Recommended starting point for jetting on Thermoquad

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Brooks James

Brooks James

VET, CPT, Huey Medevac Pilot
FABO Gold Member
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Location
Fruitland Park Fl
Carb is 1977 Heavy Duty Truck
Auto trans, Kalifornia
Would the jetting be richer on HD 440 truck
Than passenger car

Would a truck Carb produce more or Less emissions than passenger

Going in
1994 360 Magnum
Stock block, pistons, Rods,heads
Heads portedd to 250-260 CFM
Camshaft lift and duration:::
Intake .498. 274 durtion
Exh. .512. 286 duration
113.5 LSA (extra exhaust duration for maximizing 150 shot of nitrous, same for LSA
This 850 CFM TQ
Knock off air gap
3420. Lbs. 70 Dart with my fat *** in it
1969 742 case sure grip 3.91 Richmond gears
904 manual reverse valve body, deep pan, B &M 3500 converter
Dougs 453 headers 1 5/8

I thought that putting this stock carb on would be a Good startin point, and I will get some jet sizes you guys recommend

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Start with what's in it so you'll have a base line.
 
What do you care about with emissions? Florida does t have testing. Please lift the duration @ .050.
 
Heck, if that’s the case, get a better TQ!
(earlier/less vacuum ports)
 
Press reply, wait, enter your text after the quote tags.

Both durations

OMGoosh, why… why….. why….:BangHead::BangHead::BangHead:
 
Agree with Rusty. Put that on and let it eat. Check plugs then you'll know. I highly doubt it's too far off.
 
OK, Just looked a little rusty and dirty on the outside. Don't know the condition inside.
Just a shame to put money into the engine ( a lot $$$ I'm sure ) and then go cheap on the carb...Like putting old spark plugs in a new engine.
Thermo quads are great carbs. But you need to know it is in top condition and flowing well. The guys like at Harms flow test the carbs before they return them.
 
Brooks James said:
Everything is tight, little use, throttle shaft bushings excellent
Click to expand...
It’s still a model TQ I would t recommend, but you use what ever your little heart wants to use, to for it!
Are u saying that the cam is too small
Click to expand...
In order to know that I’d need to know more information of which much you seem unable to reply with. Furthermore, I don’t known YOU and YOUR GOAL of the car. So, excuse me while I try to contact rusty rat rod for his crystal ball if it’s not all ready in use for your problems.

I ******* give up, this guy is impossible.
# Dullard, nit wit, I-D-10-t issue, blown light bulb, low wattage, anomalous, anomalous, blackened grey matter,
Etc….
 
It might be a smogger carb, but, it has the right things going for it. It has the timed port for vac advance and the idle speed screw. The bowl vent can be wired to twelve volt switch, or easier way, eliminate the bowl vent rubber stop altogether.
 
Honestly I wouldn't even waste your money on it.
Definitely wouldn't waste mine. Get yourself a Edelbrock avs2 or a Holley 4150.
There is nothing easier to make power & drivability than those 2.
I have 2 tq's that I'll put on my tunnel ram as soon as I build it but they'll just be for a street truck for looks and sound basically
 
By the way in the jetting would only be different on a police cruiser. Gotta remember power was way down on 440s in 77.
If that's what you really want to run, find a great carb shop and have it gone thru, hopefully the plastic isn't warped and it's a leaker
 
It looks just like a model I reworked recently, #9150, had that odd vent/crap at the rear. I had to block off a few passages etc, but other than that it should work as well as any other TQ. What is the # stamped on the mounting foot?

I would check/do two things before installing it:
- check the sec high speed air bleeds & enlarge if not already 0.039-0.040"
- enlarge the sec jets to 0.143".

Depending on cam duration, IFR may need enlarging & more bypass air. Do NOT drill the pri blades for bypass air, it encourages nozzle drip; drill the sec blades.
If the air valve dashpot is old, it may be slow to release & is worth a few $$$ to replace it & save some odd tuning problems down the track [ pardon the pun ].

You are in Fl, similar mild climate where I live. I have never needed a choke with a TQ, so for more air flow, I remove ALL the choke mech as well as the bar that runs across the top of the AV. This leaves a small hole in the AV from the linkage & I braze a thin plate over it. May not be needed, haven't tried it without it.
 
