Desperation

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71Duster

71Duster

Well-Known Member
Joined
May 22, 2004
Messages
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Location
Alberta Canada
With the money I've wasted and time spent I'm almost fed up with my cursed Duster.

Starting with the mild original 340 and chaseing the bog down and decideing the motor was tired and having a 360 built for it and tossing a shiny new Demon at the problem and wholenew fuel system, ignition you name it I still cant kill the bog of the line. I'm a mechanic but will honestly say am young and currently they taugh us so little about carbs short of theory my Dad is 56 and also a mechanic and even he can't get it to run right.

To top it all off I've had lifter noise issues from day one, with racer brown cam and 1.5/1.6 adjustable rockers I've tried 2 sets of lifters and on my second cam with the same result. Lifter noise that will fade in and out with rpm.

What I am trying to find is someone in Alberta who can tune on a Demon... I'm almost ready to go spend more cash and get a Holly and put my stock rocker shafts back on
 
yea my friend just bought a new demon that boged he contacted there tech line told em his combo and ordred the jets+sqirters they said he needed well when he took it apart it didn't have the jets and sqirters that were suppoese to be in it anyway it took him a month of ordering stuff to get it right i've never had anyluck with a holley design i just take the eldebrock out the box tune it and go goodluck
 
To top it all off I've had lifter noise issues from day one, with racer brown cam and 1.5/1.6 adjustable rockers I've tried 2 sets of lifters and on my second cam with the same result. Lifter noise that will fade in and out with rpm.



Are you getting oil to the top of your motor? Could be pluged oil passage from the cam bearing to the top of your block, cam bearings not installed right. Pull the dist and rocker shaft off one or both sides, use a oil pump primer while slowly rotating the crank to line up the oil hole in the camshaft with the passage leading to the top of your motor to varify oil getting to the top. Since your on your second set of lifters and second cam, I think you can eliminate the bad parts theory.
 
BG strikes again. I had a road demon that I put on a 360 and then after 3 weeks of retuning the carb everyday durring my lunch I just put the Eddy carb back on and sold the demon.
They sure as hell look cool but I will never try to put another one on a street car.
 
I primed the motor before I started it and it was getting oil to the top of the engine, it was built by a reputable guy so I'd like to "assume" that its not an oiling issue its strange I put the new cam in quite as can be.

All good for the break in etc I finally drive the car about 3 blocks and its starts to fade in and out a bit. So I figure If I give them all another 1/4 turn down it should be set?

Few weeks pass I get time to do it the car hasn't been touched since then re-set them and it almost seems worse now, Engine makes great oil pressure about 70-75psi cold idle and about 30-35 hot idle. Running 10w-40 castrol in it.
 
About the bog, have your checked your fuel pick up filter in the gas tank and make sure that is not clogged up?
 
i'll ask anyway them rockers are adjusted at zerolash i got all the info. on adjusting them if you need it that could cause a bog to
 
you didn't say where the car was boging so here is a direction to take related to bogs if the car bogs off the line you have too much carb/if the car launches then bogs you don't have enough carb basically the second situtation is like running outta gas .in order to tune the carb you need to read the spark plugs/know how much vaccunm the engine is pulling and what size jets are installed as a starting point. now on the ticking i would check to make sure something isn't hitting or rubbing inside the valve cover /pushrod rocker arm etc hope this helps
 
