Previous Thread
Next Thread
Print Thread
Page 1 of 3 1 2 3
any Thermoquad experts here? #2874957
01/16/21 12:49 AM
01/16/21 12:49 AM
Joined: Jan 2003
Posts: 2,863
middle Tennessee
mopower440 Offline OP
master
mopower440  Offline OP
master

Joined: Jan 2003
Posts: 2,863
middle Tennessee
How do you richen the secondary mixture? Would you tighten the secondary air door so it wouldnt open as quick so the fuel would be flowing more before the air door started letting the air through? Having a hard time with detonation when all the way wide open, even after having the distributor on a machine by a proffesional. I have fooled with it on my own for a while before trying the distributor machine. I can be cruising along at say 50 mph and tromp it all the way down without it dropping to the passing gear and it will ping. I can do the same thing but just tromp it maybe 80% into the secondaries and it doesnt ping, but give it that last bit to where the secondaries are all the way open and it pings..
Its right at 9.5:1 using 91 octane pump gas. Its got a heavy elongated spring and a lighter spring in it. 34 degrees total. If cruising at say 45, and i kinda ease into WOT slowly, it doesnt ping, but stab the throttle all at once and it pings. I can stab the throttle to about 80% and no ping, but tromp it that last little bit all at once and pinging..Like its not getting quite enough gas thrown to it at once that it wants. There is absolutely no bogging ever at all, it runs great otherwise.

Last edited by mopower440; 01/16/21 01:09 AM.
Re: any Thermoquad experts here? [Re: mopower440] #2874976
01/16/21 04:40 AM
01/16/21 04:40 AM
Joined: May 2006
Posts: 1,744
Phila
P
PhillyRag Offline
top fuel
PhillyRag  Offline
top fuel
P

Joined: May 2006
Posts: 1,744
Phila
Quote
Have you thought about the accel pump linkage? Some year levers had 2, some 3 holes for the rod insertion.

Re: any Thermoquad experts here? [Re: PhillyRag] #2874989
01/16/21 08:19 AM
01/16/21 08:19 AM
Joined: Jan 2003
Posts: 2,863
middle Tennessee
mopower440 Offline OP
master
mopower440  Offline OP
master

Joined: Jan 2003
Posts: 2,863
middle Tennessee
yes, its on the second one, also the pump shot has been drilled out. Demonsizzler who used to be on here went through it. Just weird how i can stab the throttle to 80% and no ping, but go that last little bit and she pings even though theres not much of an RPM difference, thats why im thinking that when the secondaries are all the way opened it goes lean for a second

Re: any Thermoquad experts here? [Re: mopower440] #2874998
01/16/21 09:14 AM
01/16/21 09:14 AM
Joined: May 2005
Posts: 1,944
Apollo, PA.
B1MAXX Offline
top fuel
B1MAXX  Offline
top fuel

Joined: May 2005
Posts: 1,944
Apollo, PA.
The way I see them the tension adjustment is there to prevent a bog. If you need a richer tune then you would larger secondary jets. But I think you need a can of octane booster and I bet it will go away. The last 20% of throttle is exactly where they ping when octane deficient.

Re: any Thermoquad experts here? [Re: mopower440] #2875000
01/16/21 09:18 AM
01/16/21 09:18 AM
Joined: May 2019
Posts: 6,174
nowhere
S
Sniper Offline
master
Sniper  Offline
master
S

Joined: May 2019
Posts: 6,174
nowhere
Originally Posted by mopower440
yes, its on the second one, also the pump shot has been drilled out. Demonsizzler who used to be on here went through it. Just weird how i can stab the throttle to 80% and no ping, but go that last little bit and she pings even though theres not much of an RPM difference, thats why im thinking that when the secondaries are all the way opened it goes lean for a second


To state the obvious, air moves faster than fuel. Might be that the secondary is opening just a bit too fast. Have you looked at that?

Re: any Thermoquad experts here? [Re: Sniper] #2875010
01/16/21 09:50 AM
01/16/21 09:50 AM
Joined: May 2005
Posts: 1,944
Apollo, PA.
B1MAXX Offline
top fuel
B1MAXX  Offline
top fuel

Joined: May 2005
Posts: 1,944
Apollo, PA.
As I think back to thermoquads. There is a stop that you bend to set total air door opening (max air flow).

Re: any Thermoquad experts here? [Re: Sniper] #2875011
01/16/21 09:51 AM
01/16/21 09:51 AM
Joined: Jan 2003
Posts: 2,863
middle Tennessee
mopower440 Offline OP
master
mopower440  Offline OP
master

Joined: Jan 2003
Posts: 2,863
middle Tennessee
Originally Posted by Sniper
Originally Posted by mopower440
yes, its on the second one, also the pump shot has been drilled out. Demonsizzler who used to be on here went through it. Just weird how i can stab the throttle to 80% and no ping, but go that last little bit and she pings even though theres not much of an RPM difference, thats why im thinking that when the secondaries are all the way opened it goes lean for a second


To state the obvious, air moves faster than fuel. Might be that the secondary is opening just a bit too fast. Have you looked at that?


