#1  
Old 09-27-2018, 03:49 PM
Navy Horn 16 Navy Horn 16 is offline
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Default #2 exhaust port temp....

I ran a rally back in June, and notice that all of my headers had bleached white from the heat except for #2. On closer inspection, I found that the spark plug was loose and it wasn’t getting full compression as a result. I fixed the issue, and there is no blow-by in that cylinder. The car runs good, has no sound of running rough, but I expected that header to turn white from heat like all the others. It didn’t. Yesterday, at Auto-Zone, I bought one of those infa-red thermometers that you can take the temp of something by pointing at it. Well, sure as hell that header is way colder than all the others.....like 200 degrees colder than #1.

After running for a few minutes with the engine fully warm, the #2 header got up to about 350 degrees and #1 was about 550. I pulled the valve cover and the valves are not hanging open. When the lifters are on the base circle a .008 feeler gauge can still be worked under the roller. I pulled the plugs, and they all look fine. #8 was white, which is weird. 2,4, and 6 were the same.

I’m running Auto-Lite 3924s, recommended by many here.

I know that the coolant pattern goes to #2 first, but I wouldn’t think that the head temp at that location would keep the header pipe that much cooler a couple inches from the head. Every port on the drivers side is much hotter than the passenger side.

It is a HSD intake with a 1inch spacer, so there is zero chance that one side of the motor is getting a dramatically different fuel/air ratio than the other side.

Do I actually have a problem, or am I just looking for one.

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  #2  
Old 09-27-2018, 05:09 PM
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Sounds like a Q-Jet expert question.

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  #3  
Old 09-27-2018, 08:31 PM
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for every open-plenum Single-Plane CYL 1 robs CYL 2; just a matter of how much.

try a dual-plane and see the balance come back.

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Old 09-27-2018, 10:42 PM
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Maybe #2 is using coolant. Get one of those $15 USB bore scopes and see if the piston top is clean.

Not sure if that would cause it, just a guess for something to check.

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Old 09-28-2018, 01:51 AM
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If you were getting coolant into #2, I would expect white 'smoke' from the ps exhaust. Also, coolant level should be down.

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Old 09-28-2018, 02:04 AM
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Sometimes a simple answer is the best answer. I'd say #2 is firing part of the time. All you have to do is find out whether it is a bad wire or bad plug. Swap #4 with #2 plug and take a drive and see if the cylinders swap temperatures. Next would be to substitute out the plug wire and see if that makes a difference.

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Old 09-28-2018, 02:12 AM
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Quite possible if #2 plug was loose that the plug was arching on the head, generating higher voltage through the wire to jump the gap, breaking down the wire, degrading the distributor contact for that wire etc. Check the contacts in the cap, replace the wire.

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Old 09-28-2018, 05:20 AM
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Quote:
Originally Posted by Greg Reid View Post
If you were getting coolant into #2, I would expect white 'smoke' from the ps exhaust. Also, coolant level should be down.
Only if the leak is big enough. I had a small leak (coincidentally on cylinder #2) and never saw anything abnormal out the tailpipe. Piston and chamber were spotless though, no carbon like the others. No misfire either.

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Old 09-28-2018, 09:32 AM
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Thanks guys...

I spoke to a few gentlemen on the phone who are way more experienced with this stuff than I am. One of my big errors was only doing the testing at idle. I'm going to run it up to about 2000 for 90 seconds or so, then check the temps.

One thing that I didn't even consider, was that a lower temp could actually mean that it is running more efficiently, because less still burning fuel is ending up in the header tube.

I also learned that #8 is consistently a "problem child". It is common for bracket racers who control timing on each cylinder to pull as many as 3 degrees of timing out of the back cylinders to keep from preignition.

I am certain that I don't have a coolant leak.

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Old 09-16-2019, 12:59 AM
wbnapier wbnapier is offline
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Did you ever get a read on this?

I'm searching the forum as I have the same issue on #1. About 400, when the others are 550-650.

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Old 09-16-2019, 07:54 AM
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My first guess is that the number two plug needs to be replaced.

Confirm this by swapping it for one who's cylinder reads a normal temp.

If that fails then it's time to do a leak down test and confirm that the valves are sealing .

If this checks out then it's time to dive into the Dizzy and plug wires, in fact now that I think about it before you swap out plugs swap out plug wires to see what takes place .

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Old 09-16-2019, 08:22 AM
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Sinlge-Plane Plenum wars: CYL#1 robs #2 air/fuel charge.

CYL #1 colder...Intake lobe or lash? or run it at highway rpm and load for a reading?

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Old 09-16-2019, 08:35 AM
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Cylinders 1 and 2 are not in the same bank of cylinders to rob fuel from each other like 5 and 7 do!

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Old 09-16-2019, 01:10 PM
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Quote:
Originally Posted by steve25 View Post
Cylinders 1 and 2 are not in the same bank of cylinders to rob fuel from each other like 5 and 7 do!
Oh yea! Well last time i looked the Port 2 faced Port 1 in a Single Plane; where some single planes don't angle the ports, or VEE the front plenum wall to restrict crossflow. I think Ports facing can rob better or as-well than side-side ports like 5-7. Really depends on what plenum you are staring at.

218436572

1 robs 2 CYL filll before #2 Intake closes. As you know so does 7 rob 5.

3 robs 4
5 robs 6

Certain Single Planes can play well on the Street for MPG at low rpm for this matter, and turn-up the HP with a large Throttle plate CFM delta. Whereas a Dual-Plane is always ready...huh.

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Old 09-16-2019, 02:23 PM
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HIS, You ever Video Record what actually happens inside of a 4 cylinder Plenum?
6 cylinder Plenum? 8 or 10 Cylinder Plenum? or an Aston Martin 12 cylinder plenum?

Well I have on a Research Dyno. We used video cameras installed in the actual running engine plenums.

I will just say that what you THINK happens does not happen in real life many times.

You might want to read about what John Kaase presented at a 2015 Advanced Engineering Technology Conference held just before the PRI Show.

https://www.enginelabs.com/news/amaz...th-his-finger/

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  #16  
Old 09-16-2019, 05:59 PM
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The Kaase video was fun then.

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