White smoke and I cant figure it out.

[Falkon]

I have been slowly getting my midget ready for its final steps in restoration. Iv got the interior ready and new lights all the way around. Its a half a days work away from getting its first coat of paint on it, but after rebuilding the motor and messing with little things here and there it is still blowing white smoke. :confusion:

Summery
Iv got all the vacuum lines replaced and connected.
Its been timed with a timing light.
Carburetors are properly adjusted (to my knowledge). As in its idling around 700rpm, and does not appear to be running lean or rich, although it was running very rich for a while until I figured out exactly how to tune the carbs. The engine appears to be running smoothly.
All the internals of the engine have been replaced except the crank and cam shaft.
Iv done a compression test and got 127 135 134 135
ALL of the spark plugs have a dark black soot on them. May be from running rich when i first got it running. But i did clean them off and it came back.
Oil pressure at idle sits around 70
Iv noticed the the warmer the engine gets, the heavier the smoke becomes. When its at idle its not that noticeable but when you rev it up a little bit, it becomes more noticeable.

My concern is that there is an internal oil leak and that it may be dripping from each one of the valve seals, but those are all brand new. I was thinking maybe the new head gasket was messed up but the compression test tells me that it is holding fine.
Does anyone have any other ideas as to why it would be blowing white smoke? I'm lost at this point and want to avoid taking the head off until i have a good reason too. Iv got my little midget so close to being ready to drive this summer and I don't want this keeping her in the garage till next summer.

 

[SaxMan]

In my experience, white smoke is usually indicative of a head gasket gone south. Anything oil-related is going to have a bluish tint to it, while overly rich carburetor mix will give off black smoke.

Is this a 1275 motor? The compression numbers seem to be on the low side for a 1275. I have a '69 Sprite with an original 1275 that has at least 106,000 miles on it, and possibly 206,000. The compression is closer to 145 - 155 per cylinder, and based on the marks on the valve cover, was as high as 160 - 165 at one point in its life. Have you tried a leakdown test? That will pretty much tell you what's going on.

 

[Falkon]

It is a 1275 engine. My next step was to do a leak down test, I just don't have the tools yet, but ill be giving it a try tomorrow.

 

[nomad]

white smoke is usually indicative of water. The brass plugs in the head have been gone over often. Do you remember if the head had any signs of the brass plugs not being exactly flush with the face of the head? Check and see if there is any sign of compression leakage into the radiator. Bubbles, frothing? Compression seems low but that may just be your tester...it seems even at least.
If everything else looks OK I'd take it for a short spin and let it cleans out before becoming too concerned.

 

[Hot Wings]

Was the engine using oil before it was rebuilt? And is the exhaust system the same?

The reason I ask is that occasionally I've rebuilt engines for a customer that brought in a non running vehicle and when the new motor was installed it smoked just as you describe. There was so much built up oil and carbon in the old exhaust that when it got hot and the engine revved up (increased flow) smoke came out. Only 2 solutions: Drive it until it quit smoking, or replace the exhaust system.

This assumes you have checked the usual suspect as noted by the others above.

 

[dklawson]

The compression numbers may seem low at first, but what pistons are in the engine? Are they dished?

If you have access to compressed air do a leak down test. Leak down tests can reveal problems that are missed by a compression test.

As above regarding smoke, white with a sweet smell = antifreeze, white with an acrid smell = brake fluid (not likely unless you have added a servo), blue and heavy smell = oil, black = fuel. Take the old plugs and heat their tips with a propane torch to burn off the sooty deposits, don't brush the deposits with a wire brush. If the cleaned plugs get sooty again quickly go through the carbs one more time. Make sure the float valves are closing and set correctly, adjust the mixture again, and look for problems with the plug wires, cap and rotor.

 

[Falkon]

@nomad-I do not recall anything about the brass plugs. It was about 3 years ago when i had the engine apart and then college happened. It kind of slowed things down. Looking in the radiator cap, it does appear to be a little low, maybe 2-3 inches down from the top and has some stuff floating on the top.

@Hot Wings- When I bought the car, the engine was seized and it had no ran since 76, its a 72. The exhaust system is all new except for the headers.

@dklawson-The pistons are dished and the walls are bored out to .002. Ill burn the soot off and see what happens.

Iv got a compressor, so now im off to find the tool for a leak down test. Wish me luck!

 

[Deleted member 8987]

You can't really trust a compression gauge to give accurate readings.
You can use it to compare between cylinders.

I've seen hundreds of compression gauges over the decades, not one has ever had a calibration tag sealing the case together.

Walk through the cloud.

I usually breathe in with my mouth partially open, some air in mouth, some in nose.
You will taste anti freeze.
You will smell oil.
You will quickly learn what brake fluid (from a booster into inlet manifold) tastes and smells like.

