As a final note for this engine job, with ~5,000 miles on engine:

The front oil seal leak is fixed. Using about 1 qt in 2000 miles.

Engine is running really strong, pulls hills well. Will do 80 mph easily, probably make 90! Mileage is up from 6-6.5 to 7.5 about 15% better.

FINAL WARNING: BE SURE YOU HAVE THE CORRECT DISTRIBUTOR GEAR!

I recently found out the hard way that camshafts and distributor gear materials have changed over the years.

The older flat tappet camshafts were made from iron and were matched with iron distributor gears. This was standard from the 60's to the 90's.

In the late 80's to early 90's the auto makers switched to roller cams which are made from steel. These camshafts are not compatible with the old iron gears. You must use a hardened steel (melonized) distributor gear. (Melonizing is a fancy term for a proprietary hot salt nitriding process)

I was not aware of this and paid the price. Sat on side of the road 24 hrs waiting for replacement distributor drive gear, one of very few parts I did not have in my spares.

Steve G linked an article on this subject. They list 3 different cam materials and 4 types of gears! A good discussion, however, the GM melonized gear (#19052845) they recommend does not fit the .491 OEM distributor shaft, it has a smaller inside diameter.

http://www.onedirt.com/news/it...-gear-compatibility/

The correct GM melonized gear is part #10456413 Can you find the iron gear?



Another example of what you don't know can hurt you. When I replaced my 454 with a factory GM crate 454HO there was a recommended distributor but no mention of the need to have the later style gear, even though the engine is specifically designed to replace early pre-emission engines which all had iron gear distributors.

The crate engine has camshaft #24502611. If you go to the GM parts website (and others like JEGS, etc) they warn that you must use gear 10456413, but not in the factory "Installation instructions" that came with the engine!

Meanwhile, I replaced the gear on the distributor with the proper gear and I will monitor for gear wear. Hopefully the camshaft gear is not too worn. I posted a separate thread on the subject to make it easier for others to find.

Overall, I am very happy with the performance of the 454HO. Oil seal and distributor gear issues should not have happened but otherwise a good setup.

Steve,
I hope this is the end of this problem, BUT I also hope that you have changed motor oil and filters a couple of times since this happened. That ground-off iron didn't just disappear...I hope it ended up in the filter. If you have it, it might be worthwhile to cut it open to see how much metal it trapped. Also, while you had the distributor out, did you get a look at the cam gear? You should be able to see it with a good pen light or even bore scope, if you have access to one.

Steve Griffin

The oil and filter have been changed. Big chunks will not pass through the oil pump screen. The small and medium stuff will trap in the filter. As long as the medium sized ones didn't damage the oil pump I should be OK by now.

Cam gear was not destroyed but did show some wear. I finally got the correct gear in there, for now I will keep an eye on it.

If it keeps wearing I will replace the cam and gear with a new set. About $200 and a few hours work…

Mabey want to put 1 of them stick on magnets on the bottom of the pan by where the oil pump pick up is till next oil change. Cheep and can't hurt.

Magnets would be a good idea.
There is one in the bottom of my transmission pan.

There may be an addendum to this post soon.

Things have been great, should have known the turd fairy was overdue.

I was supposed to be heading to the UP for a boat trip to Isle Royale with my Dad. The west winds have been cranking and Lake Superior is riled up, so we decided to delay a couple days.

86Barth had developed a rough idle after Allegan. I hadn't swapped plugs or plug wires so I thought I'd get things right. After I removed the plugs, I decided what the heck why not do a compression check… uh oh… one cylinder 95, one 80, one 60 the rest 120-140.
It appears to be time for a valve job after only 15,000 miles!

I pulled the intake manifold and heads.







I will drop them off to the machine shop tomorrow. Meanwhile I have the boat trip on Wed and Minnesnowta GTG soon.

I'm wondering why this happened…. more factory screwups, or could my fuel injection be too lean?

to be continued:

"No rest for the wicked" Grandma used to say

Steve , Sorry to hear about the problems.

Did you talk to GM about the problem , before taking the engine apart ?

By what I read you have a 50,000 mile , 18 month warranty on the engine .

I would of taken the coach to a GM service center first to see what they would do .

Bob

As I recall, the warranty was "parts and labor only" provided it was installed by a "qualified technician" and the engine is approved only for non road and EPA exempt applications, ie replacement of pre 76 cars, etc.

I don't really care about the warranty, it only matters when they sell you junk. If they built em right, no one would care about/need a warranty.

It appears that the burned valves were not rotating, the rocker arms may not have been lined up properly when assembled. The heads should be ready when I get back next week, in time for Minnesnowta.

There is a possibility the fuel injection was too lean but I doubt it. I'm checking into it.

to be continued:

From the photos, I don't think it's running lean. The #5 header looks a bit lean-ish but the exhaust port on the head looks just fine. Plus the piston tops showing look fine also. Might be a little fat but I haven't seen any other heads off of motorhomes.

I agree. If anything it is rich at idle and may be a bit so when running. My datalog files do not show any extended periods of lean mixture at any rpm/power settings. I emailed my chip guy for his opinion.

Lack of valve rotation may be the problem. Two of the cylinders had discolored valve edges and also showed localized heat signs on the adjacent seat area. My head guy will inspect them soon and make them right.

we'll see

Steve, I have some thoughts and would like to share with you, What would be a good time?

I will be on the road for the UP. After then off to Isle Royale for a few days. I will PM my phone number.

Update: I returned from the UP.

Went in to th shop to check on the heads. Strangest thing… there were 3 INTAKE valves burned! I have never seen in all my years any engine with intake valves burned. This worries me. My shop guy has also never seen this before. (OTOH, if the boneheads who assembled this engine did not allow enough valve clearance maybe they were held open and burned.)

These heads do not have valve rotators. It appears they are running hot…

I decided to replace the semiradical HO cam. Also, my HO cam has some wear on the cam drive gear from the wrong distributor gear. I put in an OEM GM motorhome cam from the late 90's. It allows for 21 degrees less exhaust duration, also less lift. This gives the valves more time on the seat, cooling down. Should bring the torque band in at lower rpms.

I am considering other heads with smaller valves like the OEM 454 trucks, etc. For now, I'll have a semi stock Gen VI 454 with extra large HO valves and manifolds.

Pulled off "a few more parts:"





Out with the bad, in with the new:



Old trick: while removing the cam put clips on the cam followers so they don't drop into the oil pan when you pull out the cam. (8 more to go here)



Just be REAL sure to clean those clothespins so your wife doesn't get any oil on her clean sheets…

to be continued: