This is really 2 questions and probably stupid ones at that. If you guys can't already tell by my username, I am new at this whole thing.

So I am making my first upgrade to my A15 engine. Last weekend I picked up a weber 32/36 carb setup from bert and I am planning to have it installed in my stock ute. (Thanks bert for the sale).

I was told by a work mate that there's no point upgrading the carb without also upgrading extractors and exhaust at the same time as it is like, as he said, "sticking your thumb up your butt and trying to fart at the same time" Is this true?

Second, is there any way for a newbie such as myself to tell whether my ute came with modified extractors / exhaust without taking the parts off? The thing sounds loud as hell as is.

Thanks guys.

They are not stupid questions at all.

A good way to tell if a bigger carburetor will increase performance it to connect a vacuum guage to the intake manifold and put the engine under full load (wide open throttle in a high gear right through the rev range). If the guage doesnt drop nearly all the way to zero and stay there as the revs increase, there is a restriction in the carb or air cleaner. If this is the case a larger carb will help performance.

An engine and it ancilleries are fairly well matched/balanced from the factory to do their job. If you change just the carb you may get a performance increase but not as much as if you change all the other components on the engine to match/balance with the new carb.

Hope that makes sense

A 32/36 weber on an A15 is fine mate just got to tune it a little. As far as the exhaust goes take a picture from side on and post it here or get ya mate at work to tell you if its got extractors and a bigger than standard exhaust. Cheers And welcome

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Yeah I dunno, normally carb, cam and extractors go hand-in hand, but there is nothing wrong with upgrading, bit-by-bit so to speak. I guess he's sorta right saying you won't get the full potential of the carb without all the other gear but that could also mean I'm not getting the best performance out of my setup without EFI and a decent computer to power it all. So it's true but it's also fairly obvious and somewhat open-ended/limitless (largely dependent on money)

But like the two gents said just above; nothing wrong with a single carb on the biggest of the A-series.

I think you're doing all the right things for a cheap power-up, starting with the big block of the A-series and then addressing it's carburation. Most the dudes miss the mark entirely and jump to twin 40's and a giant-ported GX head 'double springs', 'big valves', 'really lumpy cam' and then they sit there wondering why things are so difficult to get running right (I did that....)

You're on the right track with a very good start, beginning with a simple cost-effective arrangement will mean it is less complex and will give you a golden opportunity to learn how it all works with (arguably) a fairly simple configuration.

nothing wrong doing that. my mate used 32/36 on stock A15, the ride is faster than stock A15.


step by step mate, your wallet rules!

Thanks guys for the generous feedback! Good to know I can get away with upgrading bit-by-bit as you guys say or else I am going to go broke fast... My work mate had me believe it all needed to be done at the same time (carb, extractors, exhaust)....but he drives a Lotus not a Datsun and his salary is double mine.

Unfortunately, I never met the previous owner of my ute, his brother sold it to me so I have no idea what mods, if any, were done to it other than the A15 swap, 5 spd transmission, and front disk brakes. I decided to take a few photos of the extractors and exhaust. Maybe you guys will be able to tell if they are stock or not? I have no idea, if you would ask me I would say no because of the rust. I also measured the exhaust pipe which is 2" but dunno if this info is useful. All I know is that little kids cover their ears when I drive by...hehe. Cheers.

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2inch is very large for a stock engine. That's why she's so noisy, it also flares after the tail pipe (the part that follows the exhaust manifold flange) so that setup is mostly for noise. Won't offer much benefit and would most likely hinder performance (slightly) due to the lack of back-pressure (queue jmac to explain the importance of back pressure etc or re-think your understanding of the term extractor).

It does look small-ish for a 2 inch setup though, did you measure across the pipe or across the angle cut at the end? (no offense but you'd be surprised).

Your pal with the Lotus would be very right in saying it all has to happen at once as much of the gear in a lotus the may actually not fit without replacing/modifying all the componentry, that and the fact that his mechanic may realize he has more money than the average JD so he simply insisted he get the lot (both parties win).

Your exhaust manifold is stock, so a high quality set of extractors will be a big help.
Often available here second hand.

Good to know, thanks again for the insight guys. According to your observations it sounds like someone must have tinkered with the exhaust system and that's why it sounds so loud, I don't mind but the old lady across the street does .

I did measure across the pipe, not the angle, but I measured it at the end. You can see in the photos that the end is slightly bigger than the rest of the piping so it may not exactly be 2" all the way down...and I think you are right Chris on both points about my Lotus colleague.

As for extractors / headers (assuming they are the same) anything I need to know before buying a set? I just want to make sure I don't buy a set and have a mechanic tell me they won't fit. Thanks again in advance.

As your a beginner, go to Bunnings and buy a cheap but complete set of spanners/sockets and start working on the car yourself, the A series is the perfect engine for a novice.

Ask any questions you have here and you wont go wrong,(a shop manual is good too.)

When you do get some extractors, buy a gasket and fit them yourself so you learn how it all goes together, then drive to your exhaust shop and get them to join up the exhaust you have if they think its suitable or fit a new free flowing exhaust.