Hitachi v "Original" SUs

jonbills

Membership Secretary
Staff member
Site Administrator
jonbills said:
both blah blah?
Sorry, I don't follow you - both and then three examples given ?:confused: I was comparing analogue triples to Efi as per Ali.

This is a comparison between three things if you ask me.

Triples is all about showing off a bigger sinep than SUs
SUs can easily deliver all the road power needed.
EFi is knowing that one's sinep is bigger but keeping it zipped up discreetly.
 

toopy

Club Member
Hi All,

I wondered if anyone with an L28 engine has swapped from Hitachi carbs to SU HS6 for the better / easier parts supply?

If so, was there any noticeable drop off in performance?.

Having just read through this thread, I see you say HS6, but everyone is talking about 2" SU's

HS6 are 1.75"
HS8 are 2"
 

Rob Gaskin

Treasurer
Staff member
Site Administrator
Let's go right back to the original post. What is wrong with your Hitachi's?

By the way I have those on my current L28.
 

SeanDezart

Well-Known Forum User
This is a comparison between three things if you ask me.

Nope, not me : I was comparing analogue triples to Efi as per Ali.

3x twin-choke (triples) = 6
6x ITBs = 6

One can compare SUs together or 2"SUs with triple 40mm carbs but imho, that's it.
 

Nmd14

Well-Known Forum User
Let's go right back to the original post. What is wrong with your Hitachi's?

By the way I have those on my current L28.

Hi Rob,

One is doing around 70% of the work; the other has much lower suction, tends to dry out and is bleeding petrol. Things like the butterflies are pretty knackered.

On top of that, they seem pretty worn out. With the old 2.4 engine which itself was down on power, they were ok but with the new 2.8 they are causing all manner of trouble.

I haven't yet taken them apart and this is something I will do next week to take a proper look but my fear is as and when I find problems, I will be out of time to source replacement parts in time for Le Mans trip.

In an ideal world, I will source a replacement pair to use in the interim, whilst getting the original Hitachis rebuilt.

Cheers
 

Nmd14

Well-Known Forum User
Having just read through this thread, I see you say HS6, but everyone is talking about 2" SU's

HS6 are 1.75"
HS8 are 2"

Hi,

I got carried away having seen Sean's photos of his 2 inch SUs. In reality, I'll be sticking to 1.75"

Cheers
 

toopy

Club Member
Hi Rob,

One is doing around 70% of the work; the other has much lower suction, tends to dry out and is bleeding petrol. Things like the butterflies are pretty knackered.

On top of that, they seem pretty worn out. With the old 2.4 engine which itself was down on power, they were ok but with the new 2.8 they are causing all manner of trouble.

I haven't yet taken them apart and this is something I will do next week to take a proper look but my fear is as and when I find problems, I will be out of time to source replacement parts in time for Le Mans trip.

In an ideal world, I will source a replacement pair to use in the interim, whilst getting the original Hitachis rebuilt.

Cheers

I have a set of 2" SU's that were on my car, but i swapped back to the Hitachi's as i thought they were a bit overkill for a standard 2.8.

Plan is, at some distant point i will fit a sportier cam etc but for now the 2" are in storage.

Where abouts in London are you? your more than welcome to borrow the SU's for your trip, they were running fine before i removed them about a year ago, maybe not perfectly, but as a temporary solution with a little fettling :thumbs:
 

datsfun

Club Member
I too have a spare set of Hitachi SU's that I bought recently , came of a running car was the seller's claim: all mounted on manifold etc: you are welcome to borrow and try given the timeline. I am in NW London.
 

Nmd14

Well-Known Forum User
I have a set of 2" SU's that were on my car, but i swapped back to the Hitachi's as i thought they were a bit overkill for a standard 2.8.

Plan is, at some distant point i will fit a sportier cam etc but for now the 2" are in storage.

Where abouts in London are you? your more than welcome to borrow the SU's for your trip, they were running fine before i removed them about a year ago, maybe not perfectly, but as a temporary solution with a little fettling :thumbs:

Thanks for your very kind offer.

I'm hoping a parcel will be arriving from the US in about 10 days time so fingers crossed things will get sorted in time.

Cheers
 

Nmd14

Well-Known Forum User
I too have a spare set of Hitachi SU's that I bought recently , came of a running car was the seller's claim: all mounted on manifold etc: you are welcome to borrow and try given the timeline. I am in NW London.

Thank you that's very kind.

I'm in SW London and hope parts from the US will arrive shortly. If not, I'll send you a PM.

Cheers, Nick D.
 

Farmer42

Club Member
Just reading through this thread and considering the HS6 carbs but wondering whether there is anything that needs to be done to linkage etc to make them fit or is it a case of just bolting on the bodies and using the linkage from the Hitachi SUs?.

I have a set of 1.5 inch Hitachi SUs on the car from my old L20A engine which I had to use as I couldn't get the 1 3/4 inch Hitachi SUs that I had to run properly on the L26. I am starting to get problems with tuning as I would have expected and I think the other set of Hitachi's are too far worn out to use a refurb kit. There is a lot of play on the throttle shafts.

Had a look at ZTherapy replacement carbs but they are too rich for my wallet when the shipping and import duties are added. I thought HS6s my be an easier and cheaper option if they fit ok and you can get the bits easier.

Interested to hear from anyone that has HS6 carbs fitted on how they did it and how they run.
 

AliK

Vehicle Dating Officer
Staff member
Club Member
Give ZT a call and ask about the postage details. I think they mark them as repaired goods with a nominal value so not a huge amount of import duties.
 

Jimbo

1978 260z in yellow
Club Member
i put twin hs6 carbs on my 2.6 and they seem to run great.
the only issue was the sm needles from my old carbs wouldnt fit the hs6 carbs due to the needle holder design being different so used dx needles which have the correct tops and are a little richer than sm needles and have had no major issues.
the car definaately runs better than it ever did on the 240 carbs it had on it as they were worn out.
 
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