Hello to every one out there. I am new to this forum, but I am not new to the automotive hobby. I have been a Chevy man for 25 years, so if I ask a question that everyone knows the answer but me, forgive me.
The vehicule in question is a 1987 Ram 225/904 combo, and I have been banging my head(on the hood latch)for some time trying to figure the problem's fix.
I have this wicked misfire @idle,or shudder or shake which is so bad that the box and hood shake in different directions at the same time.
Its really bad when I release the brake in drive at a light to start moving, and just as bad in reverse.
I can hear and feel a miss at low rpm in drive, but only up to 20 mph(40 kph-hey i live in Canada), but after I lean into it its as smooth as buttered butter on a frying pan.
From a stand still, if I hammer it, its very smooth(no miss).If I gas/brake as if to fry the rear snows on the back, it will missfire up to about 1500 rpm(no tach).
Kickdown brings a bunch of noise and some go, but it aint no big block!!
Now, pls forgive me, but I really don't know how this beast is suppose to go.
I mean I dought that it will push your eye balls back, but its lame.
This maybe a symptom of my problem thought too. Starts great, shuts off when told and can cruise at 70mph. Revs up cleanly, no bog and is smooth all the way up 6k(about)
Here's what I have done to it so far:cap,rotor,wires,dual switch ,coil switch plate,timing@16,rebuilt carb,fuel filter,plugs(which are super white even after 300 miles(lean burn??)replaced vac line to computer adjusted mixture screw for best vac at idle(23@idle,but 15 in drive).
This missfire literaly rattles your teeth @ idle/off idle to 20 mph. It's hell to drive in traffic too. maybe there is another 100 hp (ha ha)hiding somewhere!!!.Power I'm sure is down but I guess I expect to much.
I have fooled around with cars, rebuilding chevies and outboard engines enough to know something is up.
Oh yes, I have done a propane test around the intake; zip as per the steady idle. I am planning an HEI conversion. will this help?I heard is a Lame burn system

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I call it Clifford, as in Clifford the Big Red Dog. It runs like a bag of dirt and its as slow as a dog.
This is why I signed up to this forum;to either shoot this dog or make it purr like a kitten

Check to see if your ignition wires go 153624... as others have said on other topics...don't ask how I found out...

rock
'64d100

Welcome on the board. 1987 was the last year for slant-6 engines in North America, and they were loaded with poorly-engineered desmogging equipment and a rather badly designed carburetor made worse by the quick 'n' sloppy hacks that had been made year by year for the 13 years leading up to your '87, to squeak the vehicles past emission certification tests. When everything's hooked up exactly the way it's supposed to be and everything's in good condition, the '87s run OK. Not great, just OK. But your rough idle isn't normal. Obviously, check all the basic tune-up stuff. Cap, rotor, wires, plugs, that sort of thing. Next round of checks should centre on inspecting for vacuum leaks and exhaust leaks into the intake tract.

Vacuum leaks can be found at the junction of each intake runner to the cylinder head, and at the junction of the carburetor to the intake manifold, and at anything connected to the vacuum tap on the rearmost runner (power brake booster...!). To check for junction leaks, spray carburetor cleaner at each suspected junction and listen/watch closely for the idle quality to change. If it does, it means the cleaner's getting sucked in through the leak, which you have just located.

To check for vacuum tap leaks, pinch off each hose connected to the tap and see if the idle roughness goes away.

Exhaust can leak into the intake tract through an EGR valve that is either stuck open (as by a chunk of carbon holding the valve off its seat) or that is not properly hooked up and is getting manifold vacuum at idle. Exhaust can also leak into the intake via cracks in the floor of the intake manifold. The aluminum intakes are particularly prone to this; if a magnet won't stick to your intake manifold, yours bears particular suspicion. The aluminum intakes also suffer from weld porosity that can cause vacuum leaks right through the manifold itself .

Carburetor factors are pretty standard: If the idle circuit or air bleed is partially clogged, poor idle will result.

You really, really need the factory service manual to make any headway on this truck; one of my favourite sources for such a book is in this thread.

Once you nail down what's causing the problem, post again and we'll have some suggestions for the best way to fix it and/or upgrade the problematic component.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

Dan,

If there is a piece of carbon holding it open. What are the options? Can the EGR be eliminated? If so, what is the correct procedure?

