I would look at ignition issues. I know it sounds impossible, but a slant will run just the way you described if you have the firing order completely backwards. That is, if you start at number one, and count the wrong way, it WILL run, but have the missing, and backfire as you describe. Ask me how I know.

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Also check the carb and make sure it's not dumping raw gas into the engine. It sounds a lot like you're flooding the engine.

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Joshua

Timing off?

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82 D150-225/727
02 Dakota-3.9/5 speed
87 GMC C7000-8.2 Detroit Diesel/5+2

Sounds not so much like an "RV-grind" cam to me. What caused your cam grinder to send you this particular grind?
Guess we weren't as convincing when we said "No, wrong, don't do it, you might could make it run OK but it'll wear fast, go get the right camshaft for your engine" as your (s)cam-grinder was when he said "Aw, don't listen to those guys, just crank down your valve adjustment and the hydraulic cam will work fine!". What happened to your sentiments of this past January, when you wrote:
Still doesn't sound like "such" a mild cam. That's also a very large carburetor you've got (I would say unnecessarily large).
Low.
Sometimes I do...sometimes other settings are more appropriate, depending on the setup.

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

What does your cam card indicate for valve lash, o.010 & o.020 are the correct gap for stock cam. You may have the valves set way off from what the cam was designed to run them at.
Just a sugestion.

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Part of Tyrde-Browne Racing

That's just it...he's running a hydraulic cam in his solid-lifter engine, so there's no such a thing as the lash setting it's "supposed to run at". His cam grinder didn't follow directions and sent him the wrong cam.

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

Confirm the timing setting, at what RPM was it checked? Did you try turning the distributor while the engine was running to see if it ran better at a different position? (Time it by ear)

Tripe check the firing order, 1-5-3-6-2-4

How do the valves sound, do they tick a lot or are they real quiet?

Was the cam degreed-in?

Is the carb new? What do you know about it?

Is the engine cranking over freely?
Getting spark and fuel?

Fuel, compression and spark at the right moment...and it will run.

DD

I'd check if you ain't getting 2 cyls 180 off (like 2-5 or 3-4 maybe all of them, slant will run with some or all cyls 180º off producing the effect you describe more or less)

as far as for hidro cam on solid engine, I'm running one. Valve lash is really tight (almost zero lash) I'm using .20 mm on intake and .35mm on ex (that being 0.008in and .012ex) and runs fine. Other valve lashes rendered poor vacuum and power results and bad overall feeling.

doc's advice is good, check for excessive loud or soft valvetrain noise (excessive noise indicating over advance and quietude the exact opposite) and double check your distributer's position (maybe you're way off at the dist... or maybe the cam is misdegreed in) cranking speed would indicate off-time values just like valve noise: too much speed and "happpy free spining" and your timing is retarded, to hard, and often "counterkicking" and you're way advanced.

I've ran this hidro profile cam (280ºin290ºex stock lift stock everything else (welded and reshaped cam) on my solid lifter engine for 20k mile. I gotta tell you, I made it work but you have to be up that valves lash behind all the time. I'm going to a 270º erson cam now. I'm trading off a good lobe profile and less duration with higer lift for the cam I have now, expecting to get more useable low end spunk.

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Juan Ignacio Caino

Please use e-mail button istead of PM'ing. I do log in sometimes but I'll be answering quicker thru e-mail.

The idle mixture screws wont have any effect until your idle is lower. ..

Once you get your misfire sorted out and can get it to idle at 900-1000 rpm , try setting the lash while running to get best vacumn. Lower idle to 750-800 and try for best vacumn with lash settings and timing.

Once you can get good vacumn at a smooth idle try setting timing at 3000 rpm for best vacumn and smooth running......if the advance is the same you are in the park. If you have to change the timing you need to work on your advance curve.

Remember ....a fresh rebuild will change almost daily as it breaks in.

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Yeah....Im the one who destroyed this rare, vintage automobile.....

all excelent suggestions but amen to that last one!

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Juan Ignacio Caino

Please use e-mail button istead of PM'ing. I do log in sometimes but I'll be answering quicker thru e-mail.

sounds like a bad vacuum leak to me and possibly multiple problems.
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Tl1000s
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T100

Even the most brilliant engine builders can get messed up with the initial timering of a freshly rebuilt engine. Everything changes, the distributor is hard to see on this car, it turns backwards from some engines, and to make make matters worse, with a slant it is really possible to have the harmonic balancer spin on the core and leave it registered wrong. Plus if you have a mismatched timing chain cover and harmonic balancer, you got more problems. As AC became more popular, Mopar moved the timing mark from the left side fo the engine to the right. These parts will all bolt together with no problem, but not be mated correctly if you have a balancer from an early year, and a cover from a later one. You must find top dead center reliably, mark your balancer to your timing cover, and then make sure you are clear about what position is correct for advanced relative to number one. If you are in doubt, drill a big hole in the top of a spare distributor cap, and put that on while you rotate the engine by hand. Remember that 1 degree at the distributor is 2 at the crank. It is really easy to be way off.

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I had a problem with timing when I painted what I thought was the one and only timing mark on the balancer and pulled out the distributer, well, I found there was really three ( I forgot what I did exactly) but the timing was way off anyway and the same thing happened to me. I had to turn the distributer to calm it down thats when I noticed the error of my ways. So I pulled the distributer again and lined it up proper with the real timing mark. In haste it was real easy for me to screw up things fast but now I know.