youlittlejerk

Hey guys, I did a quick search and couldn't find anything on this.
I am looking for the right spark plug for my carb'd 5.7 with ported heads,V2 cam, and a Victor Jr. Intake.
MSD 6010 box seems to be running correctly but the engine begins to miss as the RPM goes above 1,400. If I continue to hold the throttle it will start to backfire through the exhaust.
The engine currently has the stock recommend AC Delco platinum plugs but these are for a fuel injected application and I worry they may not provide enough spark for this old carb setup.
What are you using? I need some help

89C1500

Also in for answers!

Doug G

Are you using the MAP ?...zero it out until you get issue fixed (if yes or no)

More about the build would help.

Mine ran fine with the "stock" AC plugs.....but BR7's right now since they were a little too hot for my combo.

Did you gap the plugs or install outta the box ?

Timing is ?

High REV limiter is ?

Low REV limiter is ?

OR....are you using one of the MSD "pills" ?

youlittlejerk

Are you using the MAP ?...zero it out until you get issue fixed (if yes or no)

More about the build would help.

Mine ran fine with the "stock" AC plugs.....but BR7's right now since they were a little too hot for my combo.

Did you gap the plugs or install outta the box ?

Timing is ?

High REV limiter is ?

Low REV limiter is ?

OR....are you using one of the MSD "pills" ?[/QUOTE]

I started off using the MAP and the pills but have now abandoned the MAP and made a custom curve starting at 12° ramping to 32° at 2,000 rpm.
The plugs are gapped at .040" (they are the same plugs used in this engine when it was EFI)
Its a stock bore 5.7 with SLP ported heads-TSV2 cam-Victor Jr.-
I've tried a couple different carbs just testing (650 edlebrock right now)
I notice that the engine only pulls about 10 inches if vacuum, not sure if this should be higher, I called Texas Speed and they couldn't help me.
I don't have the HIGH/LOW limiters set, thanks for the help

Doug G

Another thing that comes to mind is any vacuum leaks, grounds good, and you said you tried a few carb (same issues ?).

youlittlejerk

I've checked out all the typical vacuum leak spots and went around with some starting fluid trying to get an idle spike, I found nothing.
Both carbs tested netted the same miss. I have also adjusted the fuel pressure from 5 up to 9 psi with no results.
The wiring of the MSD was the first thing I dug into. The grounds are oversized and routed directly to the battery post. Then to the cylinder head and chassis.

Doug G

I can't 100% say its the box....but leaning that way, and wouldn't be the first one.
Only other thing that comes to mind is the sensors.

RabidStreetRacer

iTrader: (1)

Do you have an air/fuel gauge to see what it is at when it is missing?
Does it do it when you are driving or even when in neutral and revving it up?

Redline Performance

We have seen bad msd wiring harnesses where one bank of coils dies, but I would check air fuel before I blame the box could have a lean miss and need to adjust the carb.

thirdgenbum

iTrader: (17)

my engine is 11.2:1 and has a custom cam 242/250 .615"/.615" 108+3. i'm running a TR5 plug with no signs of detonation. i run no MAP and have my timing at 10* under 500 rpm, then goes way up to 44* till about 1500 rpm, then drops back down to 36* to infinity. lots of timing at idle keep the plugs nice and clean.

Doug G

10.5:1 here, anything over 36* at under 1500 gives me run-on (dieseling)
At 38* I seen some specs on the porcelain (stock AC plugs)
No MAP
34*-36* gave me my best ET's/MPH
237/249 110LSA 106 ICL .623 lift
BR7's now.

speedtigger

iTrader: (16)

I like the NGK TR6 spark plug for your setup.