Dieseling problem on caddy

Automotive powered airboat discussion.
Post Reply
AirPat
Southern Airboat Member
Posts: 38
Joined: Thu Nov 06, 2008 2:57 pm
Location: Rosenberg, TX

Dieseling problem on caddy

Post by AirPat » Mon Jul 13, 2009 6:49 pm

I am almost done with my first rebuild. I finally got my cooling system set up and prop back on (thanks for the help). Now I have a dieseling problem. After running the motor for a while on the trailor it stayed at a constant 160. I shut it down and it kept running for a good 20 sec dieseling.Timing is set on 0. I am running 87 octane. The motor is a 500 cad with Potter's DD cam, sylvalite pistons and 76 cc heads. I ran the motor before putting the prop on and did not have this problem.
Thanks again for your sugestions.

User avatar
MYDIXIEWRECKED
Site Supporter - IV
Site Supporter - IV
Posts: 3634
Joined: Tue Dec 18, 2007 7:48 am
Location: Plantation,fl Area 3A south camp 9 1/2

Re: Dieseling problem on caddy

Post by MYDIXIEWRECKED » Mon Jul 13, 2009 8:23 pm

Do a search for throttle solinoids or dieseling on here. It will allow your butterflies to close completely and it will shut right off...(top right of screen in blue letters) It will get into more detail.
THOUGHT FOR THE DAY
"People sleep peaceably in their beds only because rough men stand ready to do violence ON THEIR BEHALF"

Lifetime member NRA
Owner camp 9 1/2 in beautiful 3A south, Everglades

User avatar
JAMES
Site Supporter - II
Site Supporter - II
Posts: 8569
Joined: Wed Aug 22, 2007 10:31 pm
Location: cocoa
Contact:

Re: Dieseling problem on caddy

Post by JAMES » Mon Jul 13, 2009 8:43 pm

when u shut it off at any point did the prop turn backwards ?????(detonation)
did u check your initial timing ??? when u started it up @ idel
https://m.facebook.com/321ccc/?ref=bookmarks Wp383 268 rotator 3 bld WT/EX 14.4 perdator

ditchdr
Site Supporter - I
Site Supporter - I
Posts: 257
Joined: Thu Dec 21, 2006 8:51 am
Location: Paisley Florida,Lake County

Re: Dieseling problem on caddy

Post by ditchdr » Mon Jul 13, 2009 9:00 pm

I had the same thing for a while... My problem was the carb needed a little adjustment and I have to run 93 or better to fix it. Be carefull a caddie won't put up with much of that. I have a built q jet that I run. It had a bit of a needle valve/seat issue. I still like to shut the electric pump off for a minute and then shut off the motor.
Hope this helps
Roger
For as Bad as it is It Could Be Worse
THE LAKE COUNTY DOG CATCHERS CAN GO POUND SAND

tadpole
Southern Airboat Member
Posts: 108
Joined: Wed May 20, 2009 4:54 pm
Location: Florida Panhandle

Re: Dieseling problem on caddy

Post by tadpole » Mon Jul 13, 2009 9:44 pm

If you can't shut the fuel down completely then you need to go to a higher octane, especially if you have high compression. Always worked for me.

User avatar
John C
Site Supporter - V
Site Supporter - V
Posts: 2884
Joined: Thu Jan 26, 2006 9:43 pm
Location: Palm City

Re: Dieseling problem on caddy

Post by John C » Mon Jul 13, 2009 10:30 pm

Do yourself a favor and run 93 octane in your caddy motor. I don't know exactly what your compression ratio is with those 76cc heads, but she will run better with 93 octane. I would never run 87 octane in mine. The gas we are getting now is crap anyway compaired to what is was just a few years ago. Its not worth the risk doing damage to your motor. If your motor is dieseling and won't shut right down sometimes they will spin backwards. that motor was designed to run in one direction. when they spin backwards you could shave a bearing. Run 93, You will see a differance. She will run better.

I also have a throttle solinoid. They work well.

