Friends of the Professional Car Society - Official Website of the Professional Car Society, Inc.Friends of the Professional Car Society - Official Website of the Professional Car Society, Inc.



Go Back   Friends of the Professional Car Society - Official Website of the Professional Car Society, Inc. > Professional Car Discussion > Technical Discussion Forum

Technical Discussion Forum For the discussion of technical questions about Professional Cars and their repair and maintenance. Posting in this forum is limited to PCS Members and / or Site Supporters. We encourage all website users to become members of the Professional Car Society and / or become Site Supporter.

Reply
 
Thread Tools Display Modes
  #101  
Old 03-04-2018, 09:07 PM
Blake Sherwin's Avatar
Blake Sherwin Blake Sherwin is offline
Website Member
 
Join Date: Apr 2016
Location: Owasso OK 74021
Posts: 415
Thanks: 26
Thanked 183 Times in 89 Posts
Groans: 0
Groaned at 0 Times in 0 Posts
Default

Well i told this hissing is completely normal for a carb. It wasnt making that noise last time when i was puttimg in seafoam so thought it was abnormal.
__________________
1968 Cadillac MM Combination
Reply With Quote
  #102  
Old 03-04-2018, 09:35 PM
John ED Renstrom's Avatar
John ED Renstrom John ED Renstrom is offline
PCS Member - Elected Director 2017-2020
 
Join Date: Mar 2009
Location: Hot Springs SD 57747
Posts: 11,243
Thanks: 3,986
Thanked 14,509 Times in 6,146 Posts
Groans: 2
Groaned at 3 Times in 3 Posts
Default

change that switch
__________________
drop in for coffee anytime
Reply With Quote
  #103  
Old 03-04-2018, 10:45 PM
Blake Sherwin's Avatar
Blake Sherwin Blake Sherwin is offline
Website Member
 
Join Date: Apr 2016
Location: Owasso OK 74021
Posts: 415
Thanks: 26
Thanked 183 Times in 89 Posts
Groans: 0
Groaned at 0 Times in 0 Posts
Default

Quote:
Originally Posted by John ED Renstrom View Post
change that switch
What switch?
__________________
1968 Cadillac MM Combination
Reply With Quote
  #104  
Old 03-05-2018, 12:13 PM
John ED Renstrom's Avatar
John ED Renstrom John ED Renstrom is offline
PCS Member - Elected Director 2017-2020
 
Join Date: Mar 2009
Location: Hot Springs SD 57747
Posts: 11,243
Thanks: 3,986
Thanked 14,509 Times in 6,146 Posts
Groans: 2
Groaned at 3 Times in 3 Posts
Default

The car has a intermittent open in the electrical circuit. All the problems are most likely the ignition switch. But it could be as simple as the run wire off the starter or Loose wire on the coil. Mechanical problems don't normally come and go. These kind of things are frustrating not easy to trace and make you want to dump the car in a hurry. Every thing you have shown can be explained wit a intermittent open. The hissing in the carburetor was most likely a small backfire putting presser into the carb. The hissing is it going out. With the engine not running there is no vacuum.

The weak link in the 68 modal was the ignition switch. Check all the connections between the distributor and the coil the coil and the switch the switch and the starter. If they are good it's the switch. Once again simple test is the jumper wire. A piece if wire long enough to go from the pos side of the battery to the Ignition side of the coil.it. Won't start but your wire in place. If it starts take the jumper off. If it dies when you do that you have a positive test of a open circuit begween the coil and the battery. If your driving it and it starts acting up put the jumper wire on . If it starts running smooth the you have a positive test of a intermittent open between the oil and the battery. As Paul said don't run the car for any length of time with the jumper in place. You will burn the points up. But as it starts on 12 volts a short deration to test to Rule out a electrical
problem is in order before you dpend money you don't need to
__________________
drop in for coffee anytime
Reply With Quote
  #105  
Old 03-05-2018, 01:02 PM
Blake Sherwin's Avatar
Blake Sherwin Blake Sherwin is offline
Website Member
 
Join Date: Apr 2016
Location: Owasso OK 74021
Posts: 415
Thanks: 26
Thanked 183 Times in 89 Posts
Groans: 0
Groaned at 0 Times in 0 Posts
Default

Thanks, circling back to the previous talks about OEM being expensive and the aftermarket being a pain to install:

In your opinions, am I better off dishing out for the expensive original:
http://www.2040-parts.com/nos-gm-del...re-68-i785109/

Or finding a good aftermarket for less and just paying a mechanic to properly do the job?

