Poly 318 Spark Plug Coloring

[R. Shackleford]

Hey all, got the Poly 318 in my '65 Belvedere and been runnin around for a little while with a Holley 4160 I've been playin with. The carb is a 80454 model so I realize its an "economy" carb so not looking for high performance or anything. I put a 8.5" power valve in it do to 17" of vacuum at idle and the 6.5"pv was stumbling off idle. Now she picks up nicely with no hesitations. The jets are stock to the carb (.622) and was thinking about taken them up to .63 or .64. Car runs great as is but the plugs seem to be a little lean. Or maybe I'm just not used to a proper running engine haha. What do you think?

 

[Don Frelier]

That's either really lean or you haven't run it enough to color anything.
But it sure doesn't seem to burn oil.

 

[Cranky]

That's either really lean or you haven't run it enough to color anything.
But it sure doesn't seem to burn oil.

Looks like some I've seen after making a pass at the drag strip and cutting the engine clean at the end....

 

[R. Shackleford]

Well I've been runnin these plugs for about 500+ miles. Yeah definitely doesn't burn oil haha.

 

[Cranky]

Well I've been runnin these plugs for about 500+ miles. Yeah definitely doesn't burn oil haha.

Looks to me like the electrode has burned off a bit? If it were mine, I'd step up the jets a point and then check again after installing new plugs.

 

[R. Shackleford]

Looks to me like the electrode has burned off a bit? If it were mine, I'd step up the jets a point and then check again after installing new plugs.

Yeah I got new jets on order so I'll bump em up a size and check. I will replace the plugs as well

 

[Cranky]

Yeah I got new jets on order so I'll bump em up a size and check. I will replace the plugs as well

Don't throw away the old plugs....if the new ones show a but more rich, then the old ones will fit in just fine. Been doing that stuff for years and have never burned up a piston. Can't say that for my buddies that like to run N2O lol

 

[Budnicks]

here's the best info I can offer, I go by it like it's mandatory
best way to learn to read plugs, it's on NGKs but it will work on any plugs
just not as easy to see color changes, good luck

 

[R. Shackleford]

Thanks for all the advice and pointers everyone! Little update: Swapped out jets from 622 to 63s and updated the accelerator pump. Smoothed out the idle a bit and she runs like a top. Accelerates nice and smooth with good power. My parts house was closed so didn't end up swappin plugs but I will pick some up today after work today.

 

[Don Frelier]

Thanks for all the advice and pointers everyone! Little update: Swapped out jets from 622 to 63s and updated the accelerator pump. Smoothed out the idle a bit and she runs like a top. Accelerates nice and smooth with good power. My parts house was closed so didn't end up swappin plugs but I will pick some up today after work today.

I'm not sure why you would need/want to change the plugs?
They should only get a bit darker here and there.
I wouldn't expect any other gains just cost and time to install the new ones.

 

[R. Shackleford]

I'm not sure why you would need/want to change the plugs?
They should only get a bit darker here and there.
I wouldn't expect any other gains just cost and time to install the new one

Thanks man. I have a hard time deciphering the colors due to being color blind haha. I appreciate it!

 

[R. Shackleford]

Ok car runs fantastic in the morning time. Cool air keepin the engine cool and its perfect (heat gauge sits about 1/4 up from cold). After work on the way home, it's about 85 out, and she runs awesome until the heat gauge gets close to half way. Then the idle gets rougher and runs a bit rougher until I get movin more and the heat gauge drops back down a little. Maybe the fuel is gettin too hot? Thoughts?
I haven't changed out the thermostat yet so it's about 25+ years old and not sure what the open temp is. I have a 180 I'd like to throw in cause she seems to like a colder engine

 

[RemCharger]

Is the exhaust flap flappin' ?

 

[Ron H]

My 2-pennies, given your comments (not knowing overall condition of things) you might do a cooling system flush (radiator + block) if that’s not been done in years. Get some flush cleaner. Replace the t-stat. If the hoses are old check their rigidity. Old hoses get thin skin like old people, ask me how I might know, lol. Given your motor runs so sweet, hesitant to say adjust the timing or carb. You likely know too lean can mean heat.

Different circumstances as my poly has been bored .60, among some other HP things, had overheating problems leading me to do several things getting the desired result. If you have an infrared thermometer, check that against your dash gauge. Part of my travels here checked it against the dash so I know where the temp is. I changed the sending unit as it was a few decades old.

 

[Budnicks]

Just spitballing here, pretty common in hotter temps/summer...

The new gas formulas out here especially 'on the west coast' eco-nazis crap, sucks...
Fuel could be borderline vapor locking, gas almost boiling in the carb,
lots of ethanol continent in that gas now too...
(very corrosive & bad for rubber & aluminum parts, esp. in these older cars, use an additive)

your heat riser, from the cylinder heads combustion,
that makes heat into the intake thru the choke crossover passage
is probably the culprit...

too retarded ignition timing or cam timing, can cause heat too

Probably...
Maybe put a 'thicker gasket' under the carb, like 1/4 insulator/spacer
or a aftermarket heat shield, could solve the borderline vapor lock issues...
You will/may have to do a lil' bending of the 'choke stove rod'
straighten it out or bend the spring a tad
to make it work right still...
If it even still has one...

Or block off the heat riser passage all together, take the intake off get the
Felpro style intake gaskets, with the metal blocking plates
if the car is in a warmer climate, you may not even need a choke
unless you drive a lot in the winter, colder months, if it needs a choke to start easily...

good luck

 

[R. Shackleford]

Ok thanks all for the responses. I'm using the stock '65 dash gauge so doesn't have any actual degrees. I have an inferred heat gauge that shows the crossover is heating up more so than the intake ports. Also carb is on a 3/4" riser with an auto choke. The engine was rebuild in the late '90s and as far as I know nothing has been done since. I will flush the system and start fresh. It never goes above the half way mark on the heat gauge so at least there's that haha. Oddly enough today I went to start her and got nothing... Oil light, radio and heater all come on normal when key is turned but when I went to actually start it there was nothing. Maybe neutral safety switch? Ignition? Fuse? I'll have to figure this out when I get home. Then I'll get to the heat issue

 

[HEMI-ITIS]

Going back to the plugs,,the strap shows very hot plug.
I would run a colder plug

 

[Cranky]

Ok thanks all for the responses. I'm using the stock '65 dash gauge so doesn't have any actual degrees. I have an inferred heat gauge that shows the crossover is heating up more so than the intake ports. Also carb is on a 3/4" riser with an auto choke. The engine was rebuild in the late '90s and as far as I know nothing has been done since. I will flush the system and start fresh. It never goes above the half way mark on the heat gauge so at least there's that haha. Oddly enough today I went to start her and got nothing... Oil light, radio and heater all come on normal when key is turned but when I went to actually start it there was nothing. Maybe neutral safety switch? Ignition? Fuse? I'll have to figure this out when I get home. Then I'll get to the heat issue

The first thing I always checked on a 'nothing' happening deal is the neutral safety/starter relay. Had two 66 Belvedere's that did the same thing on occasion. Usually just crossing the terminals did the trick. Just make sure the car in park or neutral and the park brake is set before doing that.

 

[R. Shackleford]

Going back to the plugs,,the strap shows very hot plug.
I would run a colder plug

I guess I'm not familiar with a colder plug. Any suggestions?

 

[HEMI-ITIS]

When you buy your new plugs take the old one and ask for 2 steps colder. Or,,post your plug number and the guys will give you the right number.