Starting Carb Conversion: Flat Tops to Paltechs

[Dadsun]

An update... I've acquired the choke cable clamps, and removed the EGR housing at the top of the manifold. I am trying to sort out the differences in the flat tops hookups and round tops. 

Q1: Are there any other connections I should be expecting besides the 8 noted above (plus 2 choke cables and the 1 throttle arm)?  [Edit: I also found the small distributor vacuum capsule line hookup]

Q2: Coolant lines: It looks like the flat tops had four (4) coolant line connections and the round tops just the two (2) noted above, so I will need to cap/swap out a couple of connectors coming off the coolant lines to the new carbs. Any tips or links to parts that you've needed? See pics of the 4 current connections:

Q3: Two (2) EGR wires run off into a bundle and I'm looking for the relay.  I'm assuming I can just snip them and wrap them off instead of removing the relay?

Q4: See air filter housing back.  I know that #1 and #2 are the lines to float vents.  And #3 connects to the hose to top of valve cover.  What are #4 and #5?  #4 looks like it takes my breather housing rubber plug (currently sitting on #3).

Thanks for any help!

Edited November 27, 2020 by Dadsun

[Freez74]

4 is for air pump.

[jfa.series1]

#5 is for a line from the Vapor Flow Valve (see pic). It is a small valve/manifold mounted under the ballast resistor. Fumes from the gas tank and the crankcase are sent to the carbs for combustion.

[jfa.series1]

BTW - if you don't use an air pump, you want to cap #4 and avoid unfiltered air into the carbs. A 1" chair leg cap from a big box store is a perfect fit.

[Dadsun]

I found the free hanging vapor flow valve hose that goes to #5. See pic. It is in the blue zip tie. Thanks. Sigh, so many hoses to replace.

The other hose within the blue zip tie goes to the crankcase and it looks like the big port there is where my PCV hose from carb linkage is, according to diagram I found, supposed to connect? It is currently not connected to anything. The flat tops setup I inherited had the PCV hose going straight to the air cleaner housing.

Also, I've been reading about wrapping my headers, since they'll be exposed, and some even wrap the heat shield to prevent percolating in the carbs. Any thoughts on this?

[siteunseen]

I have my pvc to the block and the balance tube as shown here. What kind of headers? Mine are heat coated already and do not get hot at all. The carbs are actually cool to the touch, more on top though.

 

Edited November 27, 2020 by siteunseen

[siteunseen]

I'll say something on percolation that will get some disagreements I'm positive. I've never had, heard of actual heat problems. It always ends up being something else. Low float bowl levels more than anything. The guys that race use electric pumps to keep the fuel flowing and cool through the return line. 

We've all read about heat causing problems, ad nauseam to the extreme.

 Wrapped headers, youtube heat shields, electric fans and more. Wound up being low fuel level.

[Dadsun]

@siteunseen - thanks.  I have no background knowledge here, so it's good to hear that.  I have thought about taking the headers off (they are the standard 3-2-1, which are stock headers, as far as I know) and sending them to get Jet Hot coated instead of wrapping.  But, that's like $400. I just figured if some see it as a problem then now is the time to address it.

But, if the braintrust on this forum think no wrap or coating is necessary, then that's good to know. I have an electric fuel pump back just off the gas tank.

 

[Dadsun]

I went ahead, since my header was rusty and fugly, and shipped it off to Jet-Hot in OKC. Two week turnaround. $225 plus one way shipping. 

In the meantime, I'm going through hoses and coolant lines. See pics. What is this inline valve in the coolant line near the break booster (where it connects to a hose that runs around under air filter housing to thermostat)?

[Patcon]

I believe that is the thermostat for the carb water. If it works its a rare part for those wanting to run flat tops

[Dadsun]

Ok. So I can take it out. Btw, Do people sometimes just cap off the intake coolant lines on the round top setups? Talked to a guy in a Datsun shop in Georgia who said it's common. As for now, I plan to run the coolant through the intake manifold. 

[Patcon]

Maybe somebody else will confirm. I wouldn't think twice about deleting manifold heating