60's SBO HC - GAS? - ClassicOldsmobile.com

Go Back  ClassicOldsmobile.com > Repair & Restoration > Other
60's SBO HC - GAS? >

60's SBO HC - GAS?

60's SBO HC - GAS?

Reply

 
 
 
Old October 22nd, 2018, 05:19 PM
  #1  
Registered User
Thread Starter
 
Join Date: May 2018
Posts: 54
60's SBO HC - GAS?

Several questions on gas for the stock high compression SBO's 10.25:1 or higher...
What gas and/or additives have folks used with success?
(no hardened seats or SS valves)

I am getting a HC SBO for a street cruiser .... Should I use a higher octane? ethanol free?

Is anyone using additives?

I typically use 91 octane with no ethanol for a late 70's 403. Small noticeable difference, and idles better cold.

Would it be even better to use a higher octane like 100 ? There are few 100 octane pumps around my area.

I was understanding Higher octanes are better efficiency, and also higher compression is better for efficiency too... so spending a little more in gas may offset some of the cost.
Via3d is offline  
Reply With Quote
Old October 22nd, 2018, 05:31 PM
  #2  
Phantom Phixer
 
Charlie Jones's Avatar
 
Join Date: Dec 2011
Location: Apopka, FL
Posts: 2,007
For 10.25 compression , the minimum octane I would recommend would be 91 octane .
Ethanol free is preferred if the carb or fuel pump still has non ethanol resistant components .
Charlie Jones is offline  
Reply With Quote
Old October 22nd, 2018, 05:33 PM
  #3  
Moderator
 
oldcutlass's Avatar
 
Join Date: Oct 2009
Location: Poteau, Ok
Posts: 30,827
I would try the 91 and see if you can run your desired timing, if not then move up to 93. I doubt you need 100 octane.
oldcutlass is offline  
Reply With Quote
Old October 22nd, 2018, 08:11 PM
  #4  
Registered User
 
Fun71's Avatar
 
Join Date: Feb 2013
Location: Phoenix, AZ
Posts: 5,681
Originally Posted by Via3d View Post
I typically use 91 octane with no ethanol for a late 70's 403. Small noticeable difference, and idles better cold.
That 403 is 8.5:1 compression at best and likely would run fine on 87 octane fuel.

Originally Posted by Via3d View Post
I was understanding Higher octanes are better efficiency, and also higher compression is better for efficiency too...
Higher octane fuel is not more efficient on its own. It has a greater resistance to spontaneous combustion (pre-ignition) for use in high compression engines, which is where the increased efficiency come in. Using it in a a low compression engine does nothing but drain your wallet faster.

Last edited by Fun71; October 22nd, 2018 at 09:00 PM.
Fun71 is offline  
Reply With Quote
Old October 22nd, 2018, 08:47 PM
  #5  
Registered User
Thread Starter
 
Join Date: May 2018
Posts: 54
Originally Posted by Fun71 View Post
That 403 is 8.5:1 compression at best and likely would run fine on 87 octane fuel.
Yes concur... in the 403 I was using non-ethanol. Ran better noticeably (maybe just the octane level higher than 87 I was using) .
Originally Posted by Charlie Jones View Post
Ethanol free is preferred if the carb or fuel pump still has non ethanol resistant components .
and agreed Charlie, I felt safer with no ethanol gas being the stock carb, hoses, etc, since ethanol deteriorates those older items

Originally Posted by Fun71 View Post
It has a greater resistance to spontaneous combustion (pre-ignition) for use in high compression engines
Ethanol has higher temp for igniting right? burns clean.... So is using ethanol better?

Originally Posted by oldcutlass View Post
I would try the 91 and see if you can run your desired timing, if not then move up to 93. I doubt you need 100 octane.
Thanks old cutlass,

Summary All, IF ethanol is o.k. or better to run then I will just use and pay the cheaper pump gas 93 rather than than ethanol free blend. Otherwise stick to the 91 non-ethaol if it runs well as as oldscutlass suggests.

So is the main concern soft valves?
and pre-ignition banging deteriorating the non-hardened valves?
In this regard, does a Lead additive or octane boost relieve this concern of excessive premature wear? I prefer to stay away from Lead additive if possible.


