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Need a little help getting some plug readings... I seem to be all over the board with what looks like really fouled to about perfect depending on the cylinder. Running Autolite 3924's which are a mid-range heat plug according to Autolite. Last digit in the part # indicates heat range, 1 being the coolest and 5 being hottest (I think that's' the whole range anyway)... Fi-Tech EFI and 10.9 compression with 93 octane pump gas. That # 2 makes me think I have oil getting into the cylinder.. Either that or I need hotter plugs to burn off the carbon?? Other thoughts?
Cylinder 1 top left Cylinder 2 and 4 are drastically different, 4 looks correct and 2 is seriously fouled.
Definitely burning oil. Also looks a bit rich but could be from the plug being a bit on the cold side. If I remember my autolite numbers correctly the 3926 is hotter. You can also try the NGK BKR4E-11, it's pre-gapped to 0.044". Or if you prefer 0.035" the BKR4E. These are one step hotter than 3924's.
Appreciate that Zwede, so I'm guessing I should do a quick compression test on all the cylinders and see if I'm getting oil by the rings??. I can't imagine it would be from the valve guides. The AFR heads only have ~3k miles on them.
From: Las Vegas - Just stop perpetuating myths please.
Unless you saw blue smoke out the tailpipe I would say your Fi-TECH is way to rich. And I would expect black smoke from that. Have someone follow you when you go WOT. But yes a compression test would show blowby on the rings as low compression. But if your compression target was high in the near 200psi range and you find 160psi or greater you may not recognize that as low. That where a leakdown test can help.
Thanks Cardo0, I'll do the tests and see what that looks like. I get smoke on startup but it's not blue, more of a rich condition black/grey and fuel smelling vs. oil. Really hoping it's just the FiTech, but if it is I must have pretty poor fuel distribution across all cylinders given how a couple of plugs look really good and others totally fouled. Running an Edelbrock Performer RPM Intake with a 1" spacer so it's about as good as it's going to get distribution wise I think.
Can plugs be cleaned and put back into service by lightly wire brushing or something or should I just chuck them and start over? Thanks!
There are spark plug cleaners which are basically mini sand blasters. But with those you run the risk of sand particles stuck in the plug and then getting into the engine. So short version is replace the plugs.
From: Las Vegas - Just stop perpetuating myths please.
Well if the plugs are fairly new and you are still troubleshooting then a wire brushing and a little sandpaper (if even needed) will get you back to base line. You can put new plugs in once problem is resolved. I just think this would be not only cheaper but faster. But on the other hand I don't think trying a 1 step hotter sparkplug would hurt anything either. Tough decisions are yours my friend - sorry.
As for the intake I have read of problems with dual plane intakes using wet flow EFI - right on this forum. Why? My guess it's how the fuel puddles inside due to the sharper bend angles of the dual plane. And many aftermarket EFI have a tuning parameter called Tao which relates to the added enrichment of fuel as it comes off the runner as flow increases. I realize it's a lot of work but maybe a single plane with gradual bends and down slope to the head ports may not have the same issue. But I'm just assuming here so please don't jump on any big changes until your ready.
Hope this can help. But I'm interested in what works here.
Yep,, throttle body EFI 's like single plane , just my experience,,,,
Thanks guys, I'll do some digging around on this forum and see what I can find about Dual-Plane and EFI. I don't have a problem changing to single-plane but already have a relatively big cam and don't want to lose any additional low-end. That said, the cam probably a little mismatched with the dual-plane intake, it's a 237/237 duration with .560 lift and a 110 lsa with a mfg rated operating range of 2400 - 6400 rpm.
If it is on all cylinders your Carb needs adjusting or rebuilding.Try some spit fire spark plugs that have two or more electrodes on end of plug ,less chance of fouling!
It looks to me you have both a rich condition and an oil condition.
What A/F ratio are you with idle and cruse speeds ?
This^^^^^. The plugs look wet to me. If you have wet oil on the threads then you are sucking oil
through the rocker arm studs, or the PCV valve, or sucking it directly from the valley between the
intake and head. So... if wet, you have to fist that problem first. It will also through the EFI system
off wack trying to compensate for the rich and lean variations during plug foul burns.
Originally Posted by fake
If it is on all cylinders your Carb needs adjusting or rebuilding.Try some spit fire spark plugs that have two or more electrodes on end of plug ,less chance of fouling!
Spark Plug Readers Needed
