340 valvetrain help

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fire_medic

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Hi guys, I am new here. Just picked up a 340 Duster and have been going through it. When I drive it I get quite a bit of knocking noise around 1500 to 2500rpm.
I took the valve covers off and it has nice shaft roller rockers.
I am not sure what cam is in this engine, what type of lifters or anything.
Checked the timing and it was at 25 degrees initial and around 42 total. Sounded kind of high to me so I retarded it some.
Any help or a point in the right direction would be really appreciated. Here is a photo of the new ride.
AndrewView attachment photo.jpg
 
Wow 25 initial is allot. Was the vacuum advance disconnected.
Depending on your engine build 25 initial could be correct.
42 total with vacum advance is also not out of line.
I would try less 18 initial 18 mechanical for 32 plus vacuum advance.
Slow down your curve with heavier springs to have timing all in by a 3400 rpm.
It's a tuning thing could take a while.
If you give details of you engine people could recommend a more accurate
base tune to start with.
 
Nice ride!! Welcome aboard...I agree with abv in regards to timing 25 sounds like a lot for initial! Make sure to use the search box, there is TONS of info here.
More pics please
 
Welcome! Very sweet car you have.
Yea, make sure you have the vacuum advance disconnected when you time it. Is your vacuum hose connected to a timed port or the manifold port on your carb?
 
Don't have many details about the engine. It has been through a few hands and the info I got was very limited.
Its a 340 with the original heads. Not sure if the seats have been changed out. It has a performance cam but im not sure on any specifics. Don't know what kind of lifters.
The distributor doesn't have any vaccum advance. Has your basic holley 4 barrel double pumper. Not even sure if its a 600, 650 or what.
 
Andrew,
First off, welcome aboard the Mopar ride! As for your new ride, NICE Duster! As for the 340, valve train, tune and carburetor set up, I bet what I'm about to say all will agree upon, more pictures! By looks we can help you with the type of Carburetor on the intake, and that can lead us to tell you what you need to do for timing (I agree 25 initial sounds a bit high, and I agree with the 18 that someone said.)

But pictures of things in question can be "seen" or spotted so, get the best up close pictures that you can for anyone here to see that way we might be able to tell you by "sight" and then you can take that given info and look it up on your search engine to get some real numbers and or settings for the tune your looking for and what to go as a "base" tune.....

Needless to say theres a buncha smart ones that can help you out I'm sure specially the "seasoned" ones that go hunting in a yard or spot things in pictures from yard hunting....

NICE ride man!
 
Nice lookin car and welcome aboard. The more info you can give, the better answers you'll get. My advice is to get a video with GOOD QUALITY audio of the noise when it's at its worst. That will help tremendously. Oh yeah, and keep the narration to a minimum. All too often when people make a video, they cannot shut the hell up enough to hear the problem.
 
Fire-Medic,

Sharp Duster

Plan #1

#1 > Try to get some Part #'s off the Carburetor and Distributor.
#2 > Get that 'timing' down a bit, and see if the knocking persists.
#3 > Get the highest rated Octane Gas as possible in that Fuel Tank.
#4 > Pull the Spark Plugs, and inspect {color and gap}.
#5 > Compression Test {see what those cylinders are pumping}
#6 > What Temperature is the engine coolant reading at.

Note; The 'Mechanical Advance' Distributor may be the problem here.

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With an all mechanical advance distributor you probably want the timing advanced 15° to 18° at idle, and a total advance of 35°-38° by around 2500 RPM. At least that works on my 340.
 
sounds like low oil pressure... goes away after 2500 rpm

probably a lot of miles on that engine.

but, maybe if you are lucky it's not that. if they are roller rockers, i'm assuming they are adjustables. if that's the case you will want to have some adjust the valve lash if they are solid lifters, or set preload if it's hydraulics.

if it's knicky knockin with hydraulics maybe the car has just been sitting too much.

but like others said, we need more info.
 
