CoupeDTS Posted July 26, 2012 Report Share Posted July 26, 2012 I've been restoring a 1970 calais with the 472. It has 97k miles on it and has been stored indoors all its life but not ran for 15 years. It needed a new fuel pump, I upgraded the points to a crane cam conversion piece that is not points, new cap rotor plugs wires coil, rebuilt the carb and so it runs but has a miss at idle and pinging when medium throttle. I still haven't adjusted the idle air screws I need to get my hands on a digital tach to do it properly so maybe that's the problem with the idle miss. But I put 87 octane gas in it with lead substitute, does it need higher octane? * 1966 Deville Convertible * 2007 Escalade ESV Black on Black * 1996 Fleetwood Brougham Black on Black V4P -Gone* 1983 Coupe Deville Street/Show Lowrider -Gone* 1970 Calais 4dr Hardtop GONE* 2000 Deville DTS - Silver with Black Leather and SE grille GONE* 1999 Seville STS - Pearl Red GONE Link to comment Share on other sites More sharing options...
BodybyFisher Posted July 26, 2012 Report Share Posted July 26, 2012 Does it not say so on the dash? If I recall, its premium, in order to run regular hardened valve guides were required, that was the situation with my 74 Eldorado with 500 ci Pre-1995 - DTC codes OBD1 >> 1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/ Cadillac History & Specifications Year by Year http://www.motorera.com/cadillac/index.htm Link to comment Share on other sites More sharing options...
CoupeDTS Posted July 27, 2012 Author Report Share Posted July 27, 2012 They are high compression kind of like northstars so that would make sense to use premium. Ill add some octane booster to save the tank of gas in it now was just hoping a gas hog might use the cheapest gas not the most expensive * 1966 Deville Convertible * 2007 Escalade ESV Black on Black * 1996 Fleetwood Brougham Black on Black V4P -Gone* 1983 Coupe Deville Street/Show Lowrider -Gone* 1970 Calais 4dr Hardtop GONE* 2000 Deville DTS - Silver with Black Leather and SE grille GONE* 1999 Seville STS - Pearl Red GONE Link to comment Share on other sites More sharing options...
BodybyFisher Posted July 27, 2012 Report Share Posted July 27, 2012 I have a Chiltons manual that has specs for your engine, Ill see what I can find. The 74 got terrible gas mileage. I often think how far we have come since the 70s in terms of improved fuel economy and reducing emissions. I don't think environmentalists and polititians realize how far we have come. Pre-1995 - DTC codes OBD1 >> 1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/ Cadillac History & Specifications Year by Year http://www.motorera.com/cadillac/index.htm Link to comment Share on other sites More sharing options...
KHE Posted July 27, 2012 Report Share Posted July 27, 2012 Use premium fuel to stop the pinging. The 472 was a high compression engine - 10 or 10.5:1 which was about the same as today's Northstar engine that can run on regular but the combustion chamber design on the 472 was not as advanced as the Northstar so the 472 needed premium fuel. Premuim fuel in those days was leaded. That fuel became difficult to find in the late 1970s. If you ever need to rebuild the engine it might make sense to install updated valves that will withstand unleaded fuel. Kevin '93 Fleetwood Brougham '05 Deville '04 Deville 2013 Silverado Z71 Link to comment Share on other sites More sharing options...
CoupeDTS Posted July 28, 2012 Author Report Share Posted July 28, 2012 The premium has helped the ping. I think I narrowed down the aweful rough idle to the points conversion I installed. Going to be taking that back for a new one or money back * 1966 Deville Convertible * 2007 Escalade ESV Black on Black * 1996 Fleetwood Brougham Black on Black V4P -Gone* 1983 Coupe Deville Street/Show Lowrider -Gone* 1970 Calais 4dr Hardtop GONE* 2000 Deville DTS - Silver with Black Leather and SE grille GONE* 1999 Seville STS - Pearl Red GONE Link to comment Share on other sites More sharing options...
BodybyFisher Posted July 28, 2012 Report Share Posted July 28, 2012 That is what is was, NOW I remember when I read KHEs post, these engines had problems with unleaded when regular gas went away, that is when I had hardened valve guides installed. Pre-1995 - DTC codes OBD1 >> 1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/ Cadillac History & Specifications Year by Year http://www.motorera.com/cadillac/index.htm Link to comment Share on other sites More sharing options...
Cadillac Jim Posted July 28, 2012 Report Share Posted July 28, 2012 Another problem for older engines was carbon build-up. In high compression engines with iron heads, you just can't run regular gas, particularly in town and with carbon build-up. A good 500 mile road trip, once the miss and pinging is resolved, may reduce the sensitivity to octane, but a couple of weeks around town will bring back the carbon. -- Click Here for CaddyInfo page on "How To" Read Your OBD Codes-- Click Here for my personal page to download my OBD code list as an Excel file, plus other Cadillac data -- See my CaddyInfo car blogs: 2011 CTS-V, 1997 ETC Yes, I was Jims_97_ETC before I changed cars. Link to comment Share on other sites More sharing options...
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