Installed NGK v-power plugs today. Drove the car about 30 miles doing numerous accelerations from a dead stop. And the answer is..........no difference with the NGK plugs. Still breaking up and loosing power at about 5200/5300 rpm's. It was worth a try for $20.00 and 45 minutes time. The next item I hope to try will be valve springs. Unless of course someone has some other suggestions.
Jim B. :D

 

Sorry to hear it did not work for you. I hoped it would be an easy fix. I guess BBA was right. I hope it still proves to something easier than the springs.
Tony

 

Hmmm...This topic is a bit more interesting than I thought it would be.

The suggestion to go to titanium retainers is a good one. Any reduction in weight on the valve side of the valve train is a good and the correct place to do it.

For what its worth, here are my experiences with plugs:

Stock LT1:
Ran great with Champion premium gold plugs. They only lasted 20K miles but they worked very well. Bosch Plats gave it a very annoying surge as you accelerated through 1200 rpm but only when the engine was warmed up. It did the same thing with Bosch +4s too.

383 stroker with AFR heads:

Rapidfires - the motor ran well with these but not as good as some others. Bosch +4s - the car surged more at part throttle. I have been thinking about cutting off two electrodes and making them +2s and trying them. These might work as they are but I'd have to reduce the spark advance all over the spark advance table to get them to work and I don't feel like putting the time into it. I think the four electrodes on the plugs retain too much heat causing unstable mixture problems.
Autolite platinums with cut back electrodes - They worked well but I cut the electrodes back to far on some of them. I recommend cutting the electrodes so 1/3 of the center is exposed.
Champion Premium Gold 2071s - car runs really smooth with those.
I think the cut back Autolites might have been the best over all but the Champions work very well.

78 Pontiac 400 - I had NGKs that ran really well in that engine. I tried Bosch Platinums and immediately replaced them with Autolite Platinums with very good success. Put the Platinums in a 76 Pontiac 400 with 7.6:1 stock Cr and they performed very well and outlasted the car.

1988 305 TPI - Replaced the stock plugs with Bosch platinums @ 20K miles. No difference in performance at all.

Bottom line - Champion Premium Gold (Lingenfelter used to recommend these for LT1s), Autolite and possibly Rapidfire are good choices. Autolite and Champion are cheeper then Rapidfires so if your on a budget. I haven't used NGKs but they have gotter good recommendations from a lot of people.

I want to try Iridiums but I am not in the mood to spend 100 bucks and find out they suck. They are supposed to take less voltage to fire because of the their design.

 

Hey...if it's any consolation, the springs are not that hard to change.

The way I did it took 3 hours. Here is what I did:

1. Removed both valve covers. I found the easiest way was unbolting EGR pipe on the passenger side, swivel it out of the way ( disconnect it's wire behind the distributor ), remove the AIR pump outlet hose behind the AC compressor ( for clearance ) and pull the cover. For the driver side, loostening two accessory bolts on the front end of the driver side head, unbolt the alternator upper bracket, loosten the air pump bracket nut on the water pump stud, remove the air pump back side bolt, remove the fuel injector wiring hold down nuts and pull it up out of the way, slightly bend the cold start injector fuel tube for clearance, tilt forward the AIR pump accessory enough to get the driver side cover off. You do not need to remove the accessory drive belt.

2. After valve covers are off, rotation of the engine will be needed, using a 5/8's socket on the crankshaft balancer bolt ( rotate in tightening direction only or the bolt will back off ) ( also make sure you pull hte plugs out...makes turning engine easy. ). Rotate the engine until each cylinder you are working on has both it's intake and exhaust valve shut and is at top dead center.

3. I used a K-D tools screw type valve spring compressor ( about $25.00 )...very easy way of compressing valves on the engine. After you remove the rocker arms for each valve in question, tap the retainer via placing a socket over the valve stem tip and hitting the socket once with a hammer. This loosens the valve retainer keepers. Compress a spring, remove it, clean any debris around the valve stem, put a new seal on the guide, compress the new spring and put it in. Reinstall the rocker arm, adjust it until it comes close to removing all slack.
Do this for all cylinders.

4. After replacing all valve springs, tighten teh accessory bolts loosened before, and reattach the egr pipe/wire. I fabricated some oil splash deflectors out of heavy cardboard box flaps, and inserted the cardboard between the springs and head lip to catch oil while I ran the engine. Then start the engine, do a rough valve adjustment with the engine running, then let it idle in gear long enough to turn the engine fan on...now re-adjust all valves to about 1/8 turn past the tappet noise disaperaing, but not far enough to make the in gear idle rough.

5. Put it all back together and enjoy a new running engine that does not smoke!




[Modified by BBA, 3:48 PM 10/21/2001]