Hi Folks,

A few years back I inherited a 1964 Valiant Convert from my wife grandfather. At 94 he is still around and I would like to take him for a ride. I love the car and am determined to get it running correctly. I have gotten close but never quite there. I have found some good info on this site and am hoping you can point me in the right direction. I have put about 1500 miles on the car since my ownership began.

The car idles a little lumpy but doesn't stall. When I am under load full throttle going up hill it will miss followed by a small back fire. Its pretty consistent. The acceleration is slow. During warm up there are small puts and backfires as well. I had it running great for about 20 miles but it didn't last. I really don't know what changes.

Had the carb rebuilt about 3 years ago.

I have replaced

distributor
wires
plugs (and removed the seal ring)
coil
rotor
cap
tried both new points/condenser and mallory elec ignition (currently in car)
resistor

I have tried timing at 0, 5 and 10 BTDC. I have checked to make sure the damper has not slipped. It bounces a little but doesn't seem the chain is bad. There is very little play looking at distributor shaft movement.

The valves are adjusted

The fuel pump and filter are a few years old so I have them on order. They were cheap enough.

I don't think its the original engine but i believe it is period correct. Their is no heat transfer to the air filter.

There is no smoke on startup or running.

The car needs a good few minutes to warm up or it will stall.

I pulled compression and from back to front 110/105/95/110/115/116

Am I chasing my tail due to bad valve seats? Thinking the unleaded has taken its toll over the years.

Thanks in advance for any pointers.

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Reach out your hand if your cup is empty, if your cup is full may it be again.

sounds like a wonderful project and a cool car,, post a photo or two,

I am sure that you will get info on this forum,
sounds like an ignition issue,with the compression being low, there is also probably plenty of blow by,,,

I would try a HEI ignition conversion,, will allow you to open the spark plug gap, and get a bigger spark,,

no guarantee it will cure everything, but upgrading the ignition would be a step in the right direction.

You mention a Mallory ignition,, so maybe you have already addressed the ignition, not quite sure what a Mallory ignition consists of, but usually an engine miss under load is caused by a weak spark....

also check this post

http://www.slantsix.org/forum/viewtopic.php?t=57563

What is the valve lash set at? Was the adjustment done hot and running?
Looser is better on a SL6 with lots of miles on it.
DD
.

Thanks for the response. With the Mallory its the points that were replaced.

I will dig into the factory wiring. Its in a small loom so who knows what is lurking inside. Thats a good possibility.

Pictures to come.

The valves were set .01 intake hot and .02 exhaust hot according to the manual I have. I am not sure what you mean by running.

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Reach out your hand if your cup is empty, if your cup is full may it be again.

Brads2002:
[quote]The car idles a little lumpy but doesn't stall
During warm up there are small puts and backfires as well.[/quote]

Sounds like sticking valves/lifters from old gas and or sludge buildup, or burnt valve where it won’t seal when seated due to small notches formed. When you adjusted valve lash was top of head all caked up with hard black gook? Or when adjusting lash did one or two valves have a much larger lash gap then the others indicating valve was not full seated?

One can test for sticking valve with feeler gage. Remove valve cover, idle engine down enough to keep from flinging oil all over, and slide in correct feeler gage and feel for a moment when the gap becomes wider and engine misses, poops of farts, and that is the sticker.

One can add Marvel Mystery oil to fuel tank, or add one of several valve/lifter national brand name “mechanic in a canâ€￾ remedy add to motor oil as directed, Sea Foam per directions. Others have added a quart of transmission fluid to oil at change which would replace one of the five quarts of motor oil. (Tranny fluid has a lot of detergents which clean gook from internal engine parts).

Or the dreaded expensive valve job if you find burnt valves that won’t seal.

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67' Dart GT Convertible; the old Chrysler Corp.
82' LeBaron Convertible; the new Chrysler Corp
07' 300 C AWD; Now by Fiat, the old new Chrysler LLC

https://1964valiant.shutterfly.com/pictures/17#19

Here are a few pictures of the old lady. I couldn't figure out how to add them to the thread. If someone would like too feel free.

Regarding the valves. Yes the grime was pretty thick. I will take a look while things are running, that is a good idea. I will also add some cleaner to the crankcase. It for sure couldn't hurt.

Is a valve job expensive for these motors? It looks like the head would come off fairly easily. [/url]

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Reach out your hand if your cup is empty, if your cup is full may it be again.

I have had lazy valves in a gunked /6; to free them, you really need to work some solvent (like carb cleaner) around the guides. It'll effect the valve stem seals so I would arrange to pull the valve springs one at a time with the rope in the cylinder trick and put in new seals at the same time. That is a 'let's try this to see if it works' thing to do; it might help or not.

With the backfires, it could be valves sticking/burnt or it could be timing. You don't know anything really about the timing chain unless you check the valve timing versus crank timing, or pull the timing cover and check the slack. Doing the first would expose a slipped chain which could cause backfires. A lot of chain stretch even without slipping will cause the engine to be sluggish and have poor throttle response off-idle and mid RPM.

Another backfire-following-miss cause is the ignition cutting in an out. Could be wiring, the ignition parts, or the ignition switch cutting in and out.

A valve job will likely run several hundred $$ for shop work if you pull and install the head yourself... it is a fairly easy head R&R if you can lift it.

The compression numbers are weakish; did you have the throttle propped open when taking the readings?

Thank you for all of the helpful replies.

I did not check the compression with the throttle open. It was checked with the engine up to temp. Would the throttle open have a big impact? I am guessing that it would add to the reading positively from your question.

Seems like most indications are pointing to some sort of valve issue.

Can you explain the string through the cylinder trick? I am assuming that keeps the valves from falling in the motor? Would putting the cylinder at TDC accomplish the same thing?

I may just go ahead and pull the head and replace the chain at the same time. I have been told the original engine was replaced with a high mileage engine sometime along the way. Is it common for these 6es to need a valve refresh in their lifetimes? From what i have heard the motors are pretty bulletproof in general.

_________________
Reach out your hand if your cup is empty, if your cup is full may it be again.

Yup.

Pulling the head would certainly make finding & repairing any valve problems much easer if in fact you have some type of valve/seat erosion requiring new or reconditioning of valves, and grinding new seat surface. Also a good time to bump up compression by shaving head once all pertinent engine measurements are made so as to get satisfactory results, and de-rust head's water jacket.

Before you get the wrenches out, do the easy stuff first, try above chemical decrudding, than go from there.

Compression test; place a screwdriver down carb or spacer in throttle linage to hold throttle wide open, remove all six spark plugs, and than run test rolling engine over several times until highest pressure achieved at each cylinder.

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67' Dart GT Convertible; the old Chrysler Corp.
82' LeBaron Convertible; the new Chrysler Corp
07' 300 C AWD; Now by Fiat, the old new Chrysler LLC

Running means with the engine running. Warm the engine up fully, turn the idle speed down as far as possible with the engine still running, then adjust the valves.

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Casually looking for a Clifford hyperpak intake for cheap.

Read about valve adjustment to learn what's meant.

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