70 500cid on 87 octane? - Page 2
Cadillac
 

Cadillac Forums | Help Us Help You | Advertise | Cadillac Parts | Cadillac News | Cadillac Classifieds / (Old System)

Cadillac Technical Archive | Cadillac Dealers | Cadillac Reviews | Cadillac Dealer Reviews | Cadillac Vendors

CadillacForums.com is the premier Cadillac Forum on the internet. Registered Users do not see the above ads.
+ Reply to Thread
Page 2 of 2 FirstFirst 1 2
Results 16 to 24 of 24
500, 472, 425, 368 Discussion, 70 500cid on 87 octane? in Cadillac Engine Technical Discussion; Took me all day, but I just fixed the power steering leak. That totals about 20 man hours of work, ...
  1. #16
    davesdeville's Avatar
    davesdeville is offline Banned
    Automobile(s): 1995 ETC, 75 Deville, Cad500 powered 73 Apollo, 94 Mark VIII
    Join Date
    Aug 2003
    Location
    Albuquerque, NM
    Age
    27
    Posts
    7,971
    Took me all day, but I just fixed the power steering leak. That totals about 20 man hours of work, 15 mine and 5 my dads. And 3 hoses. And 3 quarts of fluid. I'll check the filter before I drive up to the parts store tomorrow and replace it if needed. I also need to replace the speedometer cable, get it washed and get the engine compartment steam cleaned, get the car washed, and put some Armor-All on the top to try to save the remaining vinyl.

  2. #17
    Tickle Me Eldo is offline Cadillac Owners Member
    Join Date
    Jun 2004
    Posts
    10

    Re: 70 500cid on 87 octane?

    Quote Originally Posted by Allante North *
    Spend a few pennies more and give that big ole 500 the juice she deserves.
    :drinker

    I can't think of an engine that would need premium (91+) more than a 30 year old, 500ci with 10:1 compression. I'm take a wild guess that you'd lose about 15% power with 87 octane and I don't think it would be good for the engine.

  3. #18
    JTraik is offline Cadillac Owners Enthusiast
    Automobile(s): '68 DeVille '95 FWB '99 Eldo '96 Cummins Ram 5MT
    Join Date
    Mar 2004
    Location
    Rochester, NY
    Age
    27
    Posts
    760

    Re: 70 500cid on 87 octane?

    Quote Originally Posted by davesdeville
    Took me all day, but I just fixed the power steering leak. That totals about 20 man hours of work, 15 mine and 5 my dads. And 3 hoses. And 3 quarts of fluid.
    ...The price you pay for being able to steer a 5000lb car with your pinky...

    As far as gas goes i have never put anything in there cept for 93. I want to put some race fuel in, 97 or 100 maybe...they sell it at the delta sonics 3 somthin a gallon. Im curious! Ill just burnout all the way home.

  4. #19
    wurstarme is offline Cadillac Owners Member
    Join Date
    Apr 2004
    Posts
    22

    Re: 70 500cid on 87 octane?

    Do the fuel pumps on 70's caddies go bad often? Mine is dogging on me if I floor it, and I have tried 2 different carbs to make sure it wasn't the carb. I'm going to try a new filter just for the hell of it, like you said it's $3 at autozone. Also, I am running low octane fuel (87) right now. I have yet to spend the extra couple dollars at the pump for the premium stuff. What kind of difference will I see if my 472 runs 8.25:1 stock compression?

    As for the power steering, I had all sorts of problems with mine a while back. First I had to replace a gasket in the steering box; then the pressure hose running from the box to the pump; then the pump itself; then the pulley when the belt kept snapping. I know what you went through.. many hours covered head-to-toe in steering fluid can get to you. Everything is fixed now though, no leaks and effortless steering make everything worth it

  5. #20
    Imprl59 is offline Cadillac Owners Fanatic
    Join Date
    Jan 2004
    Posts
    300

    Re: 70 500cid on 87 octane?

    Quote Originally Posted by wurstarme
    Do the fuel pumps on 70's caddies go bad often? Mine is dogging on me if I floor it, and I have tried 2 different carbs to make sure it wasn't the carb. I'm going to try a new filter just for the hell of it, like you said it's $3 at autozone. Also, I am running low octane fuel (87) right now. I have yet to spend the extra couple dollars at the pump for the premium stuff. What kind of difference will I see if my 472 runs 8.25:1 stock compression?
    I generally replace the mechanical fuel pump on any new car I get as preventative maintenance. You should also replace the rubber lines at the pump and tank at the same time. If you suspect the fuel pump you can buy a fuel pressure gauge, hook it up and lay it on the windshield while you drive around and recreate the condition to see if your fuel pressure is bottoming out. Thats the only way to know if fuel pressure is the issue. There is also a sock filter in the fuel tank that gets clogged from sediment in the tank.

