Airbornec507

As stated. I have brand new TR6 spark plugs in the #7 and #8 cylinder but when I put the IR temp. sensor on it they read 200 and 300 respectively with the rest of the cylinders registering btw 400 and 550.

300 - 8 7 - 200
410 - 6 5 - 420
500 - 4 3 - 550
400 - 2 1 - 540

I adjusted the individual cylinder fuel trim at idle two try and get cylinder #7 3% hotter but it had no affect on a brand new plug with new wires to all cylinders hooked up to the delteq ignition. All rockers are adjusted to 1/4 TPZL. Could this possibly be an injector problem or is this normal for a Lloyd Elliot ported Intake on stock ported heads? Let me know what you all think. I'm prolly going to crank it with the spark plug attached to the wire, out of the engine, next to see if I'm getting spark.

If I can manage to get those back to cylinders to raise the temp by 200 degree F* I'll be able to get some accurate readings for tuning with the wideband. But until I find out what's up with those rear two cylinders I'm kinda stuck. I'll also see if they heat up next time with the accelerator at 40% just to see if it's the inj. table I'm in. Hmmmm.

Airbornec507

Confirmed a good spark to #7 so I dunno. The tip of the ground strap was actually white with a perfect change of collor right where the 90 degree bend is so I know the timing is dead nutz on. I reved it up real good though just prior to shutting the motor off so maybee the "off idle" gets the job done and the "at idle" table is a little off. Maybee it has to do with the flow of Lloyds intake or maybee both rear injectors stick. Dunno. Mabee I should go ahead and take away 8% more fuel from #7 and 5% from #8. Any ideas, suggestions, experience in general? Heck it could just be the different angle I'm holding my IR sensor at since those primary tubes are back up in there.

rclearyiii

Swap some injectors around and see if the problem follows.

Injuneer

Did you very carefully space the IR temp sensor exactly the same distance from each primary tube? The typical IR units have at least an 1:8 angle, meaning at 8" from the read point, the area being read is a 1" circle. It will read a lot besides what you're aiming at as you get farther from the point you want to measure. Did you point it at a spot of equal emissivity? Rust produces a different result than a shiny spot. Were you reading the point closest to the header flange? Did you allow for the fact that the siamesed cylinders in an SBC typically produce hotter exhaust, because of the limited cooling jacket in that area?

I wouldn't attempt to tune my engine with an IR temp sensor.

Airbornec507

Each time I tested I was apprx. 1" from the flange. All distances were around 2" from the cylinder as I tried to get it as close as I could for 10 to 15 seconds without scorching myself and recording the average primary heat range.

Basically I'm trying to get all the cylinders to read within 100 degrees from each other then tuning the car with a wideband. My wideband sensor is about 24" from the primary header collector on each side of the dual exhaust. I'll see if I can read the primaries from some different angles and try to find the hottest temperature reading. It's just kind of odd that the rear two cylinders are so cold compared to the rest of the cylinders.