Any thoughts on this engine issue

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demon34071

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Any thoughts on the attached engine issue you can see in this video.

Back ground: The engine is a 340 that was built very close to the same specs as a mopar muscle engine build in February 2001. Eddy performer air gap intake, Comp Xtreme Energy Cam, and 800CFM Eddy carb.... Engine was installed and broken in...Engine was built by Bowman Performance in Export, PA... Carb is now a Holley Street avenger 750 (thanks to MoparAl having it on the shelf)

Then mother nature kicked my ***. The car and engine where then flooded when my garage flooded with Katrina and Ivine hitting Pittsburgh The engine was flooded up to the side of the carb. AS soon as the water receded I worked on the car getting it drained, fluids changed (numerous times) and had the motor running again. After having a couple other buddies try to help me with no more knowledge than what I have I finally turned to one of FABO's own, MoparAl.

Flash forward to to 2012...Al and I set out to get the car running and driving again... After working through some gremlins and fuel issues (tank, fuel pump, lines, and carb) we finally get the motor to running and idle...

But here is this issue.... Watch the video.... Notice how the motor will run smooth and the it seems to load up and shake and then smooth back out... It keeps repeating this...

[ame="http://youtu.be/qGE48H9FELQ"]http://youtu.be/qGE48H9FELQ[/ame]

We have tried different different timing changes... 10degs advance seems the smoothest... tuning the carb, playing with the idle etc. -- No Luck

We double, triple, and then check the wires again.. -- No Luck

We thought we had a dead non firing cylinder...so we tried pouring some water on the exhaust pipes pipes...they all boil right off -- No luck

When we open the value covers nothing looks out of the ordinary

No water in the engine oil...

We are at a point where we are a bit stumped..... Anyone out there have any thoughts other than pull the engine and completely tear it down and start over... I don't have the money for that.
 
We tired that..... That's what is on it now. A good... Known to be working and running fine Holley Street Avenger
 
heres my thoughts

weak fuel pressure
vacuum leak
timing chain/timing
distributor
it still seems like a carb issue to me

its running out of or getting too much of something whether it be fuel, air, or spark as im sure you already know.
 
73AbodEE said:
heres my thoughts

weak fuel pressure
vacuum leak
timing chain/timing
distributor
it still seems like a carb issue to me

its running out of or getting too much of something whether it be fuel, air, or spark as im sure you already know.
Click to expand...

Fuel pressure is between 5-6psi with a new stock parts store pump... Fuel tank and 1/2" sending unit is brand spanking new only a couple weeks old in the car. Fram fuel filter is new as well (Thanks Al)... Fuel line is 8AN from tank to the filter. Then downsized from the filter to the pump to either 5/16 or 3/8.. Pressure at the carb is 5-6psi and holds solid.

Vacuum leak.... we can't seem to find one

Time chain was brand new from comp cam when the motor was built.

Distributor was brand new kit with orange box when engine was built.
 
Get right down to "the basics"

Go find/ borrow a know good points distributor and stock coil.

(Wasn't the dist/ ECU flooded?)

Unhook the fuel supply, and use known good fuel out of a siphon can hung from above

That cam should like a LOT more than 10* BTC

How much inspection was done to the engine? Tear down?

What do the timing marks look like under the light? Any sign of scatter?

Does it "want" to run at ANY RPM?
 
Sounds like a sticky valve to me. Did you change the lifters?
 
67dart273 said:
get right down to "the basics"

go find/ borrow a know good points distributor and stock coil. ---- didn't try this

(wasn't the dist/ ecu flooded?) --- dist (yes--opened up looked good, cleaned and still using) -- ecu (yes--but sealed so i never thought to replace)

unhook the fuel supply, and use known good fuel out of a siphon can hung from above --- did this--- this was how we foudn the fuel issues... Motor runs the same from a can or through the new fuel system.

That cam should like a lot more than 10* btc -- yes i agree

how much inspection was done to the engine? Tear down? -- post flood, nothing other than basic stuff, dropped pans, ran a ton of clean new fuilds through and had it running so never tore it down farther. I don't have the skill or the another big pile of money for a complete tear down and rebuild, so i am trying to avoid this as much as possible.

Does it "want" to run at any rpm?
Click to expand...
-- yes. You step on the gas this thing smooths out and runs... Let off the gas and rigt back to the shake fest.
 
Demon416 said:
Sounds like a sticky valve to me. Did you change the lifters?
Click to expand...

