Super tuning car runs good shooting for great

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its hard to hear on the computer. If i stick my phone up to my ear its more
noticeable
 
Yeah, I think I heard it that time.
But I thought I heard a couple of shots of detonation too.
So,take it up to about 1500/1800 and just gently roll in and out of it. Loading and unloading the rod. When you roll out, roll slowly.
I don't want to say it sounds like a rod bearing just starting , but it sorta does, sorta. See if you can get the stethoscope on the oilpan,above the liquid line;then have a helper,do the above test.This requires gentleness, at power on/power off transition, and only varying the rpm maybe 50 rpm or so. You are looking for the split second where the thrust transitions from pushing up on the piston to pulling down on it.That's where you'll hear a rod bearing this early in the game. Or a wrist pin.
The rod is a deep tone thud or clonk (rhymes with bonk).Kindof; clonka...clonka...clonka ...And the rod kindof echoes in the pan.
But the wp is a much quieter sorta double tap,having a very short attack/decay; kindof; tapatapatapatapa.
I hope it's neither!
But if I had to choose, it would be the wp; I think,lol.....
 
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Wow, pretty easy to hear it there!
I have heard that before. But I gotta think.
It's only noisy when the engine is working, and it does not sound internal to the engine. And you're sure it's not a header banging on something. And to me it sorta sounds like it might be coming from the bellhouse area.

Ok it's coming to me.
One time I had a thrust bearing go out on me. Also an automatic car. Eventually there was so much play that the crank was moving so far forward under power that the TC boltheads were slamming into the back of the block, and machining it. But the bolt heads were cutting right through the boss for the tin-plug that seals the back of the cam-tunnel. And it was cutting the tin.
I think I would check your cranks end play.You may have to remove the TC access cover to pry the crank rearward. Or perhaps you can push the balancer backwards by placing a pry-block at the K-member. Prying it forwards is easy, just don't bust the timing-chain cover! If you pull that cover, you can inspect the block for the tell-tale machining going on right where the TC bolts pass by it. If, that's IF this is your problem, you will also see it on the TC bolt heads.
>But it sure sounds like an OEM flexplate, where they crack thru one of the sorta triangular cut-outs. But a B&M doesn't have those.
Is there any chance that your TC retaining bolts are the wrong size for the flexplate? If they would be 3/8 in a 7/16 hole, then I suppose they could work loose.But since I've never seen that situation, I don't know what that would sound like.
And one more idea; the flex plate has an engine side and a transmission side ...right?
 
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How about I drive to Canada you can have a listen. If it makes it back I'll fix it. I'll file the paperwork to get my passport tomorrow. Hahahaha
 
that's a 10 hr drive, man!
I would still check the end play. Maybe the crank is just rattling back and forth at this point.
And I would still put ears on the oilpan.

Hey, I noticed you were driving the car for this test,lol. Does it not do this in neutral?
 
AJ/FormS said:
that's a 10 hr drive, man!
I would still check the end play. Maybe the crank is just rattling back and forth at this point.
And I would still put ears on the oilpan.

Hey, I noticed you were driving the car for this test,lol. Does it not do this in neutral?
Click to expand...

Checking crank end play, got it

I'll pack some sandwiches and bring a peppa pig DVD for the kids.

Not as noticeable out of gear. Way louder under load.
 
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Well if it was a manual trans, I would have a better answer for you, but hmmmmmm. Ima guessing you looked for an exhaust leak already,so I'm kinda out of ideas.
It almost sounds like it's too slow to be crank-related, and it seems not to be in sync with the rpm in each gear. If it was crank related, we should be hearing it slow down to 59% on the 1-2 shift. Say from 4000 to 2400.
And too seems to be too fast to be in sync with the driveshaft.
So that just leaves the cam,which turns at half engine speed; so it would slow down from 2000 to 1180, on a 4000rpm upshift into second. Yeah that kindof sounds right.
Or maybe a header leak? which if just one port was leaking,would be at same as cam speed.
But man that is so sensitive to the gas pedal; have you got power brakes?And do they work properly? Have you tried disconnecting the Vcan?(I'm thinking diaphragm flutter, or not dropping out fast enough). What's your timing at the test rpm, say 2200? with and without the Vcan.
One thing I have noticed is that your carb is not responding properly to gas pedal inputs; almost like it's running very rich, at the test rpm and conditions.Yet it has a hesitation when slammed open,indicating lean on the accelerator pump.I'm trying to tie all that together, but it's not coming to me.......yet. Nice sounding mufflers tho, mine just scream when I get on it (Dynomaxers).
What carb?
So back to being at cam-speed......It doesn't sound like rocker arms,or valve train,and you said,IIRC, that it seemed to be coming from deep down in #8. So what's down there? Windage tray,oil pick-up,dipstick,collector,Tunnel pinchweld. What else? Pan evacuators?
oh.......trans dipstick tube. You got that secured?
 
