76' American Clipper Motorhome Mid-Range Stumble

[Austech]

Hi! Long time reader, First time poster. I've been reading on this forum. and others like it (A, D bodies) forums. ETC.

(1)I have a Mopar 440 in a 21' Motorhome. It has a Thermo-Bog on top. It didn't run, Had no spark. and when I did get spark. it would leak fuel from the carb above the phenolic bowl (Top gasket)

(2) When I got it... Some guy that was an "electrician" by trade. Was trying to restore fire to the engine because it was not firing.. [Side story: This guy.. I called Sparky. Because he was good at making sparks. This guy was trying to swap MOPAR ign for GM HEI. He had no idea what he was doing. Couldn't get fire no matter what he tried... So I bought the whole thing and decided I would fix it myself... So I tore out all the wiring he did. and went back to the stock wiring harness. I checked the wiring diagram. And within an hour or two... I had fire. Weak fire.. But fire nonetheless]. Once I got fire.. It was weak.. I checked the coil. Secondary coil was 3K ohms low. So I got a new ACCEL coil that makes 42K volts. opposed to the 20K volts from the old coil.. The control module. was shot. So I got another one of those. Ballast was missing because Sparky thought it wasn't needed when using HEI. (Not sure... but I think the resistor is needed no matter what to keep the coil from overheating and dying) Got a good, hot spark. So I set it to 10* BTDC. Real loud hard pop. So I moved it back down to 8 like the valve cover and the book says.. This uses the Reluctor and coil type, not breaker point ignition. So I closed the gap of the coil down to 7 or 8 thousandths of an inch. Checked timing once more. Still good... So I don't think timing or ignition is my problem... I've only been wrenching nuts for about 10 years. I'm only 24.. And I am well aware of the problems that weak fire can cause...

(3) The thermobog was severely out of adjustment. (Sparky thought maybe it was fuel, Had no idea how to check for fire.... Idiot..) So badly out, that it wouldn't even idle in gear....The idle mix screws were WAY out. So I brought them in to 1.5 turns... With the newly rebuilt fire... I turned the key and it started... It stumbled and coughed a lot. and the exhaust was rotten just below the passenger exhaust manifold... It would die in gear. and the leak was still there.. So I took the carb off. and put on a carb from the highway patrol back in the 80s. Ran rich as a son of a bitch! So I said.. Well. Time for a rebuild... I got a rebuild for the original thermoquad. Took it apart... So I installed a new gasket. Upon installing the new gasket. I checked out the internal parts. Replaced the accelerator pump piston and the cap that goes in the end of it with the little ball in the brass. The floats were set at 1-12/32 and 1-8/32. So I set those back down to 28/32. I got it within 1/32 of spec. A smidge over. I figure a tiny bit over is better than a tiny bit under... (Thoughts? 1) I didn't have a gram scale to weigh the floats.. So I don't know if they're 8g or not.. but... I got it back together. It started within 5 seconds of cranking (Just to fill the bowls) Now it would still die in gear... But it would stay running longer in gear now! So now I'm thinking... Vacuum leak.. I start taking off hoses. confirming that they go where they are supposed to go (According to the emissions sticker that shows it) Nothing obvious (To me anyway... I've been messing with engines since I was a kid. My grandpa showed me everything I know) So I get to the choke pull off. I remove it's vacuum line. put my finger over the hole. Shift it into gear (Not sure what would cause me to do this.. but I did it anyway) and it runs in gear! I put the choke-pull off back on... continues to run in gear. Shut it down. start it back up.. it runs in gear! (Thoughts 2) Why would this cause it to run in gear? I introduced a vacuum leak when I took the hose off. Sealed the leak when I put my finger on it... Then put the hose back on. and no issues anymore... What would cause that?! The choke-pull off holds vacuum and the arm moves in and out with vacuum.... So it's working correctly I think...

