Installing a big-block carburetor: Two Questions

[1961 Futura]

Cross-posted from The Ford Falcon News:

1961 Falcon with a 1968 170 (non-LOM) and a 1970 170 head:

My carburetor (Carter YF from a ‘70 Maverick with a 170) has “issues”. Not only was it hooked up to my manual choke cable, but it has started dribbling gasoline out of the ported vacuum port, and my engine generally has been running progressively worse over the last couple months.

Rather than troubleshoot the existing carburetor, I’m thinking it’s time to overhaul the carburetor I bought for this contingency: A Carter YF from a ‘69 F100 with a 240.

Externally, the differences between it and the ‘70 carburetor are that it has a true manual choke (the reason I bought it) and a dashpot (which I only just realized). The dashpot was used in the early days to slow closing of the throttle blades on automatic-transmission equipped cars so they wouldn’t stall. Later on, all vehicles used them - probably for emissions reasons.

First Question: Should I eliminate the dashpot during the overhaul, or leave it in place? One person suggested I might save a bit of fuel by slowing the closing of the throttle butterfly.

Second Question: Assuming they are different, what float-height should I use in this carburetor? The most obvious options are: ‘70 Maverick, ‘69 F100, or ‘68 Falcon. They all came with a YF carburetor. I’m leaning toward ‘68 Falcon, since that seems to be the engine that the builder was attempting to produce.

Experiences, facts, ideas, opinions, hearsay, and scans from the Ford shop manuals are all welcome. Thanks in advance!

-Dave

 

[chad]

I rebuilt my carter yf w/help from the forum. It's run great since (1 yr). The dashpot is not hooked up. See signature. I need the plunger, boot and spring (possibly dashpot, it's been sitting idlely there 27 yrs).
Runs fine w/o it.
Starting to get harder to start - may B because I start/run it only once a month now, no Stable (gas preservative) in the tank either.

 

[1961 Futura]

I still would appreciate some input on the float setting. I wish I understood the engineering behind it, so I could figure out whether it's determined by engine specifications or the carburetor alone.

-Dave

 

[CZLN6]

Howdy Back Dave:

Is this carb going on an engine with an Auto trans? Is there an adjustment on the dashpot? What is the diameter of the Throttle bores on each carb, old and new? IIWIYS, I'd be inclined to leave the dash pot in place to begin with. If there are adjustments, I'd back it off so that it had the least amount of effect. IF this vehicle has an auto trans you may want to do some fine tuning with it once the carb basic tune is right.

On the float setting, I'd start with the middle recommended setting, then analyse and adjust from there.

PS, FYI, I have no first-hand experience with this particular carb, so my comments are based on my general approach to any carb adaptation. I hope they are helpful.

Adios, David

 

[1961 Futura]

Hi David,

Thanks for the response. Car is a manual transmission - hence my confusion as to whether keeping the dashpot maybe worthwhile.

I guess I will tinker and see what I find.

Regards,

Dave