Smoke, low compression I think I'm done for a bit

[Stewart]

I think I'm going to have an engine for a living room table this winter. Car was running great till I got off the freeway and then it did not want to idle. If the oil cap, crank case breather or valve cover vent were removed it idled fine.

Symptoms

At idle
Smoke rapidly exiting any vent on the engine be it the oil cap valve cover vent, crank case vent and if all these are connected properly it will exit through the dipstick blowing oil all over.

Compression on the 73b

warm

130 128 65 35

No signs of coolant or oil in either system.

Oil pressure was about 80 on the highway 60 at idle hot Coolant temp was never higher than 1 needle width beyond the N

Any idea's?

I cant pull the head off till tomorrow afternoon.

 

[Deleted member 3577]

Sounds like everything will be quite obvious when you take the head off.

35 psi is down around broken ring / burnt valve territory.

 

[Stewart]

Made the time and got it off.

 

[beachbumbarry]

Stewart, It looks like you need a complete overhaul. How many miles on it? If you do an overhaul It might need to be boared out. New pistons cost just as much for .040+ over as .020-.030. If you want more CC's go .040+ over. You should have the machine shop check your crankshaft, it will most likly be warn and you will need it to be machined. Also the cam shafts on 70's B's were soft and you should replace it. Now is the time to go with a better ground cam and get better gas milage and more power. You will also need new lifters and push rods. Also on the head, the valves and seats were made for leaded gas and need to be replaced with harder ones for unleaded. The valve guides need to be replaced and the rocker arm shaft and bushings. You need to make sure the head is flat - - have the machine show check it. Sooo your looking at $2,000 or more - - that's about what I put into my 72. If your going to do IT - - Do IT right the first time, I didn't and regret it. I should have gone .040 over on the bore and only went .030, I wished I had gone with a better camshaft.
G O O D L U C K
BarryE

 

[Stewart]

I'm debating what I want to do. Engine has been rebuilt at some point and the car has 105k on it. I had the head rebuilt 1500 miles ago after the previous one cracked along with a new clutch, 270 cam and lifters. Bearings at the time were good pistons are marked with .25 and have a part number that doesn't match anything so I left them alone as the compression was decent. I regret that now.

Now that I know what happened and I'm fairly sure this is going to the machine shop I'll have to decide what I want to do. I've been happy with a mild cam in a stock fresh engine (my 75b) and until today its been a daily driver. I wouldn't mind building a little extra hp but when It's back on the road its still going to be used as a daily so reliability is key.

 

[PAUL161]

Stewart, what year is that head? Just curious. PJ

 

[Deleted member 3577]

Oil can only get into the engine in 3 ways...

Valve guides
Rings
Head gasket

I still can't see how all that oil got there...

 

[Stewart]

72 big valve head