Thermo-quad Tips

[GTX JOHN]

Increase Air door Tension.

Work with Air Door Opening amt.

I am assuming carbs are put together correctly and floats
adjusted to specs.

Several books on these carbs still available.

If you supply Carb #.....I can give some jet suggestions
and Air Door starting openings.

Sometimes you get carbs that just do not work worth a *****
no matter what you do with them.

[S/ST 3040]

Originally Posted by GTX JOHN

Increase Air door Tension.

Work with Air Door Opening amt.

I am assuming carbs are put together correctly and floats
adjusted to specs.

Several books on these carbs still available.

If you supply Carb #.....I can give some jet suggestions
and Air Door starting openings.

Sometimes you get carbs that just do not work worth a *****
no matter what you do with them.

9800S?


Thank you!

[GTX JOHN]

.074/.075 primary (Holley) no metering rods

.143 Sec. with .790 Air door
OR
.137 sec with .750 Air Door

(Stock unmodified Air Door specs.)

3 turns on Air Door spring tension

These are conservative but will be good baseline in my opinion.

Do not modify emulsion tubes!

9800 Series are excellent carbs to start with.....a replacement carb
calibrated better than the factory installed stuff.

[S/ST 3040]

Thank you sir! I will swap my .149 secondary jet for one of your recommendations.

Are Thermoquads sensitive to fuel pressure? (I usually run 5.5 psi)

[dusterfinland]

Originally Posted by GTX JOHN

Increase Air door Tension.

Work with Air Door Opening amt.

I am assuming carbs are put together correctly and floats
adjusted to specs.

Several books on these carbs still available.

If you supply Carb #.....I can give some jet suggestions
and Air Door starting openings.

Sometimes you get carbs that just do not work worth a *****
no matter what you do with them.

My thermoguad number is 6545s and second is vin 6453S thanks

[GTX JOHN]

Is your Duster 340 ( High or Low Comp.) or 360.

They have different size primaries (1 3/8 vs 1 1/2).

I will research these carb # and make sure correct for

vehicle as well.

[GTX JOHN]

If I run stock needles and seats...................7 to 8 psi

If I run .110 needles and seats.....................6 is it!

I was giving just ball park baseline settings to help out........In some circumstances of real excellent air/Sea Level and a carb that a big Air Door Opening (Modifications sometimes required for Air Flow) I can use a .149. Particularly in 1 1/2 "Big" Carb (Not legal on 340). Although a lot of my smartest competitors disagree on this jet size.

The small carbs have a restriction in Secondaries Metering that effect
jet tuning. I have drilled out jet totally maybe .180 or more and it makes
no difference over a 149 or even a 143 in some carbs in A/F...as crazy as it seems. Not the case in the big carbs (1 1/2 Pri.).

Sorry for long winded reply.......Currently in bed a lot with health issues and time on my hands (Possible Congestive Heart Failure).

[dusterfinland]

Originally Posted by GTX JOHN

Is your Duster 340 ( High or Low Comp.) or 360.

They have different size primaries (1 3/8 vs 1 1/2).

I will research these carb # and make sure correct for

vehicle as well.

hi,.sir 360cid.

[GTX JOHN]

Good starting point..................076 (Holley) or .098 with 035 to 037 Rod tip

Big Carbs................................. .143 and .780 Air door to start

Open Air Door 020 at a time on dyno and see what A/F and HP changes.

I prefer 6453 carb as it came on 360 but not critical.

I worry more on AVS carbs switching as they have tabs on boosters for
different engines and manifold combos for air
flow correction ( I think that is why they are there).

[dusterfinland]

Originally Posted by GTX JOHN

Good starting point..................076 (Holley) or .098 with 035 to 037 Rod tip

Big Carbs................................. .143 and .780 Air door to start

Open Air Door 020 at a time on dyno and see what A/F and HP changes.

I prefer 6453 carb as it came on 360 but not critical.

I worry more on AVS carbs switching as they have tabs on boosters for
different engines and manifold combos for air
flow correction ( I think that is why they are there).

Thank you.where I can buy big jets and rod tips..Or kit of jets and rods.or du I need to find the adapter and use holley parts..