240z - refurbish my SU carbs or install webers?

[Graeme - CZ]

Hi all,

I need to make a decision on what I'm going to do with my carbs over the winter. It's either a) have the original SU's fully refurbished and plated with new z-therapy jets etc, or b) buy / install the weber carbs. The webers would obviously cost more than the refurb, but wondering if it would be worth it. I'm not after massive performance gains, though I will be installing a new z-Story fast road exhaust system next month.

Welcome peoples thoughts on what I should do with the carbs? I'm leaning towards refurbishing the original SU's and have found a chap locally in Edinburgh who can do the work.

Car is a '73 US import 240z.

Cheers, Graeme

(couple of examples below)

 

[Rob Gaskin]

If I were you I'd refurbish your Hitachis.

 

[jonbills]

Hi all,

I need to make a decision on what I'm going to do with my carbs over the winter. It's either a) have the original SU's fully refurbished and plated with new z-therapy jets etc, or b) buy / install the weber carbs. The webers would obviously cost more than the refurb, but wondering if it would be worth it. I'm not after massive performance gains, though I will be installing a new z-Story fast road exhaust system next month.

Welcome peoples thoughts on what I should do with the carbs? I'm leaning towards refurbishing the original SU's and have found a chap locally in Edinburgh who can do the work.

Car is a '73 US import 240z.

Cheers, Graeme

(couple of examples below)

View attachment 40792 View attachment 40793

does the bloke in Edinburgh know they're Hitachi not SU? I don't think parts are interchangeable.
IMO triple side draughts have the edge in everything, except price.

 

[Graeme - CZ]

does the bloke in Edinburgh know they're Hitachi not SU? I don't think parts are interchangeable.
IMO triple side draughts have the edge in everything, except price.

Yes, he's done a 240z already. It'll just be me that doesn't know the difference ;-)

 

[Rob Gaskin]

..............IMO triple side draughts have the edge in everything, except price.

Ok your opinion. My opinion is that on a standard car owned by a person who is not a mechanic the original carbs are best. If in good condition they will work from tickover to max revs without needing an expensive rolling road set-up and jet buying.

They use the standard airbox with it's connections to carbs, engine breathers, servo.etc With triples you need to fabricate a heat shield, sort the linkages out and the fuel supply also you lose the fuel return system.

Fuel economy - I don't think many triples are as economical and the standard carbs, far from it.

 

[jonbills]

yes, just my opinion. thats what IMO means. all the stuff you mentioned Rob, I covered under "except price" .

you don't have to lose the the return line to run triples.

 

[Rob Gaskin]

........... all the stuff you mentioned Rob, I covered under "except price" .............

 

[AliK]

Agree with Jon on do they have hitachi parts business - AFAIK, the needles and springs are the only bits you can swap from normal SUs to Hitschis.

For sex appeal, sound and top end performance - go triple OER / Webber / Mikuni etc.

For ease of install and tuning (on a stock engine) stay SUs. You can learn to tune them yourself without a PhD like Jon’s!! The thing that plagues SUs is worn shaft bearings and air leaks. Even my expensive Z therapy SUs developed some leaks after a few years due heat soak etc.

For best performance - go EFi, electronic ignition and coil on plug

 

[Rob Gaskin]

....For sex appeal, sound and top end performance - go triple OER / Webber / Mikuni etc...

I agree, the appearance is what a lot of people love including me. My blue 240 (2.8 DJR) goes really well on standard carbs and airfilter box but when you lift the bonnet you expect to see triple twin chokes.

Ali, my Samuri has triple Webers but I don't think it's improved my sex appeal - should I buy a wig?

 

[AliK]

- should I buy a wig?

Don’t do it! I hear bald men are sexy!!! Well, so I’m hoping as I’m rapidly heading that way

Back on SUs - I’m going to ditch the stock airbox and use some fully radiused trumpets from MSA and the PMAC / Skidell airbox. My AFR gauge tells me the stock one is too restrictive, especially on a modified engine sucking harder.

 

[Farmer42]

Ali

Why are you going to the humungus expense of getting trumpets from MSA? I got mine from Merlin Motorsports at Castle Combe at fraction of the cost with equal effect & performance. They do 35mm & 75mm.

 

[AliK]

They aren’t fully radiused though - or at least not the ones I found on their website. Which ones did you use?

 

[Farmer42]

I probably didn't realise what you meant by fully radiused which, now having looked more closely at the MSA trumpets, I do. The Merlin versions are what I would call flared. Having said that, I wouldn't see much gain if you were using these inside an airbox. Unless you know otherwise, I would suggest the flared trumpets would be just as effective in increasing airflow velocity whereas the MSA versions look more aesthetically pleasing on the eye if you have them in plain view and are not hiding them inside an airbox.

What is the difference in airflow from a rolled/radiused trumpet and a flared? There is certainly a difference in cost especially when you factor in the shipping.

 

[Graeme - CZ]

So it's winter, and what better time to get the carbs refurbished. I've found a chap locally in Edinburgh (Alan Wedgwood) who specialises in refurbishing SU type carbs, so my 240z Hitachi round-tops are going off for some TLC.

I have a few questions for the forum please. So I believe my carbs are likely to the be the original ones (1973 240z USA), but are attached to a 280z engine, gearbox and drive train. I've no reason to suspect that they have ever been altered from standard. I've also recently installed a fast-road header and exhaust line from Zstory.

With these things in mind, i'm wondering whether or not the carbs just get the standard refurb and reconditioned parts from Ztherapy, or if I need to upgrade in some fashion given the L28 and new headers?

Lastly, does anyone know of any alternatives to Ztherapy in the EU?

Thanks, Graeme

 

[Rob Gaskin]

Let your man strip and check them over etc. Reset float levels, probably new inlet valves. Adjust choke.

That's all I did to mine and they work fine on my 2.8

If you're not happy after that sell them (which will pay for the work done + ?) and buy triples.