|
|
Regular
Posts: 53
Location: Dublin Ga | Have a 60 Desoto with 383 when driving after warms up it stats missing around 50 on up acts like ignition is cutting out- very jerky . Does it a little as I am warming up but cannot detect it a idle When accelerating it does not seem to miss.but when gets up to speed it misses.
Have doe the following
new dist cap on old point dist- had installed electronic but it did same thing
new plugs points wires replaced ceramic coil voltage reducer removed and cleaned carb
blocked off all vacuum ports.
could it possibly be the fuel pump?
it seems to work fine- I am totally stumped
compression is 120 to 125 on all cyls
help!!
Lou Earle |
|
| |
|
Elite Veteran
Posts: 774
 
Location: Atlanta GA USA | I have heard of old fuel hoses collapsing and causing problems. |
|
| |
|
Expert
Posts: 3402
 
Location: Chestertown, NY ( near Lake George) | Coil is a possibility, poor engine grounds, reduced voltage to the pos side of the coil, low fuel pressure are some things that can cause a high speed misfire. Make sure the coil polarity is correct also and check into the electronic ign, some do not require a resistor.
Edited by Shep 2010-11-23 9:48 AM
|
|
| |
|
Expert
Posts: 2824
Location: Snohomish, WA. | Be sure the distributor wire isn't broken where it exits the distributor. I've had that one before.
Mike |
|
| |
|
Expert
Posts: 3575
Location: Netherlands | Too much vacuum-advance on the ignition timing?
|
|
| |
|
Expert 5K+
Posts: 7809
Location: Williams California | BigBlockMopar - 2010-11-23 9:50 AM
Too much vacuum-advance on the ignition timing?
I would retard the timing a bit first to see if it helps in this matter. If your initial timing is set too high, when the mechanical and vacuum advance are engaged fully, it could be causing the erratic misfire due to too much advance.
---John |
|
| |
|
Regular
Posts: 53
Location: Dublin Ga | Thanks to all for the suggestions.Sadly I have tried or checked all and no luck.
I am looking at the possibility of a vale train problem- Do these engines come with hardened seats?
Also what are the symptoms of receding valve seats?
Anyone re done seats - got any idea what t the cost is? Can the heads be removed with engine in car?-1960 Desoto
Thanks
Lou
Edited by Lou Earle 2010-11-29 4:01 PM
|
|
| |
|
Expert
Posts: 2824
Location: Snohomish, WA. | The original seats were not hardened seats.
You can have hardened seats installed, but pick a good machine shop that is really persnickity on the dimensions of the pocket and the OD of the seat. I had a seat drop on a 70's truck engine and it was not fun.
The heads come off without removing the engine, you just need to dismount the intake and exhaust and drain the block.
I'd do a vacuum check before I tore into it though. Look for really jumpy and/or low readings. Your seats are likely good with the compression numbers you stated.
You seem to have replaced most of the ignition pieces; if they were the problem you wouldn't have had it when the electronic ignition parts were in. Have you tried a different distributor? Measured the advance versus RPM to make sure your centrifugal advance is working right?
The only temperature sensitive parts are usually the coil and the condenser. Don't trust that new parts are good though. Especially electrical parts. Some pretty crappy stuff is imported these days.
Restricted exhaust could make it miss, but it would also usually heat up as well. If you've ever had a bad catalytic unit on a car you know what I mean.
Is your carb dirt free? On acceleration the accelerator pump can cover up a lean situation that returns once the pump stroke is complete. A blocked jet or vacuum setup could make an engine run crappy at higher RPM.
After this stuff, I'm outa ideas for you.
|
|
| |
|
Expert
Posts: 2679
| I had the same thing with my 361, it was the points.... check the gap and set it at 17-20 thousands.... dont go
over 20 thousands or your engine will miss when you rev the engine. So check it out. |
|
| |
|
Regular
Posts: 53
Location: Dublin Ga | Found Problem!!
Had new timing chain ans sprockett installed -rebuilt heads installed hardened valve seats and ss valves-these were needed repairs- helped a lot but still had same problem just not as bad- then I found it!! Disconnected the vaccuum advance and all problems about missing hesitation etc vanished!!!
I then adjusted the vaccuum advance by inserting a 3/33 allen into cannister adn turning 7 full turns counter clockwise to reduce advance. hooked up hose and all is well!!! so be forewarned- if you install a new distributor and notice wierd stuff that you swear is carberation check you ignition throughly!!
thanks of averyones advice- some was not the problem but helped greatly in the elimination process.
Lou |
|
| |
|
Expert
Posts: 3575
Location: Netherlands | BigBlockMopar - 2010-11-23 12:50 PM
Too much vacuum-advance on the ignition timing?
