So my box from Rock Auto arrived filled with filters, spark plugs, and other wear items. Got the first of the spark plugs out today and guess what. It is completely different then the plugs I got. It is a Bosch HP9BPX plug, the plugs I got are Autolight APP145. They have a different length of the inserted part. Help!

GM calls for AC Delco R44T which crosses to the Autolite APP145 and Bosch HR9AC, no mention of HP9BPX.

Could it be?... a previous owner installed some incorrect plugs? If anyone knows about your motor it would be Steve VW.

It could be but this was the person who put lots into it. I.E. a banks powerpack etc. so I assume he had a clue on things. The plugs that were in do list for a 70s 454.

Can you post some pictures of the differences in the plugs?

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When you send a picture of your Data tag, I will let you know which folder Bill NY has assigned to your Barth.

The website doesn't like my pics or my I phone. Can't upload them at all. I did pm you the vin a week ago when I tried to up load the data tag pic. Did you need more?

As for the spark plugs. The old ones are approx 3mm longer then the new ones. Threads are the same length, just the electrode is longer. I did replace all of them. What a PITA that was so I hope I don't have to do it any time soon again. The one plug is a bit oil fowled so hopefully that isn't a huge deal for now. At least it is the one easiest to get at.

Some of the earlier higher compression 454s used the extended tip spark plug style. (R44TS?) By the 80's GM had regressed to the standard shorter tip version.

If the thread length is the same and the heat range the same the only difference is the extended tip ones may stay a bit hotter at the electrode tip, will usually help with igntion and maybe burn off fouling better. Should be OK.

You can see why I removed both air pumps, factory AC and brackets. Front of the engine is way easier to service now. Headers are easier when changing plugs, the cast manifolds are very bulky and tight around the plugs. The engine had a rat's nest of vacuum tubes, most of which did not do anything any more. Rerouting and simplifying those helped too. Good luck working on yours!

Thanks Steve, runs just fine for the 1 minute I let her run as I didn't have the oil pressure gauge line attached. I can't even see the air pumps so no clue how to get at them. Plus I do have working Air. PO put $1500 into making it work (well it worked in the fall at least)...

Waiting on some new insulation for the covers then I should be pretty close to done under the hood. Next it is time to move to the rear axle. Any ideas what size brake shoe I would have? Decoder has brakes for a 10k-14k. Any way to check and tell so I can order the parts before taking it apart? Figure I might as well replace at least the shoes, wheel cylinders and hardware if I'm opening it up as we plan to do about 15k or so this summer (will be doing lots of mountains so brakes are important). Will also do the dif fluid at the same time and finish up with the tranny fluid. Then I should be as ready as I plan to be.

Always good to check brakes! I have disc brakes all around on the 86, not sure what the drums were on the others. I will check what info I have.

I never considered it could be a disc. Guess I will be crawling under tomorrow

Depends on chassis weight. GM used "RPO" codes for identifying brake systems. JF9 was 4 wheel disc brakes, other codes will have rear drums, etc. See if you can find the RPO for your coach. Sometimes on a chassis tag, not always easy to find.

If you do have 4 wheel discs, you will find that front and rear pads are the same, calipers too. (See my threads "gimme a brake" part 1 and part 2)


I had a list of RPOs for the coaches, can't seem to find it...

All the 25' coaches built in 86 that I have info on have 16" wheels and rear drum brakes on 8 lugs. If you have 19.5' rims with 10 lugs it will most likely have disk and tranny tail housing mounted parking brake system. There is a 25' that the data tag listed 19.5 rims but the coach had 16". The 14,500 lb. chassis is built larger and stronger frame rails.

Rats, I have the 16" wheels. I hate drums and Steve got me all excited that I wouldn't have to deal with drums. Doug you happen to know if it would be a 3.5" brake or a 2.5" brake? Pulling involves moving to the bigger part of the driveway and I don't want to have to move it then put it back together and then move it again.

My data tag say's 19.5 wheels , but has 16 in . Drum brakes in rear disk in front .
I never had to change either so can't help with part numbers . Bob

BRAKES/REAR BRAKES for 1985 Chevrolet P30 with FULL illustration

http://www.gmpartsdirect.com/a...cat/rear-brakes-scat

1985 Chevrolet P30 Brakes

http://www.tonkinonlineparts.c...1985_P30/Brakes.html