510 Su's

[Patcon]

Ok...the carbs are on Cody's car. We have done some preliminary tuning. It's drive-able but not perfect yet. Seems pretty rich. I am only 3/4 turns down on the mixture nuts. I set the floats at 11mm plus like Blues document had. Also I am looking at Ramflo for filters but can't figure out which one is right. Does the H1, H2 or H4 fit the Datsun 38mm carb?????

[Patcon]

https://www.lynxauto.com.au/ramflo-air-filters/by-cfm-series/300-cfm-series-filters.html

[240260280]

Check Fuel Level like below.  It states two different levels for those carbs.

 

Funny that average is 23mm down.

 

[Patcon]

3 hours ago, 240260280 said:

Check Fuel Level like below.  It states two different levels for those carbs.

 

Funny that average is 23mm down.

 

Is that from the inside of the lid? Not the top edge of the bowl?

[240260280]

The drawing shows the top of bowl as the reference.

[Patcon]

Another question. I don't know that I have ever heard the answer, why are the front and back set differently?

[240260280]

Different fuel levels is a mystery. 

Some speculate that it may have to do with one float swinging open under acceleration while the other closes as the fuel sloshes to the back of the bowl.

[Patcon]

These floats are detached and fit pretty snug in the bowl bores. Not really any way for them to pivot...curious...

[240260280]

Hmmm now even more interesting.

[Patcon]

They have floats like this

Section through like this

I used the dimensions off of pg 5 in the pdf you linked to, but we are still rich with about a 3/4 turn down on the mixture nuts. Starting to run out of room...

[240260280]

Could be wrong needles.

[Patcon]

One of the needles is new from Ztherapy. The other is unknown... might should have bought two...

I have another question, there is no port for the vacuum advance. Can I use another port off the manifold? In other words, is there anything special about where that port exits the front carb. The is no booster on Cody's car so I could use that port for vacuum advance and still use the center port for the PCV valve...

Also there were a number of water ports near the carbs. Best I could tell water flow was from the head into the manifold then towards the front. The port out of the thermostat housing and the 90 degree tee out of the straight line were tied together with a hose and the other went to the old carb. For now I plugged the thermostat hole and connected the su manifolds to the line that runs around the front of the head. Should I do it differently?

Edited March 23, 2018 by Patcon