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AJ/FormS said:
Well if it was a manual trans, I would have a better answer for you, but hmmmmmm. Ima guessing you looked for an exhaust leak already,so I'm kinda out of ideas.
It almost sounds like it's too slow to be crank-related, and it seems not to be in sync with the rpm in each gear. If it was crank related, we should be hearing it slow down to 59% on the 1-2 shift. Say from 4000 to 2400.
And too seems to be too fast to be in sync with the driveshaft.
So that just leaves the cam,which turns at half engine speed; so it would slow down from 2000 to 1180, on a 4000rpm upshift into second. Yeah that kindof sounds right.
Or maybe a header leak? which if just one port was leaking,would be at same as cam speed.
But man that is so sensitive to the gas pedal; have you got power brakes?And do they work properly? Have you tried disconnecting the Vcan?(I'm thinking diaphragm flutter, or not dropping out fast enough). What's your timing at the test rpm, say 2200? with and without the Vcan.
One thing I have noticed is that your carb is not responding properly to gas pedal inputs; almost like it's running very rich, at the test rpm and conditions.Yet it has a hesitation when slammed open,indicating lean on the accelerator pump.I'm trying to tie all that together, but it's not coming to me.......yet. Nice sounding mufflers tho, mine just scream when I get on it (Dynomaxers).
What carb?
So back to being at cam-speed......It doesn't sound like rocker arms,or valve train,and you said,IIRC, that it seemed to be coming from deep down in #8. So what's down there? Windage tray,oil pick-up,dipstick,collector,Tunnel pinchweld. What else? Pan evacuators?
oh.......trans dipstick tube. You got that secured?
Click to expand...
--------------------------I bought a new 1969 440 4 speed coronet rt back in the day. It made the same noise, turned out to be the heat riser , I wired it open and the noise quit.??????????
 
AJ/FormS said:
Well if it was a manual trans, I would have a better answer for you, but hmmmmmm. Ima guessing you looked for an exhaust leak already,so I'm kinda out of ideas.
It almost sounds like it's too slow to be crank-related, and it seems not to be in sync with the rpm in each gear. If it was crank related, we should be hearing it slow down to 59% on the 1-2 shift. Say from 4000 to 2400.
And too seems to be too fast to be in sync with the driveshaft.
So that just leaves the cam,which turns at half engine speed; so it would slow down from 2000 to 1180, on a 4000rpm upshift into second. Yeah that kindof sounds right.
Or maybe a header leak? which if just one port was leaking,would be at same as cam speed.
But man that is so sensitive to the gas pedal; have you got power brakes?And do they work properly? Have you tried disconnecting the Vcan?(I'm thinking diaphragm flutter, or not dropping out fast enough). What's your timing at the test rpm, say 2200? with and without the Vcan.
One thing I have noticed is that your carb is not responding properly to gas pedal inputs; almost like it's running very rich, at the test rpm and conditions.Yet it has a hesitation when slammed open,indicating lean on the accelerator pump.I'm trying to tie all that together, but it's not coming to me.......yet. Nice sounding mufflers tho, mine just scream when I get on it (Dynomaxers).
What carb?
So back to being at cam-speed......It doesn't sound like rocker arms,or valve train,and you said,IIRC, that it seemed to be coming from deep down in #8. So what's down there? Windage tray,oil pick-up,dipstick,collector,Tunnel pinchweld. What else? Pan evacuators?
oh.......trans dipstick tube. You got that secured?
Click to expand...


No power brakes

I have another set of header gaskets I could try.

Vac van is disconnected

Will have to get back to you on the timing. 15 initial 32 all in

Carb is a holley 750 street hp.
4 corner idle screws. All just over 1/2 turn out.
I would agree with the rich.


