Camshafts and Compression

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RustyRatRod said:
Yeah, you read that right. He's proved time and again compression
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You mean the low comp 400 that made a whoping 0.90 Hp per cube on 85 octane fuel or was it the 440 that made 289 hp.....

What exactly did he prove again.........Compression is cylinder pressure and cylinder pressure is power.
 
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Hysteric said:
You mean the low comp 440 that made a whoping 0.82 Hp per cube on 85 octane fuel?

What exactly did he prove again.........Compression is cylinder pressure
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Obviously more CR is better, but there's no reason an 7.5:1 or 8:1 etc.. can't make power it would just be higher with more CR.
Hysteric said:
and cylinder pressure is power.
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cylinder pressure created by combustion is power.


There you go 8.5:1 making 650 hp NA and over 600 lbs-ft, 10:1 just made more.
 
273 said:
cylinder pressure created by combustion is power.
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So you're saying the better or the more efficiently you convert liquid (fuel which doesn't burn in the chamber) to a gas (fuel which does burn in a chamber) the more efficiently it burns therefore the more pressure it creates which means the more power it transfers to the crank......
 
Hysteric said:
You mean the low comp 400 that made a whoping 0.90 Hp per cube on 85 octane fuel or was it the 440 that made 289 hp.....

What exactly did he prove again.........Compression is cylinder pressure and cylinder pressure is power.
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He proved cylinder head flow trumps compression.
 
Hysteric said:
So passing more and fuel and air through an engine will make more power.........Revolutionary!

What does a throttle do again?
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You should probably give up , you're out of your elements. but you're used to that.
 
fishmens67 said:
You should probably give up , you're out of your elements. but you're used to that.
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You mean the tight *** Mopar owning element......Maybe we should all Retard our cams so we can make more power with less cylinder pressure.


There's a reason cam companies recommend compression rations with their camshafts. Notice they go higher with increased duration and later intake valve closing points. Wonder why that is...... :rofl:
 
Hysteric said:
You mean the tight *** Mopar owning element......Maybe we should all Retard our cams so we can make more power with less cylinder pressure.


There's a reason cam companies recommend compression rations with their camshafts. Notice they go higher with increased duration and later intake valve closing points. Wonder why that is...... :rofl:
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Did anyone argue less cr is superior to more, No
Stop your usual bullshit and ruining this guy's thread.
 
273 said:
Stop your usual bullshit and ruining this guy's thread.
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The thread title is... Camshafts and Compression

The guy wanted to know if the cylinder pressures he was running where to high for Pump Gas......They're not. Maybe you can find a dyno video where they explain how you actually need to compress the mixture to convert it to a gas to burn?

It might explain why people advance camshafts and they make more power........Nah......That couldn't be it.
 
Thanks Bewy, great stuff. I have done a lot of the things with the carb you’ve mentioned there, I have got the acc pump in the outer hole, just not in the photo. I have a pair of 100 jets, I’ll put them in, take out the 103’s. I have the floats set at 29/32’’ not 1’’.

I did have an issue with nozzle drip at idle at one time, ended up the ‘economiser’ orifice in the air horn was blocked. I fed a thin nylon guitar string through there to clear it. This TQ has the 3/32’’ holes in the throttle plate to by-pass the air, probably because it’s off a 440? I also don’t use the 1.25 turns on the air door, usually I go for 1.75 to 2 turns.

I’m a bit torn on the lifters ATM, I’ve always wanted to modify an electronic distributor to have two pickups in it. The original one for full advance, then the other retarded 4-5 degrees as a starter pickup. Slave a relay off the starter solenoid, then the distributor goes back to full advance once you let go of the key. Easier on the starter.
 
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Bewy said:
Valman,
I am in Sydney. Your Rhoads lifters will make it easier, not harder, to crank the engine. I wouldn't be in a hurry to remove them just yet. I modify std lifters to work like Rhoads. While they crank up the low end, they also act as anti-pump up lifters on the top end. Not saying they stop pump up, but they will reduce it because of the bleed down feature.

The TQ. I posted some pics of TQ mods in the Fuel & Air section, Dec 14, 2023. These WORK. Recently did the mods on a 6394 for a bloke in WA. A friend of mine with a 455 Pontiac ran 119 mph at Eastern Creek with the TQ modified. 3900 lb without driver, 3.36 axle, T400, Victor int man, street radials, reverse patttern cam, street registered & driven, 850 rpm idle in gear. He had little drag racing experience, running low 11s. NO tuning was done at the track such as ign timing, air valve [ AV ] position etc.

