Full tune-up with no results. Please Help.

[BubbleBrad]

Just got a tune-up today, all ac/delco, plugs, wires, cap, rotor, and pcv. Didnt notice much of an improvement. Car still seems sluggish off the line , and I still cant spin my back tires or even make them squeal of the line. I have a '92 5.0L 305 V8 with only 70k miles on the clock. My old '91 had 114k and I could easily screech the tires of the line and around corners. Is there something wrong with my exhaust or cat converter? And how can I tell if my cats are clogged? Since the tune-up I've noticed a constant flow of white smoke from the tail pipe, more than usual. And, theres a strong smell (im guessing fuel) coming from the tail pipe. I have emissions in 2 weeks, and want to everything possible to pass.

[silicon212]

#1 - the 305 has never been a torque monster.
#2 - the '92 you have might have taller gears than the '91, giving you more speed but killing your acceleration.

[HLandin]

Correct, the 305 does not have as much torque as the 350, and of course, your gearing. The 350 was available with 3.42 ratio which gives you more of a torque multiplication at the driving wheels when compared to the 2.56 or even 3.08 ratio.

Now maybe you guys can answer a question for me: I know the 350 has more torque than a 305, but maybe you can tell me why. Since torque is supposidely a function of stroke length, and horsepower is supposidely a function of bore, a 350 should have as much torque as a 305 since it has the same stroke, but more horsepower since it has a larger bore. But I know that a 350 has more torque than a 305. I'm just trying to figure out why.

[TommySS]

More bangs = more power

Bigger bangs = more torque

A 305 produces neither, the 350 produces the latter

[BubbleBrad]

I wouldnt really be concerned if this was my first 305, but its not. My previous had over 40k more miles than my current, and I could rip the tires on that one no problem. Could the posi be shot, or not functioning correctly?

[GranniesCaprice]

You probably have a 2.56 7.5" gear in your rear end. Whereas your old Caprice may have had a 3.23 or a 3.42. It makes a big difference off the line. My 91 has a 305, 700R4 and a 2.56 rear end with 42K miles. Its doggy as hell. However, I do get 26 MPG Highway. As far as the white smoke goes, you could have an internal coolant leak. Most likely your intake. It's a real common problem. After running it awhile pull your PCV and check for a white/tanish goo. Kind of resembles a loogie. Thats excess condensation in your oil. Which very well, could be Coolant.

[silicon212]

Torque is the basic measure of power on a rotating engine. Engine dynamometers do not directly measure horsepower, they measure torque. Horsepower is arrived at by implementing the following formula:

XY/5250

where "X" is torque and "Y" is RPM. This is the reason why torque and horsepower are always equal on any engine at 5,250 RPM.

Stroke is not what determines torque. Displacement is (there's "no replacement for displacement" is the saying). On two equal displacement engines, torque will be greater on the engine with the longer stroke (greater leverage) at the expense of maximum RPM (reciprocating mass; the "redline"), all else being equal (valve size, cam duration/lift/lobe center etc). If both had the ability to breathe equally, the Chevy 305 will out-torque the Ford 302, but the Ford 302 will out-rev the Chevy 305. Remember that horsepower is the measurement of torque over time. If the Chevy 305 is putting down 260 ft. lbs. of torque at 2600 RPM, but the Ford is peaking at 245 at 2800, then you'd think the Ford was less powerful than the Chevy - but this isn't so. Think that the Chevy will, stock, probably hit redline at about 4500 RPM, while the Ford can breathe to 5500 or so. Now, if the Chevy was making 175 ft. lbs. at 4500 RPM, then its max horsepower at that RPM is ~150 H.P. If the Ford, equal to the Chevy in other words, was making 165 ft. lbs. @ 5500 RPM, then it's producing ~162 HP at its redline, 12 more than the Chevy. This is oversimplified, but that's the general idea.

[BubbleBrad]

Originally Posted by GranniesCaprice

You probably have a 2.56 7.5" gear in your rear end. Whereas your old Caprice may have had a 3.23 or a 3.42. It makes a big difference off the line. My 91 has a 305, 700R4 and a 2.56 rear end with 42K miles. Its doggy as hell. However, I do get 26 MPG Highway. As far as the white smoke goes, you could have an internal coolant leak. Most likely your intake. It's a real common problem. After running it awhile pull your PCV and check for a white/tanish goo. Kind of resembles a loogie. Thats excess condensation in your oil. Which very well, could be Coolant.

How can I tell if it has 2.56, 3.23, or 3.42?

[BubbleBrad]

Nevermind, I now know my rear is a 2.56. Can I upgrade to a 3.42 or 3.73 with no modifications? If so, what all do I need to make the switch? Is a brand new posi required?

