1979 oldsmobile regency 98 - slow to start - cause?
April 24th, 2012, 07:16 PM
#1
Registered User
Thread Starter
Join Date: Feb 2008
Location: Minnesota
Posts: 24
1979 oldsmobile regency 98 - slow to start - cause?
I have a 1979 oldsmobile regency 98. 350. When I start it when it has been sitting overnight, I push the gas pedal and the choke closes appropriately. Then I turn the key and with either holding the pedal to the floor or pumping the pedal (doesn't matter) the starter turns and turns for 5-10 seconds, then all of a sudden it fires up. Once it goes it runs fine. This only happens when it is cold. When its warm it fires up right away. I've owned this car for a year and it seems that the time it takes to start has slightly increased. What do you think the cause of this is? One person mentioned that the gas is different now vs 1979 and being slow to start is expected. Does that make sense? Should I replace/rebuild the carburetor? Fuel filter? Or just keep driving it like this (it still always starts). Thanks in advance. Any thoughts appreciated.
May 1st, 2012, 07:18 PM
#2
Registered User
Join Date: Aug 2011
Posts: 2,999
Does the Choke Plate Stay Closed?
Hard cold starts are usually carburetor/choke related but not always. If it is a high mileage motor it could be low compression and/or a stretched timing chain causing late valve timing. How many miles are on the engine?
Start with some of the basics: Are the spark plugs fresh and the exact ones it calls for? Some GM's in that era called for a very wide plug gap that caused hard starting. If the recommended gap is over .060" I would try changing to AC standard plugs (nothing fancy just standard) and gap them at .060" If the factory already calls for a smaller gap use the smaller gap specification.
Has the ignition timing been checked? Does the choke plate stay shut while cranking, it should or is the choke pulloff opening it too much? Does the choke plate close with the air cleaner lid on? This is rare but, sometimes the plate will only close when the air cleaner lid is off. Take the lid off and with the choke plate closed note the position of the choke linkage on the side of the carb. The linkage on the side should be in the same position the next time you press the pedal down to engage the choke with the lid on, if not the choke linkage is binding. The choke pulloff should open the plate approx. 1/8" once it starts. With the engine off and the choke closed if the throttle is floored the choke unloader should also open the choke plate approximately 1/8". With the engine off, cold and not being cranked can you get more than one to two pumps from the accelerator pump? Sometimes the carburetor leaks down through the plugs on the bottom of the fuel bowl. In this case the 5-10 second cranking is the fuel pump refilling the fuel bowl.
If the engine has good compression and is tuned properly (this includes all carb adjustments not just idle speed and mixture) then yes the carb probably needs an overhaul. My suggestion is to overhaul the one on it if it has performed well in the past but, find a rebuilder that is experienced with Quadrajets. They are excellent carburetors if done correctly and tell the rebuilder that you are rebuliding it because of a cold start problem.
Start with some of the basics: Are the spark plugs fresh and the exact ones it calls for? Some GM's in that era called for a very wide plug gap that caused hard starting. If the recommended gap is over .060" I would try changing to AC standard plugs (nothing fancy just standard) and gap them at .060" If the factory already calls for a smaller gap use the smaller gap specification.
Has the ignition timing been checked? Does the choke plate stay shut while cranking, it should or is the choke pulloff opening it too much? Does the choke plate close with the air cleaner lid on? This is rare but, sometimes the plate will only close when the air cleaner lid is off. Take the lid off and with the choke plate closed note the position of the choke linkage on the side of the carb. The linkage on the side should be in the same position the next time you press the pedal down to engage the choke with the lid on, if not the choke linkage is binding. The choke pulloff should open the plate approx. 1/8" once it starts. With the engine off and the choke closed if the throttle is floored the choke unloader should also open the choke plate approximately 1/8". With the engine off, cold and not being cranked can you get more than one to two pumps from the accelerator pump? Sometimes the carburetor leaks down through the plugs on the bottom of the fuel bowl. In this case the 5-10 second cranking is the fuel pump refilling the fuel bowl.
If the engine has good compression and is tuned properly (this includes all carb adjustments not just idle speed and mixture) then yes the carb probably needs an overhaul. My suggestion is to overhaul the one on it if it has performed well in the past but, find a rebuilder that is experienced with Quadrajets. They are excellent carburetors if done correctly and tell the rebuilder that you are rebuliding it because of a cold start problem.
May 10th, 2012, 11:23 AM
#3
Registered User
Join Date: May 2012
Posts: 5
same problem
Hi guys
Im owning a 1979 98 as well. I got the same starting problem.further the engines Idle is a bit bad. It seems to stutter once, then runs good for circa 15 seconds.that circle repeats in a more or less regularly time.When i give the engine some more rpm in stand i have the same stuttering.when driving i cant hear anything of it.
hope somebody knows something about it
With regards
Jan
Im owning a 1979 98 as well. I got the same starting problem.further the engines Idle is a bit bad. It seems to stutter once, then runs good for circa 15 seconds.that circle repeats in a more or less regularly time.When i give the engine some more rpm in stand i have the same stuttering.when driving i cant hear anything of it.
hope somebody knows something about it
With regards
Jan
Thread
Thread Starter
Forum
Replies
Last Post