Bewy, what is your location?
And these words from you;

“I would check/do two things before installing it:
- check the sec high speed air bleeds & enlarge if not already 0.039-0.040"”

Can you post a picture? That would help a lot of people and the OE poster.
 
Rumble,
I am in Sydney, Australia. Don't know how to post pics, sorry.
But easy to describe the sec HSAB: remove the sec jets & there is a thin brass tube left, which is pressed into the air horn; it is 'pinched' where it is in the a/horn & that pinch is the air bleed restriction that may need enlarging. I have only ever struck two sizes, 0.029" & 0.040", with 040 being more common & used on bigger engines.
 
I’ll take pictures tomorrow or the area.
 
The "s-link" on the accelerator pump is on backwards. Do NOT use anything harsh on the plastic bowl. NEVER soak the bowl in carb cleaner. I just use mineral spirits "softened" with some ATF so it doesn't burn your skin. It's hard to tell from your pictures, but if the shafts still have that green teflon-like coating, that's good, you want to save that as best you can, so don't soak the throttle body and cover too long in any harsh carb cleaner. The same goes for the cad/gold iridite plated pieces, but it looks like that ship has already sailed on you on that carb. I think you'll need to run "98" primary jets to begin with, hopefully that's what's in it already.
Edit: after reviewing the pics, it looks like it might be too late for the green coating on the shafts, too. Somebody may have soaked them for too long in carb cleaner and/or bead blasted the top and bottom.
 
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rumblefish360 said:
It’s still a model TQ I would t recommend, but you use what ever your little heart wants to use, to for it!

In order to know that I’d need to know more information of which much you seem unable to reply with. Furthermore, I don’t known YOU and YOUR GOAL of the car. So, excuse me while I try to contact rusty rat rod for his crystal ball if it’s not all ready in use for your problems.

I ******* give up, this guy is impossible.
# Dullard, nit wit, I-D-10-t issue, blown light bulb, low wattage, anomalous, anomalous, blackened grey matter,
Etc….[/QUOTE
Click to expand...
 
Rumble, thank you so much. Mission accomplished. I got what I wanted, a strong response, whether it be good or bad. Youre response is the best one yet. I post provacative, controversial, WTF, posts, designed to elicit strong responses. You bought this one hook, line, and sinker.Please continued to respond strongly in the future.
Thank you !

BTW, mostly street, stop light to stoplite, occasionally strip.. i didnt post anything about camshaft selection, because that decision has already been made.
 
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Brook, my strong response is to your lack of response as you come off as a total ******* idiot or someone looking to figure out how to press someone’s buttons while acting stupid as hell.

I post a simple question and you can’t even respond with a simple answer but yet question the question. Then you make an asshole statement starting with “Are you saying….”

No muthafucker! If I got something on my mind I just say it.
If I have an opinion, I just say it. Here’s an example;

“Your a dick.”

Do not take this reply as if I’m pissed off.

I like to help people out but your not a willing person interested in actually helping yourself. I think that after I post up a picture of the TQ, I’ll stop replying to your posts. You just seem to be more interested in nonsense.
 
Not responding to your question was an oversight, i was entirely focused on Getting some jet and metering rod numbers.
My car in street trim, will eventually be able to pass any enissions test in any state Many states have them , soon all 50 will.
1. I do all I can to stop global warming, for now, and future generations. It's the right thing to do.
2. I am hoping the truck carb is richer thanan a apassenger. IIRC, years ago ago, emissions srandards were Less stringent on heavy trucks, heavy equipment, which made me think that it would work well, unmodified, One a warmed over+ 360 mag.
Im sorry I caused a problem.
 
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rumblefish360 said:
Brook, my strong response is to your lack of response as you come off as a total ******* idiot or someone looking to figure out how to press someone’s buttons while acting stupid as hell.

I post a simple question and you can’t even respond with a simple answer but yet question the question. Then you make an asshole statement starting with “Are you saying….”

No muthafucker! If I got something on my mind I just say it.
If I have an opinion, I just say it. Here’s an example;

“Your a dick.”

Do not take this reply as if I’m pissed off.

I like to help people out but your not a willing person interested in actually helping yourself. I think that after I post up a picture of the TQ, I’ll stop replying to your posts. You just seem to be more interested in nonsense.
Click to expand...
You're not your
 
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