TheViper

i got an edelbrock 1406 and it runs good exept it is fouling plugs. i thought it was the distributer so i put on a vacume advance and i think it is still fouling plugs. i set the idle as lean as i could with a good idle. i cleaned the plugs so i could tell if they were getting fouled. after about 2-3 mins i pulled some plugs and the were dark tan and in some parts black. if i let it go much longer they will turn completely black.
i don't think it should be rich fro the factory since it is set for maximum fuel economy, but could it be too rich?

i don't have a timing light so i set it by ear, would this have any afect if its off just a little? if so which way should i go?

right now it has .098 main jets and 075 x 047 metering rods. i'm thinking about going 6% leaner to .095 main jets and 073 x 047 rods. what do you think?

TheViper

i didn't put in new plugs since i changed the distributer, could the already fouled plugs make them build up carbon faster?

if the plugs are to cool could that have an effect on it fouling? i have bosch supers for a 69 302 z28 in it right now. it has a little lower compression than the 302 so would that have anything to do with needing a different heat range?

should i just put in new plugs and see what happens?

also, i don't have the pcv valve hooked up. i hooked it up once and it opened and closed a lot making the idle go up and down. why is it doing this with the pcv valve conected? could it be a wrong pcv valve? could not having it hooked up making it run rich by not having the extra air?

Vader

Yes. If it has already started,it isn't going to get cleaner through continued use if the root cause is not addressed.



Yes. You could try a heat range higher, and avoid the "designer" spark plugs. Plain old copper cored, 'J' nosed Champions are going to work just fine, and maybe better.



See above.



If the valve operates rapidly (about 20-60 Hz.) at idle, the calibrations springs are probably wrong for the amount of vacuum being produced.



Yes, especially if it said "Fram" on the package.



Yes - definitely. In addition, your crankcase will get filled with moisture and contaminants in short order, compounding the problem.

TheViper

thanks a lot, that realy helps.

F-BIRD'88

Once plugs are carboned fouled they generally won't work right again even when you clean them.
Get new ones. You do not need a racing plug (cold heat range)
for the street. Or any kind of funky specialty plug.What heat range are they? Replace them with normal heat range AC delco or NGK or Champion spark plugs gapped at .035"....
You have old large plug 041 heads so look up the plug for a 68 chevelle
with a 327/300 hp motor not a 302 z28.
A faulty distributor can cause the plugs to foul. Same with bad plug wires or a bad rotor.

The out of the box carb jetting should be ok (certainly not too rich to turn the plugs black.) Unless you're at real high altitude.
The carb will be rich at idle unless there is a proper PCV system hooked up. Be sure the other valve cover is vented so the PCV "breathes" as opposed to sucking all the air out of the crank case (vacuum) if there was no valve cover breather.
If the stock intake manifold's exhaust heat crossover is open
allowing full manifold heat, this could cause the fuel to over vapourize from the plenum being too hot. This is a common senario on a Edelbrock performer intake. The remedy is to remove th intake and restrict the exhaust crossover flow
(intake gasket restrictor inset) Useing a edelbrock square flange
carb on a qjet intake with an adapter is not the best either. ( fuel distribution)
Get a qjet or get a square flange or dual flange intake like a performer or wieand action plus.

TheViper

what do you mean by large plugs? it has the smallest plugs i've seen on a car. there only like 1/2" reach(they are the correct reach) and there the same diameter as most other plugs. from what i've found out there off of a 69 302 or 350.

TheViper

i just checked mortec and they come up as 69-70 302/350 heads.


also found this,
"041" – 3947041, also 3947041X. A good performance head. They were found on 1969-1970 302 and 350 engines. They had either 1.94/1.50" or 2.02/1.60" valves, 64CC combustion chambers, DO have accessory holes, I don't have port volume data for the regular 041, the 041X intake port should be 165CC's, the 041X exhaust port should be 65CC's. These heads have a single somewhat triangular shaped casting mark (slope on the upper left).

and this,
3947041 63cc 1.94 1.50 1969-70 302/350 Right angle casting identifier, accessory holes. Good HP heads.
041 64cc 2.02 1.60

TheViper

what do you think could be the cause of the problem? could it just be the pcv valve?

TheViper

ok, i put a new pcv in that dosn't go up and down much and new plugs. it is running rough still and i can't get it to smooth out messing with the distributer and idle screws. could it be a vacume leak? it is also fouling the plugs still. i don't know what to do.

F-BIRD'88

5/8" hex peanut plug 70 up

13/16" hex large plug pre 69/70

1969 was the cross-over year. Some heads of the same casting number had both types. But most of the old hi perf (camel Backs)
had large 13/16" hex plugs. Which hex size are yours?

The plug heat range for a 302 Z28 will be a little too cool for every day street driving. Can tend to carbon up. That's why I suggested getting
a plug for a simular "low perf motor" like a 68 or 69 chevelle
327 or 350 ci 300 hp motor. ( hotter heat range)
What are the numbers on the white part of your plugs now?
What Brand?
The carb is designed to idle right with the PCV hooked up and functioning properly. Without this the car will idle rich.
If it is not hooked up right, then yes that is a contributing factor.
May not be the only factor.

Carbon fouled plugs will not "clean up" Even if yu clean them.
The carbon creates a short path so the spark does not jump the gap. ( in a regular fashion) (They're curb side material)

TheViper

i got the idle smoothed out good. i took the carb off and sealed the gasket up good and the brake line. it got plugs for a 327 this time, there bosh super i think. the #s are r6 282 i think on the new ones, the old ones where r6 191. i ran it around the block for a while and it didn't build up much carbon. it has the 13/16 hex.