Apologies for the kazillion questions... learning experience thanks for all the quick responses.


Via3d is offline  
Reply With Quote
Old October 23rd, 2018, 09:31 AM
  #6  
Registered User
 
Tedd Thompson's Avatar
 
Join Date: Oct 2004
Location: Forest Ranch Ca.
Posts: 4,855
I think the harden valve thing is a exaggerated problem. I have been running a SBC (as late as of yesterday) with 9 1/2 compression for 20 years on stock fulie heads with no problem. If you had some killer valve springs and freshly ground valve seats maybe but on a stock upper end that has had some leaded gas run through it I haven't seen any problems.

On the other hand if I were to rebuild the heads I most certainly would give it a three angle valve job, the cost is the same..... Tedd
Tedd Thompson is offline  
Reply With Quote
Old November 1st, 2018, 10:28 PM
  #7  
Registered User
Thread Starter
 
Join Date: May 2018
Posts: 54
99 octane - 67 SBO High Compression motor & gas

OK, I references the AMA specs for 66 & 67 SBO. The high compression motors were spec'd to use 99 octane.

Hmmmmm,,,,, How best to achieve? Am I correct to assume meeting this spec of using 99 octane, would be better if there truly is an issue due to using no Lead and the valves are not hardened???

Last edited by Via3d; November 1st, 2018 at 11:19 PM.
Via3d is offline  
Reply With Quote
Old November 2nd, 2018, 09:25 AM
  #8  
Old(s) Fart
 
joe_padavano's Avatar
 
Join Date: Mar 2007
Location: Northern VA
Posts: 30,433
Originally Posted by Via3d View Post
OK, I references the AMA specs for 66 & 67 SBO. The high compression motors were spec'd to use 99 octane.

Hmmmmm,,,,, How best to achieve? Am I correct to assume meeting this spec of using 99 octane, would be better if there truly is an issue due to using no Lead and the valves are not hardened???
You need to understand the difference in RON vs. MON octane ratings. 99 is RON. MON is a different octane rating standard that is typically 8-12 points lower. Today's gas uses an Anti Knock Index that is really (R+M)/2. 99 octane RON is closer to 93 octane AKI. More to the point, the actual octane rating needed by your particular engine depends on the CR, carbon buildup, ignition timing, cam profile, and other factors. The factory octane ratings assumed a blueprinted engine (specified CR with no carbon), stock timing, and stock cam profile. Olds engines came from the factory with larger than blueprint combustion chambers, to allow carbon buildup and head resurfacing without exceeding the blueprint CR specs.
joe_padavano is offline  
Reply With Quote
Old November 2nd, 2018, 11:09 AM
  #9  
Registered User
Thread Starter
 
Join Date: May 2018
Posts: 54
Thanks Joe !! I knew there was some more science behind the 'Olds madness. LOL

SO, thanks for the brief intro to gas octane differences and terminology. What is AKI?

I live 18-20min. from Road Atlanta Speedway, can get 100 octane... or higher, ethanol or no ethanol.


What is the opinion on gas to use for :

motor = '67 330ci High compression 10.25:1 stock motor.
cam = stock cam is 278 @ 433 & 282 @ 433
Distrib. = HEI from my '79 403ci unit on it (put new stock points in I suppose)
Carb = 800cfm 4bbl Q-Jet the '79 17095253 (rebuild w/. Cliff R. hp kit)
intake manifold = #16 stock iron intake from my '79 .403ci (more on this later post)
exhaust = going 2.5" dual exhaust
exhaust = likely headers too ceramic coated (outside only)
timing = TBD
Spark Plug and gap TBD (another post)
Gear ratio = 3.23









Via3d is offline  
Reply With Quote
Old November 2nd, 2018, 11:17 AM
  #10  
Old(s) Fart
 
joe_padavano's Avatar
 
Join Date: Mar 2007
Location: Northern VA
Posts: 30,433
Originally Posted by Via3d View Post
SO, thanks for the brief intro to gas octane differences and terminology. What is AKI?
Originally Posted by joe_padavano View Post
Today's gas uses an Anti Knock Index that is really (R+M)/2.
joe_padavano is offline  
Reply With Quote
Old November 7th, 2018, 09:53 PM
  #11  
Registered User
Thread Starter
 
Join Date: May 2018
Posts: 54
GAS SPEC 1967 .330 high compression = 99

O.k. I read up on the RON/MON values for octane ratings.
Interesting read...

