Camshafts and Compression

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Hysteric said:
Its the same. Plugs tan in America like they do in Australia. Grey is usually the plug working in exhaust gas residual, ie the chamber doesn't exhaust very well and the left over exhaust hangs around and is present at the next ignition event so leaves a grey colour.

Bruce discussed this with Mattax about his engine a long time ago. If you don't evacuate the cylinder what is left over becomes part of the next cycles AFR.

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What are you using for headers and exhaust Valman?
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I have a dual 2.5 inch system. The headers are 1 5/8’’ tri-y. I got all that when it had the old engine in it - 360.

Most likely too small for the stroker. I’d like to put 1 7/8’’ headers on it. Can’t find any for our RHD Valiant’s. Even the custom fabricators don’t want to do it. The ones I’ve spoken to anyway.
 
Well, that’s a surprise. It looks pretty rich to me. The photos do look slightly darker than my eyes tell me.

You can see the band at the bottom of the insulator, but it’s very thin.

I’ve seen them lighter than that, new fuel and a re-run maybe..

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Well ok, here it comes;
I grossed your numbers up to a conservative 280/288/108 in at +4 and got;
68* overlap, an Ica of 64*, which at 10.7 Scr, the Wallace spits out;
@900ft; a Dcr of 8.64 and pressure of 176psi
@300ft; a Dcr of 8.64 and pressure of 179psi

IMHO, you need a new compression tester

My 367 has run at up to 11.3 Scr with an Ica of 61*, and Wallace Pressure of 192psi@ ~9.23Dcr.
This runs on 87E10 @34*@3400 rpm, with alloy heads.

There are reports of several FABO members running their strokers at up to ~205psi albeit on best pump-gas.
 
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Thanks for the input. My comp tester is good quality, I have borrowed another off a mechanic friend. 210-220psi.
 
Valman said:
Well, that’s a surprise. It looks pretty rich to me. The photos do look slightly darker than my eyes tell me.

You can see the band at the bottom of the insulator, but it’s very thin.

I’ve seen them lighter than that, new fuel and a re-run maybe..

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That’s very rich. Almost pig fat. But not quite. You need to strip some fuel out of it for sure and the all in timing looks a degree or two soft. Get the curve sorted out then work on the fuel. The heat range is about perfect.
 
But we need to know WHAT we're reading. Was it idling in the driveway, for example?
 
Hysteric said:
Not really. Any shade of tan is good. What carb are you using?
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The photo is slightly darker as well. I’m running an 850 Carter TQ. I had a slightly modded Holley 750 on it originally, I prefer the TQ.
It’s on top of a Performer RPM. Non air gap. It’s been massaged to equalise the air flow through each runner.
All plugs look almost identical.
 
Valman said:
Thanks for the input. My comp tester is good quality, I have borrowed another off a mechanic friend. 210-220psi.
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IMO, if you truly have that much pressure, then either;
>your Ica is not where it's supposed to be, aka the lifters have bled down, making your cam appear smaller, or the cam is outta time,
>or the Scr is not 10.7,
>or the cam is just not what you think it is.
Personally,
If I estimated the advertised close to correct, I would totally love that cam. The intake duration is only a couple more that I have, but the overlap is around 13% greater. I would run that straight up in my 367 and still have lots of pressure.

This is incredibly easy to solve.
Just put #1 piston on the beginning of the Compression stroke, then inject about 20 psi air-pressure into the chamber. Then Slowly, with a big bar rotate the crank CW until the intake just closes, and compression starts. When you find this point, Mark the Balancer next to the TDC index on the Timing Tab. Stop the test, release the air. Now go figure out where your mark is relative to BDC.
Using your numbers, which I grossed up from 050 to .008, as best as I could, this should occur near 64 ABDC. aka 116* BTDC.
If you have a calibrated Balancer, or a timing tape, this is so easy.

Caution;
At 20 psi, on a 4.04 bore, if you try to close that intake valve, the top of the piston will generate 250 pounds of force. You will need a long bar to fight that. If it slips, it can do serious damage to various body parts and/or your rad. You have been warned.

Most likely the bar will start bouncing, so be prepared.
As previously stated, if your lifter bleeds down, it will give you an erroneous reading.
 
Hysteric said:
Awesome! What's the number on the foot of the base plate?

