[PAUL K]

Something one might not learn from their butt meter .... More times than not, optimum A/F and total timing found on the engine dyno isn't optimum for the engine installed in the car.

[Dragncar]

Originally Posted by Cliff R

"So if I'm understanding correctly, the "butt meter" works accurately for fine tuning metering rods, jets and vacuum advance but fails miserably when picking camshafts, cylinder heads and intake manifolds."

I prefer to use "Dairy Queen" tuning for camshafts, cylinder heads and intake manifolds. I measure how far I can do a burnout in a hard right hand turn leaving the DQ parking lot at WOT. I back that tuning method up with how far it "chirps" the tires on the 1-2 up-shift.

My last tuning method for LOW compression engines with big camshafts on "tight" LSA's is to see if they will spin the tires when I drop the rear of the car off a floor jack at WOT........

My old 455 with low compression HO heads and flat tops with a .690 lift cam on a 106 would pull the wheels on a 1.43 60 foot run. It had serious torque right off idle. But it was a drag strip tune with open exhaust.

[Cliff R]

1.43 60' would take a LOT of converter with that combo and hardly anything that would work well in a street car.

I actually had a custom show up to the shop once with a later Firebird and a "fresh" 350 build with stock compression. What were those later 350's 8 to 1 or so? He had installed a RAIV cam and even with the initial timing at 36 degrees it turned over really easy fully warmed up, but BARELY made an vacuum at all. I didn't have a floor jack that would get it high enough off the ground to do much more than "chirp" the tires when we dropped in on the pavement!......

[Cliff R]

"More times than not, optimum A/F and total timing found on the engine dyno isn't optimum for the engine installed in the car."

+2

The dyno is an excellent tool, but just that. I use it strictly to "cut to the chase" but do all final tuning once the engine is in the vehicle.

One has to consider it's a "static" test with perfect fuel delivery and PLENTY of cooling media for the engine. It's not loaded down with accessories so tends to idle much better there. Plus it's not surrounded by inner fenders and topped with a hood trapping in a butt-load of heat. You can get away with more on the dyno and I've learned to er a bit on the conservative side once the makes it between the fenders of the car when it comes to timing and fuel curves........

[Formulajones]

Originally Posted by HWYSTR455

If you don't run anything more than max WOT timing it's like running without vacuum advance. You're missing a lot of benefits.

.

I think you maybe didn't understand what I meant. Of course I run timing curves and a vacuum advance, but none of that matters on a dyno. On the dyno I'm looking for where the engine makes best power at wot. The drivability comes later when the engine goes in the car

[Dragncar]

Originally Posted by Cliff R

1.43 60' would take a LOT of converter with that combo and hardly anything that would work well in a street car.

I actually had a custom show up to the shop once with a later Firebird and a "fresh" 350 build with stock compression. What were those later 350's 8 to 1 or so? He had installed a RAIV cam and even with the initial timing at 36 degrees it turned over really easy fully warmed up, but BARELY made an vacuum at all. I didn't have a floor jack that would get it high enough off the ground to do much more than "chirp" the tires when we dropped in on the pavement!......

That 60' was with a cheap 10" 2800 GER converter that I eventually shredded. They used to guarantee their converters and sent me a new one. Still have it. It was so loose you could not hear the car shift. I had a local guy re stall it and it was too tight, so its under the bench.
Even with a high end TCI 8" 4500 converter it would get me 1.44-1.45 on a good day.
But the GER did not last long.

[PAUL K]

Originally Posted by Dragncar

That 60' was with a cheap 10" 2800 GER converter that I eventually shredded. They used to guarantee their converters and sent me a new one. Still have it. It was so loose you could not hear the car shift. I had a local guy re stall it and it was too tight, so its under the bench.
Even with a high end TCI 8" 4500 converter it would get me 1.44-1.45 on a good day.
But the GER did not last long.

2800 is tighter that the Jim H 10" converters

[Dragncar]

Originally Posted by PAUL K

2800 is tighter that the Jim H 10" converters

You are right. I asked for a 2800 and they talked me into a 3200. It was my first foray into the automatic world after being a big 4 speed guy. It would flash pretty high foot braking it off a fast idle.
My car has always 60 footed far better than its ET , MPH would indicate. The norm is for me to be side by side for the first 100 feet or so with a much faster car in time trials, then they pull away.
Even with the new engine so far. But I have not done any tuning yet. Just ran it.
Why people use dyno,s , I get it now.