CHT temps, individual cylinder differences? Options

[falcor75]

For those of you that are running 4 CHT sensors under the plugs, what differences do you see between the cylinders?

Whats your typical temps for each cylinder with:

A: Engine warmed up sitting at idle for a minute or two.

B: Engine warmed up, cruising at 50-55 mph in fifth gear.

[era vulgaris]

I don't own the car anymore, but on my old 75 with the 2270 I had a 4 channel digital CHT. This is going from memory so don't take these numbers as gospel, but I would see warmed up temps in this area:

1) 315
2) 300
3) 325
4) 315

That's not exact, but that type of ballpark. 2 is coolest, 3 is hottest, and 1 and 4 are about the same.
Cruising between 3k and 4k rpm in gears 1-4, temps remained pretty stable. They'd go up a few degrees while accelerating or climbing a hill, and then level off again while cruising or idling.

Also, below approx 60mph you'd have one set of temps that would hold steady for gears 1-4. Once you pass that 60-ish mph barrier temps start to climb and will level off around 15-20 degrees higher across the board at around 70mph, simply due to air resistance, which is why it's so important to keep the revs up in 5th gear. Take the top off above 60mph and temps go up another 10-15 degrees because you've further increased the car's air resistance.
So please, don't EVER cruise in 5th at 50-55mph. You're doing the engine a major disservice. Drive at that low of an rpm in 5th long enough, and you're virtually guaranteeing to have cracked heads or dropped valves in your future because the cooling fan isn't moving fast enough and your temps will creep up up up. 5th gear should not be used below 3k rpm, which equates to about 70mph.

[VaccaRabite]

So please, don't EVER cruise in 5th at 50-55mph. You're doing the engine a major disservice. Drive at that low of an rpm in 5th long enough, and you're virtually guaranteeing to have cracked heads or dropped valves in your future because the cooling fan isn't moving fast enough and your temps will creep up up up. 5th gear should not be used below 3k rpm, which equates to about 70mph.

This is my experience as well.
I never touch 5th till about 70. Especially climbing the long gradual hills going home from work.

Zach

[Mark Henry]

So please, don't EVER cruise in 5th at 50-55mph. You're doing the engine a major disservice. Drive at that low of an rpm in 5th long enough, and you're virtually guaranteeing to have cracked heads or dropped valves in your future because the cooling fan isn't moving fast enough and your temps will creep up up up. 5th gear should not be used below 3k rpm, which equates to about 70mph.

This is my experience as well.
I never touch 5th till about 70. Especially climbing the long gradual hills going home from work.

Zach

(IMG:style_emoticons/default/agree.gif) Don't lug a T4, 3000 rpm minimum

I only use #3 because I know it's the hottest cylinder.
I aim for just over 300* at 3000-3600 rpm on the flats, pulling a hill 350*.
Much higher and heat soak begins and over 400*+ the alunimum begins to soften.

When you pull hills on the downside the temps should recover to near flat temps.
If the temps are not recovering then you are leaning your AFR too far and/or you're into heat soak issues.