carb question

[texacejr]

I have an 82 faimount futura with the 200-6, auto trans and holley 1946 smog carb. All the smog equipment is gone,plus the cat.
I need a little more low end torque. The Holley runs well(starts after 1 pump) and is fine at highway speeds. I've advanced the timing as far as I can with no knock and that heped some.
My question is, would a Cater YF from a late 70's to early 80's helped with low end pickup? I want to keep the bowl vent to the charcoal canister and the Carters I have seen hookup properly for this plus they should let me retain my cruise.
Any help is appreciated.

P.S. I intend to direct mount a 2 barrel Holley in the future as $$$$ allows.

 

[Anonymous]

Some of the things that are hurting you are a low compression ratio and a VERY lazy cam profile, all in the name of reducing emissions.

A cam swap would help a bunch, and milling the head would help a bit, too.

For more "get-up" out of the hole, lower rear end gears or a little "looser" torque converter will help.

Non of these things can be done cheap (i.e., tweaking timing and stuff) you are just gonna have to live with it's gutlessness until you can afford to do some upgrades.

Another note: Oftentimes, a larger carb will increase power at higher revs, but make low end torque WORSE.

 

[CZLN6]

Howdy Texacer and All:

I'd certainly consider swapping the #1946 for a YF- if for no other reason than the tuneability. My experiences with the Holley #1946 are that they work moderately well if all original equipment is in place as functioning as designed. because of that they lack adjustibility and ease to work on and to change. They are very cluttered and I doubt that they would flow 180 CFM. The Carter YF was used on 200s from 1970 until '79. I'd be looking for an early 70s YF. The later ones were more cluttered up with emissions and feed back stuff, and less adjustible. Another option to consider is the Carter RBS one barrel used on 250s beginning in 1970. The Carter YFs are rated at 187 cfm while the RBS is rated at 215 CFM.

Linc's assessment is right on- that, normally a larger carb will show performance increases at the higher rpms, but in this case it would help accross the board, to be able to tune it to this engines new characteristics.

Also note that the stock cam has fairly good specs. It's the cam's timing gear set that is retarded- literally. The gears retard the timing to improve low end torque, to compensate for under-powered and over-gearing, and for emissions and mileage. If you were to change your cam timing gear set for a straight up timing gear set, you'd notice a big difference in engine characteristics.

What is your current rear end gear ratio?

Adios, David

 

[texacejr]

I'm running 2.73 ratio. I do an even amount of hiway and city running.
Mostly i need just a little more oomph on the on ramps.
Do you think swappin the timing chain and gears for an early 70's 200 will help.
As I've said before, $$$ is a little tight and this is my daily driver, so downtime will also be a consideration.
Thanks to both for the advice so far.

 

[CZLN6]

Howdy Back:

Yes, a new cam gear set would help, but a rear end upgrade to a 3.00:1 or even a 3.23:1 would be more helpful.

Here is a list of all that needs to be addressed order of priority. If you're going to a two barrel carb you might want to do that while the head is off, and mill and adapt a direct munt two barrel.
1. Gear ratio of 3.00:1 or lower.
2. A valve job to include a three angle valve job, milling the head .075" to increase CR, and to compenste for the thicker aftermarket composite head gasket.
3. Install straight up cam gear. Best would be a double roller set from FSPP.
4. Upgrade to a 2" exhaust system with a turbo type muffler.
5. Upgrade the carb.

Keep us posted on what you decide to do and how it goes.

Adios, David

 

[Anonymous]

I have to come to the defense of the model 1946, if for no other reason other than it has got me this far!!!

If you know your way around carburetors, you will be able to look a 1946 over pretty well and see what each area does and how it meters fuel. I have no changes to mine other than:
1) choke removed,
2) re-jetted
3) drilled power valve a little
4) removed or plugged what I didn't need.

They use regular Holley jets, just like their big brothers. If you are looking for gas mileage, then leave the main jet alone. You *could* drill the power valve a little bit for a little more fuel under hard acceleration, but tht would be your decision.

Since you are looking for more low end, the fact that it flows 180 CFM will help you, not hurt you. I think going bigger than 180 CFM will only help over 3000 rpm's - - - again, that is your decision. Smaller carbs just have better low end torque than larger ones.

As CZLN6 says, it is a very cluttered carb. If you don't know much about carbs, you should probably NOT learn on the one you NEED to drive the car. You can take apart carbs you find at the scrap yard if you want to see how carbs are made and how they work.