Checking correct fuel level at Round Top 3 screw SU CARBS Float bowls

[Mark Maras]

@jalexquijanoSitting here sipping my PineSol and Quinine I seem to remember previous trouble with one of those center plugs that I thought you cleared up with a new quality (Bosch?) cap and rotor. You already had new wires and plugs. Is this the same problem cylinder and problem that has come back or is it ongoing?

[siteunseen]

Thanks for the idea Mark. I'm having trouble sleeping these past few weeks so I decided to mix up a warm nightcap of Pine sol topped off with some whipped oven cleaner. Having a hard time finishing this post, getting very slee

[jalexquijano]

14 hours ago, Mark Maras said:

@jalexquijanoSitting here sipping my PineSol and Quinine I seem to remember previous trouble with one of those center plugs that I thought you cleared up with a new quality (Bosch?) cap and rotor. You already had new wires and plugs. Is this the same problem cylinder and problem that has come back or is it ongoing?

I have new wires, new rotor, new cap. I just replaced all those plugs with new ones and do experience change in idle in plug 4. I had this problem previously and with some hard acceleration i could clean that plug to make it go away. 

Edited May 8, 2020 by jalexquijano

[Mark Maras]

 Interesting. How many miles do you drive before a new plug in #4 starts to crap out when accelerating? "Back in the day" if we had one cylinder that loaded up a plug more than the others we would use a hotter plug. In your case you'd use a BPR5ES in that cylinder, but the problem with #4 is most likely an electrical or a problem that would show up in a compression test..

 

[jalexquijano]

12 hours ago, Mark Maras said:

 Interesting. How many miles do you drive before a new plug in #4 starts to crap out when accelerating? "Back in the day" if we had one cylinder that loaded up a plug more than the others we would use a hotter plug. In your case you'd use a BPR5ES in that cylinder, but the problem with #4 is most likely an electrical or a problem that would show up in a compression test..

 

Last compression test results

[Mark Maras]

 Those numbers are excellent. I remember going down this road in the past. Deja Vu all over again. I can't think of any other reason for the dark #4 plug than electrical and it has to be somewhere in the cap, rotor (unlikely), or the wire. As I recall you replaced the cap and rotor with a good brand along with many sets of plugs. The wires were fairly new and of good quality but I'd start looking at #4 wire connections, both ends and measure the resistance in all the wires to see if #4 is going bad before the others. Meanwhile how is your float project going?

[Zed Head]

How about a bad valve seal?  And, the oil rings scrape oil, the compression rings create pressure.  You can have a bad oil ring with good compression rings.  A possibility.

This is an old California Datsun engine, maybe Datsun Parts LLC.  Quality was suspected from the start.  I'd put that hotter plug in and just drive it.

[siteunseen]

1 hour ago, Zed Head said:

This is an old California Datsun engine, maybe Datsun Parts LLC.  Quality was suspected from the start. 

Bingo!

[Mark Maras]

@jalexquijano If you're going to try the hotter plug in #4, I'd use a BP5ES not a BP5RES. The rest of your plugs are BP6ES. No need to throw a resister plug into the mix.

[jalexquijano]

31 minutes ago, Mark Maras said:

@jalexquijano If you're going to try the hotter plug in #4, I'd use a BP5ES not a BP5RES. The rest of your plugs are BP6ES. No need to throw a resister plug into the mix.

I.have a new set of bp5es. What will i achieve with that? Wouldnt using such plug value damage the engine?

[Mark Maras]

 Heck, you're all set. No damage to the engine. The hotter plug extends into the combustion chamber a bit farther is all.

[siteunseen]

Learned something new. Thanks Mark!

Is it the porcelain tip part or the overall length of the plug? Gap stays the same?