I am restoring a 1966 Cutlass and have had the engine rebuilt by a speed shop that is no longer in business. I had it built 6 years ago and have just tried to get it running.

It will start and sounds clean. The only issue, and it is a big one, is that the smoke is black and the fumes smell like gas. Can't even deal with the smell in an open 2 car garage.

I have a 750 Simmit carb. Edelbrock high intake and MSD ingnition system.

When I check the oil it is low and has a creamy tint to it. It is not the type of froth or color when water is in oil.

The oil also has a strong smell of fuel.

Any help would be appreciated.

I ha double checked timing and is 10 degree TDC

 

You kind of answered your own question. To much fuel which explains the black smoke and fuel in the oil. You either need to tune that 750 or buy a smaller carb. Others feel the 750 is a good choice I personaly think its too much . A 650 will work very well has for me . I think 10 degrees is too little initial timing. If you have a bigger cam etc etc. I would start at 12. I'm currently running 16 initial but my small block is no where near stock. Also sharing your specs will help with the pin pointing.

 

I have bored the engine and had a comp cam put in. I also had dual exhaust added. It has high compression heads.

It is a 330 engine.

 

It has a high capacity fuel pump. The carb only accepts 7 psi. If the fuel pump sends top mocha fuel can this overload the card and cause the heavy fuel problem?

 

That carb might be to big. Maybe a 670 street avenger might work better. Also if its that summit brand carb they are a really old outdated design that holley decided to not make anymore. I'M currently tuning one for a friend and its the 600 cfm version and it feds his chevy 350 very well and its a stout little engine.

 

Yes high fuel pressure will make the carb run like crap. Always run a fuel psi gauge and regulator. Makes setting things very easy.

 

Imo 750 is to big for a 330.Nick

 

I have a Holley 600. Would that be one to try?

 

Yes. I ran a 600 cfm on a 350 that ran 13.3's @ 103 mph. It fed the engine very well didn't miss a beat.

 

X2 yes also you should change the oil if it's contaminated with fuel so you don't damage the bottom end.Nick

 

Oil that is discolored and smells like fuel "usually" points to a bad fuel pump diaphragm. When ruptured it allows fuel to be directly pumped into the crank case.

As for the black exhaust it sounds like it is excessively rich. Often from a sunk float. In other words one of the floats is no longer air tight and has filled with fuel. Once filled with fuel it is no longer buoyant and does not shut off the fuel going into the carb which allows the fuel level to rise a significant amount and cause the AF to be on the extreme rich side.

The size of a carb has absolutely nothing to do with how much fuel is allowed into the engine. The only difference a large carb has over a small carb is the ability to allow more air and fuel into the engine for situations where there is need for it. A carb that is technically too big for an engine will not make it run rich at idle, thus the same with too small a carb will not make it lean at ilde. Or else ware throughout the RPM range.

 

I changed the carb to an Edelbrock Performer 600 and wow! Car runs smoother and no black smoke. It is still burning rich but no where like it used to. I don't want to play with it any more until I get the oil changed.

Will off timing cause a car to run rich?

Will flooding of the carb cause the fuel in the oil? I am very concerned about the fuel pump diaphragm post.

Mark

 

It is technically possible to get fuel dilution from the carb but it is rare. Your talking about a good amount of fuel to get past the rings into the oil. It's easy to pop off the fuel pump and check it out.
Timing won't necessarily make it run rich but can have an effect of being rich as far as performance goes. After you get the oil changed find out what the total timing (mechanical + initial) is by using a dial back timing light and bringing the rpm of the motor up until the timing stops advancing. That will give us a better idea of what you should have for your initial timing and at what rpm you should be setting it.

I brought my '67 home from Marietta, Ga. Small world.

 

Don't let anyone come around smoking when you change the oil.

 

Okay guys, so this is where I am at now.

Changed oil which was mostly fuel - very thin and watery

Changed oil filter

Car starts and runs fine and I am able to get a nice idle. However, there is still the smoking and gas smell. Would this be caused by what was left over from previous carb issue (I replaced the summit carb with edelbrock performer)

I took off the old fuel pump ( which actually new) and am Glinda to replace with a stck fuel pump I have on hand.

What could I be missing? Could an intake manifold leak cause fuel in oil and rich running?

All help appreciated

 

The smoke is no where near as bad as it was.

 

If the old carb was leaking while sitting, there may have been some fuel sitting in the intake manifold when you swapped carbs. But it would have been burnt off within a few seconds of firing it up.

