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Engine build problems. Desperately need help :,[

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This probably isn't going to help, but I have experienced very similar symptoms with my rebuilt 1275. In fact, I'm still trying to sort it out.

Everyone kept telling me to just drive it and that it may take a goo 500 miles or so for the rings to seat completely. I did, but it has never stopped smoking completely.

It mostly smokes when it sits at idle. Oil consumption is very low. I don't have to add oil between oil changes. Before the rebuild, I would go through a quart every 500 miles, but it didn't smoke at all!

Mine is a blueish smoke, and I'm pretty sure by the smell that it's oil. I didn't touch the carbs during the rebuild, and they never ran rich before...

I've always suspected valve guide seals. I question the competence of the guy who did my head work, and wonder if he even put the seals in there! I've been planning to try to replace them at some point.

One other thing that I've noticed is what seems to me to be a lot of oil in the air cleaners. I've wondered if oil is being forced up through the crankcase recirculation system and into the carburetter that it connects to.

My engine has good even compression across all cylinders. I plan to do a leak down test before I d anything else at this point.

Good luck with yours, and keep us posted. I for one am curious.
 
Kurtis - what color are your plugs? I had to tighten up my choke cable and just that was enough to need to adjust the carbs a little - with all else that you've done, it might just be that you are running rich
 
JPSmit said:
Kurtis - what color are your plugs? I had to tighten up my choke cable and just that was enough to need to adjust the carbs a little - with all else that you've done, it might just be that you are running rich
Click to expand...

My plugs do seem to indicate a rich mixture. Of course I only ran the car for a few minutes last time I ran it, and never really warmed it up or ran it past a high idle.

The plugs definitely don't seem oily.

I'll try leaning it out a little, but I'm pretty sure that the smoke I'm seeing is oil. It smells like oil to me and seems to have a bluish tint.

I'll have a leak down tester this weekend. Hopefully that will provide additional information.
 
OK, correct me if I'm wrong on a couple things here.

1) Overly rich mixture will have a blueish tint like oil.

2) If it is oil burning and not rich with gas, the plugs will be oily and not sooty. Oil=oily Gas=sooty

JACK
 
1) Over-rich mix results in black smoke and some "splooty" running. Oil is bluish white.


2) Depends on how much oil and how hot the plug.
 
Blue smoke means oil where I come from.

While I would get a good blast of smoke for the first minute I ran a new engine, that cleared right up in the first minute of running. I never had a rebuilt 1275 engine that belched smoke until it was broken in. Maybe a puff of blue when I shifted for the first 100 miles, but that is all.

The person above who raised the crankcase vetilation brings up the point I would investigate. Does this engine have a positive crankcase ventilation valve? If not, is the crankcase vent simply piped to the intake some how? If it does have a PCV, have you checked the diaghram? If that is cracked it will let oil pass into the intake.

If that does not clear it up, I would look at the head. Were new valve guides installed? Remove the valve cover and make sure they are all at the proper height. I have seen bad guide jobs that let oil leak between the guide and the head.
 
I was wondering about CCV as well, especially since you went to MS. You got a pic of your set up?
 
Kurtis said:
Regarding the crankcase ventilation issue...

My 1275 has some kind of oil trap canister attached to the timing chain cover. This is connected directly to one of the air cleaners. No PCV. Could this be my problem?

Here's a link to a picture showing the setup...

https://www.britishcarforum.com/bcforum/photopost/showphoto.php/photo/2205/ppuser/3212
Click to expand...

You are describing an oil seperator attached by hose to the air filter. That is the wrong set-up for a 1275. See item 70 in the diagram from Moss:

https://www.mossmotors.com/Shop/ViewProducts.aspx?PlateIndexID=29286

The PCV valve is designed to create a negative pressure area in the crankcase and limit the amount of liquid oil that gets pulled into your intake. It is supposed to mount to the intake manifold. I believe the picture you posted shows an intake manifold with a plug in the port where the PCV valve goes. A hose running from the timing cover oil seperator to one of the airfilters works, but not as well. You have a much lower vacuum and nothing to block the liquid oil if it should get past the seperator. The PCV was used on the bigger A series engines.
 
Bill,

I did a little research. According to a Haynes manual I have, the setup changed for the later 1275 engines and the hose went directly from the oil separator to the intake side of the carburetors (via a connection point added to the carburetors), and (according to Haynes) this eliminated the need for a PCV. This would essentially be the same setup I have.

You're right about the plug in my intake manifold. It would be easy enough for me to add a PCV and connect it there.
 
You are correct that the later 1275 engines used a different point to connect PCV tube to. The early ones uses the crows nest Smith unit mounted in the middle of the intake manifold. The later model units no longer used the Smith PCV unit, but the hoses connected directly to the SUs at the butterfly valve, not to the air cleaners. The hoses from the crankcase were connected to the SUs at the "controlled depression chamber" of the carbs. In addition this later set up was only used with the absorption canister which influenced the flow of crankcase gases back into the engine. <span style="font-weight: bold">If I were you, I would try a Smith PCV valve as plumbed on the early 1275s and see if it helps.</span> This is what I am doing for an engine which is a 1974, an obvious late 1275.
Scott in CA
 
What Scott said.

The 1275s used a point of higher vacuum than the smaller engines. Also, be sure that the vent hole in the valve cover is not blocked
 
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