No windage tray

Kevko 5qt pan

Trans dipstick is tight (locking)
 
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The last time I heard noise like that (3 cyl two stroke outboard mercury) it turned out to be piston slap. At idle was quite off idle at about 1500 on up accelerating could here it no problom. Also could here it decelerating until back at idle again. I figured it was #1 due to scoffed piston (oil injection failed) even with new piston & rings at TDC I could rock the piston with an all or screwdriver back & forth alot! & if I did it fast enough could almost duplicate the noise. #2 & 3 were notably tighter in there bores. Id make sense because it would make a "rattle" every time that offending cylinder would fire making p.s.I. spike rocking itIin its bore. Is it any worse cold or hot?
 
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Hipo65 said:
The last time I heard noise like that (3 cyl two stroke outboard mercury) it turned out to be piston slap. At idle was quite off idle at about 1500 on up accelerating could here it no problom. Also could here it decelerating until back at idle again. I figured it was #1 due to scoffed piston (oil injection failed) even with new piston & rings at TDC I could rock the piston with an all or screwdriver back & forth alot! & if I did it fast enough could almost duplicate the noise. #2 & 3 were notably tighter in there bores. Id make sense because it would make a "rattle" every time that offending cylinder would fire making p.s.I. spike rocking itIin its bore. Is it any worse cold or hot?
Click to expand...

no difference cold or hot. how could I test for piston slap? get #8 up to the top of the stroke and try and rock it through the spark plug hole?
 
comments inside the quote
skep419 said:
No power brakes

I have another set of header gaskets I could try. You're going too fast; that's a lotta work to just try. I'd wanna prove it first.

Vac can is disconnected.That is part of the response problem. tip-in will be much smoother if you reconnect it.

Will have to get back to you on the timing. 15 initial 32 all in.Very good

Carb is a holley 750 street hp.4 corner idle screws. All just over 1/2 turn out. My combo with the 223/230/110 cam,very similar to yours,right? did not require any idle air bypass with 14* of idle timing, and consequently no idle-fuel in the secondaries.
A half turn on the front mixture screws means the T-port sync is pretty close.
I think your automatic could run a bit more idle-timing and that might/should help with the tip-in response. Unless it fudges the T-port sync too much.
Have you already tried it with;say 16 to 18* of idle timing, the secondaries closed up tight, the front screws at 3/4 to 1 turn out,and the Vcan hooked up? If yes, how was that? If no, that's what I would work towards and see if the tip-in improves. Then I would try to bring the PV in a little sooner. And finally I would work on the pump-shot.
Where does your TC stall at?

I would agree with the rich.In the long-run, not so good

No windage tray, Kevko 5qt pan, OK

Trans dipstick is tight (locking). No, I meant the tube;is it secured to the block at one of the bellhouse bolts, so it cannot rattle?
Click to expand...
Yeah marine pistons are pretty sloppy in the holes,lol. The first time I ever took an outboard engine apart, I was very surprised that so much could be normal. Old air-cooled sled engines were set sloppy-loose too. And I have heard that certain aircraft engines were also pretty loose.
But, in your case,I don't think that's piston slap, and I doubt you could get any meaningful results thru the plug-hole. My experience with piston slap and multi-cylinder auto engines is; if one slaps, they all slap. The slap could be due to; design,or to carelessness on the part of the builder, or to a prolonged overheat situation.
Recall that back in the day,some early engines with forged pistons,the skirt clearance was spec'd to be over .005; that's a lot, and I always heard them at start-up,in my nearly-new,1970-340. My KB-107s were spec'd to be .001 to .0015, but I run them at .0035 ish. And I run the cooling system at a minimum 205*F not to quiet them down,but that does do the trick. I only hear them at start-up when the ambient is below freezing. And then they quiet down in a minute or two.
As to heat-riser valve rattle, that was part of the 340 CI exhaust manifold experience, and I loved it. Mine only rattled at or near idle.
 
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No power brakes

I have another set of header gaskets I could try. You're going too fast; that's a lotta work to just try. I'd wanna prove it first. Ok. Test is on the back burner

Vac can is disconnected.That is part of the response problem. tip-in will be much smoother if you reconnect it. I had it disconnected because I was scared of detonation. With all the problems I'm having I figured it could wait. Although I did hook it up and couldn't get it to move with ported vacuum. It maxed out around 45-46 when hooked up to manifold vacuum.