I talked to the guy that I bought it from and he said they put new hydraulic lifters in it. It has adjustable shaft rockers in it. So would these be set at zero lash and then 1/4 to a 1/2 turn for preload? I had the valve covers off the other day and got the feelers out and without turning the engine or anything a few of the rockers had some lash. A few of the rockers also have some side play.
Thanks in advance.
I will try and get some more photos tomorrow.
 
So when you say 'knocking', do you mean a heavy metallic knock like in the bottom end, or a high pitched, erratic and rattly type of knock, like ignition knock or pinging? And does this occur only when accelerating or at all times in the 1500 to 2500 rpm range? Trying to figure out what 'knocking' you mean exactly....Did it change/go away after you retarded the timing?

Nice color BTW..
 
I would describe it as a lifter tick or rocker arm tick. I will try and upload a video. It may just be the rockers out of adjustment.
 
If it starts OK hot with 25* initial, leave it alone is my suggestion. 42* total is a little steep for a street driver in a lot of cases.

If it's detonation, fix the mechanical advance to limit it to a more reasonable total number and possibly slow down how fast it comes in.

Pull initial advance out and idle quality goes away.
 
Hmmm, slight exhaust leak?

Now, for something completely off subject: Crackedback, you have put some really funny videos in your tag line over the years. Keep up the good work! Oh, yeah, and here's a fond rememberance shout out to Miss Bumpsteer.
 
Can't hear anything abnormal in the video but if the total timing was set at 42 it's a good possibility it's spark knock. You said you backed the timing down. Did that seem to help? What year is the 340? 70 and older models are higher compression and I usually find 34 degrees total is all they need. 71 and later are lower compression and may handle 36. I haven't had to run any more than that on any I did to get maximum power but each application can be a little different. Nevertheless I can't imagine any needing 42 degrees

Your correct about how to adjust the rockers but hydraulic lifters bleed down pretty fast when you shut the engine off so the lash you saw may not be there with the engine running. The way I adjust them is to get the cam lobe your adjusting on the heel and back the adjuster off until lash is evident then using 2 fingers rotate the pushrod on the rocker your adjusting while tightening the adjuster. As soon as the pushrod begins to drag that's the point of zero lash. You then tighten the adjuster 1/2 turn and lock it down

BTW: beautiful Duster and welcome to the board
 
Thanks Fishy68, after I backed the timing down I couldn't tell a difference in the noise but I did loose the idle quality. I will probably have to go back up on the initial and try to figure out how to limit the dizzy or get a new one that I can adjust.
It does have a pretty good ticking noise once you get rolling. Sounds perfect at idle. I have been scratching my head. Probably going to do the manifold gaskets since thats the easiest to try first.
 
fire_medic said:
It does have a pretty good ticking noise once you get rolling. Sounds perfect at idle. I have been scratching my head. Probably going to do the manifold gaskets since thats the easiest to try first.
Click to expand...

Let the engine go cold so the exhaust manifolds/headers contract. Get a 2 to 3 foot long piece of hose (think stethoscope) start it up and put one end of the hose to your ear and the other around the manifolds, moving around of course, that will help you hear a slight manifold leak better.
 
I heard it. Sounds like an oiling issue on the top end. Do you have an aftermarket oil pressure gauge in the car? Something you can tell how much actual oil pressure you have?
 
yes it is an aftermarket guage. What do i need to do to correct the oil issue? I seem to have decent pressure. Maybe 15-20lbs idle and around 50 when I get her going.
 
I would pull the valve covers and make sure the rockers are not hitting the valve covers first. Then look and make sure the pushrods are not rubbing the heads. If everything checks out good there, crank the engine and make sure you have oil coming from the rocker arms. If it doesn't look to be oiling good you may have to pull the rocker shafts and make sure they are turned correctly. I mention this because you said the previous owner said he had put in new lifters.
 
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