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PostPosted: Tue Oct 29, 2019 9:51 am 
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This doesn't have much to do with the water pushing issue on the 393C - except maybe for the color of 4 and 8, so maybe it does - but looks like I'm a hair on the lean side of things. Methanol, plugs are NGK BCP7E. Might need a hair more jet and/or maybe a colder plug? Assessment appreciated. 8 is interesting due to the red tint. The engine started pushing water out past the cap and filling the overflow tank on the first pass Saturday. #4 especially looks crusty. Only thing in the cooling system is distilled water and about 1/3 of a small bottle of Water Wetter.

4 to 1 (left to right)
Image

5 to 8 (left to right)
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Closeup #4
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Last edited by Falcon67 on Wed Oct 30, 2019 8:58 am, edited 1 time in total.

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PostPosted: Tue Oct 29, 2019 2:51 pm 
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Well FWIW:

4 does look a tad lean, 1 is fine, 3 & 2 look to be oil or perhaps fuel wet.

5 is lean, 6 is fine, 7 is weird and 8 is fine.

I'll ask though:

-how many runs were on these plugs? I'd try new ones and 1-2 runs at most, WOT, then a clean shutoff (as you already know!) and compare.
-how do all these plugs compare to the last set or the last time you looked at these same plugs.
-have you noticed in the past any cylinder to cylinder variations that may be caused by the intake manifold not feeding each pretty much evenly?


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PostPosted: Tue Oct 29, 2019 3:37 pm 
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Set has been in there all year. 100 plus passes at least, maybe more. No old set, tossed last year, no notes Running the same plug number for the last 3 years. Been on methanol for about 2 years, no noted changes in performance or anything else. All good until I got a hot water bath in the shutdown on Saturday. Car ran 5.378 on a predicted 5.38 from the weather station. Then puked its guts everywhere.

No water in the oil, so still unknown what's going on with that. I can't do the "run and shut off" method of plug reading because we don't own anything capable of towing me and the car back to the pit.

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PostPosted: Tue Oct 29, 2019 5:45 pm 
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Falcon67 wrote:
No water in the oil, so still unknown what's going on with that. I can't do the "run and shut off" method of plug reading because we don't own anything capable of towing me and the car back to the pit.



I've pulled one on the return road more than once. Carry a spare and a ratchet. Kill it at the stripe, coast to the return road, pull a plug, swap it with the spare you carried, then drive back to the pits where you can inspect the plug.

I'm curious as to why it puked water out the radiator but there isnt any in the oil. Do you think it popped the head gasket? Or did the cap get weak? Are you going to run leak down on it before tearing it apart to see if anything looks strange?

How much compression is that motor? A 7 seems hot to me unless it's only 11-1, and then it's still borderline for my tastes. I've got 9's in my 13-1 motor.
Oh yeah, which heads are on that? Those look like a gasket seat plug instead of a tapered seat. You probably have some "fancy" aluminum head on that thing. LOL

Just looking at the pictures, it looks like it could use a touch more timing as well as a bit more fuel.

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PostPosted: Wed Oct 30, 2019 5:07 am 
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Couple of lean holes, plugs too hot, too much timing. They all could be related.

If the timing is locked out, all of the straps are showing too much timing, by about 2 degrees or so. You're also showing about 6 threads with heat in them and it's hard to tell from a computer, but a couple look peppered to me.

#5 looks gleaming white from here, but it could be glare or flash. If it's very clean and gleaming white, you could have a water leak there. A red tinge usually indicates a race gas additive or maybe a little rust.

As for timing, here's how you read them: I've put yellow marks pointing to where the timing marks are. You usually want these to be in the apex of the curve of the strap, but ultimately the timing is set to where the car goes the fastest.

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PostPosted: Wed Oct 30, 2019 8:52 am 
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Thanks very much Brent - that helps.

Timing is locked at 28. 5 is pretty white and most of the insulators show a bit of pepper. I didn't get a good pic in the phone of that set, will try again tonight LOL. I have spares but I will order some #6 which is one step colder. I'll talk to my carb guy about possibly going up a jet size. The car has never had the typical "methanol attitude" - hard to warm up and such. It's not much different than when running race gas. Starts easy, warms up in a reasonable amount of time. I did have to squirt some gas in the carb Saturday to start it up because it was only 48F at 10 AM. One I got it to fire it was OK. It also heats up after a run which is counter to what most people see when running alcohol. The red plug has only been on methanol and I only use Klotz in the fuel so that may be rust. Not good either.

The plan right now is to try and get the pit bike 70cc motor off the bench (hand finishing an exhaust seat using crude tools) and get the motor out and on a stand to do forensics. First I'll drain some more water out and put air in it with the plugs out to see if I can hear a leak.

I'm worried a bit that it's the block because the car was fine until it got to around 170F then started blowing out water. So either a head gasket, or worse. I doubt the cap because once it got to temp the water started and just kept coming until it was nearly dry. Static test in the pit it lost about 1/2 gallon just idling, shut it down at 220F.

Motor is 11.8:1 and the heads are those fancy AFD units from Australia. :)

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PostPosted: Wed Oct 30, 2019 11:31 am 
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Other direction on the NGK plugs heat range. The higher the number the colder the plug. Which means my 9's are ridiculously cold for a 13-1 motor. LOL

I always thought the farther towards the end of the strap the mark was, the more timing it had? That's why I thought it didnt have enough.
My mark was originally out on the flat part of the strap, over the electrode when it had 38*. I backed it off a couple of degrees to 35* and that put the mark in the bend. And the car went faster.

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PostPosted: Wed Oct 30, 2019 5:53 pm 
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Thanks for the correction, had that backwards for NGK.

Found this on the net - echoes what's been said I think
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PostPosted: Wed Oct 30, 2019 6:34 pm 
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Looks like I've had it backwards on reading the strap for timing.
Good to know.

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PostPosted: Wed Oct 30, 2019 9:09 pm 
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Anybody got an NGK part number for the BCP8 plugs. Not finding easy for some reason

Edit - NGK 3923 BPR8ES is what i found. That right?
EDIT AGAIN - can't be, B = 14mm 13/16 hex and BC is 14mm x 5/8, I don't think a 13/16 socket will fit these AFD heads.

Per NGK site "NGK BCR8ES Is Not Available In The US" - ???

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Last edited by Falcon67 on Thu Oct 31, 2019 11:15 am, edited 2 times in total.

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