carburetor/mainfold question

Engine, Transmission and related drivetrain.
MRGAME
Posts: 16
Joined: 26 Mar 2016 22:39
Location: santa maria,california

carburetor/mainfold question

Post by MRGAME »

check the link please!
i have a question about these flat top hitachi carburetors
http://www.youtube.com/embed/ZZbfJgJr4TY
Image
Image
Image
Image
User avatar
defdes
Supporter
Posts: 5050
Joined: 12 May 2005 14:45
Location: Vermont

Re: carburetor/mainfold question

Post by defdes »

They are likely Hitachi's, they are they most prevalent on the Datsun's....and the word on the street is that they suck!
User avatar
James
Posts: 2136
Joined: 26 Nov 2007 19:58
Location: Laguna Beach, Ca

Re: carburetor/mainfold question

Post by James »

Those are Hitachis - and I have a set of round top and flat top like these - and I think they are great. Need to be in good tune,and need to make sure the throttle shaft bushes are not worn, but they are simple!
The flat tops from the z cars were crap - but these, if they are de-smogged (easy to do) can work just as well as the round tops….
Finished is better than perfect......
User avatar
defdes
Supporter
Posts: 5050
Joined: 12 May 2005 14:45
Location: Vermont

Re: carburetor/mainfold question

Post by defdes »

Hey James, what's the difference between these and the Z flat tops? I was under the impression that all of them were the same.
Three B's Racing
Supporter
Posts: 1288
Joined: 03 Mar 2009 11:58
Location: New Hampshire

Re: carburetor/mainfold question

Post by Three B's Racing »

The Z flat tops were Stromberg's with a very different internal design that were/are junk. When I was a mechanic at Sun Datsun in Whittier Ca back in the 70's we replaced those carbs with SU's and all those Stromberg carb issues went away with the carbs into the trash bin 8>) These flat tops and SU's are no different other than them being flat tops.
"Lastnight the wife said oh boy when your dead you can't take nothing with you but your soul oh "Think"
- John Lennon
User avatar
defdes
Supporter
Posts: 5050
Joined: 12 May 2005 14:45
Location: Vermont

Re: carburetor/mainfold question

Post by defdes »

Three B's Racing wrote:The Z flat tops were Stromberg's with a very different internal design that were/are junk. When I was a mechanic at Sun Datsun in Whittier Ca back in the 70's we replaced those carbs with SU's and all those Stromberg carb issues went away with the carbs into the trash bin 8>) These flat tops and SU's are no different other than them being flat tops.
Ye olde' Stromberg's, got it, thanks.
User avatar
James
Posts: 2136
Joined: 26 Nov 2007 19:58
Location: Laguna Beach, Ca

Re: carburetor/mainfold question

Post by James »

510 Engine-small.jpg
510 Engine-small.jpg (124.54 KiB) Viewed 4924 times
This is the same thing you have - on my car. I will get you a pic of the linkage. You have some wire that is trying to connect the dual chokes (I think so you could use a single cable). I was able to find a dual choke cable. The chokes work great, and can be a necessity to start my cars when it is cold.

I have a few books on SU carbs - once you understand how they work they are really quite simple.

You have a few things going on there, and may be trying to troubleshoot multiple problems at the same time.

Post up what you are running into, and we can definitely help you out.
Finished is better than perfect......
MRGAME
Posts: 16
Joined: 26 Mar 2016 22:39
Location: santa maria,california

Re: carburetor/mainfold question

Post by MRGAME »

James wrote:
510 Engine-small.jpg
This is the same thing you have - on my car. I will get you a pic of the linkage. You have some wire that is trying to connect the dual chokes (I think so you could use a single cable). I was able to find a dual choke cable. The chokes work great, and can be a necessity to start my cars when it is cold.

I have a few books on SU carbs - once you understand how they work they are really quite simple.

You have a few things going on there, and may be trying to troubleshoot multiple problems at the same time.

Post up what you are running into, and we can definitely help you out.

sweet. yes if you can please i need a picture so i can see how it operates and whats it needs to operate.

okay ill check into the su books.

alright this is what im running into

https://www.youtube.com/embed/mXfmV_Wnid4
User avatar
James
Posts: 2136
Joined: 26 Nov 2007 19:58
Location: Laguna Beach, Ca

Re: carburetor/mainfold question

Post by James »

Since the car starts - you have spark and fuel at some level. Where I would start:

Check the level of oil in the damper. Black knob on top of the carb - unscrew that and there is a dipstick with two marks. There should be oil to between those marks. If there is no oil - I use marvel mystery oil (people say its too light but I like it) - easy to get and will get you started.

Stick your finger in the carb and lift the piston - it should move freely and have some resistance.

There is a screw that adjusts the idle - it pushes on a plate that adjusts both carbs make sure the screw is at least hitting that and
I would give it another turn or two (it may not idle if thats too far backed off).

once you get it to idle - have you checked the timing?

