340 Static Compression Numbers and Test Procedure
- Thread starter 340inabbody
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No idea.
340inabbody
Well-Known Member
340inabbody
Well-Known Member
Here is another question that may be a clue. Are the timing locations on the 318 340 and 360 in the same locations on the block? Is it possible that this 6 degrees is an offset to an original location say on the 318? It might explain why my 318 appeared to line up with the crank key way....... just thinking out loud here.
340inabbody
Well-Known Member
Ok double checked on the 318. Sure enough it too is the same as the results you guys got. That being the timing mark is 5-6 degrees BTDC from the keyway........
yellow rose
Overnight Sensation
Not sure why the engineers decided that's where to put the key, but I'm going to assume they had a reason for where the did it.
In my small mind, it would seem to me they could have put it anywhere in the 360 degrees of the crank snout, and just changed the location of the key way in the cam gear.
gzig5
Well-Known Member
It would have something to do with where they put the zero and scale on the timing cover, wouldn't it? Different scale location would require a different mark placement on the balancer relative to the key? Weren't the early small blocks zero'd on the passenger side of the cover, which would require a different zero mark location?
340inabbody
Well-Known Member
Early forget what years pre 67? timing marks were on a bracket on the passenger side. That definitely would require a different mark on the damper. Way different not 6 degrees different.
Since we're already in the weeds here's my two cents. Pictured is a 360 mopar and 350 chevy crank. It appears the standard ( if there is one) is to line the keyway up with the crank pin. The timing marks are probably placed where it is convenient to get a line of sight ( right or left side ,etc.). Then the balancer is marked accordingly.
yellow rose
Overnight Sensation
Can you do me a favor??
If you can, can you take a picture with the cranks oriented as close to the exact same position if you can, with the oil feed holes in the mains pointing at the camera?
Also, since we are off the rails here, if you have a SBC and a SBM can you take a picture of the two blocks side by each with the main caps off 1 or 2 of the mains so we can see the oil feed holes in the block??
That would help with some understanding of the oil feed issues with the SBM.
TIA
Looks to me like they are timed about 22.5 degrees apart. And yes I'm very interested in this subject also. Block pictures comming up.
340inabbody
Well-Known Member
Seems that way to me but truthfully I'm just guessing. You made reference to your balancer being off a long way. Do you think it could be the wrong balancer for the timing mark location you have or do you think it may have slipped?
340inabbody
Well-Known Member
Not sure, it’s probably the wrong balancer as the guy who put it on wasn’t very bright. Now I have to verify that the flexplate is actually an externally balanced unit. So the whole thing is a disaster. I am now planning on a complete tear down and do it right. That old adage is true.......”If you want something done right do it yourself”
yellow rose
Overnight Sensation
It would be easy enough to verify TDC , time it, put some race fuel in it and see how it runs. Not much to loose and if it runs good have it whistled. If the compression is too high then maybe a compression adjustment is all thats needed. If the compression ratio is acceptable and you're really lucky maybe all it needed was timed correctly. Worse case is it still runs bad and you learned some new skills. Then you can tear it down and start over. On the other hand if tearing it down is what you want to do anyway and your tired of screwing around with it I can relate to that. Have at it.
yellow rose
Overnight Sensation
I'm not sure yet on the cranks.
If you stick the drill bit in the other hole you can see the difference in oil hole location. You have the drill bit in the cam feed hole. The other hole feeds the mains.
I've laid a SBC and SBM crank side by each but it's been long ago enough that I though the cranks had the exact same oil hole location.
340inabbody
Well-Known Member
Depends how far it needs to be adjusted and what you have now. Some options are, head gaskets, valve shape (dished or flat), cylinder heads have varying sizes of combustion chambers, pistons (lots of options here but would require engine removal). I would cross that bridge when you get there.
Yes, mains on dodge feed from the pass side lifter galley but feeds the main bearing at the same location as the chevy. 12 o'clock as viewed from the front of the engine. Strictly position wise I think the crankshaft would see it as the same as a chevy but I'm open to other ideas.
nm9stheham
Well-Known Member
I just saw this.... could be an old damper. On pre-70's, the timing marks were over on the right side, and the scribe mark was in an entirely different spot when #1 was at TDC. It was waaaay over to the right (CCW) from the 70 and later marks.
So is you timing 'tab/marks' on the right (passenger) or on the left (driver) side of the car? And where is the scribe mark on your damper when you are approximately at TDC? Give us a scribe mark location in an 'x o'clock' type of way.
340inabbody
Well-Known Member
Hi its a 1973 block so mark is on the driver side. Timing mark is way way off like 50 degrees haven’t measured. But like its for the other side meaning old unit or slipped. This should be a cast crank so externally balancer is needed and I don’t know if it is. I am going to yank it and get a new one.
nm9stheham
Well-Known Member
OK, well if it was for the old timing marks, it would be showing up about 90 + or - degrees CCW vs the newer marks, or about 10-10:30 o'clock.
When you pull off the present damper, set the engine at #1 TDC and note where the keyway is... it ought to be at about 1 o'clock. I'm not expecting anything to be wrong there but it is just another thing to take note of to make sure all is right.
Now, one thing we don't know is if your engine was re-balanced for all internal balance. And do you know for sure it has the original cast crank? Or was it rebuilt with an earlier steel crank? The pistons are different so who knows? (If we had a weight for those L2322's I could make a good stab at the bobweight, and then we could make a better guess on the balance situation.) My point is that, unless you have other info, there is not any real way to know if you need a balanced or unbalanced damper. So more mysteries to solve if you really want to know. The pan would have to come off to even start finding this stuff out.
So if you are having vibration issues, at the least buy a new damper with the weights that can be screwed on the back, to be either neutral balanced or unbalanced. I would not be buying a very expensive damper at this point not knowing what's inside. (You can always change to a fluid type later and sell this one off.)
Then proceed to do the timing work as you have planned. It will help to know what you really have for timing, both in ignition and cam timing, and find out of the cam is installed right. But ultimately, you have quite high dynamic compression due the combination of the cam and those domed pistons and even cam/ignition timing changes may not get you out of the woods for running pump fuel. It may take a cam change or piston change to get this to be workable.
When you pull off the present damper, set the engine at #1 TDC and note where the keyway is... it ought to be at about 1 o'clock. I'm not expecting anything to be wrong there but it is just another thing to take note of to make sure all is right.
Now, one thing we don't know is if your engine was re-balanced for all internal balance. And do you know for sure it has the original cast crank? Or was it rebuilt with an earlier steel crank? The pistons are different so who knows? (If we had a weight for those L2322's I could make a good stab at the bobweight, and then we could make a better guess on the balance situation.) My point is that, unless you have other info, there is not any real way to know if you need a balanced or unbalanced damper. So more mysteries to solve if you really want to know. The pan would have to come off to even start finding this stuff out.
So if you are having vibration issues, at the least buy a new damper with the weights that can be screwed on the back, to be either neutral balanced or unbalanced. I would not be buying a very expensive damper at this point not knowing what's inside. (You can always change to a fluid type later and sell this one off.)
Then proceed to do the timing work as you have planned. It will help to know what you really have for timing, both in ignition and cam timing, and find out of the cam is installed right. But ultimately, you have quite high dynamic compression due the combination of the cam and those domed pistons and even cam/ignition timing changes may not get you out of the woods for running pump fuel. It may take a cam change or piston change to get this to be workable.
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