T-REX
Site Supporter - IV
Site Supporter - IV
Posts: 1696
Joined: Sat Mar 12, 2005 2:10 am

Re: Dieseling problem on caddy

Post by T-REX » Mon Jul 13, 2009 10:39 pm

ya first try 93 octane.

do you mean that your cam is installed at 0 degrees ? what is your actual timing at? how does she start? is your starter stuggling alittle?

Ruagatr
Site Supporter - VIII
Site Supporter - VIII
Posts: 3689
Joined: Thu Mar 09, 2006 9:29 pm

Re: Dieseling problem on caddy

Post by Ruagatr » Tue Jul 14, 2009 7:51 am

As has been posted many times, the number one cause of Cadillac engine death is mismatching balancer and timing pointer components/pulleys. So it LOOKS like it is timed correctly, and it is very advanced. Check top dead center on number 1 and look at the marks on the balancer pulley--does it line up? If not, put a timing tape on it and then time it.

Maddog

User avatar
crowhater
Site Supporter - III
Site Supporter - III
Posts: 3490
Joined: Thu Feb 01, 2007 8:47 pm
Location: Conroe Texas

Re: Dieseling problem on caddy

Post by crowhater » Tue Jul 14, 2009 12:07 pm

Ruagatr wrote:As has been posted many times, the number one cause of Cadillac engine death is mismatching balancer and timing pointer components/pulleys. So it LOOKS like it is timed correctly, and it is very advanced. Check top dead center on number 1 and look at the marks on the balancer pulley--does it line up? If not, put a timing tape on it and then time it.

Maddog
Once again Rugar is dead right!!! I like 10* advance on a Cadillac and I always run the best fuel. Even if everything is perfect it will still run on a little if you shut down right after a hard run if you do not let it idle for a few seconds. You can get a solinoid system on your carb and take out your idle screw so when you shut it down it closes your carb all the way. Another good thing to do when building the motor is to polish your combustion chambers to get rid of any high spots and this will help. Are you running the factory intake?? If so there is a hole in the bottom of it under your carb that will hold fuel and this will cause it to diesel, you can plug this hole with a small freeze plug so fuel can not collect.
18x8 Alum, 496 BBC, 2.6 CH4, 4B 82" S-blades

AirPat
Southern Airboat Member
Posts: 38
Joined: Thu Nov 06, 2008 2:57 pm
Location: Rosenberg, TX

Re: Dieseling problem on caddy

Post by AirPat » Tue Jul 14, 2009 3:16 pm

Thanks for the help.
I am running a edlebrock carb and intake. The prop never turned backwards but what is detonation? I was told to set the timing at 0 by the cam manufacturer. Let me make sure I got it right becuase basically i don't know sh*t. This is the first time i have built a motor and I basically did it from what i learned here and 2 books i bought. I am still suprised it runs.
1. Run 93 octane
2. Check top dead center
3. Get idle solenoid
Thanks again

User avatar
crowhater
Site Supporter - III
Site Supporter - III
Posts: 3490
Joined: Thu Feb 01, 2007 8:47 pm
Location: Conroe Texas

Re: Dieseling problem on caddy

Post by crowhater » Tue Jul 14, 2009 3:35 pm

Sense you are a DD motor I would set the cam 3* advanced so you bring your torque in quicker. Then you set your initial timming at 10*. This is the timming you read at idle. At full advance you should try to get 32* total timming. If you have a factory HEI you will be lucky to get 25* total timming. I like to get my total advace timming in by 2000-2500rpm. You should not be using your vacum advance at all. If you have it you should unhook it.
18x8 Alum, 496 BBC, 2.6 CH4, 4B 82" S-blades

User avatar
WBG444
Southern Airboat Member
Posts: 62
Joined: Thu Apr 23, 2009 7:44 pm
Location: I live on a Ranch in Texas out in da middle of nowhere, far away from all You crazy people…
Contact:

Re: Dieseling problem on caddy

Post by WBG444 » Wed Jul 15, 2009 10:24 pm

Dude turn you idle down…way down…like 500rpm and run 93 octane. It may still run on after a hard long run but it should help =)

Post Reply

Return to “Automotive Power Only”