340 Static Compression Numbers and Test Procedure

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Wyrmrider said:
Whistler looks like something dreamed up by tech inspection
run another compression check after moving the cam
let us know what you find on the tdc valve lift check
UDHarold was an expert at that check- he could get more out of it than I ever could
degree the cam with degree wheel before pushing advance
cheers
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When I was in the pavement racing promoting biz our sanctioning body had a Whistler to enforce the 9-1 compression rule in the late models.
 
Mattax said:
Followed Vizard down the rabbit hole once - that was an interesting, confusing journey. Never would have made it back out without Tuner, Shrinker, and some of the others that contributed to the Innovatemotorsports forum. DV is a good writer and smart cookie but ....

Sometimes we just got to make work what we've got. Or at least we think we do. Often we can do that messing with timing and fuel mixtures etc. That's basically what @340inabbody was hoping to do here. Get some understanding of the engine build and work around it, and tune it to work better, as good as we can.
However at some point there is a limit. Shrinker always was always saying that everything can't be fixed with fuel preparation. Build the engine 'right' and the related systems fall into place.

So that really does tie back to 340inabbody's engine. The valve events as well as the compresion, the piston and cylinder shapes etc are all related to how the fuel gasifies and burns at different rpms and loads.
The question at this point seems to be what is the best plan for @340inabbody ?
Continue on current path?
..that is, measure the cam timing events, then pull the intake and heads

..or, take the engine out.
Then do some measurements and a partial or full teardown
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Thanks Mattax this thread has kinda evolved into several threads of interest here. I am now exactly at this threshold yank and tear the whole thing down or start peeling back the engine part by part inside the bay. I got the 3.55's in today and the engine just does not seem to be making any power. So I now know I have a major issue or major issues. I am leaning towards pulling it out but I am not all that experienced at diagnosing assembly issues. But I guess this is how I am going to learn.
 
340inabbody said:
Thanks Mattax this thread has kinda evolved into several threads of interest here. I am now exactly at this threshold yank and tear the whole thing down or start peeling back the engine part by part inside the bay. I got the 3.55's in today and the engine just does not seem to be making any power. So I now know I have a major issue or major issues. I am leaning towards pulling it out but I am not all that experienced at diagnosing assembly issues. But I guess this is how I am going to learn.
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Before you pull the motor out one thing you could try is to put 110 race fuel in the tank. Give it the timing it wants without worrying about detonation. See if the motor runs to your satisfaction fully tuned and no compromises on timing. Hopefully this will narrow things down a little. If the motor still doesn't run well then just lowering the compression probably isn't going to help much. it would be better to know this before you tear it down.
 
92b said:
Before you pull the motor out one thing you could try is to put 110 race fuel in the tank. Give it the timing it wants without worrying about detonation. See if the motor runs to your satisfaction fully tuned and no compromises on timing. Hopefully this will narrow things down a little. If the motor still doesn't run well then just lowering the compression probably isn't going to help much. it would be better to know this before you tear it down.
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I see Rusty Rat Rod has already recommended this with 114 way back in this thread.
 
Back when we Had Dyno Don power timed our Max Wedge on Don Blair's Dyno he would always get it too far advanced for the top end pull
we put a switch on the dual point
maybe he just wanted to beat us with his Z-11 :) Hayden Proffitt was tough too, a graduate of fellow El Monte Mickey Thompson, Nicholson was then in Pasadena and also did the "little old lady from Pasadena" Milne brothers white dodge
crowed loved it when the driver would show up in the grannie dress, take off the bonnet, put on the helmet and then show off the tall lace up motorcycle boots
I knew Don and bought parts from him till the day he died- he'd deliver in his old chevy
RIP Don
 
Ok so here is an update. I thought I would start with the basics first and not make any assumptions with the set up. So I thought I would start with the distributor set up. What I found has confused me. There is a painted line on the harmonic balancer that I have been using and appears to correspond to TDC. However the harmonic balancer factory scribed mark line does not appear to line up with TDC? Are the HB keyed so that the factory scribed line/mark are always TDC? Why would the factory mark be off?
 
340inabbody said:
Ok so here is an update. I thought I would start with the basics first and not make any assumptions with the set up. So I thought I would start with the distributor set up. What I found has confused me. There is a painted line on the harmonic balancer that I have been using and appears to correspond to TDC. However the harmonic balancer factory scribed mark line does not appear to line up with TDC? Are the HB keyed so that the factory scribed line/mark are always TDC? Why would the factory mark be off?
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The factory mark can be off. If it is...that is usually bad. It can mean the outer ring has slipped on the hub and the damper is junk.

