GTR Header

[Harv]

Maybe the change to the Y-pipe happened late in HD production.

Yes, the early HD's changed to the HR type rear header at engine number 186K171370.

Cheers,
Harv

[Errol62]

Dr Terry will pipe up eventually, but master parts cat shows the two engine pipes and flanges as separate assemblies where hr LC etc show one part for y pipe assembled with flanges.


FB ute fixer upper, EK van on rotisserie

[ardiesse]

. . . except that 186K171370 is an HR engine number, and would have been sold new in late May 1967. It'll be the changeover from X2 to 186S.

Rob

[Dr Terry]

Maybe the change to the Y-pipe happened late in HD production.

Yes, the early HD's changed to the HR type rear header at engine number 186K171370.

Cheers,
Harv

Hi Guys.

I reckon the whole X2 header thing has caused more confusion over the years than just about anything else Holden.

Engine no. 186K171370 is mid-HR production, not HR. HD X2 engines are prefixed 179X.

186K171370 is only 1130 engines before the X2 to 186S change in May 1967, this number includes all HR engines, This means that very few X2 engines got the new type rear manifold.

AFAIK all HDs got the two separate engine pipes & the dual inlet muffler, while all HRs got the Y-pipe & single inlet muffler. Parts catalogues, including supplements from that era seem to confirm this.

So in summary, as others have mentioned there are only 2 variations of the rear header, changing at the above mentioned engine no.

The "type 3" (using Harv's list) front header was needed for the 186S (WW Stromberg) auto choke so must have been introduced at (or before) the 186S intro date.

These 2 headers remained unchanged for all 186S as well as 161S & 173S for the LC GTR. For the LC XU1 they simply deleted the choke heat riser tube from the 186S casting, resulting in type 2.

LJ GTR had the stock 202 with the single outlet header, so it missed out on this set-up. Late XU1 got tubular headers (extractors) so they didn't get them either.

The main thing to remember is the all 3 front headers will interchange if you don't need the auto choke, but the rears will not swap without mucking around with the engine pipe(s).

Dr Terry

[ardiesse]

"Ad fontes", as they say in Biblical scholarship.*

I went down the back, into Arachne's realm, and brought out one set of X2 headers, one set of 186S headers, and one HR 2-into-1 engine pipe.

Yes, the X2 headers are as shown in the photo above, and yes, the 186S headers are also like in the photo above. The X2 headers came from a bloke at church in the early '80s who put a 186 into a Peugeot 203 ute, and then had great fun at traffic lights with people who fancied themselves in 253-engined Holdens, and the occasional 308. As far as I remember, the 186S headers came off a very late '67 manual HR Special sedan (+disc brakes, +LSD) that I bought in '83 for $300 (I think) as a parts car. The things you do as a 21-year-old . . .

Where was I? The engine pipe (I needed one for my HD, but bought two to be prudent) fits the X2 headers. I have to straighten out bent studs and run a die nut down them, so the photos will have to wait until tomorrow. Good rainy-day project.

Rob

* "Back to the sources." Essentially, go back to the original material.

[ardiesse]

Terry,

Thanks for the heads-up.

My HD X2 (bought 35 years and one day ago) had the HR-style engine pipe and single-inlet muffler. Probably by the '80s the exhaust manufacturers had ceased to make the HD X2-specific engine pipes and mufflers.

Given, then, that the rear header changed in May 1967, there must have been two styles of 2-into-1 HR engine pipes, effectively X2 and 186S. So I got the right pipes when I went to the exhaust shop and said, "I'd like to order two engine pipes for an X2, one to use, one as a spare."

Rob