17059212 Quadrajet RV application on a 454

[wimpy88]

Have an estate barn find '79 Revcon motorhome which had been parked for ~10 years. I was told the 454 had been rebuilt 20K miles back. The Quadrajet has a reman sticker. I was able to drive it home (approximately 90 miles) with no major problems other than obvious carb issues, which I think are accelerator pump related. Backfiring, stumbling, etc. It idled fine, problems when accelerating, having to play with the throttle to keep it from dying or backfiring.

It has been a long time since I've played with a carb. While removing the carb, discovered the choke heat tube wasn't connected and the hole designed for the end was filled with rust & crud. Does the heat tube need to actually enter the hole to work effectively?

Disassembled the carb & on the underneath side of the main body encountered a gooey rubber like substance covering a whitish-yellow epoxy? Anyone have an idea as to what the rubber? stuff was? In removing the gooey mess also had some of the epoxy come away. Should I remove all of the epoxy & reapply some other brand (is there a preferred brand) in order to cover the area? Since this RV carb could be 15-20+ years old, should I remove all the old epoxy and re-apply more?

I've read several forums & can't find answers to these questions. Any help would be appreciated.

 

[olds307 and 403]

Yes, that tube needs to be connected to the intake and the tube in there needs to be cleaned out and intact. You can convert it to electric choke. Just replace the coil with electric and dab rtv in the little hole in the housing behind the coil as there can be a potential vacuum leak. Use JB Weld on the well plugs.

 

[pontiacgp]

Just replace the coil with electric and dab rtv in the little hole in the housing behind the coil as there can be a potential vacuum leak.

when I converted my quadrajet to an electric choke with the research I did I found that the carb is calibrated for the "vaccum" leak and to just leave it open

 

[olds307 and 403]

when I converted my quadrajet to an electric choke with the research I did I found that the carb is calibrated for the "vaccum" leak and to just leave it open

Yah I have ran them open. There is a chance of leakage past where the thermostat sits, since the gasket must be removed for the electric coil to ground but unlikely. A dab could also just be put where the hot air tube goes in, if there is an issue. I have considered going back to the hot air choke on the 70S, on a carb that is nearly perfect for tune like my custom calibrated 78 Olds 403 800 cfm, it only needs choke first thing in the morning, the hot air choke only comes on if the motor needs it compared to the timed electric choke.

 

[pontiacgp]

Yah I have ran them open. There is a chance of leakage past where the thermostat sits, since the gasket must be removed for the electric coil to ground but unlikely. A dab could also just be put where the hot air tube goes in, if there is an issue. I have considered going back to the hot air choke on the 70S, on a carb that is nearly perfect for tune like my custom calibrated 78 Olds 403 800 cfm, it only needs choke first thing in the morning, the hot air choke only comes on if the motor needs it compared to the timed electric choke.

hot air choke is bases on the conditions, not timed coil. The hot air chokes are the best.

 

[airboatgreg]

Most q-jets are ruined when people mess with the main well plugs. That was a very limited issue for a short period of time early on.

 

[olds307 and 403]

Most q-jets are ruined when people mess with the main well plugs. That was a very limited issue for a short period of time early on.

Agree but I have seen minor seepage from the plugs on later carbs.

 

[olds307 and 403]

hot air choke is bases on the conditions, not timed coil. The hot air chokes are the best.

You have converted me, I agree. Really the only the electric choke is better, an ultra lean tune, which I ran.

 

[MrSony]

Quadrajetparts.com sells o-ringed 3/8 plugs to replace the factory plugs. I use a 3/8 bit (or a little smaller) to drill out the plugs. Half the time it ends up pulling them out on it's own. I use black rtv to smear around the oring, tamp the plugs in with a socket and hammer, then file off the little nipples (they hit the base plate, I assume they are there to keep the plugs from backing out, but I remove them) and then I jb weld over the plugs and any other plugs on the bottom. Be liberal with the JB weld, but remember the base plate has to go over the plugs, so a nice thin but well covering coating is all that's needed. Let it cure for a day or so in a warm dry environment and assemble.

 

[StreetStock#72]

I've hated 'stove chokes' forever. Starting with the GM ones where the tube came from the exhaust manifold, they were the worst.
Electric is better.
Don't know what you are putting this 454 in but even if you leave it in the motorhome I'd say Manual choke.
Come on we are 'car guys' and would think we know better when the fuel air mix needs to be a little fatter.
I'll take MY Brain over any stove or coil or computer trying to get all stoichiometric for me.

hey .. You could have even 'compensated' somewhat to overcome the l the pop n' bang motorhome on the way home