--->>> So are the AMA spec ratings RON back in the 60's for octane ratings ??

Via3d is offline  
Reply With Quote
Old November 8th, 2018, 05:27 AM
  #12  
Moderator
 
oldcutlass's Avatar
 
Join Date: Oct 2009
Location: Poteau, Ok
Posts: 30,827
oldcutlass is offline  
Reply With Quote
Old November 8th, 2018, 12:27 PM
  #13  
Phantom Phixer
 
Charlie Jones's Avatar
 
Join Date: Dec 2011
Location: Apopka, FL
Posts: 2,007
Originally Posted by Via3d View Post

--->>> So are the AMA spec ratings RON back in the 60's for octane ratings ??
Yes , Research Octane Numbers were the standard back in the sixties
As noted , today's gasoline ratings are an average of Research and Motor ratings . so they are 8 to 12 points lower .

Charlie Jones is offline  
Reply With Quote
Old November 8th, 2018, 02:15 PM
  #14  
Registered User
Thread Starter
 
Join Date: May 2018
Posts: 54
DOH!

Charlie Jones, The pic that oldscutlass posted indicates that cutrent AKI was introduced 80 yrs ago. Which means it may not have been RON only in the 60's.

I did see that Pontiac in late 70's indicated (research octane) when stating its rated octane fuel for a particular car/engine for MVMA specs. But other mfg's did not distinguish this.

I am leaning towards using lead alternative/additive and run highest octane at the pump in Georgia and see if that works but it still has 10% ethanol.

I just wish I had more definitive data on the 99 octane specification form late 60's. And when the current AKI standard was implemented, still researching.
Via3d is offline  
Reply With Quote
Old November 8th, 2018, 02:32 PM
  #15  
Registered User
 
Fun71's Avatar
 
Join Date: Feb 2013
Location: Phoenix, AZ
Posts: 5,681
Originally Posted by Via3d View Post
run highest octane at the pump in Georgia and see if that works but it still has 10% ethanol.
All I have available here in Arizona is 10% ethanol fuel and my car has been fine with it for the past 20 years.
Fun71 is offline  
Reply With Quote
Old November 8th, 2018, 05:18 PM
  #16  
Phantom Phixer
 
Charlie Jones's Avatar
 
Join Date: Dec 2011
Location: Apopka, FL
Posts: 2,007
Originally Posted by Via3d View Post
DOH!

Charlie Jones, The pic that oldscutlass posted indicates that cutrent AKI was introduced 80 yrs ago. Which means it may not have been RON only in the 60's.

I did see that Pontiac in late 70's indicated (research octane) when stating its rated octane fuel for a particular car/engine for MVMA specs. But other mfg's did not distinguish this.

I am leaning towards using lead alternative/additive and run highest octane at the pump in Georgia and see if that works but it still has 10% ethanol.

I just wish I had more definitive data on the 99 octane specification form late 60's. And when the current AKI standard was implemented, still researching.
You are overthinking this .
Yes , both methods have been around for over 80 years . However , the Research number was higher. So it was the one used by the oil companies in their advertising . And auto makers in their recommendations .
About the same time that leaded premium gas disappeared , the "new " octane ratings came to be . Can't remember the exact year , but it was between 1975 to 1980 .

I had a '63 Dynamic 88 with 10.25 compression as a daily driver between '97 and '02 . I put 40,000 miles on it ,
I used 93 octane unleaded with ethanol in it . And Mobil 1 oil .
I never had any problems with it .

Last edited by Charlie Jones; November 8th, 2018 at 05:27 PM.
Charlie Jones is offline  
Reply With Quote
Old November 8th, 2018, 07:19 PM
  #17  
Registered User
Thread Starter
 
Join Date: May 2018
Posts: 54
Thanks all...

