Plugging Head Port

[RRoller123]

I have a spare 2L head that I am putting on my engine to assist with some diagnostic and performance comparison work. It has stock cams and a brand new std size valve job, so this will help me a lot in identifying issues I have with my heavily modified engine. Anyway, I need to plug a port that is on this earlier head, my 80 doesn't have it. You folks with older cars may know off hand what the thread is to cap this off?

Thanks.

Pete

[18Fiatsandcounting]

Pete, as you probably know, this fitting is for the air injection system, AKA the smog pump. None of my cars have this, so I can't tell you what the thread sizes are, but I would think any decent plumbing shop that carries metric sizes would have a cap. The other alternative is to find an original check valve and just screw that on. The valve is designed so that air can be pumped into the head, but exhaust gases can't come back out.

You may be able to just leave it open, but if the passageways and ports into the exhaust stream are clean, you will have exhaust coming out of that fitting, plus the associated noise. But, I've seen some in the past that were so plugged up with carbon that the fitting had essentially "self plugged". Judging by the cleanliness of your head, that's probably not the case, though.

-Bryan

[18Fiatsandcounting]

PS: For what it's worth, from the casting number on your cylinder head, it's from a 1979 Brava (131) with a single air injection port and the EGR passageway in the front. Other versions of cylinder heads had separate injection port fittings for each cylinder.

[geospider]

I had to plug mine. pull the fitting and match it with a short bolt or allen hex plug.
AR has them as well, but costly.

[RRoller123]

Thanks all. It was represented as a 2L Spider head, I am hoping it will fit with no issues. Does anyone know: Did the 131 Brava use our same block 2L engine?

I am only putting this on temporarily, to help with diagnosis. I have a constant low vibration that is either somewhere in the cam/valve system or the FI system. It is easier to just swap on a head with a brand new valve job and stock valves and cams than go through diagnosis. (I have a new short block with only a few hundred miles on it.)

The problem lies either up top or in the FI. Maybe the AFM. I have so many mods (flywheel, cams, large valves, lightened crank pulley, cam wheels, 9.8 pistons), etc that I think this will give a simple split diagnosis, the problem lies either in the head or the FI and I can then take it from there in detail.

[18Fiatsandcounting]

Thanks all. It was represented as a 2L Spider head, I am hoping it will fit with no issues. Does anyone know: Did the 131 Brava use our same block 2L engine?

I wish I knew enough to answer your question, and indeed, my earlier comment about the cylinder head appearing to be from a 131 Brava could well be wrong. I believe I saw it on the Mirafiori website archives somewhere, so you might check that as there could be more info on heads and blocks.

-Bryan

[Nut124]

Twincam head ID:

https://www.mirafiori.com/faq/content/h ... eadid.html

[warrenrhen]

The thread should be 18 x 1.5 mm I just ordered a couple from Amazon

[RRoller123]

Thanks, Warren. The plan is to put the AFM on as soon as it comes back from Fuel Injection Corp, and see what improvement that yields. Then a new Fuel Pressure regulator that is sitting here waiting. Then put this replacement head on, and between all that, the vibration and idle problem should be clearly isolated. I remain pretty sure that it is in the cams or valve guides, (but not the seats, as the leakdown test was passed fine).

In the meantime, I have found a beautiful Jaguar XK8, but am really hesitant to pull the trigger right now. Too much going on overall in life to add it at this moment. But we shall see. I would really like a powerful and comfortable toy car for the more distant shows and meets; just getting from here to Tutto in Brookline each year nearly kills my back.