Welcome to the IHoP v.2

[dem beats 1,223]

I'm going to be up processing photos tonight... Then meet my new boss tomorrow.

Bleh.

Good subject matter?

New boss?

J

It was my old boss going away party.

And I didn't have the ISO high enough.

Grain>nothing in focus.

I couldn't get the settings right in for auto I SO and I got greedy.

Had to shoot way too much at 1.2.

It was so low light...

I may have left it at 1600 or 3200 or some such.

Catching action in low light with a ton of backlighting...

:-(

I need to increase the auto ISO, and decrease the auto shutter speed settings.

The AF system even had trouble catching some shot. Calibration for each lens would be smart too.....

[Penguin4x4 1,761]

poast

[///M5 2,833]

 

 

 

 

My understanding of the combustion engine, is that the vacuum is created by the thermal dynamics of the engine. From my understanding the timing is what controls where the heat is in the motor. This affects the cacuum being pulled through the Venturi.

On a Holley carburetor all functions except for the Excelerator pump are vacuum operated. The Excelerator pump is controlled mechanically with the throttle linkage. There are three variables to Excelerator pump, the diaphragm, the linkage Cam and the squirters.

Suck, squeeze, bang, blow.

Vacuum is created on the initial stroke which fills the cylinders. The up stroke compresses the air/fuel mixture. Spark ignites the mixture which forces the piston down or the power stroke, then final stroke back up is to exhaust the gases and empty the cylinder to begin again.

Poor choice of words on my part. Should've said, vacuum strength can being manipulated with timing. Without overthinking it, I believe this is because of the thermal aspect. Am I wrong in theory?

I am pretty keen on the four cycles btw, but still appreciate your knowledge.

Cam timing yes. The reason you hear "big" cams having a lopey idle is they are struggling to stay running due to valve overlap. You have both valves open at the same time, but not fully, and vacuum quickly ,goes away. This is why some radical cars need to run a vacuum pump.

Temp of course will affect it as well, but cam timing is the big determining factor.

Yes it has a very lumpy cam. Did not realize both valves are opening at the same time, big clue. Unfortunately I do not know the cam specs.

I started with the timing at 12 degrees before top dead center at idle (factory spec), and it had hard start and was sluggish. Moved the timing to 18 BTDC, and was better, now at 28 BTDC at idle and starts good, and runs like a rapped ape at higher rpms. I changed the mechanical to only advance 8 degrees and all in by 2000 rpms. So idle is 28 and advanced total timing is 36 degrees. Did I get carried away with the idle timing? What benifit does a race car get from locking the timing out at 36, with no advance? Can the cam be clocked when installed, throwing me off?

Ambient temp could play into it. I started setting everything up in the winter. That's another factor I forgot.

 

Race cars optimize the spark flame for a particular high range of RPMs.  On the street you need it to vary since the velocity of the piston changes with RPM and the flame front needs to be balanced to match it.

 

ie, the speed of the "explosion" is the same.  To make it "time" the same in the piston stroke you need to have it happen earlier the faster the piston is moving.  Their is an ideal point which is somewhat dangerous in case any conditions change, but at that point you maximize the pressure in the cylinder.  Higher pressure = more torque.

[///M5 2,833]

 

 

I'm going to be up processing photos tonight... Then meet my new boss tomorrow.

Bleh.

Good subject matter?

New boss?

J

It was my old boss going away party.

And I didn't have the ISO high enough.

Grain>nothing in focus.

I couldn't get the settings right in for auto I SO and I got greedy.

Had to shoot way too much at 1.2.

It was so low light...

 

Bounce flash

[///M5 2,833]

 

Curious at what rpm you are experiencing the issue to J.

 

My problem now is that 1) I've never adjusted anything beyond the choke and idle on a carb, and 2) I've read Banish's book on tuning once (almost 2 years ago now, lol) and think of the myriad of ways you can adjust whatever with fuel injection and more importantly what you can log.  Of course this makes me want the equivalent even more on my sled than my car.  A 2 stroke can gain a ton of pull from having optimized temperature injector cycles based on rpm, load, & temperature (air/engine).

 

For some reason the OE's are having trouble keeping them alive under hard use though in particular on sleds.  Emissions and lubrication are generally what is blamed, but if everything was optimized AND measured with a better controller I don't think that would be the case.

Not really an at rpm, just when I gun it. Collates with the vacuum dropping from 8-12 to 1 at best on the gauge. Then the vacuum Rockets back up and the car takes off. Yes the holley has a retarded amount adjustment. The Excelerator pump works off the mechanical linkage, so I would think it would fill the void, once set correctly.