A few observations... You're irritated and rightly so. Stuff happens, everybody's human. I would suggest you find a local performance place that can look at everything. Quality "hands on" is 1000% better than any internet jockey's advice..(including this one...lol) I see you're in Canada. There's a guy somewhere up there on the Cuda-Challenger.com site named Neil. He goes by ChrycoPsycho on there and Moparts I think. He's up there too, and seems to have a pretty decent grasp on things. Go find him, and maybe he can help. Now, as for internet jockeys...IMO, the problem may simply be inexperience on your part (may Dad's too..no offense meant) with regard to performance stuff. I'm no fan of Demons. I can tune them, but I find the first step in any Demon tune is taking it apart and fixing what BG F'ed up building it. Drilling holes that they overlooked, removing aluminum particles that werent removed in machining or washing, things like that. Then you can get to the business of tuning them. And that is a bear too. I know personally several dyno operators that consider Demons a huge waste of effort. They simply cannot be brought into the perfect zone of performance in many situations. Some work great, some dont. I find an old school Holley to be worth it's weight in gold. Most of the stuff I have a hand in designing I spec Avengers of one type or another. Because they use many of the same ideas BG has, but they have MUCH better quality control. Everything in a performance setup has to be expected to be tweaked for it to be 100%. There is no "fits all". Not in engine parts, or anything else. Assume that, and you'll only be happily surprised if something is perfect out of the box. As far as inexperience, I know a lot of guys that dont know the sounds a performance engine makes. You may hear the roller rockers, or lifters, or the washers on locking header bolts (until they back out and "lock"), or even the sound of the exh charge entering the header primary tube. Sometimes it's only the choice in valve covers that made the things audible, but for the most part, they are not quiet. In some respects, they are not smooth like a stock setup should be. That's where a set of experienced hands come in. Just to say "That's normal, to silence it you'd have to do 'x' "... Sometimes that's all you need. I suspect if the bog was there in the 340, and is now there in the 360, there is an issue witht he guys setting it up or the car itself. It could be just overlooking something. It could be a belief that there is only one "right way" and if it doesnt run with it, there's a problem. Not trying to bash, just pointing it out. Bad performance is the end result of some problem or problems with various systems all converging in the one car. Ive seen perfect engines hurt by a wiring harness problem. great tune ups ruined by 5 minutes of "I can do better" by someone who shouldnt be playing with tools, and dangerous accidents caused by using the wrong part and that part failing when the driver needed it most. Stuff happens. The best we can do is try to eliminate the issues one at a time until we're all satisfied lol.
 
The valve covers are unbaffled Mopar performance anodized ones sitting on the fairly tall re-useable gaskets. I have the small bolt in moroso baffles but no signs of anything touching there.

All the valves where set to zero lash then 1/2 turn down from as per the builder. They also where done with the intake off the first time to insure being on the base circle of the cam.

As far as fuel pick up I dont run a stock pick up but a sump in my fuel tank with the large -3?? braided line all the nice AN fittings. Going to check my fuel filter though but the bowls always look to be sitting at their respective levels.

This same Demon was also on my 340 and has been checked, cleaned and certified before it hit my door step. The car will start on the first crank idles nicely and and speed runs great with good throtttle response. But WOT off the line if I keep it rugged up to about 2400-2500 rpm I feel like I should get out and push it just falls FLAT after that its a rocket.

I've tuned and retuned as per the instruction guide I was given with the same result great top end no wot off the line. I was told for my gear ratio, tire size etc this was the carb for me. The distributor is even curved to match the set up.

Moper I dont disagree with you at all I follow the KISS solotion here and aside from my TERRIBLE luck with this car -If it can be defective, late, wrong etc I got it-

This is why I was hoping to find an experianced Demon tuner to make sure I'm not missing the obvious. My dad was a hot rodder and muscle car guy from way back in the day and was really into it. He's forgotten a lot but still very good its just the Demon is so new to what he remembers as a Holly or TQ, Carter etc.

As far as the valve adjustment goes the man sets valve son multimillion dollar 280ton plus diesel dump trucks I figured between him and me a valve adjustment was a no brainer.
 
71Duster said:
The valve covers are unbaffled Mopar performance anodized ones sitting on the fairly tall re-useable gaskets. I have the small bolt in moroso baffles but no signs of anything touching there.

All the valves where set to zero lash then 1/2 turn down from as per the builder. They also where done with the intake off the first time to insure being on the base circle of the cam.

As far as fuel pick up I dont run a stock pick up but a sump in my fuel tank with the large -3?? braided line all the nice AN fittings. Going to check my fuel filter though but the bowls always look to be sitting at their respective levels.

This same Demon was also on my 340 and has been checked, cleaned and certified before it hit my door step. The car will start on the first crank idles nicely and and speed runs great with good throtttle response. But WOT off the line if I keep it rugged up to about 2400-2500 rpm I feel like I should get out and push it just falls FLAT after that its a rocket.

I've tuned and retuned as per the instruction guide I was given with the same result great top end no wot off the line. I was told for my gear ratio, tire size etc this was the carb for me. The distributor is even curved to match the set up.

Moper I dont disagree with you at all I follow the KISS solotion here and aside from my TERRIBLE luck with this car -If it can be defective, late, wrong etc I got it-

This is why I was hoping to find an experianced Demon tuner to make sure I'm not missing the obvious. My dad was a hot rodder and muscle car guy from way back in the day and was really into it. He's forgotten a lot but still very good its just the Demon is so new to what he remembers as a Holly or TQ, Carter etc.

