head manifold compatibility

[cski]

Considering an 1800 engine pulled from a Spider for use in my '74 1800. Thing is, the head on the potential replacement longblock has "extra" manifold ports at the front on both sides. According to miafiori's head id chart the head is from a '79 Brava.

Are the original '74 exhaust manifold (which I think is a 4-2-1) and the original '74 intake manifold (carrying a 34 DMSA) unusable with the extra-ports head? Sure looks like it - they will bolt on, but won't cover the forward-most ports.

Thanks

[manoa matt]

Those extra ports are for the EGR system. The intake and exhaust manifolds "should" work with that head, however the head may also have air injection ports near the spark plug holes. Those will need to be pluggd.

If you are concerned about performance and looks of the engine, I'd put the money into rebulding your current 74 1800 head, instead of buying another motor. The 74 head will look "cleaner" and flow better without all the extra emissions stuff added on to later year heads.

[cski]

Yea, I was looking at an option to get the car rolling for just a few hundred dollars of engine-specific spending. A temporary shortcut.

I actually (embarrassed) put the engine in the car yesterday evening before noticing the mismatch, so it is very tempting to now button it up and drive it for the first time in 25 years. (In the last few weeks the brakes were renewed, carb rebuilt, fuel tank rehabbed, every rubber hose and some metal lines replaced, so maybe its possible) It could come out pretty easy too at this point if this is a really bad idea.

Two questions:

Do I correctly deduce that the EGR ports (both intake and exhaust) communicate only with other EGR ports?

The breathing of the Brava head is unavoidably compromised, whether or not the EGR stuff is in use or plugged?

[BEEK]

correct, the ports are thru the head only to themselfs. probably didnt say that correctly. but yes, the head will be fine, plug the air pump valves in the head, probably only 1 on a brava, a rubber heater hose stopper is sufficiant. the head will work just fine, performance might be off a little, but if you havent driven the car in 25 years, it is definatly not noticable. rebuiold your 1800 head when you get the time and money, then swap it back. but you dont need to be in a hurry, the 2000 head will run fine forever, or until it needs a valve job.

[So Cal Mark]

a rubber heater hose stopper should be considered a temporary plug at best for the air injection. There is exhaust in that spot and rubber won't last very long

[cski]

OK, thanks for the replies (heck, thanks for the forum and all the great info on it - wish I was better at searching it).

I'm going to ask the same question again, this time with pictures, because it is indicated by some replies that there are/will be exhaust gases circulating in the passages accessed by these ports.

Again, the forward-most ports in the photos (2 on the intake side and 1 on the exhaust side) will be exposed, wide open, visible and available for sticking fingers into, when the car is running - and that is cheesy but is perfectly workable?

intake


exhaust

[So Cal Mark]

your question was sort of side-tracked in efforts to help. That port in the front of the head as pictured, is the egr port. It's merely a crossover, not connected to anything except the two manifolds. The air injection port on top of the head is the one of concern. It's connected to the exhaust port, so it should be plugged with a pipe plug or something similar

[cski]

Thanks - you, manoa mark, and beeks did get the answer across, I just wanted to remove the last shred of ambiguity, which you have done.

Three more questions! :

There are 2 ports on top of the head, both have some sort of little can/valve screwed into them - both are EGR?


Notice how, on top of the head, the forward sensor is missing, replaced by a plug with suspicous-looking hardened goo.
Notice the enormous-diameter fitting on the rear EGR(?) valve/can on top of the head.
Did a PO screw up some threads?

There is a socket cap screw (allen head) screwed into the rear-facing back of the head just behind the rear-most head bolt, on the exhaust side.
There is a symetrically-located, empty, threaded hole in the rear-facing back of the head just behind the rear-most head bolt, on the intake side.
Should I be shopping for a (M12?, 1.25 pitch?) cap screw to fill that hole?

[BEEK]

yes on the brava the overheat switch was not used on some cars, others it was relocated to the top of the waterneck housing. you will most likely not be able to remove the plug as fiats sealer is awesome, and the plug may strip.
the bolt hole in the back of the head is just a hole, no need to do anything

[cski]

Put a wrench on that plug, ya, something would be breaking but that plug wouldn't be moving so I put my tools away, watched the sunset, then came in and read your post with the good news. Tx

[So Cal Mark]

Those two valves on top of the head are check valves for the air injection system. That is what I was writing about when I wrote that rubber plugs aren't suitable

[BEEK]

the plug i was refering to is the temp sensor plug , used where the sensor cant be used because the air injection valves. but not to make differences with you mark, but if the valves are working a rubber plug will work, i have used them many times, for years. the valves are for injecting air, not letting exhaust out. but you know that, ive also put slugs under the valves and stopped the air injection that way as well. they have rubber hoses on them from the factory.

[So Cal Mark]

yes, if the check valves are good exhaust won't come through. BUT, once those valves don't have air being blown in from the top they fail pretty quickly. From your first response, I understood you advised removing them and using a rubber plug to fill the hole.

[BEEK]

no actually what i ment to say was, capping them with a heater hose cap, but removing them and using a plug made of steel is the best. sorry for the confusion. after re reading what i wrote, i understand what you are saying, its hard to picture whats in my minds eye.

[cski]

I'll replace the valves with tidy metal plugs. The open EGR ports will look ridiculous, a motivation to turn a couple boxes of parts back into a working 1800 head.