I will start with 93 with ethanol and alternatively try 91 octane no ethanol. If it runs well either of these, if I am still hesitant on the hardened set myth or curse I can always use some Motor Medic lead alternative
Via3d is offline  
Reply With Quote
Old November 8th, 2018, 08:51 PM
  #18  
Moderator
 
oldcutlass's Avatar
 
Join Date: Oct 2009
Location: Poteau, Ok
Posts: 30,827
The lead alternative is not really needed. If your really want to use a lead additive, Octane Supreme is the best. See link below:

http://www.wildbillscorvette.com/OctaneSupreme01.htm
oldcutlass is offline  
Reply With Quote
Old November 9th, 2018, 05:25 AM
  #19  
Registered User
 
olds 307 and 403's Avatar
 
Join Date: Dec 2006
Location: Melville, Saskatchewan
Posts: 4,359
What motor is that carb off, I assume a 403. They are calibrated lean but should be passable on a high compression 330. The lead additive doesn't seem necessary unless it helps with spark knock, valve seat wear isn't an issue. I would try 34 to 36 total and add a much vacuum advance as it will tolerate. I ran a 9.6 to 1 Olds 350 with around .065" quench and a 204/214 280/290 .448/.472 114 LSA Performer cam with a Holley reman 800 cfm Qjet then put my 403 carb on. It stumbled and pinged at part throttle no matter where I set the timing on 91. I sent the 403 carb to Everyday Performance and that made a huge difference, like I said the idle and off idle are very lean. I had to cut back the vacuum advance to 10 degrees and slow down the advance curve. Most HEI's come in very slow that will help. Also buy an adjustable vacuum advance canister. Also the very cold NGK 5670-8 plugs also helped. Good luck.
olds 307 and 403 is offline  
Reply With Quote
Old November 9th, 2018, 10:19 AM
  #20  
Registered User
Thread Starter
 
Join Date: May 2018
Posts: 54
yes Qjet '79 .403 17059253.
Cliff R suggested change to 44 primary rods and new piston springs. This should help calibrate/allow more fuel from the original lean condition
I anticipate my manifold has more volume too. for another post......

going with the stock R44SZ ('z' for HEI') and I settled on starting at .045 gap...

I think I will make a post re: overall 330 tune and adjustments, etc.

Timing I have no idea yet and will be hands on.

Last edited by Via3d; November 9th, 2018 at 10:22 AM.
Via3d is offline  
Reply With Quote
Old November 12th, 2018, 07:25 AM
  #21  
Registered User
 
olds 307 and 403's Avatar
 
Join Date: Dec 2006
Location: Melville, Saskatchewan
Posts: 4,359
You are on the right track. Get this https://www.google.ca/url?sa=t&source=web&rct=j&url=https://www.summitracing.com/parts/acc-31035&ved=2ahUKEwiT1aabhc_eAhWI7oMKHZrjCxAQFjACegQ ICBAB&usg=AOvVaw1KEaFZ0TM81Jt002mheOSm
Or this https://www.google.ca/url?sa=t&sourc...e8rhCBYEs6E15P
I have used both with success and it will reduce the vacuum advance from probably 30 degrees to 20 degrees before you even adjust it. The mechanical advance curves can vary a lot. I find most are slow, even with lighter springs don't come in before 3000, which help tuning with high compression.

Last edited by olds 307 and 403; November 12th, 2018 at 07:27 AM.
olds 307 and 403 is offline  
Reply With Quote
Old November 12th, 2018, 10:21 AM
  #22  
Registered User
Thread Starter
 
Join Date: May 2018
Posts: 54
Vacuum advance

interesting, I haven't considered vacuum advance units yet. I will look into these
Via3d is offline  
Reply With Quote
 
 
 
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
young olds
Racing and High Performance
43
March 8th, 2017 04:02 PM
chip-powell
General Discussion
17
April 7th, 2015 10:19 AM
joepenoso
Big Blocks
4
July 19th, 2013 01:44 PM
f-85
Parts For Sale
0
August 15th, 2010 12:15 PM
shaks 442 clone
Small Blocks
2
October 18th, 2008 10:41 AM


Thread Tools
Search this Thread
Quick Reply: 60's SBO HC - GAS?


Archive Advertising Cookie Policy Privacy Statement Terms of Service

We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.