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storm
Samba Member
Joined: April 28, 2008
Posts: 299
Location: Juneau, Wisconsin
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 Posted: Sun Jul 26, 2020 3:28 pm Post subject: Head temp 1&2 360 degrees |
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Have a Scat engine 2027, 8.5 compress. Question: have cht sensors under #2 and #4. #4 temp 300 degrees, # 2 360 degrees. Going down road at 60 mph
In a 66 bus approx 3200rpm on a 85 degree air temp. Ok 3&4 temps ok, but 1&2 temps higher why? Performance right on no pinging, I use high test gas 91. Why a difference between 1&2 and 3&4? Oil pressure 40# oil temp 190. Your input is required thanx
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Wreck
Samba Member
Joined: July 19, 2014
Posts: 1218
Location: Brisbane
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| Posted: Sun Jul 26, 2020 3:59 pm Post subject: Re: Head temp 1&2 360 degrees |
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what sort of intake ? Carb synchronisation if even a little out will make a difference in CHT's If the #1 #2 side is open more at idle then it will also be at cruise so that side is has more load the other less load . get them even and one goes up slightly and the other comes down .
I've asked the question ,what is the normal CHT spread for all 4 cylinders on a stock 1600TP with late factory tin and no seems know . |
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madmike
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Joined: July 11, 2005
Posts: 5292
Location: Atlanta,Michigan
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| Posted: Mon Jul 27, 2020 5:33 am Post subject: Re: Head temp 1&2 360 degrees |
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It also depend on gearing ,stock trans? Head winds/hills plays a HUGH part with Buses,I know I drive a 70 Bay every day spring-Fall 
good tune as in air/fuel ratio gauge? good flowing exhaust?
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76 Drag/Street bug 2180cc 'Turbo' 11:85 @113 mph"If I go any faster I'll burn up the Hamster" ,gets 28 mpg. also 10/09/22 11.90 @115 mph
"If I'm ever on Life Support,UNPLUG Me, Then Plug me back In see if that Works" |
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Lingwendil
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Joined: February 25, 2009
Posts: 3988
Location: Antioch, California, a block from the hood
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jeffrey8164 
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Joined: January 06, 2018
Posts: 3819
Location: Georgia
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| Posted: Mon Jul 27, 2020 11:51 am Post subject: Re: Head temp 1&2 360 degrees |
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I’m jealous of your numbers.
My heads seem to level out at around 420° and I have all the tins, and a venturi ring. I even backed my timing down to 28°. Don’t really know where to go from here.
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storm
Samba Member
Joined: April 28, 2008
Posts: 299
Location: Juneau, Wisconsin
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| Posted: Mon Jul 27, 2020 5:57 pm Post subject: Re: Head temp 1&2 360 degrees |
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Thanks for the responses. Yes all cooling tins and thermostat. Scat fan housing. I will try to balance both carbs IDFs. Thinking that 1&2 side is working more than 3&4 side. If that doesn’t change things, then look for vacuum leaks and other important items so far mentioned on this post. Otherwise the engine runs strong without any problems. I figure that both heads will balance with better temps. Maybe 325 degrees on a 90 degree day.
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74 Thing
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Joined: September 02, 2004
Posts: 7394
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| Posted: Tue Jul 28, 2020 8:57 am Post subject: Re: Head temp 1&2 360 degrees |
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#3 is usually the hottest you should change the sensor to that spark plug.
It probably has a lot to do with the fan shroud.
Jake Raby did a fan shroud test years ago that was very informative. |
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petrol punk
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Joined: August 21, 2007
Posts: 977
Location: Las Vegas, NV
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| Posted: Wed Jul 29, 2020 3:40 pm Post subject: Re: Head temp 1&2 360 degrees |
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| storm wrote: |
Have a Scat engine 2027, 8.5 compress. Question: have cht sensors under #2 and #4. #4 temp 300 degrees, # 2 360 degrees. Going down road at 60 mph
In a 66 bus approx 3200rpm on a 85 degree air temp. Ok 3&4 temps ok, but 1&2 temps higher why? Performance right on no pinging, I use high test gas 91. Why a difference between 1&2 and 3&4? Oil pressure 40# oil temp 190. Your input is required thanx |
Have you tried swapping the thermocouples and/or gauges? They could be inaccurate. My CHT gauge reads 150f-200f with 110f ambient air temp and 180f oil temp. There's no way the heads run THAT cool, I just know that if it goes significantly higher than that something is up.
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madmike
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Joined: July 11, 2005
Posts: 5292
Location: Atlanta,Michigan
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| Posted: Thu Jul 30, 2020 3:31 am Post subject: Re: Head temp 1&2 360 degrees |
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Scat shroud is a prudy good one compared to some others 
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'Black Ice'Drag Buggy 'Turbo'
Rail Buggy 1915 turbo
76 Drag/Street bug 2180cc 'Turbo' 11:85 @113 mph"If I go any faster I'll burn up the Hamster" ,gets 28 mpg. also 10/09/22 11.90 @115 mph
"If I'm ever on Life Support,UNPLUG Me, Then Plug me back In see if that Works" |
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storm
Samba Member
Joined: April 28, 2008
Posts: 299
Location: Juneau, Wisconsin
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| Posted: Mon Aug 17, 2020 7:42 pm Post subject: Re: Head temp 1&2 360 degrees |
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Solve! Well after some time has passed, I finally found out why #2 side of the head was so hot compared to the other temps. Turns out that the idle circuit was clogged. Not the idle jet but the channel that air and fuel goes I passed a thin wire like a guitar string and found sticky dirt in one of the idle circuit tubes. Now the temps on #2 sensor under that spark plug is similar to the other readings. How I determine this by increasing the idle jet from .52 to .65. Doing this increased the amount of fuel that mixes with air. That experiment brought down the temps.
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Dan Ruddock
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Joined: October 25, 2012
Posts: 3594
Location: Sarasota, in my adopted state of Florida
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| Posted: Mon Aug 17, 2020 8:44 pm Post subject: Re: Head temp 1&2 360 degrees |
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| storm wrote: |
| Solve! Well after some time has passed, I finally found out why #2 side of the head was so hot compared to the other temps. Turns out that the idle circuit was clogged. Not the idle jet but the channel that air and fuel goes I passed a thin wire like a guitar string and found sticky dirt in one of the idle circuit tubes. Now the temps on #2 sensor under that spark plug is similar to the other readings. How I determine this by increasing the idle jet from .52 to .65. Doing this increased the amount of fuel that mixes with air. That experiment brought down the temps. |
Well done, #2 spark plug probably looked leaner? Without dual cht sensors you would of never known there was a problem. |
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vwinnovator
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Joined: July 11, 2005
Posts: 1555
Location: Still doing it in the back of your VW
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| Posted: Thu Aug 20, 2020 7:55 am Post subject: Re: Head temp 1&2 360 degrees |
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| jeffrey8164 wrote: |
I’m jealous of your numbers.
My heads seem to level out at around 420° and I have all the tins, and a venturi ring. I even backed my timing down to 28°. Don’t really know where to go from here. |
run methanol ..lol |
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