As far as the valve adjustment goes the man sets valve son multimillion dollar 280ton plus diesel dump trucks I figured between him and me a valve adjustment was a no brainer.
Click to expand...
Have you been over your ignition timing,initial,advance-curve etc.......??
 
Ok 71, I was hoping you wouldn't jump all over me for suggesting that...lol. I certainly meant no disrespect, and it sounds like you have done you due diligence. What I've found with some cars is the squirtor size is too small. What happens is that if you move the throttle slowly, you get a certain volume, then it stops, because the throttle stops openning. That's how things normally work. The problem comes with full throttle and a gdod traction car, with a lower stall speed (like street/strip deals). When you board the pedal and open the throttle to WOT, the accelerator pump start to pump the instant the lever moves. But it keeps going with a small squirtor. It keeps squirting until the pump's full volume is exhausted. Now, the first say 1/3 of the volume of fuel is probably enough to overcome the slow air speed when the throttle blades snap open. But as soon as the engine reaches say 2400rpm, the air speed (and signal strength) is back up, abnd drawing fuel. So you end up with a large rich spot in the fuel curve, only at WOT, and only until the accelerator pumps stops squirting. What I would suggest is this. Go up approximately 4 squirtor sizes. If you have 31s, go up to 35s. But thenreplace the pump cam with a smaller one. (notice how every cam EXCEPT the secondary cam for 4150s are all smaller than the factory ones?) So the accelerator pump will shoot slightly more fuel but for a much shorter time. The bigger holes allow more fuel out over less time. See if it still bogs. The MOST important thing right now is a constant tuning spot (like the track) and making one change at a time, and fully documneting where it starts from, and what you do. Then you can put it back shouldd things not chenge for the better. I think you have too much accelerator pump shot at WOT for that Demon. Remember...they like to be lean, and they are designed to have a much stronger signal at lower air speeds.
 
I agree with Moper, but I would leave the pump cam alone until most if not all the bog is removed, as it's easy to get lost in changing the pump cams and the squirters and not knowing which one is now causing the problems. I would also start with a 37 or so if the carb has a 31 in it now, and you may have to go bigger yet. They run about $10.00 a set or so from the local parts store.
 
whats the vacuum at idle in gear? what is the power valve # you have in it? i have never had a demon run right. do you have access to a known good carb to eliminate a variable? as 44dart said, what's your timing at?
 
I had a similar problem with my 340, where I knew that the engine wasn't running up to par......the Holley Street Avenger seemed to work just fine and had checked everything from the ignition to timing, etc. The timing was way too high but if i lowered it, the engine wouldn't run at idle. To make a long story short, I took it to a local 'mopar-nut' garage.....he listened to the engine, revving it a little, watching the vacuum guage, ...... etc, ended up that my linkage to the carb was way too short which made for having to adjust the throttle open more and in turn again, I was getting way too much gas even before driving. When I would attempt to leave a stop light, the car would 'bog down' and then finally 'half-***' run. When the 'mopar-nut' added about 2" to the linkage at the carb & 2" to the linkage to the passing gear rod to the tranny, this made all the difference in the world. The engine now runs at about 8°BTC, idles great at about 800-900 RPM. SO the whole time, I thought the car was doing good, I was only running with 'half throttle' and gas streaming into the intake even before the gas peddle was pressed!!.
Now the engine runs GREAT. I hope this might be something to check to see if it might be your situation.......Good Luck.
Greg..........mtn_jakae
 
You may want to talk to 388Dart, (Leo) in Calgary. He just sold me a Speed Demon that he had set up for my engine. After putting it on and fixing another problem, I adjusted it with a vacuum guage and I have never had a carb work this good on any engine I have had.

Jack
 
I've forgotten - what carb do you have? jet sizes and pv size? what vacuum at idle? and in gear? timing is all in at 34* at what rpm?
 
The jets are 778 Factory jets. Its a 650 Speed Demon.

I'm currently working with Don from FBO that Dave from Daves Mopar Specialties might be able to look at the car as Castrol Raceway August long for the mopar show.

I went camping this weekend and dulled the pain with 12 or so beers and hopefully once the weather cools off and Don gets back on tuesday I'll see where things are at and let you guys know the findings.
 