But, if the mark is BEFORE the actual engraved line on the damper, that may have been used to set total timing.

To do the math on that, is diameter times Pi divided by 360. Take that number and multiply it by the number of degrees you want to mark. It will show you how many inches away from the OE line you need to be to get 35 degrees.

So.....(remembering I hate math)
7.25*3.14159=22.776527/360=0.0632681*35=2.2143835

All that means is that 2.215 inches around the damper (ahead of he factory marking) is 35 degrees BTDC.

You can do the same for any circle to find out how far around the circle is any degree you want to know.
 
340inabbody said:
There is a painted line on the harmonic balancer that I have been using and appears to correspond to TDC.
Click to expand...

How did you determine this? With a piston stop and degree wheel? That is the only way to know for sure.
If the balancer is old it could have slipped as YR stated. Mine is off about 3 degrees and waiting for replacement. I was chasing my tail on tune and timing and while the 3 degrees wasn't enough to kill me, it wasn't helping.
 
yellow rose said:
The factory mark can be off. If it is...that is usually bad. It can mean the outer ring has slipped on the hub and the damper is junk.

But, if the mark is BEFORE the actual engraved line on the damper, that may have been used to set total timing.

To do the math on that, is diameter times Pi divided by 360. Take that number and multiply it by the number of degrees you want to mark. It will show you how many inches away from the OE line you need to be to get 35 degrees.

So.....(remembering I hate math)
7.25*3.14159=22.776527/360=0.0632681*35=2.2143835

All that means is that 2.215 inches around the damper (ahead of he factory marking) is 35 degrees BTDC.

You can do the same for any circle to find out how far around the circle is any degree you want to know.
Click to expand...

Thanks YR, if the HB has slipped or not correct then marking out a 35 degree point will not help right? I am using the finger method in cylinder one to find TDC or in actuality roughly TDC as its not perfect. Thats why I was looking for the factory HB scribed line so I could line up with 0 on the block to confirm plug one alignment on the dizzy. So how do I confirm an accurate TDC if my HB is off?
 
gzig5 said:
How did you determine this? With a piston stop and degree wheel? That is the only way to know for sure.
If the balancer is old it could have slipped as YR stated. Mine is off about 3 degrees and waiting for replacement. I was chasing my tail on tune and timing and while the 3 degrees wasn't enough to kill me, it wasn't helping.
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Right mine is way way off like 50 degrees. A piston stop method with a degree wheel takes me right to the point of yanking the dam thing and tearing it down and putting a new known cam in and lower comp pistons..........I think I am almost at this point then.....
 
I would say that a new balancer is the first step. I got one of the PRW/SM fluid filled ones to try. Whatever it takes to gain confidence in the motor
 
gzig5 said:
I would say that a new balancer is the first step. I got one of the PRW/SM fluid filled ones to try. Whatever it takes to gain confidence in the motor
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So I assume they are keyed. I wonder if I pull my old one off if I can determine if its bad from the keyway to the mark is right?
 
I have to get my hands on one I am thinking that the keyway does in fact line up with zero.
 
340inabbody said:
So I assume they are keyed. I wonder if I pull my old one off if I can determine if its bad from the keyway to the mark is right?
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Might get in the ballpark if you had a known good one you could check against with a degree wheel in a lathe or something that would spin the balancer accurately so you could check offset from key to TDC mark.
It really isn't hard to find TDC with a piston stop. I think I did it without removing the timing cover with a wheel I printed out and taped to a hunk of plastic. Aluminum or steel sheet would have been better. Made my own hub.
 
gzig5 said:
Might get in the ballpark if you had a known good one you could check against with a degree wheel in a lathe or something that would spin the balancer accurately so you could check offset from key to TDC mark.
It really isn't hard to find TDC with a piston stop. I think I did it without removing the timing cover with a wheel I printed out and taped to a hunk of plastic. Aluminum or steel sheet would have been better. Made my own hub.
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I can use a piston stop BUT haven’t pulled my heads YET lol. If I start to disassemble I might just start a full tear down and do it right. This guessing game of whats in there is driving me nuts.....
 
yellow rose said:
The centerline of the key is 6 degrees BTDC.
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WTF why 6 degrees? What does that come from? It should center on 0 on the block right? I just looked at my 318 I pulled and it is aligned with the notch as best I can see.
 
