Upgrade Exhaust to 4-2-1

[tartan18]

My car is a 1975 with the stock 1756 engine. A PO removed the cat and what is on the car now is a 4 into 1 manifold, then to a resonator and then a rear muffler.

I want to upgrade to a 4-2-1 exhaust system as I have read that will improve my engine's performance. Recently I found in a junk yard both a manifold and downpipe but now I wonder if these are the proper ones for my car. As best as I can determine, based on the part numbers stamped on the manifold and downpipe, I now wonder if these came out of a fuel injected (later model) and may not work on my car. The 4-2 manifold has a stamped number of 4462282 and the 2-1 downpipe has the number 4442168.

Here are several pictures of what I have.









What concerns me is that the downpipe outlet measures only 1.75 inch and I understand that the ideal is 2 inches.

The sound I am looking for is something "Italian" -- not the "fart" type that kids hang on their Honda Civics

Any help would be appreciated.

[4uall]

what are you talking about? they make you look so much cooler

[tartan18]

Sorry Jay ... I didn't know you owned a Civic.

[narfire]

That is a 80 and later manifold, number is the same as my 80 and Jimb's 85. Six stud, no gasket required.
it should fit just fine, however the down pipe I understand is a bit longer as the 2L engines are a bit taller. I had the down pipe cut at the 2 into one and a flange welded on then 2" back.
Chris

[MrJD]

NO gasket? Well thats interesting.

[wizard124]

NO gasket? Well thats interesting.

I also found it odd......
So, I made one. Material bought from Napa Auto Parts. Hasn't been on too long but holding up so far:

[WYSpider]

You can us a bead of RTV Copper and be good to go.

[WYSpider]

That is a 80 and later manifold, number is the same as my 80 and Jimb's 85. Six stud, no gasket required.
it should fit just fine, however the down pipe I understand is a bit longer as the 2L engines are a bit taller. I had the down pipe cut at the 2 into one and a flange welded on then 2" back.

Can you clarify where you cut? How far after the hanger did you cut for the flange?

[narfire]

From the picture above, I believe it was not far from where it goes into the single, pretty much at the same spot I believe. Now you mention it, I wanted a flange but I think they just cut back and directly welded the 2" pipe to the corresponding opening dimension.
I haven't looked at it for quite some time.
If you end up taking it to a muffler place they can cut and weld, but I found they will bend the pipe(diminished inner diameter) where cut and weld direction changes is superior. (I've been told)