I've looked around this site and haven't seen any reference to anyone using rocker shaft plugs other than the stock press in type (?)

On other Mopar engines, it's common to use O-ringed plugs or NPT threaded plugs for better security and easier cleaning.

Has anyone done this? I'm thinking of driving out my stock plugs and using one or the other of the above type.

Well, the rocker shafts aren't that difficult to clean and the shaft plugs (in my experience) are not really a weak spot on these shafts. Might be overkill on a slant.

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-MattMan
LEANED & MEAN

I doubt they will blow out, but then again, oil pressure is oil pressure - whether on a Slant Six or a Hemi. It's good peace of mind to not rely on a press fit. The only difference, of course, is a Slant Six can run without oil for a few months, lol.

Raise your hand who's ever had a stock Slant-6 rocker shaft endplug blow out.

C'mon, now, don't be shy, get those hands up there, surely it's happened to somebody sometime in the last sixty years!

(Is it just me, or do y'all hear those cricket noises, too?)

The hot rodding world is full of stuff people do even though they've never had a failure before. Why pick on this particular mod?

I'll bet no one here has had a ball joint nut loosen up - yet everyone uses cotter pins. I'll bet practically no one has had a main cap bolt break - yet we spend big bucks on ARP hardware.

I have never seen that failure and have never heard of anyone replacing these plugs. I would say you are more likely to cause damage than prevent a future problem. For reference, I have had rocker shafts on and off Slant engines at least 100 times, probably a few 100, and have put maybe 400k miles on about 10 different Slant engines.

I like your analogies with ARP hardware and cotter pins. I often wonder why I am putting in cotter pins given how tight I make everything. ARP hardware is definitely overrated (and overspent) on engines like ours, unless you are heavily modifying them (well over 300 HP). Reuse your old head and main bolts, everyone!

Lou

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Home of Slant6-powered fun machines since 1988

Because if you are running in sanctioned auto events (most), the rules require them.

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Charrlie_S
65 Valiant 100 2dr post 170 turbo
66 Valiant Signet 170 nitrous
64 Valiant Signet
64 Valiant 4dr 170
64 Valiant 4dr 225

back when I was working,,,
all Part Designs and all Manufacturing Process were put through a study called a
Failure Mode Effects Analysis

basically one would
begin by listing every failure mode the part or process could produce.
Then for each failure mode one would
1) estimate the occurrence of the failure one a scale from 1 to 10
2) estimate the severity of the failure on a scale of 1 to 10
3) estimate the ability to detect the failure on a scale of 1 to 10

then multiply occurrence x severity x detection to develop a Risk Priority Number
to identify the ranking for items that needed inprovement.

an additional ranking of items for improvement is high severity items that could cause injury or death.
In this case occurrence had no influence. Parts or processes that impacted safety were flagged for immediate attention.

And that is why steering linkages have cotter pins,, the occurrence of failure (a loose steering linkage) is very low,
however the severity of a steering linkage coming apart is very high.


a true story
Back in 1961 Tony Bettenhausen , an open wheel Championship driver and an Indy 500 favorite was testing Paul Russo's Indy car.
Paul was having issues getting his car up to speed, the car's handling was not good. Being a friend of Paul, Tony B offered to
take the car for a few laps.
At speed on the front straight the car veered into the wall, Tony B was killed, one of the steering arm nuts that should have been
held with a cotter pin was found on the straight way, just short of the crash site.

https://www.youtube.com/watch?v=IIfFxOscYKE

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Doo Ron Ron and the Duke of Earl are friends of mine.....
https://www.youtube.com/watch?v=uX8Nj8ABEI8

If you lose a rocker shaft plug, you won't die but your engine no likey.

I once had a friend in high school who bought cobble-up 55 Chevy. He drove it for over a year, then one day asked me to help with some brake work. When we pulled the front wheel, I noticed the tie rod had a cotter pin. No nut, but a cotter pin.

I was half joking about the cotter pins. I am familiar with risk/failure analysis. I will keep using them. I do think ARP bolts are overused in our engines, but if it makes you feel better, go for it! I have used them once or twice (notably after a head gasket failure).

Lou

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Home of Slant6-powered fun machines since 1988