(4) So now that there are exhaust pipes on it. on the way home from the exhaust shop.. I decided I would mess with it a bit.. Fire seemed legit.. So I figured FUEL would be the next step.. Idle mix is set with screws to highest vacuum. then backed off a tiny bit. (Correct?)
It didn't seem to have much power when accelerating (I've never driven a motorhome before... So maybe they are sluggish? But the engine sounded like my motorcycle when it's either drowning in fuel. or starving for fuel... So I figured.. It's probably Metering rods that control the mid-range.. So I moved them all the way down while holding the piston down, got to 1.5 turns UP from the point it STARTED moving.. It was WAY higher than this adjustment...about 5 turns UP from "baseline" So... While driving down the road.. I reached down there with a screwdriver and brought the rods UP, by turning clockwise, I gained a fair amount of performance from this..But it still feels like there is a "bog" while getting to WOT. If I just hold WOT, The 727 will downshift and the power comes alive. The "hiss" of the TQ goes away and it turns into a ROAR. It has VERY decent power at WOT. But it could take a bit more power IMO. Getting moving from a stop, it still lacks power, mid range still seems like not enough power.. Placing my hand over the choke does increase RPM. but I haven't tried that while driving to see if it makes more power. What adjustment procedure should I follow to get the factory power back out of this engine? I'm for the most part, VERY mechanically inclined... I rebuilt a 5 speed manual transmission in my garage floor on moving blankets. I also restored an 82 honda cb750K from nuts and bolts into a motorcycle that nobody has seen any part of but the tail-light. I know that this carb should be able to make the 440 SCREAM and it should make close to 370HP with STOCK. I just don't FEEL that in the seat when driving this motorhome. Mind you. it's heavy, but not loaded. all cabinets are empty, tanks are empty, and even some of the hardware is missing, (Leveling hardware, jacks, spare stuff, coach batteries, etc) So it's actually lighter than it will be once it's loaded.)

Sorry for the long post! Just trying to get most of what I've done out there so I can be critiqued on what I should have done or haven't done. Or done wrong. List of stuff done below for reference!

Currently. This motorhome is 2K miles away in California, and I'm in Missouri, I will be going back to work on it a bit more before attempting to bring it back here.

There is fluid coming from the mastercylinder of the brake/power steering booster thing. I think it's probably brake fluid. But my grandpa says trans fluid because he says it doesn't smell like brakes... I think it's brake fluid because that's where the master cylinder is for it... The other part of it controls steering.. sure... but that's only a vacuum booster there. the PS pump, and reservoir are both further down on the engine, I THINK!

Stuff I've done
Checked hoses for vacuum leak
Restored factory ignition module
Changed coil to hotter coil
Set reluctor gap
Set idle mix
Set Timing
Adjusted Metering rods while driving down the road for best power at the pedal
Voltage regulator lets 20V to battery, Reading spikes up and then down to 12.8 Battery voltage.
Changed Valve cover gaskets, Still leaking oil
New PCV valve, New Canister that goes into valve cover.
Broke off oil check tube that goes into oil pan, (Rotted through with hole from rust/heat?) How do I replace this? It was a steel line with a compression fitting screwed into the side of the oil pan.
Looking at videos on youtube of other RVs like mine, and thermoquads, it seems that my linkage isn't hooked up right. Pressing on the gas opens the butterflies, but I think the kickdown arm is supposed to be on the same post as the gas pedal.. Could this cause bog in mid-range? I don't think so.. but maybe some black-magic that the TQ holds inside might count on this being right?

Any ideas on what I should do or look at? I won't be able to look immediately. But in a few weeks I will be able to get back to it. And I want to be a little better prepared this time because I need to drive it 2K miles.

 

[Photon440]

Hi there Austech, welcome aboard!

 

[Austech]

Hi there Austech, welcome aboard!

Thanks!! I see a LOT of friendly helpful people here!

