Predator 212 Hemi Won't Idle After Valve Lash Adjustment

SquidBonez

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I recently installed a stage 2 kit in my Predator 212 Hemi. While I was testing it out, the valve lash adjustment screw on the exhaust rocker backed out and allowed the pushrod to fall out from beneath the rocker. No big deal, this happened once before and all I did was reset the lash and I was fine. Now, after setting the lash multiple times, I can not get the engine to idle. It will only start with starting fluid, idle for about 5 seconds, and then die. The pushrods aren't bent, and when I cycle the engine everything works as it should valvetrain wise. I picked up a new carb to see if that would fix it (last time I couldn't get my engine running I just swapped the carb and it fixed it...plus it's only $12). But if/when that doesn't work, what should I try? (EDIT: It didn't work.)

LIST OF MODS:
PVL Flywheel, 4 Degree Offset Timing Key, ARC Billet Rod, 22lb Valve Springs, 0.01” Head Gasket - $5 MOD2 Camshaft, Header Pipe, Muffler, 0.38 Carb Jet, Chromoly Pushrods 5.54”, Autolite 3910X Spark Plug
 
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madprofessor

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Sounds like Predator cap curse. As a hemi, both the intake and exhaust valves each have a lash cap sitting on top of the valve stems. Just a little pea-size cup sitting mouth down on the valve keepers, so that the rocker arm is pushing down on the cap and not on the valve stem. (Except non-hemi, I think they only have a lash cap on one of the valves.)
The cap curse is you unknowingly letting a cap (or both) get pushed off, maybe with your feeler gauge, leaving a huge amount of flapping around by the rocker arm, letting the pushrod fall out from under the rocker. The caps usually fall down the pushrod openings into the case, where they seriously need to be removed before running it again.
Trying to adjust the lash without the caps won't work, the excessive tilting of the rockers will prevent the valves from operating in correct lift and duration of the cam.
Pull off the rockers enough to see if both valves have a cap sitting on their stems, or if you've adjusted the lash with the rockers pressing directly on the stems. If missing, look for them in the head space there. If gone, you've got to split the case and get them out of there.
Please don't split the case without a new sump sidecover gasket in hand. People who live by gasket sealer have troubles with shaft spacing after putting it back together. If you're ordering a new (for hemi only) gasket set, might as well get a hi-performance set with a thin racing head gasket for the same money. Mine was $14, came with a .012" stainless steel head gasket. Noticeably increases the performance due to the increased compression.

Compression: Need to know if your ARC billet rod is stock 3.308" or the longer 3.328" that increases compression. Guessing you did a typo on the head gasket, meaning to say 0.10" thickness. My own hi-perf gasket is 0.12" thickness. Need to know the exact of yours. Currently checking on what stock compression should be, don't know yet.
Carb jetting: My performance guy says that the .036 jets he supplies me with should be the max for my 15+ hp. Predator using any carb, and even that should run quite rich. It's mainly for more low end power. That rich mixture means the spark plug will soot up black very quickly, but not foul. You can basically wipe off that kind of thing. Remember that soot contains carbon, which can divert a spark.
On that same subject, all that fuel is premised on having maximum air flow from a hi-flow air filter, a venturi-face (not flat) filter adapter, and free-flowing exhaust. Have you tried running that engine with the muffler removed? All mufflers have at least some degree of restriction.
Checking also on what stock length is for pushrods, to see if yours are standard. My guy says the only thing better than stock valve retainers is if you go to stainless steel valves, then he sells a valves/retainers/spring kit for $60. Nice to have your chrome/moly pushrods, but wondering just how much help they are.

That's really interesting. Motor mount is set up for spinning a hub/brake drum/sprocket as a single wheel drive of the left wheel. Mounting plate is so far left that nothing else would easily work there.
OOPS! Just noticed plate is missing in one of pictures, must have only been laid there where it is seen. You have the option to put it anywhere. I recommend setting up a live axle, gets you 2-wheel drive and 2-wheel BRAKING.
Also recommend welding in some more steel for mounting a third bearing between the 2 existing bearing brackets, hopefully right next to axle sprocket, and to a brake disc if used. Axles are made to flex a little.
Thanks for the great advice about the extra bearing. You are right, always a live axle is better.

Thats not a rupp dart its a simple dingo or american express the axle mounts the iver head bar and supports on the spindles tell all not a rupp i had one
That’s a really nice frame.
 