340inabbody said:
WTF why 6 degrees? What does that come from? It should center on 0 on the block right? I just looked at my 318 I pulled and it is aligned with the notch as best I can see.
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IDK the answer to that. I just grabbed my Fluidamper off the shelf and laid two squares on it. One through the center of the key way and the other on its edge and it lines up at 6 degrees BTDC
 
340inabbody said:
I can use a piston stop BUT haven’t pulled my heads YET lol. If I start to disassemble I might just start a full tear down and do it right. This guessing game of whats in there is driving me nuts.....
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Piston stop I'm referring to requires no tear down. Pull plug from #1 cylinder, put the stop in place and adjust to contact piston a bit before TDC, 20-30 degrees and go from there.
I think this thread goes through it pretty well. probably videos on utube
How to find tdc
 
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340inabbody said:
Right mine is way way off like 50 degrees. A piston stop method with a degree wheel takes me right to the point of yanking the dam thing and tearing it down and putting a new known cam in and lower comp pistons..........I think I am almost at this point then.....
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This can frustrating but you really need to verify TDC before you can set the timing. You can use a piston stop that screws into the sparkplug hole. Remove all the sparkplugs. This makes it easier to turn the motor over by hand. To be safe pull valve cover and loosen rockers on #1 or shaft assy. if non adjustable rockers. The reason for this is that in some cases the valve could contact the piston stop as it is opening. Screw piston stop in #1 sparkplug hole. Turn motor over by hand GENTLY until piston bumps against the stop. Put a mark on the balancer that lines up with zero on the timing cover. Now GENTLY reverse direction until piston contacts the stop. Again place a mark on the balancer at the zero mark on the timing cover. REMOVE THE PISTON STOP NOW. You don't want to accidentally leave it in and crank the motor over with the starter. Last step is to measure the half way point between the marks placed on the balancer. This is TDC.
 
92b said:
This can frustrating but you really need to verify TDC before you can set the timing. You can use a piston stop that screws into the sparkplug hole. Remove all the sparkplugs. This makes it easier to turn the motor over by hand. To be safe pull valve cover and loosen rockers on #1 or shaft assy. if non adjustable rockers. The reason for this is that in some cases the valve could contact the piston stop as it is opening. Screw piston stop in #1 sparkplug hole. Turn motor over by hand GENTLY until piston bumps against the stop. Put a mark on the balancer that lines up with zero on the timing cover. Now GENTLY reverse direction until piston contacts the stop. Again place a mark on the balancer at the zero mark on the timing cover. REMOVE THE PISTON STOP NOW. You don't want to accidentally leave it in and crank the motor over with the starter. Last step is to measure the half way point between the marks placed on the balancer. This is TDC.
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So does it matter if the piston stop stops the piston at an arbitrary point in the stroke so long as you revolve to the other direction and mark both sides and find the center of those two points? Also stock valve train don’t think they are adjustable....
 
Theoretically it could be anywhere, but you will be most accurate a little before the crank reaches max throw and the vertical velocity of the piston is nearing zero. So you do it on the compression stroke, just before the piston reached the top, mark it, reverse, mark it, and then split the diff between the marks to get the real TDC. I guess you could mount a pointer and do it directly on the balancer but the degree wheel is easier IMO.
 
yellow rose said:
IDK the answer to that. I just grabbed my Fluidamper off the shelf and laid two squares on it. One through the center of the key way and the other on its edge and it lines up at 6 degrees BTDC
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The balancer I looked at appears to be about 6 degrees.
 
gzig5 said:
Theoretically it could be anywhere, but you will be most accurate a little before the crank reaches max throw and the vertical velocity of the piston is nearing zero. So you do it on the compression stroke, just before the piston reached the top, mark it, reverse, mark it, and then split the diff between the marks to get the real TDC. I guess you could mount a pointer and do it directly on the balancer but the degree wheel is easier IMO.
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What gzig5 said. You really don't need a pointer or degree wheel. Use the zero mark on the timing cover and mark the balancer. If the TDC Mark is off remark it at the correct location and label it to prevent confusion later. I like to mark the front of the harmonic balancer from the outer ring across the rubber to the inner hub. That way I can tell if the outer ring slips on the hub. If that happens you need to replace it before the ring falls off.
 
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