cap has a vent, it lets air into the tank but I don't think it lets it out- based on blowing on it. I'm not sure where a tank vent would be run. Don't think I've ever noticed pressure in the tank when I open it up. When this issue occurred the tank was fairly low on gas- below 1/3 a tank. I don't typically let it get this low, as in I'm not sure if I ever have.


sometime this week I'll pull the carb apart, my dad seems to think the float could have a hole, making it sink and flood the intake.
I do run a pressure regulator before the carb.

 

[rich weyand]

If the vent won't let pressure out, pressure in the tank from temperature cycling could push gas all the way through the system, into the carb, down the intake and into the pistons where it will seep past the rings. Since it lets air in, when it gets cold it will recharge the air in the tank, then push gas again when it gets warm.

That is another candidate for what happened, and could account for a large amount of gas in the oil.

Drill the cap. 1/16" hole all the way through is all you need.

 

[MadOgre]

If the vent won't let pressure out, pressure in the tank from temperature cycling could push gas all the way through the system, into the carb, down the intake and into the pistons where it will seep past the rings. Since it lets air in, when it gets cold it will recharge the air in the tank, then push gas again when it gets warm.

That is another candidate for what happened, and could account for a large amount of gas in the oil.

Drill the cap. 1/16" hole all the way through is all you need.

I drilled mine with a 1/8 bit in the center. You don't have to drill all the ways through the cap just drill from the inside out, until you hit the pocket area that vents to out side

 

[MadOgre]

We arnt gonna start this again.........

Timed vacume is the performance way. Manifold is poor man's throttle response XD.

I have a stock 350 85' block and heads 4 bolt mains HD truck application. I have an Edelbrock 2701 intake with an 1806 carb, all brandnew. Stock HEI distributor and weights with a high output accell coil 8mm wires. 70s W exhaust manifolds on dual 2 1/2 inch exhaust. Using a 700r4 3.42 gears and brand new 33" tires.

I have absolutely no emissions control at all!

I put the carb and intake on a couple 3-4 weeks ago and have run it only on manifold vacuum for timing advance.

So yesterday I switched it to timed manifold vacuum.

I must say I have better throttle response, better fuel economy, the transmission shifts even better, much better power from idle to part throttle, the secondary's perform better and over all a much more powerful and pleasant drive all around. It even sounds better.

So my input is that timed vacuum is the correct way for a daily driver.

Sorry Rich

 

[rich weyand]

Hi, MO:

Like I said, try them both.

Our setups are a little different. Here's my full setup.

I started with a stock original 1978 350 with factory duals and a new Edelbrock 1406 with an open-element air cleaner. Everything else was bone stock.

I now have a 350/260hp crate engine, Comp stump-puller marine cam, Edelbrock 2601 air-gap manifold and 1406 carb, hot and cold air induction with the thermostatic air cleaner, stock distributor with Accel super coil and high voltage cap/rotor with Taylor spiral wound wires, 16" Flexolite electric fan and controller, Hooker 2453 headers, mandrel-bent 2.5" duals with an H-pipe, through Flowmaster 40s, coupled to a TH350 with modified shift points running on 3.73 axles and 31" BFG tires. I'm running 87 octane on a base timing of 17* BTDC with stock 20* centrifugal advance and 15* (crankshaft degrees) vacuum advance. Carb was re-jetted and tuned right on the numbers in all modes with an NGK AF/R meter and wideband sensor.

On ported vacuum in either setup I had rough idle and about a half-second off-idle throttle hesitation. On manifold vacuum, idle is smooth and throttle response is nearly instantaneous.

So, it may depend on your setup, your carb, your carb tune, or a myriad other factors. In particular, components designed from the ground up since 1968 may assume ported vacuum.

I am old enough to remember when A.I.R. pumps and ported vacuum were introduced on new vehicles beginning on 1/1/1968 to meet new emissions laws. 1968 models built in 1967 didn't have them. My dad ordered a '68 Ford LTD wagon with the 390 4v in fall 1967 and specified the car was to be built before the end of the year so as to avoid that stuff, or he wouldn't accept it. I worked on my own 1961 Chrysler 361, 1962 Plymouth 225, 1962 Buick 401, and 1966 Chevy 195, and all of them ran on manifold vacuum. So for most non-emissions, old-school setups, that's probably the way to go.

But there's no substitute for trying them both. I only tell people to switch when they complain about throttle hesitation, rough idle, high engine temps at idle, etc.

 

[Skweegle89]

I just swapped mine from drivers side to passengers side at lunch. Couldn't tell much difference on the 6 block drive back to work, but I will cruise around this evening and see if I can tell a difference. I didn't notice any problems with the way it was, just doing this out of curiosity.

 

[DoubleDingo]

For a stock 81 rochester quadrajet, which is the correct ported port? I would like to switch to see since I have done some changes to my engine (vortec heads, 300hp Blueprinted Crane Cam), everything else is how it came from the factory. Would pics of the carb help?

 

[Driver4r]

Front drivers side.

 

[rich weyand]

This help?

You must be registered for see images attach

 

[DoubleDingo]

Thanks Trevor and Rich. I didn't know if the one on the top of the rear of the carb was ported or not on mine. But I will switch them around and see what happens.

 

[rich weyand]

... So yesterday I switched it to timed manifold vacuum.

I must say I have better throttle response, better fuel economy, the transmission shifts even better, much better power from idle to part throttle, the secondary's perform better and over all a much more powerful and pleasant drive all around. It even sounds better.

So my input is that timed vacuum is the correct way for a daily driver.

Sorry Rich

Just some follow-up. MO, I debated whether to post this, but I thought you might want to know.

I had occasion to speak to a Professor Emeritus of Aviation Technology last night. 30+ years teaching engine theory, engine overhaul and maintenance, as well as doing engine research.

His reaction? No way ported vacuum yields superior performance to manifold vacuum on the advance circuit, assuming other engine parameters are tuned properly. If switching to ported vacuum results in superior performance to manifold vacuum, then some other tuning parameter is incorrectly set. In particular, if the idle mixture is set too rich, that mixture will burn faster, requiring less advance at idle. Rich enough and ported vacuum (which is less advance at idle) may result in better performance than manifold vacuum, but it is compensating for the incorrect mixture.

It becomes self-fulfilling if you put the advance on ported vacuum and then adjust the idle mixture for best vacuum. That mixture will necessarily be rich compared to an idle mixture set for manifold vacuum. Simply swapping the vacuum line at that point may result in worse performance on manifold vacuum. Resetting the idle mixture, though, will result in better performance than is achievable on ported vacuum.

An engine with the idle mixture properly dialed in to the numbers using an A/FR meter should always run better on manifold vacuum. Since I dialed in all my numbers with the A/FR meter, he was sure that my tune would run better on manifold vacuum.

Anyway, that's what he said. You guys can do whatever you want, but I will continue to recommend manifold vacuum for best performance.