[jaseology]

Hi Everyone,


I am a newbie to all of this and need some guidance on identifying parts on my carburetor. I have a 1966 289 V8 2-barrel San Jose, CA version, which means is has the emission/thermactor system. I got a Weiand intake manifold and I want to upgrade the carburetor to a Holley 4-barrel 600 CFM, but I am lost on a few things:


A) Does my car use a manual choke or electric?
B) What are names and functions of the parts/hoses I labeled in the herein attached photos?
C) Is the carburetor I linked above compatible with my setup?



Any help would be greatly appreciated! Thanks!

 

[LeeFred]

#1 and #2 are your choke assembly. #1 is the heat tube from the exhaust that goes into the #2 choke housing and heats it up. As the engine warms up, the heat from the exhaust goes up the tube and into the choke which then opens up flap on the top of the carburetor to allow more air in.

 

[Jedi]

5 is the accelerator pump, 3 is a cold/high idle dashpot

 

[myfirstcar66]

And number 4 is the air horn feed that comes from a second tube inserted into the passenger side exhaust manifold.

AND it appears you have an original intact Thermactor system, so don't throw away any parts. Those are sought after by restorers and can command a high price.

 

[GT289]

I'd be tempted to run the Summit carb and not a Holley. Probably the smallest one...... unless you
were planning additional engine (and exhaust) upgrades.

 

[myfirstcar66]

Can't go wrong with an Autolite 4100 !

 

[Daisy]

I agree. Research your CFM needs to match the carb to the engine.
You cannot simply bolt up any size carb and get good performance.

 

[Huskinhano]

I'd stick with a 500 cfm carb. This size is better suited. Go with something like the original Autolite 1.08" 480 cfm, the Summit 500 or the new Edelbrock 500 cfm. All of these carbs use annular Venturi boosters that will provide crisper throttle response, power and fuel mileage.

 

[awhtx]

3 is a cold/high idle dashpot

Are you sure about that? It looks to me like it's just a plain dashpot to prevent the throttle from closing too rapidly and killing the engine. It was used on AT equipped cars.
Some cars had a high idle solenoid that was electrically activated to increase the engine idle speed during cold temps or when the A/C was turned on. I added one to my '65 to bump the idle speed up 200 rpm when the A/C is turned On.

 

[jaseology]

Are you sure about that? It looks to me like it's just a plain dashpot to prevent the throttle from closing too rapidly and killing the engine. It was used on AT equipped cars.
Some cars had a high idle solenoid that was electrically activated to increase the engine idle speed during cold temps or when the A/C was turned on. I added one to my '65 to bump the idle speed up 200 rpm when the A/C is turned On.

Also, I noticed that my carb doesn't have a transmission rod connected to it. I don't even see the rod. Why is that?

 

[myfirstcar66]

The kick-down cable should be attached to the bell crank lever that swings on the firewall. It is a threaded rod on one end with a clip connected to a small lever at the shift selector on the trans on the other end.

 

[jaseology]

The kick-down cable should be attached to the bell crank lever that swings on the firewall. It is a threaded rod on one end with a clip connected to a small lever at the shift selector on the trans on the other end.

I see it!

So does that mean I don't have to worry about the transmission connector on the carburetor I want to purchase?

 

[Woodchuck]

It looks like your Thermactor system is somewhat disconnected. If you don't have to worry about smog testing you can remove the remainder of the components and plug the ports in the heads (Summit sells the 5/8 plugs) and run a shorter alternator belt.

Anyhow, the Autolite 2100 you currently have installed uses a "hot air" choke unit that draws fresh air from the carburetor air horn, circulates it to the passenger side exhaust manifold and hot air comes back up to the choke unit. A swap to a 1.08" (480 cfm) Autolite 4100 will retain your "hot air" choke functionality as well as be the least complex regarding linkages, etc.

If you were going to go with an AFTERMARKET carburetor, one choice would be the Holley 1848, which is suitable for use with an automatic transmission and has a "hot air" choke provision. If I was going to go this route I'd get a different banjo inlet fitting though and STILL use the OEM aluminum spacer plate with PCV tube.

Another choice would be the Summit M2008VS500 with electric choke, which would be connected to your alternator Stator post and would do away with the choke tubes (and would help facilitate things if you were going to install headers or the HiPo exhaust manifolds). I'd again use the OEM aluminum carburetor spacer with PCV. You'd have to check with Summit about the Holley 11-4 dashpot... it's the one used with the Holley 4010-4011 which is pretty similar to the Summit carb. You might not even NEED one, but better to be safe than sorry.

 

[jaseology]

It looks like your Thermactor system is somewhat disconnected. If you don't have to worry about smog testing you can remove the remainder of the components and plug the ports in the heads (Summit sells the 5/8 plugs) and run a shorter alternator belt.

Anyhow, the Autolite 2100 you currently have installed uses a "hot air" choke unit that draws fresh air from the carburetor air horn, circulates it to the passenger side exhaust manifold and hot air comes back up to the choke unit. A swap to a 1.08" (480 cfm) Autolite 4100 will retain your "hot air" choke functionality as well as be the least complex regarding linkages, etc.

If you were going to go with an AFTERMARKET carburetor, one choice would be the Holley 1848, which is suitable for use with an automatic transmission and has a "hot air" choke provision. If I was going to go this route I'd get a different banjo inlet fitting though and STILL use the OEM aluminum spacer plate with PCV tube.

Another choice would be the Summit M2008VS500 with electric choke, which would be connected to your alternator Stator post and would do away with the choke tubes (and would help facilitate things if you were going to install headers or the HiPo exhaust manifolds). I'd again use the OEM aluminum carburetor spacer with PCV. You'd have to check with Summit about the Holley 11-4 dashpot... it's the one used with the Holley 4010-4011 which is pretty similar to the Summit carb. You might not even NEED one, but better to be safe than sorry.

Thanks for all this insight.



I was thinking about going with the carburetor and installing a manual choke cable. What are your thoughts?


As far as smog emissions. I removed it all and plan on selling it.

 

[Woodchuck]

Thanks for all this insight.



I was thinking about going with the carburetor and installing a manual choke cable. What are your thoughts?


As far as smog emissions. I removed it all and plan on selling it.

I'd have a hard time using an Edelbrock carburetor on my desk to hold pens and pencils. The Summit carb is a MUCH better piece.

 

[jaseology]

I'd have a hard time using an Edelbrock carburetor on my desk to hold pens and pencils. The Summit carb is a MUCH better piece.

HA! alright, this is good to know

 

[Grimbrand]

Edelbrocks are "meh". They run, but I've never seen one do better than any other carb. Hard to fine tune. Holleys do fine at WOT, but they will never perform as well as a Summit M-series when it comes to everyday driving. Those annular boosters flat out deliver more power and economy in almost every driving condition. Super easy to tune, also.

 

[Jedi]

Are you sure about that? It looks to me like it's just a plain dashpot to prevent the throttle from closing too rapidly and killing the engine. It was used on AT equipped cars.
Some cars had a high idle solenoid that was electrically activated to increase the engine idle speed during cold temps or when the A/C was turned on. I added one to my '65 to bump the idle speed up 200 rpm when the A/C is turned On.

No I'm not sure, I thought all dashpots were for cold idle

 

[Woodchuck]

No I'm not sure, I thought all dashpots were for cold idle

Nope. Ford installed the dashpot on automatic transmission models to delay the closing of the throttle plates to prevent stalling. Think of it as like a drawer soft-closer for your carburetor.

 

[Jedi]

And that makes sense, You can learn a lot in this forum