14 replies to this topic

[Bazza]

HI xu1972

See the pics below. The top part of the picture shows the correct headers for the XU1 and LC GTR. You will note that the front piece has the heat riser tube. This was not uncommon on the LC and early LJ XU-1s.

You will often see headers being sold "to fit X2 186S or Torana". The X2 headers will fit but only if you get custom engine pipes made. To fit a standard XU-1 header pipe and resonator - the header flanges must point in the same direction as in the picture. I bought a set on eBay that "came of an LC". They may have, but the standard engine pipe/resonator didn't line up.

Bazza

[Dr Terry]

Hi Bazza.

This is great, it's the first time somebody has shown pictures to show the difference in the rear, X2 header. It actually changed about 1 month after the 186S was released, so very early 186Ss use the X2 rear header. But who's going to argue about 1 month & how many 186Ss would GM-H have made in 1 month during 1967 anyhow. Except for that, to my knowledge, the top rear one is fitted to all 186S, 161S, 173S, 186 XU-1 and 202 XU-1 (except the 73 'Bathursts' with extractors).

Anyway there is another front one you haven't pictured. The top one you have shown has the extra casting lugs with the automatic choke heat tube, so these must be used on all 186S, 161S & 173S to operate the choke. It was also used on LC XU-1s, it's just that the heat tube simply wasn't used, it was just left open. Later XU-1s (I'm not sure when they changed, but probably mid-'72 LJ) introduced this same front manifold, but the tube was omitted and the casting not drilled, but the 2 blank lugs where left there, because that's how they were cast. AFAIK the X2 front one (with no cast lugs) was not fitted to any engine from the factory after 1967.

Anybody out there with original unmolested LJ XU-1s to back this up.

Dr Terry.

[Bazza]

Hi

Thanks Dr Terry.

My primary objective in posting this info is to lessen the chance of people getting "ripped off" (either accidentally or intentionally) by those sellers on eBay or at swap meets that sell the headers as being "universal". Obviously they are not. I have incorporated the info as far as I have been able to verify.

I haven't seen the "blank heat riser type" so I will defer to your expertise. I have a picture provided by forum member purporting to be an unmolested LJ XU-1 showing a "drilled heat riser". Perhaps it was a carry-over from the LC range.

I know that the front section part numbers are different between the LC and LJ. Perhaps both are "heat riser" types but the LJ type has not been drilled. I assumed that the difference was that the LJ type was "plain type" as fitted to the X2. In this regard I would be interested to hear from anyone who has an unmolested XU1 with a "plain" front section.

I guess the main thing when buying GTR or XU1 headers is make sure that the flange studs all face backwards and the same angle.

Perhaps we can make a "sticky" of the subject when we finalise our research.

Bazza

[Bazza]

Thanks Aldo

Maybe they used one type in Brisbane and the other type in Adelaide? It is handy to know that they were still using a "drilled heat riser" type as late as 5/73.

Have you ever seen a "plain" one like the X2 on an XU-1?

Bazza

[Bazza]

Thanks Aldo

Just to clarify - have you seen this front section on an original XU-1?

Bazza

[Dr Terry]

Hi Guys.

This gets more interesting, the more you look into it. I've checked all my parts books & they pose more questions.

Firstly I don't believe there would be a difference between the Adelaide & Brisbane factories in this area, because the engines are built complete (& then test run) in the Fisherman's Bend (Melbourne) engine plant, so all engines are built together & in the same number sequence.

Rear
The part number listed for the X2 rear (shorter, less bend) is 7428495, this also suits very early 186S (up to June '67).

The part number listed for 186S, 161S, 173S and both XU-1s rear (longer with more bend) is 7430583

Front
The part number listed for the X2 front (no casting lugs, no heat tube) is 7428493.

The part number listed for the 186S, 161S, 173S & all LC XU-1 front (with choke heat tube) is 7433655.
The early LJ parts book also lists 7433655 for the LJ XU-1.

A later LJ parts book lists 7428493 (the old X2 no.) for all LJ XU-1s (except '73 with extractors). This re-use of the old part number could be either the un-drilled unit with lugs or the plain old X2 unit.
I've seen plenty of supposedly original LJ XU-1s with either, the tube type, the old plain type or the one with the un-drilled lug, so I'm still one the wiser.

If originality is not an issue, the rear 2 do not interchange, but the front 3 will.

Dr Terry.

[Bazza]

Hi

Dr Terry, my Feb 1972 edition of the NASCO parts catalogue gives the front header section as 7428493 (same number as for the X2).

The plain (X2 type) in the picture above was sold to me as being from an XU-1 but who knows if it original or not. As we have mentioned earlier in the thread - the only critical thing is that the correct rear section is fitted if the owner intends to use the correct engine pipe/resonater assembly.

It seems that all 3 front assemblies have variously appeared in the LJ supply chain (perhaps manifolds were outsourced to different companies). It is probably safe to say that the LC GTR and XU-1 only used the drilled heat riser type.

It would be interesting if an owner of an unmolested LJ XU-1 fitted with the X2 type front manifold would surface.

Bazza

[WhiteA9XS]

i have seen the heat tube type on a one owner unmolested car ..

its amazing that xu1,s are only 30 odd years old and some things are still not clear ...

[orangeLJ]

just sending through some pictures to bazza, but thought id chuck in the fact that there are 2 seperate sets of part numbers listed in the 75 parts manual. barry has the numbers, and im not really too fussed on looking them up again. but yeah. the plot thickens?

also found it funny that for the actual exhaust and other bits have a left hand drive part number.

Edited by orangeLJ, 07 May 2007 - 04:56 PM.

[Dr Terry]

Hi orangeLJ.

The 2nd set of part numbers in the '75 parts book is for the '73 Bathurst extractors, they come in 2 sections.

Dr Terry

[Bazza]

Thanks Aldo

I guess we are none the wiser. Until someone proves me wrong, I will assume that I have a legitimate/correct part on my car. Either way, the X2 and LJ front header section are the same part number regardless of the heat riser.

Bazza