 

[BeatersRus]

Thanks!! I see a LOT of friendly helpful people here!

this topic is in the wrong place,it needs to be in general or a more visible place to get more replies/help.

i used to provide rv advice to many on a now defunct forum.
ill hit you up in a pm after i reread this a few times.

random first read thoughts.
the oil pan,youll have to drop that to replace that dipstick fitting.
the choke pulloff,is a tiny little rubber line it shouldnt affect much for vacuum loss.
did you at any time try spraying the intake area to check for leaks?
you set the timing,but where and how did you set it at?

 

[Austech]

the oil pan,youll have to drop that to replace that dipstick fitting.

Not on this particular Mopar 440 - 4 BBL. The oil dipstick.. Hold your breath. You're gonna hiccup when you hear it... Was a steel, 1/4 or 5/16 I.D tube with a compression collar on it. with male threads that screwed into the side of the oil pan. When I found that it was leaking oil from a burned through hole in the line, I took it out, bent it over a few inches outside the threads to seal it off, then screwed it back in as a plug. Works good, but I can't check the oil.. (Wish I had a picture of this!)

did you at any time try spraying the intake area to check for leaks?

All I had was ether, and I was a bit scared to attempt it, but I powered through anyway.. I couldn't really tell, because any small amount of it even at a considerable distance away from the beast, RPM would climb because of the insane volatility of ether! So I figured I would stop, before I blew the heads, or worse, my own head.
I indeed need to get back to california and look for a vacuum leak though!

you set the timing,but where and how did you set it at?

On this motorhome, Timing is a bit of a challenge if you don't have terminals sticking out somewhere under the dash, or an extra 12v battery laying around. Stretching timing light cables from the engine bay and to the back side of the motor is a real PITA. So.. Thankfully. I had an extra 12V battery. Plopped that in the floorboard, Hooked the clamp to the #1 High tension lead. With the arrow according to spark direction of travel, of course. Because it's impossible to see the harmonic balancer and adjust the distributor from the same position.. Mopar was kind enough to include timing marks on the flywheel! There is a hole through the transmission mount (I think...? Picture attached!) I set it to 8, as I recall, the gauge stops at 0. So I assume the marks are only on the before side of TDC...

(I hope that's the case.. I wonder though.. If I do have it set at 10 AFTER TDC.... and the numbers DO continue... I haven't really thought too intently about it until now.. and now I'm 2000 miles away from it and many weeks away from getting back to it.. So now THAT'S going to eat me alive!!!!))

 

[BeatersRus]

lol !
alrighty...sounds like you bought yourself a ton of fun there..
you might wanna take one of those new fangled alum waterpumps with you for your endurance run too.
cheap insurance if it goes in the middle of nowheres..
dont forget to get the Gasket And the blue goo too.

also,while im amused by your dipstick fix,before you do the run back,
drain what oil IS in it and Ensure that you put a good 5 quarts back In it ;)

might i suggest you make it Super easy on yourself and grab one of the billion Edelbrock used carbs laying around on craiglist or facebook marketplace,order yourself the throttle adaptor from summit and then youll be set to go and have the right hookups for your trans kickdown as well.
which is Muchos importente ~

 

[Austech]

lol !
you might wanna take one of those new fangled alum waterpumps with you for your endurance run too.
cheap insurance if it goes in the middle of nowheres..
dont forget to get the Gasket And the blue goo too.

An aluminum waterpump? Do you really think the waterpump will quit?! Oh no! I really don't want to have to change a pump on the side of the interstate!!
It has 50K miles. What's 2K more?!

also,while im amused by your dipstick fix,before you do the run back,
drain what oil IS in it and Ensure that you put a good 5 quarts back In it ;)

My grandfather and I put in a fresh 5 quarts. but it's leaking some oil from the valve covers, so we are gonna TRY to get that stopped!!

might i suggest you make it Super easy on yourself and grab one of the billion Edelbrock used carbs laying around on craiglist or facebook marketplace,order yourself the throttle adaptor from summit and then youll be set to go and have the right hookups for your trans kickdown as well.
which is Muchos importente ~

Do you really think it would be best to swap carbs?! The TQ, as I've read, is just about the only carb that will stay cool in a motorhome doghouse. My grandfather had a quadrajet on his Brougham(sp?) motorhome, it was a 78 with a 440. and it would overheat and boil the fuel, then vaporlock in the lines, and it wouldn't start back up after fuel and such. And as I understand it... it would just stop all together. LOL. I really don't want to sink TOOOO much money into it.. Ya know?