SquidBonez

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Compression: Need to know if your ARC billet rod is stock 3.308" or the longer 3.328" that increases compression. Guessing you did a typo on the head gasket, meaning to say 0.10" thickness. My own hi-perf gasket is 0.12" thickness. Need to know the exact of yours. Currently checking on what stock compression should be, don't know yet.
Carb jetting: My performance guy says that the .036 jets he supplies me with should be the max for my 15+ hp. Predator using any carb, and even that should run quite rich. It's mainly for more low end power. That rich mixture means the spark plug will soot up black very quickly, but not foul. You can basically wipe off that kind of thing. Remember that soot contains carbon, which can divert a spark.
On that same subject, all that fuel is premised on having maximum air flow from a hi-flow air filter, a venturi-face (not flat) filter adapter, and free-flowing exhaust. Have you tried running that engine with the muffler removed? All mufflers have at least some degree of restriction.
Checking also on what stock length is for pushrods, to see if yours are standard. My guy says the only thing better than stock valve retainers is if you go to stainless steel valves, then he sells a valves/retainers/spring kit for $60. Nice to have your chrome/moly pushrods, but wondering just how much help they are.
Rod and pushrods are both stock length. And the head gasket is the thin metal one that OMB/GPS sells (see here, listed as 0.01": https://www.gopowersports.com/010-h..._lLwbT81pjIIteo36JTvtW9tYoeyCUYYaAtcdEALw_wcB). The jet came from the stage 1 kit. I am running a muffler and high flow air filter, but nothing changes when I remove the muffler. Gonna pull the head and check the valves. Do you reccomend swapping back to the stock jet? What size is the stock jet?
 

SquidBonez

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UPDATE:

Ok, possible development. I took the head off and I found a slight mark in the piston seen here:


Note that when I first took apart the engine to install the stage 2 kit, this mark was not there:


I'm not sure if this is normal and just is a result of the engine running, but the mark is directly over the exhaust valve, which is the valve that the pushrod fell out. I checked the valves themselves (they're still in the head, haven't taken them out) and I can't see any damage or signs of bending. Kind of at a dead end here...any suggestions?
 

SquidBonez

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Another Update:
Poured water in the valves to test for leaks. Both are perfectly sealed. Took the head apart, both valves are totally fine. I've already got the engine this far apart already, I might as well open it up again to check inside. I just remembered that when I first took the engine apart after the pushrod fell out, I noticed the exhaust lifter wasn't moving when I cranked the engine, and I had to lightly tap the pushrod with a hammer to get the lifter to go back down. Maybe that could be a clue. I am determined to get this thing running again. I will post another update when I continue working on it.
 

madprofessor

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Wow, really have brain fog, can't tell my hundredths from my thousandths right now. No matter, the OMB gasket is a hi-perf if it has that 1 in the number.
Hammer/pushrod combo is scary, has me seeing bent lifter stems.
You should see my current piston. A dot of welding slag smaller than a .177 BB fell in through the exhaust valve, was hitting the piston just enough to keep it from freely rotating when turned slowly by hand. Had to give it a little headstart spinning to roll past it. Point being, it marked the piston a little, but no unacceptable damage was done, as in scarring the cylinder wall or cracking anything.
Dug a ball bearing out of the top of a piston in an old Ford 292 V8 that had dented one piston about a thousand times before going back up through the manifold and coming down where I found it, punched six dents then embedded. Motor had run fine all that time, teardown was just for new rings. Don't worry about the piston.
OEM jets actually vary, but are usually around .016 low jet and .029 main jet. Your .038 main jet is a little rich per my performance guy, but with no other option currently than your stock jet, and as easy as it is to swap, I'd definitely try it. BTW: My guy says not to replace the stock emulsion tube when putting in his .036 main jet, the weird replacements cause rough idle. Also have to make sure not to put it back in upside-down.
Are you positive your butterfly choke is opening up all the way when turned off (perpendicular to throat)?
If you do reopen the case, slide out that cam and check the lobes very closely for scarring. Not a problem, just an indicator.
 

