spark plugs for a full top end ported engine - ZR-1 Net Registry Forums

phrogs · 08-09-2009

What are some of you using in your ported top end cars.

Mine has thottle body, heads, injector housings and plenum ported

I have the AC FR2LS plugs gaped at .35 in the car and I have a high idle and the car is running rough low on power one day I was driving and the car just felt wired It felt like I lost a cylinder very rough even at 65 in 6th gear the car is strugling shaking like a leaf in order to do 65 I have to be in 5th gear otherwise the car starts to shake itself to death.

I have newer accel injectors about 4,000 miles on them
older LT5 wires probably 25-30K miles on them and ac delco coils no idea the mileage its an old set I had on the self to replaced cracked screamon deamon coils that were on the car.
car has the chip DRM burned for it after the porting work they did.

Now tonight I pulled the plugs and looked at them all but one spark plug looked ok #6 was black the rest looked normal but I am running very rich black soot on my exhaust pipes I know im running rich.

so I swaped out #6 with another plug to see if it looks different tomorrow after I drive it to work and back home just to make sure that plug is working.

I drove it tonight removing every wire trying to locate a dead cylinder and everyone of them gets worse than it has been with them all pluged in so it seems all my cylinders are firing.

what you guys think?
do I need a hotter plug perhaps?
Im willing to try the cheap aproach first.

im going to keep messing with it but looking for ideas.

perhaps new plugs wires and coils and go from there?

flyin ryan · 08-10-2009

Can't see it being plug temp. John, that's one of the hottest plugs available you have right now. Maybe a dead plug, if anything but those are few & far between as well. Let us know what tomorrow brings.

tomtom72 · 08-10-2009

JMHO, but this proly ran thru your mind already!

Only #6? Then I suspect that (those) injector(s)? Or the wires & coils like you say just for general principal because they've been on the car a long time. No DTC's right? What's a scan look like?

Damn, where do you get FR2LS plugs from? If you are using the OE stuff from waaay back, then I'd try a new set, 42-601's are what I've been using. They don't stay in the sweet spot for much more than 10k miles but they're cheap enough to toss every yr.

Tom

jonszr1 · 08-10-2009

i had a cylinder problem like your on my blk car . did a compression test which came out fine . after tlking with jerry downey ,who said he had heard that coils have had one side go out , bottem line replaced the coil and all is well . hope this helps

Locobob · 08-10-2009

Quote:

Originally Posted by flyin ryan

Can't see it being plug temp. John, that's one of the hottest plugs available you have right now. Maybe a dead plug, if anything but those are few & far between as well. Let us know what tomorrow brings.

FR2's are on the hot side for this application, going hotter is not a good idea.

phrogs · 08-10-2009

well Ill do all my checks later on today and see what I find with the wires and the coils.

The damn injectors better not be bad on this thing!

Now if my old spark plugs are on the hot side should I get something a bit cooler?

A26B · 08-10-2009

Johnny,

A "weak" spark will show up more as a "miss" when the engine is under load such as 65 in 6th gear, than it will at higher revs or at an idle. It's not a dead cylinder problem until it's under a load like you described.

When you check spark, put an old plug in a plug wire, lay it on the plenum & start the engine. It should jump a nice, blue spark 3/4"~1" as you pull the plug away from the engine. If you see an orange spark, it's weak.

I have personally seen at least 3, single cylinder, weak spark issues fixed by replacing the coil, mine included.

Easy to check, no cost.

phrogs · 08-10-2009

I checked the spark and its kinda white not nice a blue so its pretty weak maybe damn near dead.

So it looks like coil packs thats what I figured at first but wanted to see what people were using for spark plugs on these cars.

My plugs have probably been on this car for to long and need to be changed so ill look into that as well.

jp

08-10-2009

John, anything that comes into me gets the NGK iridium plugs. I've been extremely happy with them on my 368 and other cars I've used them in.

phrogs · 08-10-2009

well I had a chance to check a spare set of coils I have.
they are a old set but the ohm out just fine, primary and secondary so now that I know I have a back up set ill check the car here in a little while and see what I get.

