Noobie with a 493cu

[ScottyG]

I got a 493cu
tf270s tf roller cam , HS 1:6 rockers
11.3:1
I got Holley terminator x efi system MPI

What spark plugs and what gap should I run on 93oct. Right now I got it at stock .035 and have autolites. I got it at 20* initial and 34 cruising and WOT at 30.
I know every engine will react different. Just trying to get some basic knowledge. Where other built engines like to run around at . Still tuning it and tweaking it.

 

[pnora]

Gap at .035 is fine. Read the plugs and adjust the heat range by the way they are burning. Forget about what someone else is running. Sounds like you are already in a decent tune.

 

[Geoff 2]

NGK '5' heat range.

 

[fourgearsavoy]

My 493 has a little over 12-1 compression with Indy EZ heads and I have been running NGK 7's and it runs really well. I set my base timing at 22 and total 34.

Gus

 

[451Mopar]

Nice setup there! On my 12.4:1 compression 499" low deck stroker I'm running the NGK heat range 7 spark plugs.

 

[not so famous bob]

I got a 493cu
tf270s tf roller cam , HS 1:6 rockers
11.3:1
I got Holley terminator x efi system MPI

What spark plugs and what gap should I run on 93oct. Right now I got it at stock .035 and have autolites. I got it at 20* initial and 34 cruising and WOT at 30.
I know every engine will react different. Just trying to get some basic knowledge. Where other built engines like to run around at . Still tuning it and tweaking it.

View attachment 1722531

you didn't say what ignition .
with a fast 2.0 , i run ngk 5`s in my 440/505 , ''M S D ign.'' , plugs gapped at .044 , locked dist. , fast controlling everything , more timing at wot....

 

[not so famous bob]

My 493 has a little over 12-1 compression with Indy EZ heads and I have been running NGK 7's and it runs really well. I set my base timing at 22 and total 34.

Gus

View attachment 1726720

I started with 7`s but don't have as much compression as you=5`s..., ditto on the 34 degrees..

 

[451Mopar]

I mentioned my 499" 12.4:1 compression Max Wedge head setup running heat range 7, which is a colder plug.
The more mild 505" 10.3:1 compression stealth headed engine has the hotter heat range 5 plugs. I usually just run a 0.040" gap.
On the 499" with 2" headers, I had problems burning plug wire boots so I finally bought some Accel 9000 ceramic boot plug wires.
The 499" was running a carb, and converted to the FiTech 1200 PA throttle body EFI, and running it with an old lean burn distributor.
The 505 was the old edelbrock XFI tunnel ram setup, but electronics converter to FAST 2.0

 

[fourgearsavoy]

My 493 has a mild Isky solid roller with 588 lift @ 248 duration. It has a nice mellow idle note but it screams at 6000. I run a Firecore distributor and wires fired with an MSD 6AL and Blaster SS coil. It's a fun street/strip car with a 4-speed and 4.10 gears.

 

[ScottyG]

Thanks for the reply’s .
Found out I have NGK r5672a-9.
did reading on plug wires and found out that am using prob the worst wires
Accel 9000 8mm with 500ohms ft, high resistance,and ferrite core . Had a lot of carbon fouling at idle and cruising

So am going to switch to some performance wires as in 8.5mm low resistance, 50ohm ft, and spiral core .
might run a step hotter plug the r5672-8 plug

 

[Geoff 2]

Absolutely no reason to be running such a cold plug......unless you are at WOT for sustained periods such as circle track or boat racing. Your plugs are fouling because the plugs are too cold, a common mistake; nothing to do with plug wire resistance. See the test below. Highest HP was NOT from lowest resistance wires!!!!! Spiral wound wires create an inductor. Now you have inductance, capacitance AND resistance in the mix. Also you have alum heads. Alum conducts heat better that iron, so more heat is being conducted away from the plugs into the coolant. Another reason to use a hotter plug to maintain tip temperature
You need NGK 5 heat range. I run one step hotter, 4s. An engine I tune, at 3900 lb without driver, with 3.31 axle has run 11.2/118 mph. It runs NGK 4s.

 

[Geoff 2]

From this chart from Bosch, you can see the operating temperature window for the centre electrode gets smaller as the heat range gets colder.

 

[Geoff 2]

Here is the chart

 

[ScottyG]

Absolutely no reason to be running such a cold plug......unless you are at WOT for sustained periods such as circle track or boat racing. Your plugs are fouling because the plugs are too cold, a common mistake; nothing to do with plug wire resistance. See the test below. Highest HP was NOT from lowest resistance wires!!!!! Spiral wound wires create an inductor. Now you have inductance, capacitance AND resistance in the mix. Also you have alum heads. Alum conducts heat better that iron, so more heat is being conducted away from the plugs into the coolant. Another reason to use a hotter plug to maintain tip temperature
You need NGK 5 heat range. I run one step hotter, 4s. An engine I tune, at 3900 lb without driver, with 3.31 axle has run 11.2/118 mph. It runs NGK 4s.

View attachment 1727832

Thanks for all the info. Reason why I made this thread. I need to learn. I will get a hotter plug than the 8s than just trying to be cautious.