Whats the rod and jet sizes? Do you have a kit to tune it?
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It’s off a 440. It’s either 6164S or 6461S check it later. I’ve got an 800cfm as well off a 340, restored that one as well, looks the same. 6394S on that one.
It’s got 103 jets in the primary, 143 secondary, 2005 rods. 1/2’’ on the air door.
I have got some jets, 1966 rods, a few other things. I don’t have one of the strip kits sadly. I’d love one!
 
AJ/FormS said:
IMO, if you truly have that much pressure, then either;
>your Ica is not where it's supposed to be, aka the lifters have bled down, making your cam appear smaller, or the cam is outta time,
>or the Scr is not 10.7,
>or the cam is just not what you think it is.
Personally,
If I estimated the advertised close to correct, I would totally love that cam. The intake duration is only a couple more that I have, but the overlap is around 13% greater. I would run that straight up in my 367 and still have lots of pressure.

This is incredibly easy to solve.
Just put #1 piston on the beginning of the Compression stroke, then inject about 20 psi air-pressure into the chamber. Then Slowly, with a big bar rotate the crank CW until the intake just closes, and compression starts. When you find this point, Mark the Balancer next to the TDC index on the Timing Tab. Stop the test, release the air. Now go figure out where your mark is relative to BDC.
Using your numbers, which I grossed up from 050 to .008, as best as I could, this should occur near 64 ABDC. aka 116* BTDC.
If you have a calibrated Balancer, or a timing tape, this is so easy.

Caution;
At 20 psi, on a 4.04 bore, if you try to close that intake valve, the top of the piston will generate 250 pounds of force. You will need a long bar to fight that. If it slips, it can do serious damage to various body parts and/or your rad. You have been warned.

Most likely the bar will start bouncing, so be prepared.
As previously stated, if your lifter bleeds down, it will give you an erroneous reading.
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You’ve just made me think of something. This engine does have Rhodes lifters in it. The type that knocks off a few degrees of duration at lower rpm. Mmmm.. I’ve verified the balancer marks, they are correct. MANY balancers are incorrect.

That’s good info on your test, thank you.
 
Valman said:
It’s off a 440. It’s either 6164S or 6461S check it later. I’ve got an 800cfm as well off a 340, restored that one as well, looks the same. 6394S on that one.
It’s got 103 jets in the primary, 143 secondary, 2005 rods. 1/2’’ on the air door.
I have got some jets, 1966 rods, a few other things. I don’t have one of the strip kits sadly. I’d love one!
Click to expand...
The kits come up now and then on Ebay but be prepared to pay around $500 for them.
 
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Valman said:
You’ve just made me think of something. This engine does have Rhodes lifters in it. The type that knocks off a few degrees of duration at lower rpm. Mmmm.. I’ve verified the balancer marks, they are correct. MANY balancers are incorrect.

That’s good info on your test, thank you.
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A few. Bout 20 at low RPM. No wonder you have high cylinder pressure.
 
Valman said:
This engine does have Rhodes lifters in it.
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aha! mystery solved

BTW
my 2014 Chevy Orlando 2.5 liter VVT/DI alloy headed engine cranks 220 on my gauge, too. It is rated 167hp at 6700 rpm.(compare that to an old 318/150hp at 4400) The switch-over on the VVT occurs at 4500, and in the four years we've had it, I only ever needed it like once that I can remember.
The point is that the bottom end is very strong. and the VVT is like a supercharger when it kicks in.
I have a hard time processing what a 410@215psi would be like to drive; I think I can taste envy, lol.
 
Valman said:
You’ve just made me think of something. This engine does have Rhodes lifters in it. The type that knocks off a few degrees of duration at lower rpm. Mmmm.. I’ve verified the balancer marks, they are correct. MANY balancers are incorrect.

That’s good info on your test, thank you.
Click to expand...
Well there’s your problem.
 
AJ/FormS said:
aha! mystery solved

BTW
my 2014 Chevy Orlando 2.5 liter VVT/DI alloy headed engine cranks 220 on my gauge, too. It is rated 167hp at 6700 rpm.(compare that to an old 318/150hp at 4400) The switch-over on the VVT occurs at 4500, and in the four years we've had it, I only ever needed it like once that I can remember.
The point is that the bottom end is very strong. and the VVT is like a supercharger when it kicks in.
I have a hard time processing what a 410@215psi would be like to drive; I think I can taste envy, lol.
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Well, it’s lively enough. I feel I can make it better of course. $$$ :) I’ll do the test mentioned by @PRH. Could be a new set of lifters coming..
It would probably idle choppier with regular hyd lifters - more duration. Will probably save the starter though!
 
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