Lou Earle - 2010-11-29 3:59 PM
Thanks to all for the suggestions.Sadly I have tried or checked all and no luck.
Lou Earle - 2011-09-26 10:59 AM
Found Problem!!
... Disconnected the vaccuum advance and all problems about missing hesitation etc vanished!!!
I then adjusted the vaccuum advance by inserting a 3/33 allen into cannister adn turning 7 full turns counter clockwise to reduce advance. hooked up hose and all is well!!! so be forewarned- if you install a new distributor and notice wierd stuff that you swear is carberation check you ignition throughly!!
thanks of averyones advice- some was not the problem but helped greatly in the elimination process.
Lou
Yeah, well, ehm... I'm sorry my advice was so wrong.
Glad you 'stumbled' upon the problem by throwing money at it and in just only 10 months.  |
|
| |
|
Expert
Posts: 1530
Location: ZH, Switzerland | With my 1956 Chrysler New Yorker I have the same problem. The second fuel pump died because of the dirt inside the tank and no additional fuel filter prior the fuel pump. The fuel delivery decreased over a very short time - I guess there is dirt under the one way valves so they don't close proper and cause internal leaking through the one way valves.
I don't know what's with your Desoto. But I thought to share my experience.
Happy Motoring!
Dieter |
|
| |
|
Regular
Posts: 53
Location: Dublin Ga | "Yeah, well, ehm... I'm sorry my advice was so wrong.
Glad you 'stumbled' upon the problem by throwing money at it and in just only 10 months. "
Well I sorry my statements caused your to feel I had made a personel attack
1-I did not throw money at a problem- to the contray I sought advice here first
then discovered needed a timing chain sproklett and valve job.
2 I also threw money at a new brake system-disks on front
Also it was never suggested to me to disconnect the vaccuum advance and see if that was the problem or to insert allen wrench into vac cannister so your observations are noted and I will try and avoid asking questioins in the furure but if I do ask I would rather the answers be directed at the problem presented rather than criticism of the person asking
thanks
Lou Earle attorney at Law not Chrysler expert |
|
| |
|
Expert
Posts: 3575
Location: Netherlands | Lou, I take it smileys don't work on your computer, or you don't know what they mean.
It would take a bit more effort to make me feel 'attacked'. You may want to disregard my postings in the future perhaps as some of them can be found to contain a bit of humor or sarcasm once in a while.
Glad you got it fixed anyway.
|
|
| |
|
Expert
Posts: 3894
Location: Northen Virginia | Lou, it is really hard to identify a problem with only descriptions.
I had a exhaust misfire for a long time only on the right side, petty much I changed everything suggested by the guys here, like Carburetor jets settings, distributor components and I even called Edelbrock! Everybody in here including the Edelbrock technician pointed to a lean condition.
But the problem was in the muffler it was rotted and make the pooping sound, now you tell me how in the world someone can suggest something like that? Most of the guys here are very knowledgeable.
Edited by hemidenis 2011-09-29 5:43 PM
|
|
| |
|
Location: The Mile High City | Recently, my De Soto started missing on my runabouts around town.
I replaced a faulty condenser recently and I thought I might have messed up the point gap, but it looks ok.
Driving up into the mountains, it started missing pretty badly. Going up hill, it was losing speed. I stopped to inspect the points, took off the distributer cap and the gap looked ok. I put the distributer cap back on (without really doing anything) and the car ran a lot better. Still though, I can tell it is missing - particularly as the car warms up.
I read this thread, I will try to check the vacuum advance and maybe retune. Anybody solve a similar problem? |
|
| |
|
Elite Veteran
Posts: 1049
Location: Auckland, New Zealand. | I had an identical problem once and it turned out to be the braided wire inside the distributor was shorting out. May not be that for you but an easy thing to check.
Glenn. |
|
| |
|
Location: The Mile High City | Thanks, Glenn - did you just check that visually, or test it with a light / ohm meter? |
|
| |
|
Extreme Veteran
Posts: 507
Location: Invermere B.C. Canada - Rocky Mountains | FURY - 2016-06-15 4:41 PM I had an identical problem once and it turned out to be the braided wire inside the distributor was shorting out..
...............what he said! |
|
| |
|
Elite Veteran
Posts: 1049
Location: Auckland, New Zealand. | Just visually on the side of the road. Limited tools/no voltmeter on hand.
Lancer Mike - 2016-06-16 11:37 AM
Thanks, Glenn - did you just check that visually, or test it with a light / ohm meter? |
|
| |
I am stumped!! missing at mostly high speed
