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> CHT temps, individual cylinder differences?
falcor75
post Apr 12 2018, 10:50 PM
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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.
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falcor75
post Apr 15 2018, 05:28 AM
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Just spend the last 3 hours fiddling with the thottles.

Started with disconnecting the throttle cable and making sure the 1-2 (master) side was as closed as it would possibly go. Then I hooked up the throttle cable again and made sure there was no slack in the slave cable to the 3-4 side so both sides open simultaneously.

I started the engine and let it warm up for about 10 minutes at different rpms. (the neighbours love me) Then I took out the air gauge and started measuring. To start with
1 drew the most air, followed by 3 and 4 and last 2. By first adjusting the slave cable slightly and then the idle air screws I got cylinder 1,3 and 4 to draw the same amount of air, just below the 6 mark on the scale. CHT temps at idle was then around 110C (320F) for #1 and 125C (257F) for # 3 and #4.

Attached Image
Cylinder 1

Attached Image
Cylinder 2


The odd one out is still #2, when the others draw just below the 6 mark, #2 draws like 4,5-4,8, about a full scale marker lower and the temp is around 95 C or 205F.

What could cause #2 to draw that much less air? air leak between head and manifold, airleak between manifold and throttle body are the only things I can come up with....
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barefoot
post Apr 16 2018, 02:12 PM
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QUOTE(falcor75 @ Apr 15 2018, 07:28 AM) *

Just spend the last 3 hours fiddling with the thottles.



The odd one out is still #2, when the others draw just below the 6 mark, #2 draws like 4,5-4,8, about a full scale marker lower and the temp is around 95 C or 205F.

What could cause #2 to draw that much less air? air leak between head and manifold, airleak between manifold and throttle body are the only things I can come up with....


I've just been playing with carb idle air flow issues with one carb. The exact opening at the butterfly's at idle was very difficult to get even on one carb. At idle, there is VERY little open area at each butterfly. The stock injection system avoids this by using a single butterfly for all 4 cylinders, so much larger open area at idle. use some very thin feeler gages to measure butterfly opening on adjacent cylinders.
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Posts in this topic
falcor75   CHT temps, individual cylinder differences?   Apr 12 2018, 10:50 PM
Porschef   :popcorn: :beer3:   Apr 13 2018, 04:19 AM
era vulgaris   I don't own the car anymore, but on my old 75 ...   Apr 13 2018, 06:38 AM
Vacca Rabite   So please, don't EVER cruise in 5th at 50-55m...   Apr 13 2018, 07:23 AM
Mark Henry   So please, don't EVER cruise in 5th at 50-55...   Apr 14 2018, 07:08 PM
falcor75   Thanks for the replies, hope some more people chim...   Apr 13 2018, 11:50 PM
era vulgaris   Dual carbs, or FI? If dual carbs, then your carbs...   Apr 14 2018, 07:29 AM
MikeM   This is a great reminder... but I've always wo...   Apr 14 2018, 09:10 AM
era vulgaris   This is a great reminder... but I've always w...   Apr 14 2018, 10:32 AM
Boomingbeetle   Warm at idle on my 2430 with stock fan/cooling and...   Apr 14 2018, 10:28 AM
Boomingbeetle   Here it is 10min driving at 3250-3500 rpm in 5th. ...   Apr 14 2018, 10:32 AM
falcor75   I've got itbs and FI. I've measured my ai...   Apr 14 2018, 12:26 PM
era vulgaris   I've got itbs and FI. I've measured my a...   Apr 14 2018, 02:41 PM
falcor75   I've got itbs and FI. I've measured my ...   Apr 15 2018, 01:12 AM
Elliot Cannon   Coming home from Rt. 66 a number of years ago, I w...   Apr 14 2018, 03:46 PM
worn   Coming home from Rt. 66 a number of years ago, I ...   Apr 14 2018, 05:33 PM
Boomingbeetle   Sorry for the sideways pictures, they are not rota...   Apr 14 2018, 04:30 PM
falcor75   Just spend the last 3 hours fiddling with the thot...   Apr 15 2018, 05:28 AM
barefoot   Just spend the last 3 hours fiddling with the tho...   Apr 16 2018, 02:12 PM
jd74914   What is your target AFR? Or do you have a screen s...   Apr 15 2018, 08:22 PM
Dave_Darling   You could see lower flows if you have some valve ...   Apr 15 2018, 09:25 PM
jd74914   Good point. Totally forgot about that.   Apr 16 2018, 05:35 AM
falcor75   Target lambda is around 0,92 (8% more fuel than la...   Apr 16 2018, 09:22 AM
falcor75   I cant get a 0,05 mm feeler gauge in so both butte...   Apr 17 2018, 03:42 AM
falcor75   I spent 20 minutes this afternoon swapping the #1 ...   Apr 18 2018, 01:37 PM
falcor75   Had a 40 minute drive today, starting with slower ...   Apr 20 2018, 08:08 AM
jcd914   After reading through this and your struggles to g...   Apr 20 2018, 11:25 AM
falcor75   No they only have one air bleed screw for each pai...   Apr 20 2018, 12:01 PM
jcd914   Too bad. Their description says there is a vacuum...   Apr 20 2018, 05:29 PM
falcor75   Yes I'm not sure there's any fault with th...   Apr 20 2018, 11:42 PM


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