How long did you let it run with the new carb? How confident are you the Edelbrock carb is in good shape? It may just be very rich at idle.

 

The Edelbrock carb has been sitting for 7 years on a shelf.

 

Smitty wouldn't the bigger carb have bigger main jets. Now I know the fuel has to pass through the main jet to get to the idle passages where there is a idle feed restrictor but don't they come fitted according to the size of the carb ? I would imagine that the 750 would be bigger than a smaller carb in those area's. Not trying to argue But I spent a great deal of time messing with a 650 quick fuel. I could not figure out why it was idling so rich. I did some cross referencing with a holley 650 and the QF was bigger all across the board compared to the holley ., air bleeds jets squirters you name it., it was 3 sizes bigger. I decided to sell it and get a 650 holley double pumper and out the box it idled very well and performed great all across the board on the street. The QF was rich at idle and just plain sucked all across the board. Just my experience with that. I don't know the internal passages of this summit 750 which is based on the old 4010 Im speaking in terms of the standard 4150 style.


Edit: I might add I did a lot to get that QF 650 to run somewhat close ., jets , squirters , I had to run throttle plates with holes in them because the transfer slots where overly exposed on both the front and back. It was not the power valve I played around with that. I bought it for 100 and it was near new I spent 125 trying to get it to run right and I sold it bought the holley and never looked back. Although I learned a lot about carbs lol.

 

The jets are sized according to the size of the venturi (actually its ability to pass a given volume of air) so as to maintain the same air to fuel ratio. The main jet size has zero effect on idle. At least it shouldn't have any effect. As far as two different carbs of same style & cfm having different jetting/bleeds that is not unusual. Main reason is that they were set up for different applications. A mild cams vacuum signal is completely different than that of a wild cam. The QF carb was probably intended for something much wilder than the box stock Holley which are usually set up for the mild cammed, stockish engine scenario. None of the carb manufactures do a good job of lusting the application for a specific part number carb. Yet they all have multiple listings for the same "size" or "rating" of the carb.

 

66cutlass.......your current smoke issue could be from issues related to your past carb issue. "IF" the old carb was putting massively excessive amounts of fuel into the engine it is very possible that the excess fuel caused cylinder wall and compression ring damage because the oil was constantly washed away and the lubrication was not there to protect the wall/rings/pistons. Add to that the oil in the crank case being severely diluted means what oil was being thrown up onto the cylinder walls was not able to do its job and exacerbated the situation.
Your smoking may or may not go away over the next few hundred miles.

You had also asked about intake gasket letting fuel into the oil. Well, yes it could, but the car wouldn't idle worth a darn because of the vacuum leak it would have presented. And as easily as it could have let fuel into the crank case it also would have caused blue smoke anytime you left off the throttle because in a high vacuum situation it would gave pulled oil into the intake to be burned.

 

My car it still on jack stands as I am still in the process of restoration of wiring and interior. Should I let it run for a while and see what it does. The car has no more than two hours of run time since I started it.

 

My engine overheats and a lot of pressure builds up. I don't have to run it long. Could this be caused by only running one fan instead of both? I have changed the thermostat twice.

 

Smitty that was what I figured. The qf was more for a race car even though it was street strip. I did have a decent sized cam in there and good compression . The holley did its job. I do agree carb size should not affect idle quality was just curious because of the way the cuircuits run inside . Sorry if I hi jacked the thread abit smitty thanks for the input really appreciate it little stuff like what I asked helps me understand a carb that much better.

 

For the cooling system did you burp it ? You could have a steam pocket and that wil overheat an engine in a hurry.

 

How do I burp it?

 

I just usually run it with the cap of the radiator and squeeze the hoses to push the bubbles out. To be honest I forgot which hose you have to squeeze but I usually squeeze to top one then the lower. But make sure everything else is in order. Timing and fuel etc.

 

I have resolved the rich burning. I went back with the Summit a Carb and put a stock fuel pump. Once I figured out how to adjust the Summit it runs great

I seem to have made progress on overheating. I probably need to get both fans running to check temp.

Does anyone have an idea of the temp. That water should run.

 

My engine runs right at the thermostat opening temperature. 180º with the current thermostat. A couple weeks ago when I was flushing the system I pulled the thermostat and the temp gauge stayed around 140º while driving.

 

As far as I know, that's far too low to be healthy for the engine.