I only adjust one thing and then test drive. I bumped up the squirter nozzle, so more fuel sooner. This should be correct based on the power to weight ratio of the car, and tall axle gear ratio. The vacuum still dropped the same but, was a lot less hesitation. Then I tighten down the carburetor more to the manifold, as I suspected I had over tightened, and got a severe vacuum leak. Then I pulled the carburetor, and cleaned the mounting surfaces, and checked the gasket. My torque wrench does not go low enough, so just tightened less than before. Also added washers, don't recall why hadn't added them before. Think I had a slight vacuum leak that I solved. Vacuum still drops to zero when I punch it parked in the garage. And was too late for a test drive, so no test under load yet.

So recap, fixed a vacuum leak, and added more fuel sooner via mechanical. Didn't get a test drive yet.

If I can't get it in the morning, I will use my phone a friend to call my step brother who is a mechanic.

 

It will behave differently under load.  Normally this will exaggerate what you see, but I've seen the opposite on my 2 strokes too.

[///M5 2,833]

 

Jared

Possible the fuel pump isn't wucking enough fuel on demand? Taking a sexond or two to catch up to the request for more fuel?

J

This is very possible J. Ideally the Holley would have a 3/8 fuel line and electric fuel pump. I replaced the factory 5/16 before I realized this. I have a fuel gauge installed out the carburetor, which reads correctly at 7 lbs. The car runs great once it is through the hesitation though, and screams when you punch it on the highway!!

I have the correct electric fuel pump, and may have to replace the line again to 3/8.

 

Mechanical or electrical pump?

 

An electric pump will only lean out at RPM as the demands for fuel are higher then.  Mechanical I have no idea what the delivery curve looks like.

[///M5 2,833]

 

 

I think I about have the holley carburetor figured out. I have the idle circuit dialed, I have the transfer slot circuit dialed, and appropriate size jets and power valve.

The vacuum drops to almost 0 when I punch it. I would say there is more likely hesitation than a bog. I believe I should install a larger Excelerator pump nozzle, to introduce more fuel quicker.

Ryan or anybody else have input on this?

Stock cam?

Does it fall instantly, or gradually, or at high rpm?

It has a very lumpy cam. The fall is instant when you try to get into it.

 

Seriously happens at ANY RPM??

 

ie, try idle to floor

2000 to floor

3000 to floor

4000 to floor

 

I would expect at some point it doesn't hesitate.  Understanding where it is in relation to your high and low speed circuits will help the trouble shooting.

[///M5 2,833]

 

J - you aren't hearing any knock are you?

I am not following the jump from Temp to Vacuum.

From what I know, the ideal gas law states. PV=nRT

Therefore more cylinder pressure = higher temp. You can surely adjust your pressure with spark timing and along with it pressure.

As for vacuum, it is created by the piston moving up and down. The carb restricts flow of air causing there to be vacuum. In a completely efficient engine the rate of flow of air would be the overall displacement of the engine multiplied by the number of strokes it takes during that time. The only time then you should have "positive" vacuum is when you are not delivering that much air via some restriction. Obviously at idle you will have more since the throttle/carb is nearly closed.

I see that as efficiency, so on one aspect less heat = more efficiency and more efficiency has more capability to "suck" air but I am having a problem connecting the two.

I am far from a guru on anything engines in the cause and effect realm, but something I'd like to learn more about.

No knocking sounds.

More timing=more heat=more power? Not looking for efficiency, but more POWER!

I have a 650 cfm carb, the engine is a 289ci. The reason I'm not asking the mustang forum is they will just tell me carb is to big. I disagree with them for my setup. Might need to find a racing forum.

 

Have you done head work?  Even with a big bump stick that carb is too big.

 

And btw, you ARE looking for efficiency.  Power is proportional to efficiency.

[///M5 2,833]

 

Your taco meat needs pretty much the exact same love as your chili, just slightly different quantities.

Do you have a good taco recipe?

J

 

I don't really use recipes, but make a mean taco.

[///M5 2,833]

And please challenge everything I say.  I am in the learning stage myself.  

 

That all being said, thanks for reminding me I need to start reading again.  Going to bring the Banish book with me to Asia.  Just ordered Corky Bell's book as well.

[puscifer2 27]

J - been talking with some old school techs. They tell me you should shrink the gap on the linkage to the accelerator pump. So it will react faster to an on demand WOT.

[j-roadtatts 1,129]

I would say the stumble is less at higher RPM's, really bad at idle and when punched at low cruising speed. I realize a vacuum leak will effect the lower rpm range as it has more effect at that point. I think I may have several very small leaks and is causing diagnostics to be more difficult. Most of my symptoms seem to point to that. There is a mechanical fuel pump now, which feeds the correct pressure at idle. I will check for fluctuations in fuel pressure at high rpms, when I fire it up this morning. May not be the sole causes, but I think its a good start.

