Why are 327 exhaust systems different to 350 HT/G exhausts?
Where is the big difference?
July 1972 publication showing different exhausts and different part numbers.


Also this is a GMH new old stock system purchased decades ago aparently for a HK 327.
Notice the straight through mufflers are not like the offset ones drawn in the parts manual.
Interested to know what the concourse gurus think of it.



Wayne

I guess if you ordered a twin system for your 308 or 253 you're only option for tail pipes are these.


Also shows the HK 307 was never optioned with a twin exhaust, I supose thats right.

The whole exhaust system concept for HK was lifted from the Camaro, in particular the transverse 2 in 2 out rear muffler. The Camaro used offset resonators, which may be part of the reason for the offset resonators on HK. (We didn't, however, get the '69 Camaro chambered exhaust option, which is a pity!)

All HK327 used the offset resonators, with a slight difference in the front pipes between type 1 and type 2 to account for the small difference in exhaust manifolds. The resonators are splayed outwards and, as you've noted, provide clearance to the gearbox crossmember, allowing it to be removed with the exhaust in place.
Its likely that the straight resonators for HT and HG 350 were possible as the gearbox crossmember can be removed and slid off the subframe extension rails without disturbing the exhaust system.

There have been a few examples of period resonators and mufflers which appear identical to the NASCO parts but have Lukey identification stamps so it appears likely that Lukey made the original parts. The internal gas passages and baffling for the original rear muffler are quite complicated, not what you'd expect, and not accurately copied in any of the reproduction seen to date, which is why they just don't sound the same as they used to. The original was actually cross flow, and not two separate chambers within the muffler.

Sure is a strong word! I was of that opinion, and checked around before answering, and the consensus supports that they were all offset.
I'll ask Ben also.

Wayne, the HT-HG 350 front driver's side pipe is different due to the exhaust manifold being different. It had to clear the different starter motor.
HK 5litte was optional with N10 dual exhaust for all body styles other than Brougham from memory - I have pricing for it. It was the 327's system. HT 5litre not sure as the 350's system wouldn't fit it.

Wayne, all HK81837 have the offset resonators, and there is no difference between Type 1 and 2.
That pipe is HT/HG81837. You may find a small WCS logo stamped into the can, which is one of the manufacturers.

Does anyone have a comment about the photos I put up?

I am interested in accuracy and happy to help others in any way.

I feel that posting the pics of the genuine resonators might have been worthy of someones point of view.

It would be great to see an accurate exhaust available.

Cheers.
Nick.

HELLO Wayne.

For what it is worth Ben has been over the car. He commented the exhaust appeared to be quite accurate. Few things to bear in mind when doing the exhaust.

*The red car I now own was built by Jeff Brown. The resto ,I understand, was commenced in the eighties when there was still a fair bit of genuine stock in dealerships. This particular exhaust is dates 1971 which indicates it was possibly stock designated for HK-T-G 327/350 by then. Hence the kink you circled.

*People in NSW, QLD and VIC Clubs have also commented on the accuracy of this exhaust over the years.

*The pipes from the front to rear mufflers is a shop bend-up (in my opinion).

*The rear muffler is also supposed to be a genuine item.

I hope this is helpful. I am happy to help with measurements/ detail pics/info etc. I am prepared to remove the exhust from the car for this if needed as I am as keen as you to see an accurate repro made. That would mean I can remove mine and protect it. I think this system is getting close to its demise.

Cheers.

Nick.

Edited by user Thursday, 5 January 2017 11:39:07 PM(UTC)  | Reason: Not specified

Hi Wayne.

Byron, do have any knowledge in this area?

Cheers.

Nick.

Thanks Byron.

An area overlooked resulting in loss of accuracy. Would love to see a pic of the pipe.

Cheers.
Nick.