Header options for 4.0 EFI on 4.2 head/block

[wathey]

Hi,
I have an 1981 with a Jasper replacement 4.2 and I believe a 4.2L head not a 4.0. The engine has the MPI/EFI system and intake manifold from a 4.0. My question is around header options. I did not perform the EFI upgrade and do not have access to the PO who completed the project (2 back). The factory header has been hacked into a few pieces and poorly welded back into something less than optimal that leaks. The o2 sensor is located in one of three straight pieces of 6in welded tubes into an attempt at a down pipe heading towards the collector/connector. If you have completed this conversion before do you know which aftermarket header might fit this application? It would be nice to have an O2 bung as part of the design. Any help based on your experience here would be great.
Whitfield

 

[tower210]

If I remember correctly; it seemed like all the aftermarket steel/welded headers weren't of great quality and seemed to crack/leak over time. I replaced the one the PO put on mine and went back with a clean cast iron header and that solved the issue. Ironically the 4.0 came from the factory with an exhaust manifold that almost looked like and aftermarket piece and it's been fine (have that now).

 

[spankrjs]

On my 258 with Mopar MPI I just use a stock replacement Dorman exhaust manifold.

On my 4.0 I also use a regular Dorman manifold, and like @tower210 alluded to, it looks like a header AND has the "anti-crack accordion things" built into it.

IMO, on a stockish inline 6 probably no reason for a header