Thermoquad Secondary
 

I have a carter thermoquad on my 360. Driving somewhere in kansas I lost the secondaries from one day to the next. From what I can tell the linkage is just not opening up the secondary. As if something got off track or a connection fell apart. Are there any good resources on how to fix this. Even a picture from the side of it hooked up correctly would help I think.

Thanks.

Sounds like the locking linkage is not catching the latch.... Make sure the choke is opening all the way.... Look in some of my Photos in my Signiture.... If you dont find any, let me know and i'll go out in the shop snap a few for you....

I'm having an issue viewing those pictures for some reason. I don't actually see anything that would be catching the secondary at all on the carburetor. This is why I think it may have "jumped track" so to speak a bit. Not sure what would have caused it to drop out from one day to the next, but we drove about 1200 miles and there was a 30 degree temp change as well as a huge change in elevation going from Charleston, SC to Denver. Currently she's in the shop as I lost all my forward gears when we were adjusting the timing. At least a rebuild on a 40 year old 727 is pretty cheap. If you have a pic of it not engaged and one of it engaged that would be great as I can see if I have the linkage correct.

Another question, is there something I could just drop on that would be plug and play that is less complicated? Maybe a two barrel without a secondary? I drove about 600 miles without them and rarely have the need for them, I only noticed it was gone cause I like the sound it makes when they open up so I put the pedal down. This was a reman from autoline and it performed great up until now. I just feel something easier and less finicky would give me peace of mind. Not sure how involved that would be beyond installing it and plugging a few vacuum lines.

Thanks for your help.

Carb linkage Thermoquad
 

https://cimg5.ibsrv.net/gimg/moparfo...7dfce25b5.jpeg
https://cimg7.ibsrv.net/gimg/moparfo...cf6457b89.jpeg

So I figured out the issue is actually on the other side of the carb and it was the choke as you stated @RacerHog. There is a thermal spring or something near the vacuum pull off that is completely broken. I just wired my choke open for the time being. Still starts when it's cold but it takes a minute. I'm thinking I might just put a manual choke on there somehow and forget about the spring. Not sure if I can find that part.

An additional question. I have my secondaries now and they do open. I no longer lose complete power, but it does lose power when I get into the secondaries. Currently I have the top of he airbox screwed in upside down as I didn't want to rejet the carb for my elevation change and it was running somewhat rich. As it is upside down there is about a half inch gap all away around the top of my airbox to let the extra air in. Could that be what is causing the secondaries to bog down. I did set the timing myself going down the road and I have no detonation or pinging in the primaries so they are running good. Got me ~520 miles from Denver to Salt Lake City. I assume if I had the timing way off going that distance I would have bent a valve or something.

My question here is - Is the bog down due to how I have the timing adjusted? Do I need to advance/retard it some. Sitting in the drivers seat with the doghouse off the vacuum advance is on the right side of the distributor. I am under the impression that to advance it I would turn it counter clockwise. There is almost a spot there where it feels as if it snaps into place when adjusting it in either direction that feels right. I went just a tiny bit past this clockwise. Or could the bog down be due to the airbox cover being reversed? Or is it simply elevation and it would need rejetted and I may possibly be ok when I get back to sea level where they previously worked?

Sorry for the myriad of questions, just trying to save myself some $$$ if it's something simple I can try to fix myslef.

Make sure the filters are clean.... Also check the fuel pressure... Could be low? Also Check to see if the secondary needles are lifting off there seats.

Air valve opening to soon or to much.

Good Point.... Or just to fast...

@Iowan - I thought that too about the air valve for the secondary too, but it was completely fine when I was at sea level. I'm thinking the vacuum advance just can't pull it fast enough because of the air being thin here in the rockies, but I do not know. I lost them somewhere near Columbia Miss, but that was to do the choke spring breaking.

When I was adjusting the timing in Denver - well the guy who was adjusting it stepped on the brake and floored it while attempting to turn the distributor to adjust it cause that's how "he" did it. This fried my transmission so I was never sure the timing was 100% correct but the primaries worked fine. The transmission was rebuilt and it drove fine on the primaries.

I'm ok with advancing the timing here a bit as that seems to resolve the problem, I'm just worried I'll break something (mainly the engine) if I advance it too far and it seems increasingly difficult to find someone who can work on these things.

Also worried what happens when I drop 5000 feet in elevations. Will I just break down along the way, have to put the airbox cover on correctly and readjust the timing to get moving again.

At this point I'm almost ready to just dump the carb altogether and get one of these efi kits from holley or one of the others and be done with the hassle.

Could just be running to rich up at that altitude?

It definitely is, that is why the mechanic who identified the broken spring suggested turning the airbox cover upside down to have a gap there for extra air flow as opposed to adjusting everything as we'll be back at sea level next week. I would advance the timing a few more degrees that I have as that feels correct and feels as if it runs better. Just afraid I'll destroy the engine or bend a valve

I think it's going lean....

I think its fat @ 5000ft...just my 2 cents..