 

[BeatersRus]

omg man,did you really just say it has 50k whats 2 k more?

well,those 2k might the hardest 2k youve ever done if the shyt hits the fan.
how long has this been sitting around?
you should probably have a good battle plan for this whole adventure...
i ran a 1300 mile road trip last week,and im always prepared for Something to go wrong.

thats a great point about the edelbrocks and the rv heat.
i had forgotten about that and needing 15 clothespins n so forth.
tell you what,if you dont have one,ill send you an extra thermoquad,
just pay the shipping.
that way youll have a backup carb just in case.

you should deffo figure out Why those valve covers are still leaking as well.
that could be a fire hazzard and i dont think youd look good in a flaming box at 70 mph on the highway.

not too Tight on the valve cover bolts!,check for flattened cover edges?
i see you have a new pcv valve,make sure its actually a good one and working.
pull the number 1 plug spin the motor over and set your timing from that and the hole/marker in trans housing.
if it was me,yes i Would take a new waterpump And a thermostat,just in case and some jugs of water too.

think i got most of it what else ya got

 

[Austech]

Oh dear lord! You have me in a full anxiety attack already. I'm glad I don't have to make this journey alone, I'll have my grandfather, who is a VERY experienced mechanic of 40+ years, But he's 80 now. His mind is still pretty sharp but some things he just doesn't know, as he's not had any experience with this particular carb either. (Albiet the QJ was a very similar unit)

It sat in a walmart parking lot for a year, then in the driveway of my neighbor's house for a year, with many "mechanics" that would come along with a screwdriver and a crescent wrench, the occasional multimeter, never with the probes attached correctly for reading continuity or voltage, but rather, amperage draw.. and always a cheap Harbor Freight meter.. (Nothing against them, I use them all the time for diagnosis. But I know how to use it like a responsible adult)

It was last tagged in 2017, or 18, So it has to have passed smog in 2016 at the very latest. So I know it has been running. My grandfather suggested it might be a cracked head just now that's leaking oil.. Not entirely sure I wanna keep listening to him. Every time he suggests something, it just gets worse! LOL.

As for the leaks, I will not let it get down the road too far while leaking. I need to wipe the places near the oily spots and get it clean and watch it leak carefully, now that I've got it running half decent and can actually focus on leaks instead of having to focus on keeping it running! We got some bad RED RTV from 2 different autopart stores. I remember when I was a kid, it was thin, easy to work with, would come out of the tube nice and gentle and you could make BEAUTIFUL gaskets with nothing more than just the RTV. This stuff was THICK and hard to get out of the tube.. but since we were sending my aunt to go get the stuff, We figured we'd use it, and not send her back.. Bad choice.. Always use good quality stuff, and fresh too!

The timing... Do you mean set it with the engine not running? I'm not sure I understand what you meant.

The TQ you've got, Will it run this 440? Will it pass smog? Will it run long enough to get me to a safer location or maybe even home if I'm half way there? I'd love to have a spare TQ in working order! Where should I get a water pump? You said New aluminum. Are the old ones cast? How much more will an aluminum water pump cost?

If the waterpump fails.. Does it break the engine? Or does it just overheat and shutdown? I try to keep a close eye on gauges in anything I drive as it is.. Nervous habit maybe? I wonder if I should replace the radiator hoses? I hear that the metal coil inside can decay and bits can lock up and destroy a water pump. True? False? Fake news maybe?