[HLandin]

Originally Posted by silicon212

Torque is the basic measure of power on a rotating engine. Engine dynamometers do not directly measure horsepower, they measure torque. Horsepower is arrived at by implementing the following formula:

XY/5250

where "X" is torque and "Y" is RPM. This is the reason why torque and horsepower are always equal on any engine at 5,250 RPM.

Stroke is not what determines torque. Displacement is (there's "no replacement for displacement" is the saying). On two equal displacement engines, torque will be greater on the engine with the longer stroke (greater leverage) at the expense of maximum RPM (reciprocating mass; the "redline"), all else being equal (valve size, cam duration/lift/lobe center etc). If both had the ability to breathe equally, the Chevy 305 will out-torque the Ford 302, but the Ford 302 will out-rev the Chevy 305. Remember that horsepower is the measurement of torque over time. If the Chevy 305 is putting down 260 ft. lbs. of torque at 2600 RPM, but the Ford is peaking at 245 at 2800, then you'd think the Ford was less powerful than the Chevy - but this isn't so. Think that the Chevy will, stock, probably hit redline at about 4500 RPM, while the Ford can breathe to 5500 or so. Now, if the Chevy was making 175 ft. lbs. at 4500 RPM, then its max horsepower at that RPM is ~150 H.P. If the Ford, equal to the Chevy in other words, was making 165 ft. lbs. @ 5500 RPM, then it's producing ~162 HP at its redline, 12 more than the Chevy. This is oversimplified, but that's the general idea.

I realize I'm probably hi-jacking this thread, but while we're on the discussion, does horsepower really matter? I know that torque is what is supposed to give you faster accelaration, which means even my 1990 Caprice 9c1 with 350-cid should wax a Crown Vic any day of the week. With the above post about output, does horsepower mean how fast the wheels are spinning (which means how fast the car can be or top) and does torque mean accelaration (how fast the car reaches top speed)? Also, since my Caprices (both the 1990s and the 1993) reach max engine torque at 2400 rpm, does it make any sense to rev it higher? Your making more horsepower since your rotations are higher (max HP @ 4800 rpm), but are you actually accelarating faster?

[silicon212]

Originally Posted by HLandin

I realize I'm probably hi-jacking this thread, but while we're on the discussion, does horsepower really matter? I know that torque is what is supposed to give you faster accelaration, which means even my 1990 Caprice 9c1 with 350-cid should wax a Crown Vic any day of the week. With the above post about output, does horsepower mean how fast the wheels are spinning (which means how fast the car can be or top) and does torque mean accelaration (how fast the car reaches top speed)? Also, since my Caprices (both the 1990s and the 1993) reach max engine torque at 2400 rpm, does it make any sense to rev it higher? Your making more horsepower since your rotations are higher (max HP @ 4800 rpm), but are you actually accelarating faster?

Even my LM1 waxes a Crown Vic, especially here in Mesa, Arizona where the official police cars run on LNG.

Torque is the "pure" measurement of an engine's ability to produce power. Horsepower, in and of itself, is a purely "theoretical" number. It's a function of both torque and RPM. If your engine produces 20% less torque at 4500 RPM than it does at 2500 RPM, you're still producing more power at 4500 RPM than at 2500 RPM because the engine is producing 20% less power at nearly double the RPM as it does at 2500. Does this make sense? I lost myself in this one!

The net power you are feeling at a given RPM is the horsepower, the torque is the measurement of power the engine is producing at any given snapshot in time. Horsepower is dependant on torque, they are both interlocked. A small engine might list a high horsepower rating (say 200 HP on a Honda) but I guaran-damn-tee you that thing has no bottom end. They build these engines so torque peaks at a high RPM hence the large horsepower number.

The 285-whatever HP that Ford advertises for its Crown Vic four-point-sick won't catch an LM1 or L05, and it won't touch an LT1.

The true tale of an engine's power is the torque curve - how much torque the engine produces over a given range of RPM. The LT1 in the Caprice is advertised at 260 HP, but the torque peaks at 330 ft. lbs. fairly low ( mid 2000s) and stays within 90% of that to 5000 RPM (the 'torque curve'). The flatter the curve, the more power your engine's going to make over a larger range of RPM.

Edit: To answer your question, your maximum acceleration rate will happen when your engine is making its most torque. The horsepower of the engine is what gives you maximum speed, torque is what gets you there. As the torque output declines, your rate of acceleration slows.

[BubbleBrad]

Since I have a 8.5, would I be able to get an Auburn 8.5 10 bolt posi with 30 spline axles? Then get the 3.42 Ring and Pinion for a 10 bolt 8.5? Are these the only materials I need to change out my posi and increase my gears from 2.56 to 3.42?

[silicon212]

Yes, generally you need to just replace the gears. However, you have to properly shim the ring so that the mesh is correct and that in and of itself can be a science.