Riddle me this...

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LivewireBlanco said:
Ok my car doesn't have positive if only one wheel turns when it's jacked up, right? In that case I did two turns of the wheel and ended up with 2 3/4 turns of the driveshaft. Making it a 2.76. I've used a GPS to measure my speed and it's 3000 Rpm at 65. Now without all the computer stuff to calibrate my tach, my ear tells me it's turning a lot of rpm, not 2500. So I'm really thinking my torque converter really may be losing that much. When I punch it the rpms will go way up and stay there (about 2600) until I hit a certain speed and then they'll climb with the mph. Also at 65 if I punch it the rpms will climb a bit to say 3300 then go up with mph.

Do you think when the local shop rebuilt my torque converter they screwed it up?
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The first description points to a 2bbl carb, and depending on your speed/rpm at the moment you floored it could be considered normal.
If the TC jumps to 3300 from 3000 that is about 10% slip and could also be considered normal.
Therefore, I would get a second opinion on either the tach or the speedO. Either the trans is slipping or One of them is a liar. And I really doubt your trans is slipping; Cuz your TC is right at 10%. This might be a little high, but you can't get to 3000 from 2461 with that TC alone,cuz this is a 22% slippage factor.So that would put the direct clutch at 12% slippage. Transmissions,don't slip 12% and then suddenly stop slipping, at that 12%.
So I'm sticking to a liar in the hen-house.
Here is your speed to rpm formula.
(65mphx1056conversion factor x2.76gear)/ 24.5tire height x3.1416 converts to tire roll-out =2461rpm at Zero-slip.
Depending on the power the engine makes and the drag on the chassis, Your actual observed rpm could be a few percent either way from that. I estimate from 2400 to 2580. Unless your engine is in a really,really,poor state of tune, then a maximum of 2700.
That's my best guess.
 
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AJ/FormS said:
The first description points to a 2bbl carb, and depending on your speed/rpm at the moment you floored it could be considered normal.
If the TC jumps to 3300 from 3000 that is about 10% slip and could also be considered normal.
Therefore, I would get a second opinion on either the tach or the speedO. Either the trans is slipping or One of them is a liar. And I really doubt your trans is slipping; Cuz your TC is right at 10%. This might be a little high, but you can't get to 3000 from 2461 with that TC alone,cuz this is a 22% slippage factor.So that would put the direct clutch at 12% slippage. Transmissions,don't slip 12% and then suddenly stop slipping, at that 12%.
So I'm sticking to a liar in the hen-house.
Here is your speed to rpm formula.
(65mphx1056conversion factor x2.76gear)/ 24.5tire height x3.1416 converts to tire roll-out =2461rpm at Zero-slip.
Depending on the power the engine makes and the drag on the chassis, Your actual observed rpm could be a few percent either way from that. I estimate from 2400 to 2580. Unless your engine is in a really,really,poor state of tune, then a maximum of 2700.
That's my best guess.
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318 has a 4bbl and cam. Some of these numbers are average. If I floor it the rpms "stall" higher before it picks up and goes. My gut is telling me the torque converter because it shifts hard and doesn't feel like it's slipping. The torque converter feels like it's "loose"...
 
LivewireBlanco said:
318 has a 4bbl and cam. Some of these numbers are average. If I floor it the rpms "stall" higher before it picks up and goes. My gut is telling me the torque converter because it shifts hard and doesn't feel like it's slipping. The torque converter feels like it's "loose"...
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You're confusing me.
"it shifts hard and doesn't feel like it's slipping. The torque converter feels like it's "loose........ which is it?
Well if it's a 4bbl and a cam, then something ain't right, about the combo.

The stall rpm moves with the rpm.But it ain't called stall anymore.
At zero mph you get the 1800stall. If the engine is idling at 600 rpm than you can think of this as 1200rpm slippage or 300% slippage!
But the more rpm you put into it, the percentage will drop and drop until it hits a minimum..... based on the amount of torque being jammed into it by the engine.
Say it takes 50hp for your TC to stall at 1800.
If your engine puts out 50hp at 1800, then this 1800TC will be an 1800stall TC. But if you put 100hp into that exact same TC, it may stall at 2100. And with 150hp into it it will stall yet higher. The stall rpm is very closely tied to the torque inputted into it.
The stall rpm affects how quickly you are gonna accelerate from a dead stop. Because your engine will make more power with higher rpm.
But at say 30mph in first gear, that 1800 means nothing anymore. The math says 30 mph should be 3000 rpm at zero slip. Like if you had a manual trans. With a manual trans, your rpm would be 3000 no matter if the carb was floored or if it was closed.
But with an automatic, the TC is a fluid coupling, so if you take your foot off the gas, you might 3% or 5%, or some percent of slip. Your rpm at 30 mph could be 2850 at closed throttle. But if you floor it from cruising, the rpm might jump to 3300 or 10% over zero slip. This is almost normal. So your engine at 30 mph could be at between 2850 and 3300; and that could be normal.
Now, if at 30 mph and still in first gear, you back off the throttle for just an instant, and then hammer it, you will have the full range of 450rpm to slingshot your car forward. But if you were still accelerating mildly when you crossed 30 mph, and actually hit 30 at say 3150, then you would have a soft hit of just 150 rpm.

If you open the secondaries too soon or too fast, you can get a tip-in hesitation.Or even a bog. And those will affect your TC hit.
And if the secondaries open late, well then she is operating as a 2bbl,right?
So that could be part of your soft versus hard.
Another part could be the cam; or more accurately what the cam did to your cylinder pressure.
Big cams in small engine are very sensitive to Scr/Static Compression Ratio,because the cylinder pressure goes away. The stock-compression ratio 318 is one of this type of engine. So If you did not bump up the Scr then you are gonna have low cylinder pressure........ and a soft hit no matter what.Especially with that stockish stall TC.
 