At $465 for the part, I'm not sure if I would just be better off getting something aftermarket and having it converted

My concern is that if I spend $465 or more on an original part and if that part is prone to failure anyway I'm going to eventually end up in the same situation again.
__________________
1968 Cadillac MM Combination
Reply With Quote
  #106  
Old 03-05-2018, 02:05 PM
John ED Renstrom's Avatar
John ED Renstrom John ED Renstrom is offline
PCS Member - Elected Director 2017-2020
 
Join Date: Mar 2009
Location: Hot Springs SD 57747
Posts: 11,243
Thanks: 3,986
Thanked 14,509 Times in 6,146 Posts
Groans: 2
Groaned at 3 Times in 3 Posts
Default

I'll send you the one I have on the wall. but it may not be any better then the one you have. I would not pay that kind of money and go back to a original one.
go to a place like USA parts, Caddy Daddy, Fisk or one of the other people that deal in replacement parts for vintage caddys and get the one they recommend.

put first you need to know that it is the problem. there is no since in swapping parts just to hope you get the right one.

now if you look threw here you can see all I did on this one. when I sold it it was just Doing the might start problem you have. Bill put up with things your describing till he swapped the switch for a universal one and then the car ran fine. ttps://www.dropshots.com/jer57747/albums/308015/2013-04-04/11:01:45
__________________
drop in for coffee anytime

Last edited by John ED Renstrom; 03-05-2018 at 02:24 PM.
Reply With Quote
  #107  
Old 03-14-2018, 11:49 AM
Blake Sherwin's Avatar
Blake Sherwin Blake Sherwin is offline
Website Member
 
Join Date: Apr 2016
Location: Owasso OK 74021
Posts: 415
Thanks: 26
Thanked 183 Times in 89 Posts
Groans: 0
Groaned at 0 Times in 0 Posts
Default

I havent had time to check any of this yet, but I did take it for its' weekly drive over this past weekend, I had less than a quarter tank of E10 left, so I diluted it with a full tank of 0% ethanol 91 octane pure gas. Its already running much better. I know this isnt going to solve all my problems, but now I can actually floor the gas without it cutting out (not that I ever do floor it, but for testing). Before if I tried that it would choke and hesitate.

Someone else on the cadillac forums had also suggested that there may be a wire harness coming from the starter that could have melted or something, so I have added that to my list of things to investigate.

I am optimistic on the gas though. I went on about a 15-20 minute drive and was able to get up to 60 without any problems. 50 used to be a challenge before.
__________________
1968 Cadillac MM Combination
Reply With Quote
  #108  
Old 03-14-2018, 12:00 PM
John ED Renstrom's Avatar
John ED Renstrom John ED Renstrom is offline
PCS Member - Elected Director 2017-2020
 
Join Date: Mar 2009
Location: Hot Springs SD 57747
Posts: 11,243
Thanks: 3,986
Thanked 14,509 Times in 6,146 Posts
Groans: 2
Groaned at 3 Times in 3 Posts
Default

As i said it starts on 12 volts directly from the starter. The in the run position on the switch it runs on the risister wire from the switch. No that high compression 472 will nor run good on any fuel under 90 octane 91 is the requirement.
__________________
drop in for coffee anytime
Reply With Quote
  #109  
Old 03-14-2018, 02:14 PM
Blake Sherwin's Avatar
Blake Sherwin Blake Sherwin is offline
Website Member
 
Join Date: Apr 2016
Location: Owasso OK 74021
Posts: 415
Thanks: 26
Thanked 183 Times in 89 Posts
Groans: 0
Groaned at 0 Times in 0 Posts
Default

Quote:
Originally Posted by John ED Renstrom View Post
As i said it starts on 12 volts directly from the starter. The in the run position on the switch it runs on the risister wire from the switch. No that high compression 472 will nor run good on any fuel under 90 octane 91 is the requirement.
good to know, had no idea 91 was actually a requirement. I'm hoping to get some free time this weekend maybe to look close at wiring, thought I would last weekend but we were too busy.

Ignition doesnt get warm after a drive it seems. Going to drive it to my dads on easter, so that will hopefully be a good distance drive to test if the issue is going to come back.
__________________
1968 Cadillac MM Combination
Reply With Quote
  #110  
Old 03-14-2018, 07:11 PM
Philip Scanio Philip Scanio is offline
PCS Member / Super Site Supporter
 
Join Date: Apr 2015
Location: Temple TX 76504
Posts: 137
Thanks: 367
Thanked 121 Times in 83 Posts
Groans: 0
Groaned at 0 Times in 0 Posts
Default

Blake, Do you have a station in town that sells 0 Ethanol gas? What brand? Thanks, Philip
Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -4. The time now is 10:57 AM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2018, vBulletin Solutions, Inc.
Copyright 2009 - 2018 Friends of the Professional Car Society