| Re: Differences between 403 and 455 [message #279067 is a reply to message #279064] |
Thu, 04 June 2015 17:40   |
Hal StClair
Messages: 971
Registered: March 2013
Location: Rio Rancho NM
Karma:
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Senior Member |
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Ouch, you are looking for some heat here.
Both were fine power plants although the 455 was probably a stronger unit. The 403 seems to be a more fuel efficient platform mileage wise and there are a lot of high mile units with this engine out there. If you are planning to tow with one, the higher torque of the 455 would probably be advantageous although either will work with the right gearing.
I think the later (1977-78) units with improved a/c might be worth looking at and the 77 came with either engine depending on date of build so you have a choice of either.
I have two 1977 Royales, one with the 455 and the other HAD a 403. The 403 with 3.55's and headers without running the a/c averaged about 10 mpg, the 455 with 3.21's closer to 8.
JMHO, Hal
"I enjoy talking to you. Your mind appeals to me. It resembles my own mind, except you happen to be insane."
1977 Royale 101348,
1977 Royale 101586, Diesel powered,
1974 Eagle Bus 45',w/slideout,
Rio Rancho, NM
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