Thank you for all your help! I hope that when I get back to california and start to prepare this thing to roll, I can call upon you for guidance!

 

[BeatersRus]

no worries.
as far as smog well now hmm..
ive been buying the thermoquads for years almost all are 440 cop car or truck which are NONsmog carbs/exempt.
are you registering it in your state and then taking it out of california yes?...
if so then it shouldnt matter.
plus you really dont want to waste money on a smogger carb.

the alum waterpump,the good ol Ebay sells them,dirt cheap dont forget to get the gasket and Good rtv ;)
a lot lighter too,weight off your engine.
you can check your old one for Play simply by grabbing the pulley/fan and gently trying to move back and forth and side to side,try to Rock it.
if Any play replace immediately.
no clue what fan you have but if its a clutch fan type check the clutch for wear too.
you dont want that coming off.


if this was Me,getting ready to do the trip.
a well stocked Toolbox of standard ase wrenches and Deepwell sockets.
throw a brand new fuel filter somewhere in the line,
replace old one if it has one install new one if it didnt.
if you have an electric fuel pump laying around bring that too just in case.
id bring an extra carb,water jugs,thermostat,a few sparkplugs and wires for spares.
an extra battery,along with an extra Voltage reg,ballast resistor and distributor cap.
a couple of brand new Hose clamps in diff sizes needed for rad,and heater hoses.

keep an eye on the gauges esp > the oil pressure and the Temp gauges.
make Damm sure you have the Kickdown set properly before you drive a single mile.
when carb throttle is pushed fully to rear,
kickdown should be at maxed position on arm at trans.
in other words,both should be as far as they will go towards the rear of the car/box/rv lol.
check trans fluids and eyeball coolers if equipped/hoses/dryrotted etc etc.

bringing along a Grandpa who knows what hes doing will be your biggest help.
make sure you double check everything.
including the Spare Tire/s

oh,ps,if it was a cracked head one cover would be leaking profusely.
when the motors running simply pull off the pcv and see if theres a ton of smoke and oil coming out,
if not << then more than likely someone in the past over tightened the bolts and flattened the valve cover rails.
you can fix this with careful hammer work and a flatedge.

 

[Austech]

All good information! The carb doesn't need to be a "Smog" carb. It doesn't have an OSAC, TIC, or ELB, or any of that fancy alphabet soup that was on other 1976 models. It had Heated Air Intake, PCV, EGR, EVAP Canister, And a CCEGR Valve that switches EGR open and closed. (From how I understand it) It appears that the fuel bowl is vented into the air cleaner, and does not have a bowl vent solenoid, like other models of the era.

You mentioned fuel filter, and I'm not sure if I mentioned it, so I will mention it again.. Does it matter that the fuel filter is installed BETWEEN THE PUMP AND TANK, and not on the "PUSH" side of the pump? In my reading. It appears that most people say that a mechanical fuel pump pushes better than it pulls. Any restriction in the "tank pickup sock" or the line, could cause weak fuel pressure, and reduced flow. This fuel filter, Being a fine micron filter of course to protect a carb, must place some amount of restriction on the pump. I intend to move it into the "doghouse" and get it on the pushing side of the pump, but I wonder, could that be causing it to stumble? Bad fuel pressure/flow? It seemed to do better at WOT than at mid-range, but it felt lacking power in both. (I have nothing to compare this to of course, I just feel like 7.2 Litres of Displacement SHOULD make a bit more power than that! Good ole Seat-Dyno has tuned in quite a few bikes, but this is a whole different ball-game and has me TERRIFIED after talking to you about all that I'll need to make the journey. I looked up aluminum 440 water pump mopar on ebay. a few hundred dollars for just the housing isn't quite "dirt cheap" but maybe I don't understand the worth of the parts... On Rockauto, a waterpump is like 20$ But I imagine it's just like OEM, Cast, Heavy, But would do the job just fine I imagine. *shrug*

Again. Thank you for all this information! I'm going to be referencing this thread religiously as the trip to California nears. I'm trying to make a list of tools that I'll need. like Timing lights, Vac gauges, Wrenches, Hammers, Prying tools, Crimp Connectors, Black tape, multimeters, ETC. I am pretty sure the Voltage regulator that is on it is quite shot because it's spiking up to 20V at the battery. So.. Probably gonna order in 2 of those "adjustable" ones from Ebay.