No I didn't. I was just thinking this morning that maybe it was the lifers. We did check the push rods since we thought maybe one was bent but nothing looks bent.
 
Was the distributor or box underwater?

Stuck lifter? Do they all have free movement when bled down?

My 2 cents... 10 degrees is not enough initial, get it into the 16-18 range.

What is the idle speed? I wouldn't want less than 800 rpm.

What is the idle vacuum, should be in the 12-14 range with a XE268H, higher end with more initial. Adjust the idle mix screws using the gauge as a guide.

That sounds like it may be dripping fuel in from the carb boosters.
 
What is your manifold vacuum? Is it possible that latest carb came off an engine with higher vacuum at idle, and, with your cam, has lower vacuum,, thus u may need to change the power valve?

Off idle, does it run good,, what do plugs look like??
 
crackedback said:
Was the distributor or box underwater?

My 2 cents... 10 degrees is not enough initial, get it into the 16-18 range.

What is the idle speed? I wouldn't want less than 800 rpm.

What is the idle vacuum, should be in the 12-14 range with a XE268H, higher end with more initial. Adjust the idle mix screws using the gauge as a guide.

That sounds like it may be dripping fuel in from the carb boosters.
Click to expand...

Yes I am pretty sure both ... dist and box were under water...

We agree that 10 degrees is not enough... as we move up it gets rougher

Idle is around 900 rpm-950/975rpm...in that range

I will talk to Al to try a vacuum gauge...
 
I think you need to check the connectors at the firewall, starter relay, distributor, alternator, steering column etc for corrosion. This seems like you have an intermittent connection somewhere.

I would also expect this engine to like a timing setting of 15-20 deg BTDC.
 
inertia said:
What is your manifold vacuum? Is it possible that latest carb came off an engine with higher vacuum at idle, and, with your cam, has lower vacuum,, thus u may need to change the power valve?

Off idle, does it run good,, what do plugs look like??
Click to expand...

Not sure on the vacuum... we are now at a point out of my limited engine knowledge (hence why some one else built it)

Off idle it runs good.... We didn't pull the plugs last night...
 
Throw the box and pickup away is my first thought. I'd get another known good piece and hot wire it. If it was underwater, it's not going to be a reliable piece, IMO

Might have to pull all the lifter and valve spring to make sure everything is moving right. Pull the covers to see if the rockers are moving OK, nothing held up or broken. May have punched a rocker arm if stamped steel.
 
The fuel system is 100% new and was only installed about 2 weeks ago... so that is not flooded items.... I will definitely try a new box though.

We did pull the valve covers and cycle the engine and everything was moving right. this was one of the first thing Al tried.
 
I had a chevy 350 do that to me one time it was the intake try tightening all the bolts for that for vacuum then im also leaning toward a distributor problem
 
scamper383 said:
I had a chevy 350 do that to me one time it was the intake try tightening all the bolts for that for vacuum then im also leaning toward a distributor problem
Click to expand...


WE sprayed some starter fluid around all of the vacuum area's yesterday carb base, intake to heads, intake bolts, etc to see if we could see any leaks... nothing. We can try tighten the bolts again....

I am leaning towards calling Mancini Racing and just getting a whole new ignition kit. Dist / Box / Coil/ wires etc... For $200 and to know that is it all 100% new may be money well spent.
 
I'd hot wire it first. See if that helps. If not then move to finding a replacement. Do you have any stock ignition boxes you can plug in?

Look down the carb barrels to see if fuel is dripping in from the boosters. Use a mirror/flashlight if you are concerned with backfiring.
 
What first jumped out at me was the fuel filter being on the suction side of a mechanical pump. You've said pressure is good and it runs ok off idle so i would have to agree that you probably need to replace the flooded ign. parts.
 
crackedback said:
I'd hot wire it first. See if that helps. If not then move to finding a replacement. Do you have any stock ignition boxes you can plug in?

Look down the carb barrels to see if fuel is dripping in from the boosters. Use a mirror/flashlight if you are concerned with backfiring.
Click to expand...

I know I have a good black race box off of an old street strip 340 car that and I have the coil off of that car as well.... oopps nope that was a mad 6al unit.... okay I need to go through the parts boxes to see what I can come up with... I know Mopar Al will read all of this later today or tomorrow and can check the carb dripping issue when he has some time since the car is at his place.

We did find a bad connection in the connectors (the main HOT RED wire) from the column to the dash harness. We are going to direct wire that one to see if it helps. We know it will help with starting the car.

The rest of these items we are going to start trouble shooting..

Thanks for all the help!
 
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