Thats exactly what im wondering but i cant remember how the fuel comes in on the secondary side on these. I know on a quadrajet, the secondary jets are actually tied to the secondary air door, so when the air door opens, it also lifts the metering rods..Its not like that on the thermoquad, i just want to clarify that if i tighten the air door spring some more to slow it down, it wont ALSO slow the fuel flow will it, because thats the opposite of what i want to happen..?

Re: any Thermoquad experts here? [Re: mopower440] #2875042
01/16/21 11:37 AM
01/16/21 11:37 AM
Joined: May 2005
Posts: 1,944
Apollo, PA.
B1MAXX Offline
top fuel
B1MAXX  Offline
top fuel

Joined: May 2005
Posts: 1,944
Apollo, PA.
It won't slow the fuel down, it will speed up the reaction to the fuel in the circuit. Once its open the circuit is mixed based on main jetting and how far the air door opens. The tension spring only regulates how fast the door opens.

Re: any Thermoquad experts here? [Re: B1MAXX] #2875055
01/16/21 12:19 PM
01/16/21 12:19 PM
Joined: May 2019
Posts: 6,174
nowhere
S
Sniper Offline
master
Sniper  Offline
master
S

Joined: May 2019
Posts: 6,174
nowhere
the air door on the secondaries has no direct connection to the secondary fuel delivery system. What puts the fuel into the secondary airstream is the flow thru the venturi effect created by the secondary air door. What i think is happening is that you are getting too much air thru the secondaries faster than the fuel can start flowing into it causing a lean spot. So I would tighten up the tension spring maybe a quarter turn at a time and test until you are happy with it.

They make a special tool to adjust this, if you don't have one it can still be done but the odds are you will loosen the lock nut and then the spring tension will unwind on you and you;ll be starting from scratch.

starts at about 4:50


Re: any Thermoquad experts here? [Re: Sniper] #2875063
01/16/21 12:49 PM
01/16/21 12:49 PM
Joined: Jan 2004
Posts: 8,192
fredericksburg,va
C
cudaman1969 Offline
master
cudaman1969  Offline
master
C

Joined: Jan 2004
Posts: 8,192
fredericksburg,va
Bigger jets in the secondary needed, door don’t do anything for mixture. What you’re seeing is marginal mixture from the step up rods in the primary’s then when door opens too lean from the back barrels. Go up 2-3 steps at first

Last edited by cudaman1969; 01/16/21 12:50 PM.
Re: any Thermoquad experts here? [Re: cudaman1969] #2875075
01/16/21 01:17 PM
01/16/21 01:17 PM
Joined: May 2019
Posts: 6,174
nowhere
S
Sniper Offline
master
Sniper  Offline
master
S

Joined: May 2019
Posts: 6,174
nowhere
The air door on a TQ is the venturi for the secondaries. It has everything to do with mixture control.

Good luck finding secondary jets for a TQ.

Re: any Thermoquad experts here? [Re: Sniper] #2875092
01/16/21 01:44 PM
01/16/21 01:44 PM
Joined: May 2005
Posts: 1,944
Apollo, PA.
B1MAXX Offline
top fuel
B1MAXX  Offline
top fuel

Joined: May 2005
Posts: 1,944
Apollo, PA.
Go to the 11:00 min mark in vid. (thanks for the link) you'll see what I mean about the air door opening affecting mixture. We are talking about a ping not a bog right? If you stay on the floor I'm assuming it keeps pinging right.

The right small screw driver will keep the tension spring from unwinding.

Re: any Thermoquad experts here? [Re: Sniper] #2875094
01/16/21 01:46 PM
01/16/21 01:46 PM
Joined: Sep 2003
Posts: 421
montana
BANDIT Offline
mopar
BANDIT  Offline
mopar

Joined: Sep 2003
Posts: 421
montana
I really wonder how much of the detonation you aren’t hearing. When I worked on them back in the 70’s, jetting AND air door were both critical. Sometimes, even primary jetting and different metering rods could be used to band-aid certain conditions. At one time, I had 2 or 3 of the strip kits for those, would have to look around for them. I still have half a dozen non Lean Burn TQ’S laying around if you need parts. Jim.


64 Dodge Coronet 440. In progress
1998. Dodge Avenger. 8.35@165. 4400 DA
250” Neil and Parks Slip Joint. 7.36@183.
4600 DA
242" Mullis Dragster. 6.90@ 200mph
Re: any Thermoquad experts here? [Re: B1MAXX] #2875100
01/16/21 01:57 PM
01/16/21 01:57 PM
Joined: Jan 2003
Posts: 1,753
Windsor, ON, Canada
D
Diplomat360 Offline
top fuel
Diplomat360  Offline
top fuel
D

Joined: Jan 2003
Posts: 1,753
Windsor, ON, Canada
Originally Posted by B1MAXX
As I think back to thermoquads. There is a stop that you bend to set total air door opening (max air flow).