Will have to get back to you on the timing. 15 initial 32 all in.Very good

Carb is a holley 750 street hp.4 corner idle screws. All just over 1/2 turn out. My combo with the 223/230/110 cam,very similar to yours,right? did not require any idle air bypass with 14* of idle timing, and consequently no idle-fuel in the secondaries.
A half turn on the front mixture screws means the T-port sync is pretty close.
I think your automatic could run a bit more idle-timing and that might/should help with the tip-in response. Unless it fudges the T-port sync too much.
Have you already tried it with;say 16 to 18* of idle timing, the secondaries closed up tight, the front screws at 3/4 to 1 turn out,and the Vcan hooked up? If yes, how was that? If no, that's what I would work towards and see if the tip-in improves. Then I would try to bring the PV in a little sooner. And finally I would work on the pump-shot.
Where does your TC stall at?
Idle air bypass? is this pcv valve or drilling holes in the throttle blades? i could try it at 17 and 34. so if I close up the secondaries the rear adjusters would do nothing correct?
all good info that I will try out. My main concern though is the terrible noise hahahaha.
just installed a factory high stall that stalls around 2400.
I would agree with the rich.In the long-run, not so good rear squarter is leaking (fuel coming from bottom of squirter). checked the accelerator pumps before work. (primary was too tight rear is leaking)


No windage tray, Kevko 5qt pan, OK

Trans dipstick is tight (locking). No, I meant the tube;is it secured to the block at one of the bellhouse bolts, so it cannot rattle? yes it is bolted tightly to the block
 
OTE="AJ/FormS, post: 1971754495, member: 33537"]comments inside the quote

Yeah marine pistons are pretty sloppy in the holes,lol. The first time I ever took an outboard engine apart, I was very surprised that so much could be normal. Old air-cooled sled engines were set sloppy-loose too. And I have heard that certain aircraft engines were also pretty loose.
But, in your case,I don't think that's piston slap, and I doubt you could get any meaningful results thru the plug-hole. My experience with piston slap and multi-cylinder auto engines is; if one slaps, they all slap. The slap could be due to; design,or to carelessness on the part of the builder, or to a prolonged overheat situation.
Recall that back in the day,some early engines with forged pistons,the skirt clearance was spec'd to be over .005; that's a lot, and I always heard them at start-up,in my nearly-new,1970-340. My KB-107s were spec'd to be .001 to .0015, but I run them at .0035 ish. And I run the cooling system at a minimum 205*F not to quiet them down,but that does do the trick. I only hear them at start-up when the ambient is below freezing. And then they quiet down in a minute or two.
As to heat-riser valve rattle, that was part of the 340 CI exhaust manifold experience, and I loved it. Mine only rattled at or near idle.[/QUOTE]
Act

Actually marine engine's piston to wall clearance isnt really any diffrent than anything else. Spec in mercury manual was .0025-.004 clearance. My 25 hp is nice and snug in there bores quite as 2 stroke can ever be. if there too loose will make noise just like any engine. Yes you could try to get it to TDC & see how much the piston will move around. Just an idea. Also if you pull the plug wire to the offending cylinder it should quite it down a fair ammout when driving with that wire off. Most engine's with old school or air cooling will have a bit more clearance & some with forged pistons up to .006-.008 clearance. They will make noise when cold for sure. Water cooled marine stuff just like automotive & if sloppy its worn out egg shaped bores. If there loose enough to make noise it will be blatantly oblivious through the plug hole & an all @ TDC.
 
Ok then
Make sure the Vcan is hooked to the sparkport. With good combustion chambers, tight Squish, and/or aluminum heads; detonation will not be an issue. The Vcan will only work at part throttle, and will vary the timing according to the throttle opening. The harder you step on it the more timing will drop out, and it absolutely cannot work at WOT. At a cruising RPM of 2200, the timing will be fine with a minimum of 40/45* to a maximum of 55/60*, TOTAL. That's initial, plus centrifugal, plus Vcan. T lazier your chamber is, the more timing it will like. The more your engine accepts, the leaner you can run it. Pretty soon you will be getting fuel mileage in the hi 20s. Ok; maybe not you, but I did,... with a double overdrive pulling like 1550rpm@65mph. That was a final drive of just under 2.0

