Coolant temp sensor could be bad, or if replaced, could have bad wiring to ECU. Might want to meter that from the ECU connector to see if you have some resistance out there, an open circuit would fool the ECU into dumping more fuel. If you have OBDII capability, it will show up as -40 degrees with sensor unplugged or open.

 

Unless somebody switched the CTS plug with the FTS plug? Probably not since this happened gradually.

 

Did you read thru the GEMS Document that Savannah linked?

I saw something in there that pretty much described your issue I think.

 

Hey Danny, I couldn't find the fuel system you reference in the GEMS thing Savannah posted.
Today disconnected the Camshaft sensor above the oil filter. No change. Tommorrow I'll take the Thermal imager and shoot the heads to see if there is still a temp difference sido to side and can also shoot individual cylinders.

 

Ok I started it up today (and it starts great) After a few minutes to warm up there is quite a difference in exhaust manifold temps. Passenger side warmed up first. Center of manifold 200degrees plus ends stayed around 90 degrees. Drivers side sorta the same. Went to 390 at the center stayed around 100 at the front. Coldn't get a good view of the drivers side rear. After warming a little Passenger side was similar 390 at the middle 100-110 at the ends. Pulled the plug wire off of number 1 cylinder(driver side front) Good spark but no change to engine(cylinder ain't hittin) Pulled number 5 (passenger Front) Good spark cylinder not hittin. Pulled number 6 next to number 5. That cylinder is hitting.
Possible analysis<
Ends of exhaust manifolds have rats nest or are clogged, middles are open(doesn't seem likely but it don't look hard to pull the passenger side)
Something internally is affecting the outside cylinders different from the inside cylinders. (pull intake plenum and see what's up there. Then valve covers)
It appears that the plenum needs to come off to pull the drivers side valve cover. I'm thinking of pulling passenger side valve cover, it looks easier and seeing if the valve stroke seems uniform. That'd check a worn cam lobe. Next would be passenger exhaust manifold(this seems an unlikely problem.) THen plenum to check out for clogged intake ports. (again unlikely as the compression was too uniform)
THe plugs missfiring could be carbon fouled again but the engine just doesn't feel like its missing. Wish I had an old Sun Scope to put it on

Any other ideas?

 

I just thought. Heavy carbon deposits on the exhaust valves outside of the cylinder would do all of this. I've seen this on some old motors back in the 50's and 60's. Not so much on modern engines. If this is so would that Sea Foam talked about here affect this. Is this a sometimes occurance on these engines?

 

No. It will need removal for cleaning properly.

 

I would pull the exhaust manifolds and see what they look like inside. You would also be able to look inside the exhaust ports at the same time. Easiest way to check for blockage in those cylinders. Other thing could be the intake blocked by a rats nest or shop rag on the front 2 and rear 2 cylinders.

Has this thing sat for a long time?

 

It sat for a while but not extraordinarily long. I just put a 78 Spitfire on the road that sat for 10 years. Just cleaned the carb and started it up. Seems like I remember cheap oil contributing to carbon build up and sludge deposits. Lack of oil changes also made it worse. With exhaust manifold removed I should be able to look in the head all the way to the valve.

 

Pulled the passenger side exhaust manifold. It's black sooty but not clogged at all. Finger in the port says the same. Gonna go for the passenger rocker cover next. One bolt on the manifold was odd. A hex head 9/16 instead of the star things everywhere else. I wonder if the heads have been off this unit.