SquidBonez

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Wow, really have brain fog, can't tell my hundredths from my thousandths right now. No matter, the OMB gasket is a hi-perf if it has that 1 in the number.
Hammer/pushrod combo is scary, has me seeing bent lifter stems.
You should see my current piston. A dot of welding slag smaller than a .177 BB fell in through the exhaust valve, was hitting the piston just enough to keep it from freely rotating when turned slowly by hand. Had to give it a little headstart spinning to roll past it. Point being, it marked the piston a little, but no unacceptable damage was done, as in scarring the cylinder wall or cracking anything.
Dug a ball bearing out of the top of a piston in an old Ford 292 V8 that had dented one piston about a thousand times before going back up through the manifold and coming down where I found it, punched six dents then embedded. Motor had run fine all that time, teardown was just for new rings. Don't worry about the piston.
OEM jets actually vary, but are usually around .016 low jet and .029 main jet. Your .038 main jet is a little rich per my performance guy, but with no other option currently than your stock jet, and as easy as it is to swap, I'd definitely try it. BTW: My guy says not to replace the stock emulsion tube when putting in his .036 main jet, the weird replacements cause rough idle. Also have to make sure not to put it back in upside-down.
Are you positive your butterfly choke is opening up all the way when turned off (perpendicular to throat)?
If you do reopen the case, slide out that cam and check the lobes very closely for scarring. Not a problem, just an indicator.
I'll try the stock jet again just to give it a shot. Emulsion tube is stock. I'll check the cam once I open the case. Not sure when I'll get to be able to work on it again. Thinking sometime next week. Like I said I'll keep you all posted.
 

SquidBonez

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Did a little more tinkering on it today. Called a small engine repair shop and they reccomended I run premium fuel and open the exhaust valve lash to 0.05" instead of the stock 0.03". Still nothing. Double checked if I had spark and I do. The last things for me to check is if I got the timing right and to open up the engine and check inside. If it's not one of those things then I'm completley lost.

If this was just a simple stage 1 engine then I would cut my losses and just buy a new one and swap all the bolt-ons over. But I have invested too much time and FAR too much money to give up on it. If I can't figure it out I'll take it to a small repair shop and have them figure it out.
 

KMEFA

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Wonder what shape that offset flywheel key is in ?
If anything partially locked up or binded when you had your initial problem,,, it might of affected the key, especially if it's aluminum.
Just something to check ….

I would also try an NGK ''BPR6ES'' copper plug in that also, & gap it to 0.030
That's all I run, & most race Guys around here do also,, plus that's Honda's O.E.M. choice on their engines.
The ''P'' designation does not mean platinum,, it means ''projected tip''.

Autolite's track record for me over the ''many'' years, seems to be,, once they partially foul,, they hardly ever come back 100% after cleaning.
Does look like you are running pretty rich, "or were",, judging from the top of the piston.
I
 
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SquidBonez

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Wonder what shape that offset flywheel key is in ?
If anything partially locked up or binded when you had your initial problem,,, it might of affected the key, especially if it's aluminum.
Just something to check ….

I would also try an NGK ''BPR6ES'' copper plug in that also, & gap it to 0.030
That's all I run, & most race Guys around here do also,, plus that's Honda's O.E.M. choice on their engines.
The ''P'' designation does not mean platinum,, it means ''projected tip''.

Autolite's track record for me over the ''many'' years, seems to be,, once they partially foul,, they hardly ever come back 100% after cleaning.
Does look like you are running pretty rich, "or were",, judging from the top of the piston.
I
I tried running with the stock plug back in it just to make sure and got the same result. How would I tell if I was running rich? Head is back on but I have pictures of the piston.
 

KMEFA

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I tried running with the stock plug back in it just to make sure and got the same result. How would I tell if I was running rich? Head is back on but I have pictures of the piston.
How wet is the plug getting now with just trying to start it ''without'' starting fluid, , & how quickly does it get wet,. if it even does. ?

When you had it going on starting fluid , did it pop or cough at all out of the intake or exhaust ??

Those things will tell a lot...

I would definitely still check that flywheel key also.

Thinking more about this,,,
Does that cam you put in have a compression release on it for the exhaust tappet / lifter ??
@ 50lbs. compression , I would hope it would,, cause that's not much.
It's possible that when the pushrod dropped ect.,, that the comp. release assy. might of got jacked, & or lifter ,, & is holding up the exhaust valve where it shouldn't.
And if that's the case,,
you would definitely have a problem, & wouldn't be able to ever adjust that valve lash even close to where it's supposed to be, unless you knew for sure that the lifter face was resting ''solid'' on the narrow side of the exhaust cam lobe.

Don't like it at all that you had to tap the pushrod to get the lifter to go back down.:eek:

Definitely need to pop the side cover off again & take a look-see...

Am looking forward to what you find. ;)

I
 
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SquidBonez

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How wet is the plug getting now with just trying to start it ''without'' starting fluid, , & how quickly does it get wet,. if it even does. ?

When you had it going on starting fluid , did it pop or cough at all out of the intake or exhaust ??

Those things will tell a lot...

I would definitely still check that flywheel key also.