As far as the chokes a dual cable would be helpful - if you can find one.

I'm not near my car - so pics will have to come late tomorrow.
Finished is better than perfect......
User avatar
okayfine
Supporter
Posts: 14154
Joined: 12 Nov 2007 23:02
Location: Newbury Park, CA

Re: carburetor/mainfold question

Post by okayfine »

OP - in your second video you're talking about the choke mechanisms. In your setup they're connected to each other by a wire but you have no choke cable. As James mentioned, the correct choke cable will be a Y cable with a single wire inside the car and individual wires for each choke mech at the carbs.

The springs that are loose are throttle return springs. You need one for each carb body and the other ends should attach to a point straight below the carbs. OE they would attach to prongs on the SU heat shield.

It would appear that you have at least one nut missing from the intake manifold-to-head stud. This will cause vacuum leaks and no end of running problems.

Go to The 510 Archives and read these issues of DQ:

DQ Volume 3 Issue 1 - Everything you ever wanted to know about SUs and more - Part One

DQ Volume 3 Issue 2 - Everything you ever wanted to know about SUs and more - Part Two - In this installment we'll cover installing the SU intake manifold and carbs, getting the carbs to run, and fine tuning them.

DQ Volume 4 Issue 1 - SU Carburetor Modification Guide - Looking for more performance from your SU carburetors? Look no further. We’ll show you how to squeeze the last bit of performance and efficiency from these carbs, one modification at a time.
Because when you spend a silly amount of money on a silly, trivial thing that will help you not one jot, you are demonstrating that you have a soul and a heart and that you are the sort of person who has no time for Which? magazine. – Jeremy Clarkson
datzenmike
Supporter
Posts: 6080
Joined: 24 May 2006 12:40
Location: Van. Isle.

Re: carburetor/mainfold question

Post by datzenmike »

That must be an early flattop set up. Mine has the idle air adjustment screw for better idling. Did not know the flattops came without this.

Image
"Nissan 'shit the bed' when they made these, plain and simple." McShagger510 on flattop SUs
User avatar
okayfine
Supporter
Posts: 14154
Joined: 12 Nov 2007 23:02
Location: Newbury Park, CA

Re: carburetor/mainfold question

Post by okayfine »

Very convinced the OP is missing some bits-n-bobs, probably lost when the PO converted it to cable actuation.
Because when you spend a silly amount of money on a silly, trivial thing that will help you not one jot, you are demonstrating that you have a soul and a heart and that you are the sort of person who has no time for Which? magazine. – Jeremy Clarkson
MRGAME
Posts: 16
Joined: 26 Mar 2016 22:39
Location: santa maria,california

Re: carburetor/mainfold question

Post by MRGAME »

okayfine wrote:Very convinced the OP is missing some bits-n-bobs, probably lost when the PO converted it to cable actuation.

yeah its missing some shit. is they any chance someone has a link to the kit i could buy? if not yolo ill save up for a new setup.
MRGAME
Posts: 16
Joined: 26 Mar 2016 22:39
Location: santa maria,california

Re: carburetor/mainfold question

Post by MRGAME »

datzenmike wrote:That must be an early flattop set up. Mine has the idle air adjustment screw for better idling. Did not know the flattops came without this.

Image
yeah see these look like my flat tops but there not the same. i was thinking they were different models. people were telling me that all flat top su's are the same. :/

thank you for sending me a picture. could you take one more of just the front where it shows the parts im missing behind the filters. :)
MRGAME
Posts: 16
Joined: 26 Mar 2016 22:39
Location: santa maria,california

Re: carburetor/mainfold question

Post by MRGAME »

okayfine wrote:OP - in your second video you're talking about the choke mechanisms. In your setup they're connected to each other by a wire but you have no choke cable. As James mentioned, the correct choke cable will be a Y cable with a single wire inside the car and individual wires for each choke mech at the carbs.

The springs that are loose are throttle return springs. You need one for each carb body and the other ends should attach to a point straight below the carbs. OE they would attach to prongs on the SU heat shield.

It would appear that you have at least one nut missing from the intake manifold-to-head stud. This will cause vacuum leaks and no end of running problems.

Go to The 510 Archives and read these issues of DQ:

DQ Volume 3 Issue 1 - Everything you ever wanted to know about SUs and more - Part One

DQ Volume 3 Issue 2 - Everything you ever wanted to know about SUs and more - Part Two - In this installment we'll cover installing the SU intake manifold and carbs, getting the carbs to run, and fine tuning them.

DQ Volume 4 Issue 1 - SU Carburetor Modification Guide - Looking for more performance from your SU carburetors? Look no further. We’ll show you how to squeeze the last bit of performance and efficiency from these carbs, one modification at a time.
are you talking about this 510 archive here? cause i dont see it
https://drive.google.com/folderview?id= ... rp=1&hl=en
yeah theres more than one missing form the manifold lol.
Post Reply