    You won't see an increase in performance by running super unleaded in your engine. Super unleaded doesn't have any more energy than regular unleaded it is just more resistant to preignition so a higher compression engine won't knock or ping.

  6. #21
    Ogier is offline Cadillac Owners Member
    Join Date
    Jun 2004
    Age
    47
    Posts
    19

    Exclamation Re: 70 500cid on 87 octane?

    Interesting note:

    The only real difference between 87 and 92 octane fuel is the length of time it takes for an charge to burn in the cylinder. The 87 is a much faster, hotter burning fuel and is more prone to spontaneous combustion(knocking, pinging and dieseling).

    In theory, if you could find a more efficient way to take away the heat at the cylinders, you could run whatever grade of gas you wanted to. Normally, with the Ethylene Glycol/water mixture that we put into our engines to handle the cooling needs, there is a thin vapor barrier that forms around the cylinder where it is in contact that actually inhibits cooling to such an extent that even under the best of conditions, you get a less than stellar heat transfer ratio.

    My cousin runs a smallblock chevy(383) in Los Angelos all year round. His engine is currently set up at 11.5 compression and he runs it on pump gas. When we were talking about this last year, I had to ask him how he kept the engine cool in the LA traffic.

    His answer, and he swears by it is http://www.evanscooling.com/main25.htm.

    I will be running this in my truck when I get it on the road next week. I haul lots of heavy stuff at low speed and cooling is always an issue.

    Hope this helps.
    Ogier

  7. #22
    barge master's Avatar
    barge master is offline Cadillac Owners Enthusiast
    Join Date
    Jun 2004
    Location
    Northern Ct.
    Age
    50
    Posts
    624

    Re: 70 500cid on 87 octane?

    If it just takes a big gasp when you floor it, as opposed to spitting and chugging, you might need to adjust the tension on the little spring that keeps the secondary air doors from opening too soon. The tension starts to relax over the years and the air doors open so fast the engine just falls on it's face when you mash it. Q-jets get a bad rap for this, and it's only a simple adjustment.

  8. #23
    Sasquatch's Avatar
    Sasquatch is offline Cadillac Owners Fanatic
    Join Date
    Mar 2004
    Location
    Bluff Creek
    Posts
    320

    Re: 70 500cid on 87 octane?

    I've posted this before in other threads and I know it sounds silly but if your motor is "dogging" during acceleration pull your dist. cap and see if your vacuum advance is working properly. Here's an easy way to check. After removing the dist. cap find the vac hose that runs from the dist. to the carb. Disconnect at carb. Place that end in your mouth and begin drawing air through the line. You should begin to see the points plate shift or turn in the distributor. If you keep sucking and sucking and nothing happens then your vacuum advance is shot. $8.00 part at the parts store and can make a world of difference.

  9. #24
    wurstarme is offline Cadillac Owners Member
    Join Date
    Apr 2004
    Posts
    22

    Re: 70 500cid on 87 octane?

    Quote Originally Posted by Sasquatch
    I've posted this before in other threads and I know it sounds silly but if your motor is "dogging" during acceleration pull your dist. cap and see if your vacuum advance is working properly. Here's an easy way to check. After removing the dist. cap find the vac hose that runs from the dist. to the carb. Disconnect at carb. Place that end in your mouth and begin drawing air through the line. You should begin to see the points plate shift or turn in the distributor. If you keep sucking and sucking and nothing happens then your vacuum advance is shot. $8.00 part at the parts store and can make a world of difference.
    If it wasn't 2am right now, I'd go try that now. I'll try it in the morning before work... thanks a lot for the tip I wonder if that could be why it sounds like thunder is coming from my tailpipe when I let off the gas..

Quick Reply Quick Reply

Register Now

Please enter the name by which you would like to log-in and be known on this site.
If you do not want to register, fill this field only and the name will be used as user name for your post.

Please enter a password for your user account. Note that passwords are case-sensitive.

Please enter a valid email address for yourself.

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.



Bookmarks

Cadillac Posting Rules

  • You may post new threads
  • You may post replies
  • You may not post attachments
  • You may not edit your posts
Read about Lincoln | Buick | Kia Forte Forum
Need products for your Cadillac? Check out your options at the links below:

custom floor mats | Cadillac Chrome and Black Chrome Wheels | window tinting