4-2-1 manifold / header. which one?

[maytag]

Hey all....
If I were to decide to look into buying a 4-2-1 exhaust manifold for the 1800 in my '76, what do I need to look out for? Will the early ones fit? How about the later 2L units? And will the downpipe I scavenged From a '78 work with all of them?

And does anyone have one they would like to part with?

[Daniel]

I've never used a late model exhaust manifold on the early cars so the clearance maybe some what of a concern
since the engine was taller then the 1800 . If your looking for best performing factory exhaust manifold it may
depend on what rpm range your looking for . Late model 2L tri-y design is more suitable for mid range power
the early 1438 & 1608 would be better for high rpm both are good but most likely you'll need to modify the
down pipes and on a side note none of the 1800s will bolt up or fit correctly with early or late manifolds .

[opus10583]

Hey all....
If I were to decide to look into buying a 4-2-1 exhaust manifold for the 1800 in my '76, what do I need to look out for? Will the early ones fit? How about the later 2L units? [...]
And does anyone have one they would like to part with?

Hi,

Try Midwest-Bayless or Chris Obert for the early manifold, the 1592/1756 downtube is your ticket.

That's what I did.

Straight bolt up if you don't have a cat.

And will the downpipe I scavenged From a '78 work with all of them?

No. Not unless it was converted previously.

Ciao,
Mark

[dmwhiteoak]

maytag, If you choose not to use the 2-1 downpipe for the 78,let me know if you decide to part with it.

[grittracing]

someone should take a 4-2-1 header / mainifold to a weilder and have some made up and sell them (need one for a 1980)

[Kent124]

Tony, you need the manifold or the header?

[grittracing]

all ! from the header to the rear bumper

[maytag]

Tony, you need the manifold or the header?

what are you thinking is the difference?

While it is true that the 4-2-1 may escape the "technical" definition of a "header", it is referred to as such because if you were to decide it is not sufficient for your needs, the replacement would be a header.

A header IS a manifold, but not all manifolds are headers.

[grittracing]

I'm wanting the 4-2-1 performance up grade

[Kent124]

Tony, you need the manifold or the header?

what are you thinking is the difference?

Cast iron OEM equipment (manifold) vs standard iron OEM 2-1 downpipe (header). My bad...

[Kent124]

I'm wanting the 4-2-1 performance up grade

You have a FI with that butt ugly turn in the pipe to the cat right?

One option would be to find a non-FI 4-2 "manifold" w/o EGR. Combine with 1979 Fiat 131 Brava 2.0L down-pipe and then run straight back with over sized pipe (say 2.25").
Brava 2.0L down-pipe

[So Cal Mark]

IMHO, spending all of that effort to swap between cast iron manifolds is not worth the time or money. I'm still waiting to see a dyno comparison with that header. No vendors have stepped up or if they have, they decided not to publish the results

[manoa matt]

I have both, a 1981 FI cast iron 4-2 manifold with the 6 bolt 2-1 down pipes, also a tubular 4-2-1 "header" of the design that is commonly offered by the usual vendors. They have both been installed on the same engine...no difference noticed with the butt dyno. The consensus of the old timers on Mirifiori is that thre is no performance difference. Probably why no dyno results have been posted.

However, the stock cast iron manifold is quieter, stock downpipe wall thickenss is more than the tubular header, and the stock system will likely last much longer. Also it does not have an existing coating that would be difficult to remove in the event you wanted to have it ceramic coated. Stock system also has a heat shield.

[opus10583]

Hi,

I believe the OP was talking about going from 4-1 to 4-2-1, as Lampredi intended, and the answer is:

Do not hesitate.

I had to replace everything on my '78 from the downtube back as I was delivered a car with parts store cast-offs for an exhaust "system"; replacing the downtube and the manifold too was a no-brainer.

Ciao,
Mark