This here is the key, it is the only way to control the seconday AFR externally, meaning: you need to bend the secondary air blade so that you end up with a smaller openning (to richen things up). Beyond this, you have to take the carb apart and go to bigger jets, some enlarge the holes in the Discharge Nozzle (this is where the fuel in the secondary circuit actually enters the airflow) if the jet actually flows enough fuel but the nozzles can not keep up with the fuel delivery into the airstream.

Take a look at the attached scan out of the Carter TQ Service Manual...most of the MP Engine Book stuff (as it pertains to the Carter TQ) which shows the fuel circuits has this information.

Remember, this is applicable to a truly lean condition on the secondaries, as opposed to the more often encountered "bog" when the spring tension is too light.

CARTER - TQ Service Manual - Page25.jpg
Re: any Thermoquad experts here? [Re: Diplomat360] #2875109
01/16/21 02:29 PM
01/16/21 02:29 PM
Joined: Jan 2003
Posts: 2,863
middle Tennessee
mopower440 Offline OP
master
mopower440  Offline OP
master

Joined: Jan 2003
Posts: 2,863
middle Tennessee
No there is absolutely no bog, i adjsuted that spring years ago and got rid of any bog, it actually performs great besides this ping..

Re: any Thermoquad experts here? [Re: B1MAXX] #2875110
01/16/21 02:31 PM
01/16/21 02:31 PM
Joined: Jan 2003
Posts: 2,863
middle Tennessee
mopower440 Offline OP
master
mopower440  Offline OP
master

Joined: Jan 2003
Posts: 2,863
middle Tennessee
Originally Posted by B1MAXX
Go to the 11:00 min mark in vid. (thanks for the link) you'll see what I mean about the air door opening affecting mixture. We are talking about a ping not a bog right? If you stay on the floor I'm assuming it keeps pinging right.

The right small screw driver will keep the tension spring from unwinding.


Yes its definately a ping and no bog whatsoever, and yes, it keeps pinging until i back out just a hair, but a hair is all it takes. I adjusted the air door years ago to fix the bog and it does great besides the ping..

Re: any Thermoquad experts here? [Re: Sniper] #2875205
01/16/21 05:55 PM
01/16/21 05:55 PM
Joined: Jan 2004
Posts: 8,192
fredericksburg,va
C
cudaman1969 Offline
master
cudaman1969  Offline
master
C

Joined: Jan 2004
Posts: 8,192
fredericksburg,va
Originally Posted by Sniper
The air door on a TQ is the venturi for the secondaries. It has everything to do with mixture control.

Good luck finding secondary jets for a TQ.

Once opened nothing, might give a little ‘choking’ action in the millisecond before fully opened. I’d look to see if the jets might be clogged a little.

Re: any Thermoquad experts here? [Re: cudaman1969] #2875233
01/16/21 07:32 PM
01/16/21 07:32 PM
Joined: May 2005
Posts: 1,944
Apollo, PA.
B1MAXX Offline
top fuel
B1MAXX  Offline
top fuel

Joined: May 2005
Posts: 1,944
Apollo, PA.
Originally Posted by cudaman1969
Originally Posted by Sniper
The air door on a TQ is the venturi for the secondaries. It has everything to do with mixture control.

Good luck finding secondary jets for a TQ.

Once opened nothing, might give a little ‘choking’ action in the millisecond before fully opened. I’d look to see if the jets might be clogged a little.


the larger the opening the less the pressure differential is on the secondary fuel tube. the harder the draw the more fluid vol. you get.

I still think the poster needs more octane.

Re: any Thermoquad experts here? [Re: mopower440] #2875234
01/16/21 07:34 PM
01/16/21 07:34 PM
Joined: Jan 2003
Posts: 1,979
s. e. pa.
C
calrobb2000 Offline
top fuel
calrobb2000  Offline
top fuel
C

Joined: Jan 2003
Posts: 1,979
s. e. pa.

HI

I KOW YOU SAID YOU HAD THE DIST WORKED ON , BUT that does ot mean it is right !

sound to me like your adv curve is too fast !

slow the curve down and i bet the ping goes away !

what rpm is it full adv at ?

Re: any Thermoquad experts here? [Re: cudaman1969] #2875236
01/16/21 07:52 PM
01/16/21 07:52 PM
Joined: Jan 2003
Posts: 2,863
middle Tennessee
mopower440 Offline OP
master
mopower440  Offline OP
master

Joined: Jan 2003
Posts: 2,863
middle Tennessee
messed with it for a while today. Filled it up with 93 octane. 1 thing i found was the vacuum dash pot that holds the secondary air door closed until the right time was blown out, so replaced it with a good one. Seemed to help a little bit. Then i tightened the secondary air door and seemed to help a small bit more, then limited the secondary air door a little more and it seemed to help a small bit, but all in all it still there some, just not as bad.

Page 1 of 3 1 2 3






Powered by UBB.threads™ PHP Forum Software 7.7.1