Comments on your TQ. There is no 6164 TQ in my master catalog, probably you have the 6461. It comes 98/137 jets & #2005 rods. I have never had to go more than about 2 thou bigger on the pri jets. 105 seems excessive. The Ferd 9000 series TQs here were 800s & had large 101 pri jets, but they also had much bigger pri air bleeds, which leaned the mixture. Probably for emissions. They also had smaller sec hi speed bleeds, 0.029" v the 0.039" used on the 6000 series carbs. The small size probably accounts for the smaller sec jets.
Since you have removed the choke, I would remove the x/over shaft that runs across the AV. Braze a small piece of steel over the opening left in the AV.
I NEVER use 1 1/4 turns on the AV spring, too loose. I use 2 turns. I would also go bigger on the AV opening, not 0.500". The opening also controls distribution as well as total air flow.
The top of the AV is bent forward. The original comp series had that straight. I straighten them sometimes. It starts the sec airflow earlier.
I have NEVER had to use the inner holes on the acc pump lever, only use the outer hole. These have a big 30cc pump & of course a very efficient design that doesn't need a heap of fuel to cover a bad design.
If you have the PCV hooked up, make sure engine vacuum is high enough to pull in the pintle. If not, cut off a piece of 3/8" bolt & drill a 1/8" hole through it; shove this inside the PCV hose.
If you need bypass air, drill the sec blades, not the pri because you could get nozzle drip.
If the engine is making a lot of HP, you should use 0.110" n/seats. Had to do this recently on a 440 I built that was laying over in 2nd gear. I just drill the factory seats. Use this chart to reset the f/level.

View attachment 1716361237
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You’re friends Pontiac sounds awesome! 11’s in a big car like that would be great fun.
That carb I have had 125 secondary jets in it when I got it, I put the 143’s in it.
 
Valman said:
Thanks Bewy, great stuff. I have done a lot of the things with the carb you’ve mentioned there, I have got the acc pump in the outer hole, just not in the photo. I have a pair of 100 jets, I’ll put them in, take out the 103’s. I have the floats set at 29/32’’ not 1’’.

I did have an issue with nozzle drip at idle at one time, ended up the ‘economiser’ orifice in the air horn was blocked. I fed a thin nylon guitar string through there to clear it. This TQ has the 3/32’’ holes in the throttle plate to by-pass the air, probably because it’s off a 440? I also don’t use the 1.25 turns on the air door, usually I go for 1.75 to 2 turns.

I’m a bit torn on the lifters ATM, I’ve always wanted to modify an electronic distributor to have two pickups in it. The original one for full advance, then the other retarded 4-5 degrees as a starter pickup. Slave a relay off the starter solenoid, then the distributor goes back to full advance once you let go of the key. Easier on the starter.
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I’m not sure why you are having starting issues.

I’ve had timing locked out at 35 and never had an issue starting.
 
Newbomb Turk said:
I’m not sure why you are having starting issues.

I’ve had timing locked out at 35 and never had an issue starting.
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What comp do you have? Cranking comp. Just my own experience, I’ve found retarding initial timing on performance engines always makes them easier to turn over. Regardless what starter you use.
I know some will disagree.
 
Valman said:
What comp do you have? Cranking comp. Just my own experience, I’ve found retarding initial timing on performance engines always makes them easier to turn over. Regardless what starter you use.
I know some will disagree.
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I don’t remember the cranking compression in that engine.

I no longer use or recommend locked out timing for a couple of reasons.
 
My slant 6 has 175-185 cranking pressure and even when I "accidentally" had initial timing on about 50 degrees when I first got the engine in (long story) it still started right up.
 

But if you have to move it more than 4 or so degrees from where the cam grinder wants the centerline then it’s probably the wrong cam.
 
TT5.9mag said:
But if you have to move it more than 4 or so degrees, to adjust where the installed centerline is compared to where the cam grinder wants it, then it’s probably the wrong cam.
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Cam grinders can't take into account all the variables involved in the cylinder that affect the burn. They are only guessing at best.

Different fuels have different distillation temps so how can a cam grinder know where exactly to close the valve to best suit what you're using?
 
Hysteric said:
Cam grinders can't take into account all the variables involved in the cylinder that affect the burn. They are only guessing at best.

Different fuels have different distillation temps so how can a cam grinder know where exactly to close the valve to best suit what you're using?
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Then I reckon we're all just fucked. Break out the horse and buggy.
 
Hysteric said:
Cam grinders can't take into account all the variables involved in the cylinder that affect the burn. They are only guessing at best.

Different fuels have different distillation temps so how can a cam grinder know where exactly to close the valve to best suit what you're using?
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The cam grinder can only be as good as the information they’ve been given. If you have a cam ground, and you make more power, or get better driveability, or get better mileage, or whatever you’re after by moving the cam 10 degrees, then you’re giving it up somewhere else. And a different grind will likely (not always) give you better results.
 
Valman said:
That’s what I mean regarding the short overlap it has. For a cam at 236 duration, you’d expect more like 60-70 degrees, not 23.

Where does that cam in your slant close the intake valve? That should determine largely how much cranking compression it has.
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You'd be better with @.050 in the mid 250's and get the dynamic in the high 8's, like cranking in the 180-190 range and some careful tuning
 
MOPAROFFICIAL said:
You'd be better with @.050 in the mid 250's and get the dynamic in the high 8's, like cranking in the 180-190 range and some careful tuning
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That’s not messing around, big cam. I thought the spec’s on this one looked pretty good. Around 8.4:1 DCR, should crank around 180psi at the elevation I’m at. Lift will be higher as I’ve got 1.6 rockers.

IMG_0051.png
 
Then again, the cam I have may be quite similar if I change to regular hyd lifters.
 
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