Straight water in the radiator?

 

[Boink]

I recall after a quasi-rebuilt that we had accidentally gotten some oil into the manifolds... and there was a HECK of a lot of fairly white smoke at start-up, and it lasted for several minutes (maybe 5-10). I've also see fairly white smoke from oil being sucked into the intake manifolds through a PCV (from the line to the oil separator). No, not fully white like water, but not blue (or black) and the vapors lasted a long time (like water/steam with exhaust).

 

[Falkon]

Well I was not able to do a leak down test per say, but I was able to pressurize each cylinder just without the gauges. I did not hear any abnormal leaking air sounds. Every cylinder was the same and my compressor never started loosing the air at a rapid rate. After accomplishing that and starting her back up....well the white smoke went away and revealed that i am still running rich, (black smoke). I tried to lean each carb out but that did not seem to help. She is still running rich and after i spent an hour trying to figure those dang carburetors out, she isnt running smoothly either. I do think that it was leaking water into the one of the cylinders but for some reason has stopped.

So white smoke is gone and black smoke is back. I feel like I'm running in circles.

 

[dklawson]

Check and adjust the float valves on the carbs, then try adjusting the mixture again. If you find any witness marks on the tips of the float valve needle, replace them. If the floats "don't float", replace them. Fuel leaking past the float valves will make for a rich, badly running idle. The engine may or may not run OK at speed with a leaking float valve.

 

[Boink]

Any leaking at the float-bowls (i.e., are they set right)?

Glad the white smoke is gone as that would have been trouble; it was probably stray oil in a manifold upon assembly.

 

[nomad]

As Doug said, No 1:make sure that the floats are set right. No 2: Make sure both carb butterfly's are opening exactly the same. No 3:Adjust both carb jets exactly even with the bridge in the carb throat then down 12 flats of the adjusting nuts. If you have oil in the dash pots it ought to be pretty close. What you do to one do exactly the same to the other and unless you have uncommon problems it will work.

 

[nomad]

One more thing. If you have your air cleaners off and the ignition switch on so the pump is pumping fuel [electric pump not early mechanical] and you raise the throttle slides you will quickly see if your float valve's are doing their job!

 

[Falkon]

Thank you guys for all the tips. The float bowls are not leaking and im know the floats work properly, but i can always double check. Ill give adjusting the carbs another shot tomorrow when its not cold and snowing, in May, in Colorado >.<.

I haven't looked into it, but since Im, on average at a higher altitude and there is therefore less air, would it be possible to put in a different type of needle that leans it out sooner. My thinking is if im doing everything correctly and when I go to lean it out, the nut will hit the top before i can get the mixture lean enough. So would a bigger needle help with this or is? Also is it possible that the cheap $20 low pressure full pump (2-5psi) that i got from the auto parts store is pushing fuel past the float shut off?

 

[nomad]

Floats need to shut off the fuel at the same level in the float bowls as well as just shut it off. As Doug mentioned the later carbs will wear the needle's and jet so checking for that is a good idea and while you are at it wiggle the throttle shafts to make sure there isn't excessive wear in them. There are different needles available but I would talk to an expert on altitude change and SU's before changing. When younger we loved SU's in the mountains because usually all that was needed to handle the altitude change was an adjustment of the jet.

Kurt.

 

[drooartz]

I've had to run leaner needles here (5550' elevation at my house). SU carbs do a generally good job of altitude compensation, but there is a limit. Figure out what you have as far as needles go, and a call to Hap or Joe Cuerto should get you some idea as to where you should be.

 

[dklawson]

Sorry, I was not talking about the metering needle and jet, I was referring to the tip of the needle that is part of the float valve assembly. There are metal on metal float valves, float valves with Viton rubber tips, and ball bearing (Grose Jet) types. I no longer use Grose Jets due to problems I have had with them. The metal on metal valves work until a ridge is worn on the tip of the needle. The Viton ones work a long time until the rubber becomes hard and takes a set due to age.

I was not suggesting that fuel was coming out of the float bowl. However, if the fuel is leaking by the float valve slowly at idle, the level of fuel in the bowl (and therefore the main metering jet) will be too high and it will make tuning and idling difficult. It will create a very rich condition.

You asked if the 2-5 PSI pump could be part of the problem. Yes. Put a gauge (at least temporarily) on the fuel line and see what you are getting for idle fuel pressure. SUs and Strombergs like about 2.5 PSI. Anything more than 3 PSI can start to overpower the float valves and pump excess fuel right through the carbs. If the leakage is not too severe it can cause a rich condition but will not cause overflow out of the bowl vents.