 

[khryslerkid]

All I had was ether, and I was a bit scared to attempt it, but I powered through anyway..

You can use water in a spray bottle, mist it somewhat.

Btw Welcome Austech!

 

[Austech]

You can use water in a spray bottle, mist it somewhat.

Btw Welcome Austech!

Hey! That's a good tip! Misting (distilled) water into the intake can also remove carbon deposits! Thank you! It's wonderful to be here!

 

[mopar 3 B]

The need for water jugs just break me up. That thing at least has a 60 gallon water tank.

 

[Austech]

The need for water jugs just break me up. That thing at least has a 60 gallon water tank.

I think that advice was for filling the radiator after a waterpump failure. I hope to not need water.. I prefer Dr. Pepper!

 

[BeatersRus]

https://www.ebay.com/itm/New-BB-MOP...411698?hash=item3d9aa380f2:g:SzwAAOSwyqleD8FW
you are right i think the prices went up a bit.
heres the best deal for you i found,looks to be 123 plus shipping = 153 plus Taxes.

ill dig a coupla of the thermos out today and get some pics for you.
also will list the model numbers so we can see what they came off of.

" it does better at wot than idle or run."
thats because you are finally powered past whatever is causing it at lower rpm/not wot.
i still suspect that you have a major vacuum leak.

 

[Austech]

Hmm. How would I go about performing a smoke test? I've seen this done on vehicles before. Blowing into a vacuum system seems bass ackwards to me as there are probably sensitive diaphragms in the brake booster system, and the choke pull off and throttle position pot.

When I get there I intend to suck on all of them and see if any of them leak down. They're all supposed to hold vacuum indefinitely right? Or for at least a reasonable amount of time?

 

[BeatersRus]

i pulled a 9097s out today for you.
it needs to be cleaned up but was working before storage.
ill get it cleaned up in the next week and shoot you some pics.
heres a link to the same model for specs.
https://bluestarperformance.com/car...ermo-quad-4-bbl-400-4-b-c-body-1976-used.html

 

[Austech]

Oi! That carb looks a bit different than mine! There are only 2 ports on the "front" of the carb (idlemix screw side) vs 3. That carb may have been one before the ported vacuum for distributor. Will I have to Tee vacuum lines to make that work?

Also. Is the fuel inlet on the side?! That's new! I didn't realize there were so many of these carbs! I've seen them with less ports. And as many as like 7 ports for various crap like bowl vent solenoids, high altitude stuff. Osac valves and all kinds of other stuff. The carb you sent looks like it's before all that. I wish I had the numbers off the carb of mine to compare dates and vacuum configuration... If that info is still out there somewhere. Thanks for digging into this for me @BeatersRus ❤️❤️

 

[BeatersRus]

i do have one smogger i think,ill dig it out and see what the numbers say.
sounds like yours is a smogger,
do you recall there being any< kind of an electrical hookup/plug connector on yours?

and if you have anyone local to that rv ?? that could swing by and maybe look at it for you.
the carb number is stamped on the Left Rear footpad,top number will be the code you need.
bring a flashlight and a pen,with the cover off and the air cleaner off it should be easy to find/Clean/see.

you mentioned earlier that you rebuilt this original carb.
did you order a general kit or a specific kit for That carb?
the stock number might be a good clue.
yes,there are still decoders and lots of resources out there for the thermoquads,
they were Great carbs if not smogg ;)