My rig does the same thing, same symptoms exactly! Idles great out of gear, put in gear the windows rattle, stoplights are hell. Go beyond 20 mph and it is smooth as silk. I suspect some leaks around the intake so I purchased the Aussie gasket. Will get a chance to install it in a few weeks. Hadn't thought about the EGR, however. It would be nice to remove it since I am not using it. Still getting great mileage and lots of power under way. Something is causing it to be lean. I read 17.5 pounds vacuum out of gear and get a shakey 15 pounds in gear.

Thanks,

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Aggressive Ted

http://cid-32f1e50ddb40a03c.photos.live ... %20Swinger


74 Swinger, 9.5 comp 254/.435 lift cam, 904, ram air, electric fans, 2.5" HP2 & FM70 ex, 1920 Holley#56jet, 2.76 8 3/4 Sure-Grip, 26" tires, 25+MPG

Depending on what kind of emission test you have to pass and whether or not you're prepared to possibly need to rework the ignition timing to handle an increased tendency to ping that may result from deactivating the EGR, yes, you can delete the EGR by replacing the valve with blockoff plate p/n 3671 447. No guarantee this'll solve your poor idle; it could be caused by any of the other problems I mentioned above, or some others I probably haven't mentioned yet!

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

No emissions testing where we live.

The EGR has not been hooked up since the complete rebuild, about 15,000 miles on it now.

I am at 20 degrees initial 10 degrees mechanical for 30 degrees combined.
I would like to swap that around to 10 degrees initial and 20 degrees mechanical if new MOPAR distributor springs are available!
Know of any MOPAR distributor spring sets for sale?????
My distributor springs are super stiff for a 15R govenor! No way can I get it to ping after I rebuilt the engine....I have left several posts over the last few months on this topic, How do you make it ping ????? I think I heard it start to ping once on a 100 degree day going up a super steep hill, but am not sure. It has a tremendous amount of power for a one barrel since the rebuild.
I have 13 degrees vacuum advance also for 43 degrees total.

Cam is clocked at 4 degrees advance. Cam was reground to a 254D .435 lift at Delta Cams in Tacoma per the good Doctors recommendation!

Where can the block off plate be purchased?
NAPA?
Do I need to JB Weld the hole in the bottom of the intake under the carb where the EGR lets the gas in? or will the block off plate stop all flow between the manifolds?

Thanks!

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Aggressive Ted

http://cid-32f1e50ddb40a03c.photos.live ... %20Swinger


74 Swinger, 9.5 comp 254/.435 lift cam, 904, ram air, electric fans, 2.5" HP2 & FM70 ex, 1920 Holley#56jet, 2.76 8 3/4 Sure-Grip, 26" tires, 25+MPG

Blockoff plate is a dealer item. No JB Weld or other measures needed, just the blockoff plate and a new EGR valve gasket installed right way round. No new Mopar distributor springs available; you have to make do with used "any make" items when recurving a dist. Sounds like you're not too far off now, if you are getting great performance with no ping.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

Well here's the thing. I'm the friend of your friend, geetee150. I went over and gave my best effort on this. I went thru the route that i though was most sensible. As in . Check there are no bridge clamps or studs missing between the two manifolds and the head.. .. Propane test around this area lead to a non result. My input was to determine the real TDC as a start point and see if the distributor was off. My gutt feeling it being a slant motor and the cam being off to the side was the chain had jumped a tooth over the years and the cam was out of faze with the motor. When we found the right stroke identified the mark and got his TDC going we found we could get the rotor into place and a close enough position.. Happily it was obvious i'd guessed wrong and the cam was not off.

The thing i found with this motor was that it had symptoms similar to a done PCV valve. On a GM straight six when the PCV goes it was obvious. Put any load on the motor and you get a huge off idle stumble.
And this is what's up with his motor. It starts & idles fine ,the wires are in the correct order. You can find #1 pole and make a new start point if needed. And it's a good motor that needs some help. Once you get clear of the off idle business it's a good strong motor.
It's not the PCV either he put in a new one.

I'd taken a length of hose of listened to every suspect spot .. Carb base
intake joints all the damn hoses.. no hissing. or pulsing ..
Pinching off the hoses.. well i overlooked that idea..

My question is.. How much effect does the EGR circuit have on this motor? bypassing it sounds fine..
Or blocking it off and testing sounds like a good route..

And that lean burn vacuum module on the back off the motor. Can it cause off idle problems. And how much of that can be bypassed?

Greg looks like you've got some hose pinching to try. Or pinch one off and drive it then the next and drive it..
And that if the connection to your brake booster is leaking you'd have crummy brakes but it's worth checking.

Jim.