Here's what Leo put in my 650 Speed Demon that went on top of a 400+ HP 360.
Jets = 72 and 79
P/V = 6.5
My vacuum is 12 to 12.5 inches at idle.
Init timing is 16 and total is 34, all in at 2500
There is no bog anywhere with this setup. The only thing I haven't checked is to see if it nose's over on a full 1/4 run.

Jack
 
Well heres how things stand. On saturday Dave sat out with me in the rain.

First he pulled the bowls and re-jetted it from a 70 - 78 down to a 68 - 76. It cleaned up the eye watering exhaust a good bit.

Next re-checked timing. My first mistake was ASSUMEING that when I set my initial of 18deg the distributor would be good for its all in of 34 deg at 2800rpm. Not so I was lacking. So setting it at 2800rpm to get my full 34deg leaves me with now 23deg initial but it still starts ok so no worries. Dave set it up but it needed a touch more so the initial set up as tested still produced a bog but not as bad. I have yet to drive with the 4 deg of extra timing.

Consensus is looking like the 650 speed demon with mech. Secondaries DP may be too much for my motor.

Here are the motor specs.
J head Castings chambers are 66-67
Piston relief's 8cc
Pistons are at zero
Deck height 9.450 is stamped in the block
Performance Valve Job
Steel Guides Honed to .0025
16 REV Stainless valves 11/32 stems
Intake 1.94 x 4.980 and Exhaust at 1.600 x 5.000
Crane Springs
Crane Retainers
Crane Locks
Steel guides honed to .0025 clearance
Viton Posi-Seals
Bowl Hog and blend Ports
Machine spring pockets
Diamond Pistons 4.030 flat tops
Diamond File Fit Moly rings
Clevite Main and Rod bearings
Racer Brown Cam Lift Int/Exh 485" [email protected]" 238
Johnson Hydraulic Lifters
Cometic Head Gaskets at 4.060 x .051
Compression at 9.62:1
Racer Brown Rocker Arms and Hold Downs 1.6/1.5 ratio
ARP Rod Bolts
Rods sized at 6.123
Cam degreed at 105
Crank at 10/10


Stall is a 2800rpm with 3.55 gears.

Playing with the car on the way home loading it up to 2000rpm and launching still creates a bog and wont even squeel a tire. The only way I ever killed the bog was disconnecting the secondaries.

I still need to try and re-set my valves to try and get rid of my lifter clatter when hot....
 
You have a lot of camshaft and not very much gear or convertor. Are you sure that it does stall to 2800? I'd say that that camshaft would like about a 3500 stall convertor and 3.91 gears (how tall are your tires?).
 
Cyote Jack:
"Here's what Leo put in my 650 Speed Demon that went on top of a 400+ HP 360.
Jets = 72 and 79
P/V = 6.5
My vacuum is 12 to 12.5 inches at idle.
Init timing is 16 and total is 34, all in at 2500
There is no bog anywhere with this setup. The only thing I haven't checked is to see if it nose's over on a full 1/4 run.

Jack"


Very interesting ... so 16 adv init and 34 total is common? I don't mean to crash this thread, but I thought 10 init and 35 total was more what one wanted. What octane are you running with this?
 
dartley,

My creation is a quench engine with closed chamber magnum heads and 10.56 or 10.58 to 1 compression. Up here in Canada our best gas is 91 Octane. I am pretty sure it is calculated different in the U.S. and it would be similar to your 93. There is absolutely no ping coming from my engine and it runs hard from idle. I really don't want to touch it, it is running so good.
Basicly I set the timing by advancing it as far as I could until I got some pinging, I then backed it off 3 degrees. I set the mechanical advance at 18 degrees and ended up with 16 init and 34 total, all in at 2500.

Jack
 
Its a Dynamic convertor so for the cash I spent it should be stalling at what it says -but ya never know-

The cam/gears and stall where all spec'ed by the engine builder who goes to Racer Brown for the cam to run with the combo.

The rear tires are 255/60/15's

A guy I work with who is also a mechanic and has a bad *** ski boat is going to try and re-set the valves with me wednesday nite so that'll make the third person to try so at least I can say its not me if this time doesn't shut them up.

After this I think I may just end up finding a race shop to have a look. It's sad because its not that wild of an engine. On a desktop dyno what numbers does it even show?
 
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