chrysler 360 starting problems

Use this forum for all your builds in progress.

Moderator: Moderators

Post Reply
og1
Posts: 2
Joined: Sat Oct 30, 21 5:05 pm

chrysler 360 starting problems

Post by og1 »

Hello,
I'm new to this forum, so I thought I'd introduce myself & my car.
It's a Bristol so not exactly Mopar, but it does have a 360 LA engine installed, so I hope that almost qualifies.
Anyway, it's always been hard to start, but once warmed up runs just about as it should.
It's got a Carter Thermoquad carb, which I 've rebuilt. After a lot of fiddling around I've just noticed the choke goes completely off as soon as it's started, and obviously no heat in the manifold. Before starting up the choke is closed as normal. It's got a "divorced" choke in the inlet manifold. I'm thinking that's to blame.
When the choke is open there's no tension on the connecting rod. After about 5-10 mins with engine off choke spring somehow closes and choke seems to be opening and shutting as it should.
Sorry to go on so long.
To add to the problems cars' got a turbo installed, which makes access to the choke difficult + the connecting rod is much longer than usual.
Any ideas about what's best to do. I've never tried adjusting these things.
Thanks for any advice
User avatar
ScottyDave
Posts: 1614
Joined: Sun Mar 08, 15 9:38 pm
Location: Dave Evans: MMA 130, Worcestershire

Re: chrysler 360 starting problems

Post by ScottyDave »

Hello and welcome to the club :thumbright:
Hopefully someone can advise on your starting issue.
73 Charger 318
MMA-130
User avatar
Dave999
Posts: 9427
Joined: Thu Feb 24, 05 10:31 am
Location: Twickenham,London, England

Re: chrysler 360 starting problems

Post by Dave999 »

360 is a nwer engine than mine but i guess it probably follows the chrysler pattern for chokes

in most cases you have a hot box bolted to the exhaust manifold this is a 2 bolt tin plate cover, usually D shaped or round with a rod coming out the side.

inside is a bi-metallic strip wound into a spiral spring that coils and uncoils as the temperature changes
it connects to a rod that pops up between the inlet runners or exhaust runners and connects to the choke flap, usually at a lever which has a couple of holes in it.

in addition you may also have a choke pull based on a small diaphragm with a pipe to manifold vaccuum. don't worry about that at the mo.
this just helps maintain a fast idle when choke is active

1) is the coil in the metal box on your exhsut manifold snapped? if you jiggle the rod you should feel resistance it should not clonk and crunch
2) is the rod bent
3) if you have 3 holes to connect the rod to on the choke flap lever put it in the middle one for the time being


set up
stone cold, the choke flap should hang with a rail ticket gap at its lower edge i.e JUST closed not hard closed
adjust rod (bend it or put it into the right hole to achive this

start car and watch choke
as it heats up it should open

if it only opens half way i.e is at 45* rather than 90* from where it started you need to adjust the spring tension in the hot box on the manifold
it will have a screw through the cover. usually rusted solid. when cool apply lots of penetring oil and work it slowly back and forth until you can twist it easily
we are talking 1/4 of a turn only either way

run car till hot
turn the screw on the hot box until the choke is hanging vertically
let the car cool and bend or adjust until the choke is JUST closed

run till hot and check it opens

however i must say 360 is a 70s/80 engine and the method i outline is for 60s engine

if your choke doesn't work
symptoms
1) it won't start
2) its starts but dies every time you lift off to use the brakes to the point where it feels like the g force of breaking stalls the car.
3) it runs exceedingly badly for the first 20 minutes
4) drving anywhere involves toe healing it to keep it going

if the choke is hard on
its starts but when warm it runs badly floods and stinks tailpipes are black with soot and so is the bumper

a themoquad in good condition on a standard motor (i.e the right thermoaquad on the motor it came on) No probs
Any old themoquad on the wrong engine hours of fun or frustration and you'd be better off with something else

if you followed the rebuild routine in Mopar action it should be fine.

look up choke stove mopar v8 360 thermoquad

if you put a new one on remember the old bolts will be rusted solid and case hardend on the outside and soft as cheese in the middle. use heat and penetrteing oil and gently work back and forth.

if they snap, you will need to weld a length of flat bar (3 or 4mm thick) with a hole in it to the snapped off stud end and work it out that way.


Turbo: i take it this is cramming a substansial few lbs of pressure into the motor when its running along at higher rpm

how much is it trying to cram in at idle. ? if its enough to overcome the springyness of the bi metallic strip then YES you choke will be, for want of a better word blown off

which begs the question...do you need a choke with a turbo set up?

if it was a carb sitting on top of a blower you could....no issue there. but this carb is seeing the Hi pressure side of the turbo....

if that is the case the choke could be blown open and the vacuum diaphrgam for the high speed idle needs to be boost referenced as well or disconnected and the manifold connection plugged off. otherwise your boost will just blow the diaphragm out of the fast idle kicker

i think you need to convert to manual choke due to the turbo


Dave
The Greater Knapweed near the Mugwort by the Buckthorn tree is dying
og1
Posts: 2
Joined: Sat Oct 30, 21 5:05 pm

Re: chrysler 360 starting problems

Post by og1 »

Thanks for the replies.
Thinking about it, what you say about the turbo causing too much downdraft, opening choke flap to maximum, makes sense. When it fires up, I keep it on pretty high revs, just to stop it stalling - so turbo probably gets going.
I bought the car with it not being used for 10+ years. The carb I'm pretty sure is the one it's always had. Presumably with current set up it did originally work ok.
I'll try and play around the with choke thermostat. A manual choke might be the answer.
Post Reply