Old vs New SU's

[S30Driver]

Getting ready to source a set of carb's for my neighbors series 1 restoration.  Motor is rebuilt & car almost ready to be dropped in.  No carb's came with the car.

The options are :  buy a set of 4 screw carbs and send them off to be rebuilt.   Or.... buy this new set from Round Top Fuel Systems.

https://roundtopsfuelsystems.com/new-products/original-round-top-carburetor-set

The cost is close to the same, say $200 for the core carbs plus about $750 with shipping for the rebuilts vs $980 for the new Round Top Su's.

What say you?  The Z Therapy route is a well known proven product.  Has anyone here purchased the Round Top Fuel Systems carbs?

I am leaning toward the new ones...

[dutchzcarguy]

If you want original... those are SU's?  The orig. carbs are HJG45W Hitachi's..  they look like SU's but are not.  

In the states everyone talks about theire SU's... they are Hitachi's made under license of SU.  they are different in a lot of ways!!  

I would go for a orig. set hitachi's.  (Do su's fit the manifold?)   Do you have the inlet manifold and all the stuff? that can also be costly..

[Captain Obvious]

I think it comes down to the authenticity of the build. With the slope of the prices for the very early cars, my leaning would be to put on something as authentic as possible. In other words... A rebuilt set of original four screws round tops.

My question would be... Even within the four screw carbs used 69-71, there were some subtle changes over the years. I don't have a good handle on those changes, but hopefully someone here does.

As a side note... I've got a pair of four screw round tops here that I think might be from a very early car. I think they're from that supposedly "completely original" BAT car that didn't sell because it had the wrong carbs on it. 

[S30Driver]

The intake manifolds & balance tube are refurbed and now on the new motor.  Missing is the linkage and carbs.

He is keeping as close to original, stock condition as possible, there is no intention to ever sell the car, it will just become part of his estate.  Hence the decision on the carbs.

[AK260]

I like the idea of brand new carbs but the main concern as you have no doubt considered is the quality and finish - how good or reliable will they be in the long term v ZT? The 60 days shipping tends to suggest a Chinese factory involved - is that a correct assumption?

The other way to look at it is you buy these new items and in a year or two they start playing up / leaking, can you go back to them? What sort of warranty do they have?

I utterly love my ZT carbs and what I particularly like is the fact that they are original high quality items with better than new spindle shaft bearings. Not withstanding the sensational post sales support.

If I was buying brand new, I would buy HS6 carbs - again, known manufacturing origin (UK), support and quality.

I think I just talked myself out of the new carbs in your link!! ;) But equally I’m glad people are starting to remake NLA items.

[Patcon]

I think I would lean towards the new carbs. They look to have had some more refinement. The domes will have zero wear which rebuilt won't. Choke mechanism looks to have been updated. Warranty would be a good question

[grannyknot]

Well you can't go wrong with ZT restored SU's, it might be a good buy to go with the new ones but you would need to find some supporting info and reviews, the website has one photo of the new carbs and that's all I could find, I don't think I could send them a $1,000 based on one pic.

[S30Driver]

5 hours ago, Patcon said:

I think I would lean towards the new carbs. They look to have had some more refinement. The domes will have zero wear which rebuilt won't. Choke mechanism looks to have been updated. Warranty would be a good question

 

QUALITY

 100% New genuine SU carburetor manufactured in the U.K. handmade to order.     @AK260

Improved technology and the benefit of over 50 years of manufacturing performance practices to create a superior carburetor.

Includes a manufacturer warranty and factory support.

 

Warranty is mentioned, I am guessing 1 year - will have to contact them to find out.

 

 

[AK260]

 

QUALITY

 100% New genuine SU carburetor manufactured in the U.K. handmade to order.     [mention=32052]AK260[/mention]

Improved technology and the benefit of over 50 years of manufacturing performance practices to create a superior carburetor.

Includes a manufacturer warranty and factory support.

 

Warranty is mentioned, I am guessing 1 year - will have to contact them to find out.

 

 

Now then, this does make it MUCH more compelling!!!! How on earth did I miss that?

Obviously they won’t look fully original but that is a minor consideration against reliability and more accurate operation of new v old worn components!

So there has always been this available here ....

http://sucarb.co.uk/pair-of-hs6-carburettors-for-a-datsun-240z-260z-conversion-set.html

I’m guessing he’s done a deal with Burlen to make them for him and the 60 days isn’t shipping but rather manufacturing time. Again no bad thing as Burlen have a stunning reputation here in the UK.

[AK260]

 

The OP pointed out that the site specifies made in the UK, which for obvious reasons is the Mecca of all things SU. Hence why I assume this is a Burlen initiated thing, being rebranded for the US market. Also in my 10 years of Z ownership I’ve only just seen this round tops site (the current one was set up in March 2018) but the Burlen 240z conversion carbs have been around longer than my time on the Z scene. I wonder if it was created in the UK for exactly the reasons you describe? We don’t have a ZTherapy here or access to the vast catalogue of new or secondhand parts in the US for the S30 range.

From what I can see, they are basically standard HS6 SU carbs with metric hole sizes and SM needles - not a remake of the Hitachi SUs. Do you see anything that suggests otherwise?

On another note, a relatively common place conversion in the UK is to HS8 carbs. Those who have done it, reported improved torque - but you do have to open out the intake manifold to receive them.

[S30Driver]

For clarity, they offer 2 versions of the carbs, the ones I am interested in are the Original Roundtop Classic HS6 carbs.  The other version are the HIF44 carbs, which look physically different and have the improvements to the cold start system.  The improved version also requires the purchase of a adaptor to bolt up to the stock air cleaner.

@AK260  In one of the pictures on their web site, the box has the name Burfen.  Is this what you meant by Burien?

[AK260]

3 minutes ago, S30Driver said:

For clarity, they offer 2 versions of the carbs, the ones I am interested in are the Original Roundtop Classic HS6 carbs.  The other version are the HIF44 carbs, which look physically different and have the improvements to the cold start system.  The improved version also requires the purchase of a adaptor to bolt up to the stock air cleaner. 

@AK260  In one of the pictures on their web site, the box has the name Burfen.  Is this what you meant by Burien?

Totally agree, I was about to point out the same! 

 

Did I mistype it as Burfen? It is supposed to be BurLen. Yes it's the same logos and packaging as the items I buy from Burlen, being shown on the round-top website. They are basically the people who own the licence for SU carbs and manufacture them here. I didn't look closely enough at the roundtop website initially as I was on my phone, but yes, they appear to be the same HS6 and HIF carbs as go on British classics but with minor modifications. Quite a few people here have ditched the Hitachis for original HS6s as we can get parts for them here.