PV combined inlet & exhaust manifold

[93240se]

Help ! I need a bit of Information please. I need to replace a cracked exhaust manifold and have sourced a good condition combined inlet & exhaust manifold to fit my B18D engine. Can I just replace the two separate ones with the combined version? I can see a minor bit of fettling required for the throttle linkage on the bulkhead but other than that will it fit OK? I also have a replacement twin downpipe to fit the new manifold.
VOC 3801
Regards, Richard

[Ron Kwas]

Richard;

I'm presuming were speaking about an Amazon here, but comments are fundamentally the same for an 1800.

The two separate piece manifolding configuration can indeed be replaced by the one-piece...obviously, you have already though about, and procured the 2-1 exhaust downpipe (I've seen where some examples of these might need a bit of "dent tuning" to clear the bell-housing, and some fitting will be necessary to connect up to the rest of the exhaust system). As you have also correctly noticed, the Throttle shaft support bracket on the intake manifold side is angled on the one-piece, but this can easily be made up with a little sheetmetal work...Firewall pivot does not need adjustment.

See also: https://www.sw-em.com/manifolding_notes.htm)

Cheers

[93240se]

Thanks Ron for a speedy reply. The car is a 1959 PV but has an 1800 B18D engine fitted, twin SU carbs and single exhaust. Hopefully I can now get on with changing the 2 manifolds for a single one. I discovered the nuts / studs are reasonably easy to undo so that's an advantage!
The link you sent is really useful.
Regards, Richard

[Ron Kwas]

Richard;

Always remember to give model when asking...often it will make a huge difference...in the case of a '59 PV, if it had a B16 originally (which I suspect given the year of manuf.), firewall throttle mount may need some TLC/adjustment...if this is the case, let me know as I can fwd a link to another owner who recently had to do this.

Cheers

[DORETTI]

Hi Ron
Thank you for an interesting article. I have a 1961 PV544 with twin SUs and was wondering if it was possible to fit a twin outlet exhaust manifold and it looks like it is. I do have a combined cast iron manifold with strange butterflies, how difficult would it be to cut off the inlet manifold? I have seen a Triumph TR3 fitted with twin choke SUs, not a great carb apparently.
Cheers Richard

[Ron Kwas]

Doretti;

If you have a combined Intake/Exhaust Manifold with secondary Throttles, like this:

...installed in a 544, you already have dual down exhaust pipes, as this Manifold only exists in the 4-2, 2-1 configuration, so I believe that answers the first question.

"...how difficult would it be to cut off the inlet manifold?" Simple, in this age of power tools, and this wouldn't be breaking new ground...!

"I have seen a Triumph TR3 fitted with twin choke SUs," [I don't even know what twin Choke SUs are...I think one Choke linkage per carb is just fine!] ...not a great carb apparently. [Says who?...I don't agree!]

Cheers

[DORETTI]

Hi Ron
Thank you for your advice, I have the standard manifolds on the car and a cast iron combined manifold in the shed which I will now attack with an angle grinder. I would love a pair of twin choke SUs but like hens teeth, Triumph used them at Le Mans so I guess they can be made to work well, the TR3 owner I saw was struggling.
Cheers Richard

[Derek UK]

Yes Triumph did use the twin choke SU but that was mainly due to the connection between BL or whatever it was called then, and their connections with SU. Not a success and Webers were more efficient and gave more power so they SU's faded away.
I have some pictures somewhere on my HD of these carbs on a stall at Beaulieu that I took a few years ago. Expensive! I can post here if interested. Ron, you might be interested in them too?
The late cast combined manifold without the butterflies is the best option. Not too rare and then everything just bolts in. It is twin outlet.

[Ron Kwas]

Derek;

...certainly interested, and happy to study them...I know there were many variations of the SUs over the years of production, and different vehicle applications, so it would be good to see them in one place for the purpose of comparison...

Cheers