[j-roadtatts 1,129]

J - been talking with some old school techs. They tell me you should shrink the gap on the linkage to the accelerator pump. So it will react faster to an on demand WOT.

I have the arms gap shrunk at this point, anymore and it will pop the diaphragm.. I installed a 35 nozzle last night, up from a 31. The carb has the 35cc accerator pump, any bigger nozzle requires a 50cc pump be installed. 

 

The thing is the accelerator pump is about 15th in the order of tuning.

[puscifer2 27]

J the advice I posted was from someone with exactly the same symptoms as you describe on a similar engine build. Wild cam, bored, stroked, ported and polished. Used to be a 289. Ended up closer to a 360cu in. Holley carb.

Just like you he step by step adjusted the carb for our altitude, timing and the like. That's what worked for him.

[j-roadtatts 1,129]

 

 

J - you aren't hearing any knock are you?

I am not following the jump from Temp to Vacuum.

From what I know, the ideal gas law states. PV=nRT

Therefore more cylinder pressure = higher temp. You can surely adjust your pressure with spark timing and along with it pressure.

As for vacuum, it is created by the piston moving up and down. The carb restricts flow of air causing there to be vacuum. In a completely efficient engine the rate of flow of air would be the overall displacement of the engine multiplied by the number of strokes it takes during that time. The only time then you should have "positive" vacuum is when you are not delivering that much air via some restriction. Obviously at idle you will have more since the throttle/carb is nearly closed.

I see that as efficiency, so on one aspect less heat = more efficiency and more efficiency has more capability to "suck" air but I am having a problem connecting the two.

I am far from a guru on anything engines in the cause and effect realm, but something I'd like to learn more about.

No knocking sounds.

More timing=more heat=more power? Not looking for efficiency, but more POWER!

I have a 650 cfm carb, the engine is a 289ci. The reason I'm not asking the mustang forum is they will just tell me carb is to big. I disagree with them for my setup. Might need to find a racing forum.

 

Have you done head work?  Even with a big bump stick that carb is too big.

 

And btw, you ARE looking for efficiency.  Power is proportional to efficiency.

 

I have not done head work. My understanding is a bigger carb will net in poorer fuel economy only.

 

The efficiency I think I am looking for is max cylinder pressure.

[topgun 262]

You've got a big cam, but factory heads?  That air has to flow in and out of the cylinders some how...  

[j-roadtatts 1,129]

I do think the key after all little things are sorted out, will be dialing the accerator pump to fill the void. 

 

Timing is numero uno in the whole process though.   

[j-roadtatts 1,129]

You've got a big cam, but factory heads?  That air has to flow in and out of the cylinders some how...  

Unfortunately cousin had the motor built, BIL bought it from cousin and lost the paperwork for the engine work. I doubt that the heads were done though. They did not even look ported when I had the manifold off.

[j-roadtatts 1,129]

On the plus side, I got to watch Ivy whoop ass in tennis yesterday!

[j-roadtatts 1,129]

I think a lot of my problem is Several small vacuum leaks. Too small to detect with propane or carb cleaner. I reinstalled the card last night and feel I eliminated that leak. I am going to recheck the torque on the manifold. Then cap All vacuum lines again. I feel I may have the wrong PCV valve also.

I will do this and report back after a shakedown run. I have an awesome gradual sloped Road next to my house that is great for applying a load.

[Tirefryr 1,742]

My understanding of the combustion engine, is that the vacuum is created by the thermal dynamics of the engine. From my understanding the timing is what controls where the heat is in the motor. This affects the cacuum being pulled through the Venturi.

On a Holley carburetor all functions except for the Excelerator pump are vacuum operated. The Excelerator pump is controlled mechanically with the throttle linkage. There are three variables to Excelerator pump, the diaphragm, the linkage Cam and the squirters.

Suck, squeeze, bang, blow.

Vacuum is created on the initial stroke which fills the cylinders. The up stroke compresses the air/fuel mixture. Spark ignites the mixture which forces the piston down or the power stroke, then final stroke back up is to exhaust the gases and empty the cylinder to begin again.

Poor choice of words on my part. Should've said, vacuum strength can being manipulated with timing. Without overthinking it, I believe this is because of the thermal aspect. Am I wrong in theory?

I am pretty keen on the four cycles btw, but still appreciate your knowledge.

Cam timing yes. The reason you hear "big" cams having a lopey idle is they are struggling to stay running due to valve overlap. You have both valves open at the same time, but not fully, and vacuum quickly ,goes away. This is why some radical cars need to run a vacuum pump.

Temp of course will affect it as well, but cam timing is the big determining factor.

