 How to determine which engine I have [message #348688] |
Sun, 29 September 2019 13:34  |
Mike_H
Messages: 16
Registered: September 2019
Location: Grand Rapids, MI
Karma: 0
|
Junior Member |
|
|
I'm trying to find tune up parts for my 1978 Royale. Looking through the Parts Book, it shows two different engine assemblies for 1978. One of them, 561032, reads, ENGINE ASSY - type 403 CID V-8 gas code RA (STD) (eff w/ 1978). The other, 561033, reads, "ENGINE ASSY - type 403 CID V-8 gas (RPO NB4) (eff w/ 1978)
How do I know if I have a standard or RPO engine? Its not listed on the VIN tag as an option so should I assume that its the 561032 assembly? I ask as they have different distributor caps...
Mike and Jessica
West Michigan (Just north of Grand Rapids)
1978 Royale Twin bed, Dry Bath
|
|
|
|
|
|
| Re: How to determine which engine I have [message #348694 is a reply to message #348688] |
Sun, 29 September 2019 16:48  |
Rick Staples
Messages: 126
Registered: May 2014
Location: Johnstown, Colorado, USA
Karma: -1
|
Senior Member |
|
|
Mike,
RPO NB4 is the California emission system engine, so you may already know whether or not this applies to you. I'm not cursed with this option, but one quick way to tell might be checking your evaporative canister down behind the right front wheel. IIRC, the California coaches had two canisters, the rest of us one. There are several other unique "features" on CA engines, notably the "throttle pusher" diaphragm and control valves on the left side of the carburetor which hold the throttle open slightly under certain conditions.
HTH,
Rick Staples
Rick Staples, '75 Eleganza, Johnstown, CO
"Advice is a dangerous gift, even from the Wise to the Wise, and all paths may run ill." -Tolkien
|
|
|
|
|
|
|
|
| Re: How to determine which engine I have [message #348708 is a reply to message #348694] |
Sun, 29 September 2019 20:50 |
Mike_H
Messages: 16
Registered: September 2019
Location: Grand Rapids, MI
Karma: 0
|
Junior Member |
|
|
Rick Staples wrote on Sun, 29 September 2019 17:48Mike,
RPO NB4 is the California emission system engine, so you may already know whether or not this applies to you. I'm not cursed with this option, but one quick way to tell might be checking your evaporative canister down behind the right front wheel. IIRC, the California coaches had two canisters, the rest of us one. There are several other unique "features" on CA engines, notably the "throttle pusher" diaphragm and control valves on the left side of the carburetor which hold the throttle open slightly under certain conditions.
HTH,
Rick Staples
DING DING! Rick, you are the lucky winner. I missed your post earlier, and figured out the California emissions thing with a little more research. Mine was delivered in Indiana, so I should be safe from the Commifornia emissions.
Thanks for replying!
Mike and Jessica
West Michigan (Just north of Grand Rapids)
1978 Royale Twin bed, Dry Bath
[Updated on: Sun, 29 September 2019 20:51] Report message to a moderator |
|
|
|
| Re: How to determine which engine I have [message #348725 is a reply to message #348708] |
Mon, 30 September 2019 09:53 |
midlf
Messages: 2212
Registered: July 2007
Location: SE Wisc. (Palmyra)
Karma: 1
|
Senior Member |
|
|
[quote title=Mike_H wrote on Sun, 29 September 2019 20:50]Quote:
DING DING! Rick, you are the lucky winner. I missed your post earlier, and figured out the California emissions thing with a little more research. Mine was delivered in Indiana, so I should be safe from the Commifornia emissions.
Don't count on it. Mine was delivered in MS and had the CA option.
Fortunately mine is a '74 so that only included the double canisters and fuel tank heat shields on the exhaust.
Steve Southworth
1974 Glacier TZE064V100150 (for workin on)
1975 Transmode TZE365V100394 (parts & spares)
Palmyra WI
|
|
|
|
| Re: How to determine which engine I have [message #348729 is a reply to message #348688] |
Mon, 30 September 2019 10:30 |
jhbridges
Messages: 8412
Registered: May 2011
Location: Braselton ga
Karma: -74
|
Senior Member |
|
|
Quick n dirty - Look behind the pax side front wheel and count the round vapor cannister(s). If there's one, you have a 49 states setup. If there's two, congratulations, you have a California setup. The two will also have different numbers for the Quadrajet, and the California one will have slightly different vacuum setups and as someone noted, a throttle 'slow to idle' diaphragm on the linkage. California runs the vacuum advance off ported vacuum, not sure about the 49 state. On my two coaches, both initially California spec, didn't seem to make a lot of difference except for the extra hose on the vapor cannisters. Replaced on both and got much better idle performance. Overall, I think the Cal setup is more to make the CARB happy than any great difference in performance - or emissions.
--johnny
Foolish Carriage, 76 26' Eleganza(?) with beaucoup mods and add - ons.
Braselton, Ga.
I forgive them all, save those who hurt the dogs. They must answer to me in hell
|
|
|
|
GMCforum
Search
Help
Register
Login
Home