Ok since you asked about idle-air bypass;
This is air you might need to introduce into the low speed circuit, to satisfy the engines craving for air,while maintaining the T-port sync.Click on the little blue M in my sig for a better understanding.
This air has to be introduced near to where the transfer ports are, so that it has time to mix with the A/F charge entering there, and be fully homogenized by the time it gets into the chamber.
The bigger the cam, the more bypass air it will want. My HE2430AL did not require any bypass air. So yes, closing up the secondaries tight but not sticking should reduce the rear idle fuel to zero.
If you advance the idle-timing, the idle speed will go up. The first response is to back out the curb idle screw. But doing that will lower the throttle blades on the transfer slot and that will reduce the fuel being delivered there. So then the next idea would be to increase the mixture screw opening so she will idle again. And that works. At idle. But as soon as you step on it, the beast goes lean, and she hesitates, maybe even stumbles; until the transfers come back on line. Sound familiar?
So, the transfer slots have a minimum operating relationship with the throttle blades. If a decent idle speed, and tip-in cannot be obtained at this minimum setting, then we have to figure out how otherwise to make it happen. This is where idle-timing and bypass-air come into play.
The Vcan is quite hard to activate on the spark-port, in Neutral/Park.Iit might need 4 to 6 inches of vacuum at the sparkport to begin it's job, and it might not finish until 12 inches or more. These numbers usually require more no-load rpm than a guy is willing to dial in. I use a vacuum pump to map it's response, then Tee in a vacuum gauge and go for a ride. Since I have previously mapped the centrifugal advance, now,with a bit of math, I can always know at any rpm and load setting, what the total all-source advance might be.

If the rear squirter is dribbling then something is wrong. Firstly the engine might be drawing a lot of air thru the secondaries. But more likely the fuel level back there is too high. And of course most likely is that the check valve underneath the squirter may be missing or hung up. It could also be that the rear squirter is the wrong design.If you don't fix this, the engine will be fat all the time and fatter when on the secondaries. That would be giving up a lot of power, and some of that gas might end up in the oil. If your "noise" was up higher,and all thru-out the engine, I'd say it might be detonation due to that fat running. Your noise does behave exactly like too much low-rpm timing for the chamber design. But your numbers kindof negate that idea. Unless it is all in at 2000,or less,lol
 
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AJ/FormS said:
Ok then
Make sure the Vcan is hooked to the sparkport. With good combustion chambers, tight Squish, and/or aluminum heads; detonation will not be an issue. The Vcan will only work at part throttle, and will vary the timing according to the throttle opening. The harder you step on it the more timing will drop out, and it absolutely cannot work at WOT. At a cruising RPM of 2200, the timing will be fine with a minimum of 40/45* to a maximum of 55/60*, TOTAL. That's initial, plus centrifugal, plus Vcan. he crappy your chamber, the more it will like. The more your engine accepts, the leaner you can run it. Pretty soon you will be getting fuel mileage in the hi 20s. Ok; maybe not you, but I did,... with a double overdrive pulling like 1550rpm@65mph. That was a final drive of just under 2.0

Ok since you asked about idle-air bypass;
This is air you might need to introduce into the low speed circuit, to satisfy the engines craving for air,while maintaining the T-port sync.Click on the little blue M in my sig for a better understanding.
This air has to be introduced near to where the transfer ports are, so that it has time to mix with the A/F charge entering there, and be fully homogenized by the time it gets into the chamber.
The bigger the cam, the more bypass air it will want. My HE2430AL did not require any bypass air. So yes, closing up the secondaries tight but not sticking should reduce the rear idle fuel to zero.
If you advance the idle-timing, the idle speed will go up. The first response is to back out the curb idle screw. But doing that will lower the throttle blades on the transfer slot and that will reduce the fuel being delivered there. So then the next idea would be to increase the mixture screw opening so she will idle again. And that works. At idle. But as soon as you step on it, the beast goes lean, and she hesitates, maybe even stumbles; until the transfers come back on line. Sound familiar?
So, the transfer slots have a minimum operating relationship with the throttle blades. If a decent idle speed, and tip-in cannot be obtained at this minimum setting, then we have to figure out how otherwise to make it happen. This is where idle-timing and bypass-air come into play.
Click to expand...

thanks
the spark port does nothing when hooked up to vacuum advance. (checking timing while reving in park)
Ill try it on my lunch break. unless there is something else brought up to check about the noise.
 
skep419 said:
thanks
the spark port does nothing when hooked up to vacuum advance. (checking timing while reving in park) That would be normal. The sparkport requires the throttle blade to be in close proximity to it, and to remain there for a bit of time, as in running at part throttle or cruising. Blipping the throttle does nothing to encourage a timing change. And running the rpm up slowly might take a no-load rpm of over 4000 to get things synced up.
Ill try it on my lunch break. unless there is something else brought up to check about the noise.
Click to expand...
 