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AJ/FormS said:
You're confusing me.
"it shifts hard and doesn't feel like it's slipping. The torque converter feels like it's "loose........ which is it?
Well if it's a 4bbl and a cam, then something ain't right, about the combo.
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It shifts into gear hard, not slipping, but while it's in gear it'll be a high rpm and stay there until the speed catches up to the rpm then the rpms will climb.
 
LivewireBlanco said:
It shifts into gear hard, not slipping, but while it's in gear it'll be a high rpm and stay there until the speed catches up to the rpm then the rpms will climb.
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Are you sure the secondaries are opening?
What cam is in there and at what compression ratio?
From where I'm sitting, the only thing I see wrong is the tach.

I don't suppose your tach has one of those switchs on the back for matching it to the number of cylinders you have,eh? If it was set to 6cylinders instead of 8, the rpm offset at 2460 rpm could be very close to reading 3000.
 
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AJ/FormS said:
Are you sure the secondaries are opening?
What cam is in there and at what compression ratio?
From where I'm sitting, the only thing I see wrong is the tach.

I don't suppose your tach has one of those switchs on the back for matching it to the number of cylinders you have,eh? If it was set to 6cylinders instead of 8, the rpm offset at 2460 rpm could be very close to reading 3000.
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I need to work on the carburetor. I know I've got a blown power valve. Let me get things sorted with that and then I'll see what's up. This was supposed be an easy gear ratio question...lol.
 
LivewireBlanco said:
I need to work on the carburetor. I know I've got a blown power valve. Let me get things sorted with that and then I'll see what's up. This was supposed be an easy gear ratio question...lol.
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Yeah it's funny howchit goes.....
How do you know the PV is blown?
If you swap it out, put a 10.5 in there. 6.5s are for racecars
 
AJ/FormS said:
Yeah it's funny howchit goes.....
How do you know the PV is blown.
If you swap it out, put a 10.5 in there.
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Nice big fireball while setting timing and it's an old Holley without the check ball. Biggest I could find locally was a 6.5. Of that doesn't work I'll take a vacuum reading and get the appropriate size. Right now the idle screws are almost closed to make it run.
 
Are you sure a leaking PV caused the fireball?
The same thing can happen when a pressure pulse comes up the intake manifold and back thru the carb, followed by fire from a leaking valve somewhere. The venturi don't care which way the air is moving thru it, to unload fuel.
I'm not saying the PV isn't blown, just that you gotta prove it.
And again, your idle vacuum has nothing to do with PV selection. That cam wants a 10.5 or something very close to it.
If you wanna prove it, put a PV plug in there, and plumb a vacuum gauge to the manifold and run it up to the windshield and clamp it there with a wiper blade.Then take it on a roadtest. Get it into second gear, above your stall speed, and roll on the throttle till the engine lays down, then grab a vacuum reading. Do a couple of those and average them out. Then move up 500rpm or so and repeat, and one more. then go home. Now average out the averages,lol, and add .5 to the nearest .5. Say you got 10.0; add .5 and a 10.5 is what you want. This is your starter PV.
If your engine wants a 10.5, and you install a 6.5, then she is gonna be lean all the way from 10.5 until the PV opens at 6.5,not good. You are gonna feel that sag and do one of two things; 1) press harder on the gas pedal to get past it, or 2) install fatter mainjets.. Now the bigger mainjets will get you thru the sag, but two other things are gonna happen; 1) now when the PV opens, she will go rich and not make the power she should,and 2) she is gonna suck gas all the time cuz your MJs are too fat.
Does any of this sound familiar?
Ok but you realize the fatness so you decrease the secondary MJs, and it seems to work pretty good...... until the plug-check shows the rearmost cylinders are now lean.
Ok just put a 10.5 in it and prove me wrong,lol. Maybe you can take a jetsize out of the primaries. Maybe She will smooth right out and be happy,lol.
 
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AJ/FormS said:
Are you sure a leaking PV caused the fireball?
The same thing can happen when a pressure pulse comes up the intake manifold and back thru the carb, followed by fire from a late closing intake somewhere. The venturi don't care which way the air is moving thru it, to unload fuel.
I'm not saying the PV isn't blown, just that you gotta prove it. And again your idle vacuum has nothing to do with PV selection. That cam wants a 10.5 or something very close to it.
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The power valve didn't cause the fireball, me messing with the timing did. If I had to guess I would say it'd be a 8.5 PV but I'll have to see what the vacuum is and divide by two. I'll keep ya'll posted.
 
So I think I found the source of my problem and I'm a bit worried. As I was messing with my carburetor I checked my Lokar kickdown cable and it was loose at full throttle. It shifted nice and firm at part throttle but at hard throttle is where it was slipping. Now I'm really worried because this is probably why I was turning so many rpm's on the highway. I didn't do it much but I realize I've probably damaged the transmission a bit if it wasn't getting enough pressure from the kickdown. I'm going to readjust the linkage and see what happens but at this point I'm pretty worried. Crap, crap, crap!!! :BangHead:
 
Ok, kickdown is fixed but problem is still there, turning about 3000 RPM at 65 mph. Could this be a misadjusted band? Car shifts and drives fine when crusing at low speed but when on the highway it's pulling too many rpms and when I get on it hard the rpms stay up a bit like a high stall converter.
 
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