As for spark plugs the only ones carried local to me are the replacment AC delco's so Im going to use them so I don't have to ship a set of plugs right now.

jp

08-09-2009	#1
phrogs Join Date: Jul 2004 Location: Kalamazoo MI Posts: 1,753	spark plugs for a full top end ported engine What are some of you using in your ported top end cars. Mine has thottle body, heads, injector housings and plenum ported I have the AC FR2LS plugs gaped at .35 in the car and I have a high idle and the car is running rough low on power one day I was driving and the car just felt wired It felt like I lost a cylinder very rough even at 65 in 6th gear the car is strugling shaking like a leaf in order to do 65 I have to be in 5th gear otherwise the car starts to shake itself to death. I have newer accel injectors about 4,000 miles on them older LT5 wires probably 25-30K miles on them and ac delco coils no idea the mileage its an old set I had on the self to replaced cracked screamon deamon coils that were on the car. car has the chip DRM burned for it after the porting work they did. Now tonight I pulled the plugs and looked at them all but one spark plug looked ok #6 was black the rest looked normal but I am running very rich black soot on my exhaust pipes I know im running rich. so I swaped out #6 with another plug to see if it looks different tomorrow after I drive it to work and back home just to make sure that plug is working. I drove it tonight removing every wire trying to locate a dead cylinder and everyone of them gets worse than it has been with them all pluged in so it seems all my cylinders are firing. what you guys think? do I need a hotter plug perhaps? Im willing to try the cheap aproach first. im going to keep messing with it but looking for ideas. perhaps new plugs wires and coils and go from there? __________________ JOHNNY P Currently own 90 ZR-1 #845 DRM 500 engine package 90 #226 Parts car Hit me up if you need anything.

08-10-2009	#2
flyin ryan Join Date: Aug 2006 Location: Edmonton, Alberta or Phoenix, Arizona Posts: 2,741	Re: spark plugs for a full top end ported engine Can't see it being plug temp. John, that's one of the hottest plugs available you have right now. Maybe a dead plug, if anything but those are few & far between as well. Let us know what tomorrow brings. __________________ There are no limit's mans ingenuity, just as mans ingenuity will never conquer the forces & behavior of this planet...Smokey Y.

08-10-2009	#3
tomtom72 Join Date: Dec 2004 Location: Jacksonville, FL USA Posts: 4,645	Re: spark plugs for a full top end ported engine JMHO, but this proly ran thru your mind already! Only #6? Then I suspect that (those) injector(s)? Or the wires & coils like you say just for general principal because they've been on the car a long time. No DTC's right? What's a scan look like? Damn, where do you get FR2LS plugs from? If you are using the OE stuff from waaay back, then I'd try a new set, 42-601's are what I've been using. They don't stay in the sweet spot for much more than 10k miles but they're cheap enough to toss every yr. Tom __________________ 1990 ZR-1, Black/grey, #2233, stock. ZR-1 Net Reg Founding Member #316 & NCM member

08-10-2009	#4
jonszr1 Join Date: Sep 2006 Location: lone pine and mammoth lakes Posts: 1,407	Re: spark plugs for a full top end ported engine i had a cylinder problem like your on my blk car . did a compression test which came out fine . after tlking with jerry downey ,who said he had heard that coils have had one side go out , bottem line replaced the coil and all is well . hope this helps

08-10-2009	#7
A26B Join Date: Dec 2003 Location: Arcadia,OK Posts: 3,394	Re: spark plugs for a full top end ported engine Johnny, A "weak" spark will show up more as a "miss" when the engine is under load such as 65 in 6th gear, than it will at higher revs or at an idle. It's not a dead cylinder problem until it's under a load like you described. When you check spark, put an old plug in a plug wire, lay it on the plenum & start the engine. It should jump a nice, blue spark 3/4"~1" as you pull the plug away from the engine. If you see an orange spark, it's weak. I have personally seen at least 3, single cylinder, weak spark issues fixed by replacing the coil, mine included. Easy to check, no cost. __________________ Jerry Downey JERRYS LT5 GASKETS & PARTS http://www.jerrysgaskets.com 1994 *ZR-1*, Black/Black, Lingenfelter Aerobody, 416cu in, 3.91 gears, coil-over susp, Brembo brakes, etc. 2016 Black-Red, 3LT-Z51 Auto 8-speed.

08-10-2009	#9
Jeffvette Guest Posts: n/a	Re: spark plugs for a full top end ported engine John, anything that comes into me gets the NGK iridium plugs. I've been extremely happy with them on my 368 and other cars I've used them in.