Yes it has a very lumpy cam. Did not realize both valves are opening at the same time, big clue. Unfortunately I do not know the cam specs.

I started with the timing at 12 degrees before top dead center at idle (factory spec), and it had hard start and was sluggish. Moved the timing to 18 BTDC, and was better, now at 28 BTDC at idle and starts good, and runs like a rapped ape at higher rpms. I changed the mechanical to only advance 8 degrees and all in by 2000 rpms. So idle is 28 and advanced total timing is 36 degrees. Did I get carried away with the idle timing? What benifit does a race car get from locking the timing out at 36, with no advance? Can the cam be clocked when installed, throwing me off?

Ambient temp could play into it. I started setting everything up in the winter. That's another factor I forgot.

If you're running fine and not getting any knock, I wouldn't worry about your timing. Just be aware hotter air is less dense and more prone to preignition.

Your cam may be advanced ir retarded depending on sprockets.

[Tirefryr 1,742]

J - you aren't hearing any knock are you?

I am not following the jump from Temp to Vacuum.

From what I know, the ideal gas law states. PV=nRT

Therefore more cylinder pressure = higher temp. You can surely adjust your pressure with spark timing and along with it pressure.

As for vacuum, it is created by the piston moving up and down. The carb restricts flow of air causing there to be vacuum. In a completely efficient engine the rate of flow of air would be the overall displacement of the engine multiplied by the number of strokes it takes during that time. The only time then you should have "positive" vacuum is when you are not delivering that much air via some restriction. Obviously at idle you will have more since the throttle/carb is nearly closed.

I see that as efficiency, so on one aspect less heat = more efficiency and more efficiency has more capability to "suck" air but I am having a problem connecting the two.

I am far from a guru on anything engines in the cause and effect realm, but something I'd like to learn more about.

No knocking sounds.

More timing=more heat=more power? Not looking for efficiency, but more POWER!

I have a 650 cfm carb, the engine is a 289ci. The reason I'm not asking the mustang forum is they will just tell me carb is to big. I disagree with them for my setup. Might need to find a racing forum.

when I read the first sentence, that was my thought. Honestly, I think your cam is too aggressive and your heads too small.

[Tirefryr 1,742]

I don't know if you've posted, but what heads are you running?

[j-roadtatts 1,129]

I don't know if you've posted, but what heads are you running?

Factory heads.  

[j-roadtatts 1,129]

 

 

 

 

 

My understanding of the combustion engine, is that the vacuum is created by the thermal dynamics of the engine. From my understanding the timing is what controls where the heat is in the motor. This affects the cacuum being pulled through the Venturi.

On a Holley carburetor all functions except for the Excelerator pump are vacuum operated. The Excelerator pump is controlled mechanically with the throttle linkage. There are three variables to Excelerator pump, the diaphragm, the linkage Cam and the squirters.

Suck, squeeze, bang, blow.

Vacuum is created on the initial stroke which fills the cylinders. The up stroke compresses the air/fuel mixture. Spark ignites the mixture which forces the piston down or the power stroke, then final stroke back up is to exhaust the gases and empty the cylinder to begin again.

Poor choice of words on my part. Should've said, vacuum strength can being manipulated with timing. Without overthinking it, I believe this is because of the thermal aspect. Am I wrong in theory?

I am pretty keen on the four cycles btw, but still appreciate your knowledge.

Cam timing yes. The reason you hear "big" cams having a lopey idle is they are struggling to stay running due to valve overlap. You have both valves open at the same time, but not fully, and vacuum quickly ,goes away. This is why some radical cars need to run a vacuum pump.

Temp of course will affect it as well, but cam timing is the big determining factor.

Yes it has a very lumpy cam. Did not realize both valves are opening at the same time, big clue. Unfortunately I do not know the cam specs.

I started with the timing at 12 degrees before top dead center at idle (factory spec), and it had hard start and was sluggish. Moved the timing to 18 BTDC, and was better, now at 28 BTDC at idle and starts good, and runs like a rapped ape at higher rpms. I changed the mechanical to only advance 8 degrees and all in by 2000 rpms. So idle is 28 and advanced total timing is 36 degrees. Did I get carried away with the idle timing? What benifit does a race car get from locking the timing out at 36, with no advance? Can the cam be clocked when installed, throwing me off?

Ambient temp could play into it. I started setting everything up in the winter. That's another factor I forgot.

If you're running fine and not getting any knock, I wouldn't worry about your timing. Just be aware hotter air is less dense and more prone to preignition.

Your cam may be advanced ir retarded depending on sprockets.

 

So you are saying I may need to back the advance off bc its warmer ouside now?  How would the cam sprocket play into the equation, or how could it effect me?