Thinking more about this,,,
Does that cam you put in have a compression release on it for the exhaust tappet / lifter ??
@ 50lbs. compression , I would hope it would,, cause that's not much.
It's possible that when the pushrod dropped ect.,, that the comp. release assy. might of got jacked, & or lifter ,, & is holding up the exhaust valve where it shouldn't.
And if that's the case,,
you would definitely have a problem, & wouldn't be able to ever adjust that valve lash even close to where it's supposed to be, unless you knew for sure that the lifter face was resting ''solid'' on the narrow side of the exhaust cam lobe.

Don't like it at all that you had to tap the pushrod to get the lifter to go back down.:eek:

Definitely need to pop the side cover off again & take a look-see...

Am looking forward to what you find. ;)

I
Thanks for the suggestions. I'll certainly update this post as I continue to work. Completely forgot about that lifter I had to tap down. The cam does have a compression release, so the compression test really wasn't accurate I think. As for how it starts, it will only start on starting fluid and then quickly die unless I keep revving it, but I have to rev it so high it just engages the torque converter and then I obviously can't get in it.
 

KMEFA

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Thanks for the suggestions. I'll certainly update this post as I continue to work. Completely forgot about that lifter I had to tap down. The cam does have a compression release, so the compression test really wasn't accurate I think. As for how it starts, it will only start on starting fluid and then quickly die unless I keep revving it, but I have to rev it so high it just engages the torque converter and then I obviously can't get in it.
It really sounds like a valve train problem.
An engine is kind of like a suction pump,, & if you have valves hanging open ect.,, it won't be able to pull fuel in like it should,, plus you have the comp. release,, that hangs the exhaust valve up a bit while starting anyways.....
 

madprofessor

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On running rich, my performance guy tells me that the .036 main jets he sends me run a little rich to keep the bottom end. Indicator is black soot, exactly what your piston looks like, mine also to a degree.
He also advised me against using a hotter spark plug than stock, as that's just for racing. Putt-putting around a little will quickly foul them. The type of black soot that shows up on my plugs from running rich wipes off in a single rag swipe, although it's a folded piece of sandpaper that I use to get between the electrode and core.
BUT, it might be important to be sure of wiping the soot off of the NON-conductive porcelain too. Why? Because soot is carbon, which IS conductive. It can trickle off power to ground around the outside of the porcelain.
 

SquidBonez

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Another update. I took off the side cover and found something interesting. When I took out the cam (which was undamaged), the intake lifter fell right out (as it's supposed to) but the exhaust lifer - the same one I had to tap down with a hammer before - was wedged into the block. I couldn't push it out with my finger. I had to take a flathead screwdriver and gently pry it out and it eventually dropped. This makes me think the exhaust lifter is sticking somehow. I already ordered new lifters just to be safe, but I can't actually find anything wrong with it. It's not bent or warped. The pushrods are straight. The holes in the block that the lifters go into seem clear (see below):


I also noticed what appears to be some wear on the side of the crank, but this has been on the engine since the very first time I opened it. Not sure if it's anything to be concerned about:

Anything I should do to keep the new lifters from sticking? Assembly lube maybe?
 

KMEFA

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Looks like from the dis- coloration ect. ,, that the exhaust lifter bore got pretty hot, & is probably distorted.
Lubes not going to help,, unless you get that bore - honed/dressed & smoothed out.
You want that lifter to be able to move free & fall out also. ;)

Just don't over do it & make it sloppy.

See how the new exhaust lifter fit's first.

If there is still a problem,, you can use your old intake lifter, & try &''rotate'' / lapping that into your exhaust lifter bore,, with using tooth paste.
 
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SquidBonez

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Looks like from the dis- coloration ect. ,, that the exhaust lifter bore got pretty hot, & is probably distorted.
Lubes not going to help,, unless you get that bore - honed/dressed & smoothed out.
You want that lifter to be able to move free & fall out also. ;)

Just don't over do it & make it sloppy.

See how the new exhaust lifter fit's first.

If there is still a problem,, you can use your old intake lifter, & try &''rotate'' / lapping that into your exhaust lifter bore,, with using tooth paste.
Would valve grinding compound work well for honing the bore?
 

KMEFA

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Would valve grinding compound work well for honing the bore?

Being that bore is semi soft aluminum,, I would try lapping the old intake lifter into the exhaust lifter bore with tooth paste that's got some grit in it, like Crest.
This is an old machinists trick, & valve grinding compound, ''even diluted with oil'' ,, would still be to abrasive
;)
 
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