|
Register or Log In To remove these advertisements. |
|
|
|
|||||||
 |
|
|
Thread Tools | Display Modes |
12-30-2009, 05:13 PM
|
#1 |
|
Right turn Clyde
Join Date: Nov 2002
Location: Cincinnati, Ohio
Posts: 2,911
|
1974 C25 octane rating
I was looking around on Jeff's site look at some vintage ads. Noticed that for 1974 the recommended octane for the 454 was 91. But the compression ratio was pretty low like 8.25:1. Looking over the ad again all the engines are recommenced for 91 octane.
So does my 454 really need 91 or is 87 okay? I just got it and put 89 in it and it seems to run okay. http://www.73-87.com/7387info/articles/74pu02.jpg
__________________
1974 C25 LWB: 454 4bbl Carb / TH400 / 3.73 1992 Camaro RS 305 TBI |
|
|
|
12-30-2009, 05:35 PM
|
#2 |
|
Dually Pride
Join Date: Jun 2008
Location: NH
Posts: 540
|
Re: 1974 C25 octane rating
I run 91 in my 74, cause it runs like junk if I don't, but I also only buy Mobil, I guess I'm just picky...
__________________
If I have to explain, you wouldn't understand. '74 Chevy C-30 350/4 speed/dually  '94 Ford Ranger |
|
|
|
|
12-30-2009, 05:37 PM
|
#3 |
|
Registered User
Join Date: May 2009
Location: Sparks, NV
Posts: 913
|
Re: 1974 C25 octane rating
i always put 91 in mine. i can really tell the difference between it running on 87 and 91. but that's just me
__________________
Greg 1974 GMC 1/2 Ton SWB Fleetside L33 5.3/4l65e .................__
............._____l __\__ ..............l_(O)_ l___(O)] |
|
|
|
|
12-30-2009, 06:14 PM
|
#4 |
|
Registered User
Join Date: Nov 2008
Location: edmonton, alberta
Posts: 293
|
Re: 1974 C25 octane rating
I've been running 91 for about two months now and there is a noticeable difference. I'm logging my efforts and tracking gas mileage so we'll see if it really does anything else
__________________
 76 Silverado, 2wd, long box, 350/th350, 3.42 posi, edelbrock performer 64cc heads, edelbrock 1405, 2101 intake, Hedman Headers, Comp Cam XE262 http://beerbreadbike.wordpress.com/ |
|
|
|
|
12-30-2009, 08:23 PM
|
#5 | |
|
Conversion Truck Addicted
Join Date: Sep 2009
Location: Denmark, Europe
Posts: 1,551
|
Re: 1974 C25 octane rating
Well here when we have build a couple of street cars we ran 97 or 98 octane and there was a very big difference from the normal 91 or 95 octane both in power and fuel economy
__________________
Thomas Quote:
|
|
|
|
|
|
12-31-2009, 03:04 PM
|
#6 |
|
Extended cab fanatic
Join Date: Oct 2009
Location: Gardendale, Tx
Posts: 314
|
Re: 1974 C25 octane rating
In my stock 454s, I havent seen any benefit for using 91 over 87 octane. The compression is low, and shouldnt really need it, also, the gas used today is different than it was in those days. I run 91 in my 468, but its pushing 10.5:1 compression. It may have to do with altittude tho because Im n the desert.
__________________
If it has a motor, it has my attention. |
|
|
|
|
| Bookmarks |
| Thread Tools | |
| Display Modes | |
|
|
Linear Mode
