hi all.

Im considering changing my inlet manifold from a swanneck type to a more straight variety. The chap on the rolling road reckoned that this was the worst part of the set up, with only a few minor things aside from that that weren't ideal.

So the question is, seeing as it was fully tuned last week, would the carbs need adjusting to account for the different manifold flow, and also, would adding 4 trumpets affect it much? And do trumpets have much affect on flow/performance? Its a crossflow with twin 40 webers.

Any help, much appreciated.

As an aside, i found bogg senior (the rolling road fella) to be very helpful, friendly and knowledgeable, and not at all shy of getting the welder out to knockup a new bracket for me. Definately a day well spent, as the car is nearly cured of its glitches!

Hi Joel

Not sure what a swan neck manifold looks like, but my pinto manifold slopes slightly downward towards the engine, I was recommended this type as it stops the fuel pudling

As for trumpets don’t you have any ? The curve at the end supposed to help and the length can be tuned to give either more top end or more mid range power

Adrian

cheers adrian.

my current manifold leaves the carbs about an inch or two above the inlets. The old chap described this as 'swan neck', maybe an old term but he certainly knows his beans! I was hence hoping to get a more level manifold - it ends on ebay in 3 mins so i dont have long to decide! No trumpets ATM, just holes into a filter.

It could well be the cam thats a bit full on, its not great at low revs. Might just buy it anyway and see!

ah well, sniped it by 4 quid and lost anyway!

this is what i would describe as a swanneck anyway:

That looks the same as mine, the trumpets help with the venture effect, depending on engine spec your supposed to have between 15" and 18" inlet tract, thats from inlet valve to end of trumpet. Depending on your air filter you may struggle to fit long trumpets

Adrian

trumpets it is then! id have to change the distributor if i got a lower manifold, not really worth the effort Its getting BEC'd over winter anyway

A proper "swan neck" manifold is one that has more of an 'S' shape, some of the Weber manifolds for mini's were like this to clear the bulkhead, but they flow very badly.

I suspect the above one isn't ideal in terms of outright airflow because of the sharp angles between manifold and carb, and head and manifold, rather than smooth bends.

[Edited on 14/8/05 by MikeRJ]

Hi Joel,

I know it's a lot of work, but you could try the old "cut & shut".

Just a thought.

Paul G
Rescued attachment Joel-manifold-s.jpg

thats an idea paul, but it could (knowing me!) lead to a few weeks off the road!