So you verify the timing using manifold vacuum port than just hook it up to ported and test drive?
 
skep419 said:
So you verify the timing using manifold vacuum port than just hook it up to ported and test drive?
Click to expand...
No! That would just give you a snapshot of the Vcan's maximum capability at it's current adjustment, in conjunction with the centrifugal advance. This snapshot could endure for a limited rpm span, right around a cruising speed of *** which varies with the gear that you are in, cuz the signal at the sparkport also varies with the load. This advance can vary according to the can's design, and to the amount of signal, and to it's adjustment. One could call it a very sophisticated device. At any given moment, it could be contributing from no advance to whatever it's rated maximum is. They are available with various specs and I have seen from a minimum of 9 degrees to a maximum of 22 degrees. So if you are cruising at 2200 and your vacuum is sufficient to pull the can to it's maximum, then you could be cruising with as little total all-source advance of say 14* on a seized system(idle timing), to 55* on a well executed system. And the engine will love somewhere between 45 and that 55, depending on its design and chamber efficiency, and the environment in which it is operating.
 
Ok so
If you want to get into this;
Get yourself a note pad,and make two columns labeled rpm and advance. Under rpm mark off 10 hash-marks and label them in increments of 400rpm beginning at 800.So you will see 800,1200,1600 and so on. Then install your timing lite, disable the vcan and let's get started. Rev it up and read the advance at each of those points, and write it down. You can stop when you get two readings in a row with no change in advance. Then rev it up to an rpm where the advance maxes out and write those two numbers down something like 34*@3300 rpm.
Now get you some graph paper or make some; with 13 divisions vertical and about 8 along the horizontal. The vertical column will be advance and mark it off in 2* increments beginning at 12 and continuing to 38. The horizontal will be rpm and mark it off in 400 increments beginning at 800 and continuing to 4000. Now transfer your results from the pad to the appropriate box on the graph. Just put a dot in the right spot. Now run a straight pencil line connecting as many dots as possible or aim it up the middle as may be required. It may be that this will require two lines; one from idle to say 2800 and another from there to 3600. Just connect as many as you can.
Now take a look at it. You can choose any rpm and see exactly how much advance your system is running. Even the in-between rpms and in-between advance dots.
Now lets make a graph for the Vcan. So back to the scratch pad; two columns the left will be vacuum and the right will be advance. You will need a way of delivering a precise amount of vacuum to the Vcan. I use a vacuum pump, like a Mighty-Vac. So with the engine idling at below the point that the mechanical advance starts, just put two inches of vacuum in the can and read the advance. Write it down; 2= xx. Then pump it up to 4 inches and repeat. Continue until the advance no longer changes.
Now make another graph with advance on the certical and vacuum on the horizontal. Transfer your data points to it with little dots and connect as many as you can with a straight line.
Next Tee a vacuum gauge to the sparkport with the Vcan hooked up and go for a ride. You will now be able to figure out exactly how much advance your engine is seeing at any rpm and at any load setting. Suppose you buzz it up to 2500 in low gear and you look on your mechanical graph and see that the engine is getting 28*. Then you look at your vacuum gauge and see it's reading 22 inches. So you look at the Vcan graph and see that at anything over 18" it is pulling in 18*. Now the math;28+18=46* perfect. Next ride the brakes and step on the gas maintaining 2500rpm but pull the vacuum down to 10inches. Release the throttle. Now the math; still at 2500 so still seeing 28 mechanical. But suppose the Vcan has dropped to 6 degrees at that 10 inches at the sparkport, so now the total is 28+6=34. Now imagine you floored it at 2500 and the vacuum at the sparkport drops to zero; now the engine is seeing just the base 28*. How cool is that?! Now put it in second gear and run it up to 2500 again. Now the Vcan might be reading just 20 inches, But this is still over the minimum 18"so the cruise timing will the same as before.
So finally, put in in third gear and run it up to 2500 again, now the sparkport might be less than 18" so then the timing from the Vcan could be less than 18 and so the all-source might also be less, even tho the 2500 still has the 28* base amount. So imagine what the timing is doing at some other vacuum and rpm settings.As you can see, that little can is amazing......
 
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