I've owned the sunfire yellow '66 coupe for five years, and have not been diligent on information gathering for this car. It was a K19 California car, bought there, and later restored for sale at Barrett Jackson. I purchased the car from the individual that purchased it on Barrett Jackson. It's developed a cold engine rattle, so I looked for the manifold temp rise valve to see if that was the problem. There is none, so I assume they were not added to the K19 cars. I'm posting the frame plates in the hope that people in the know can give me some information on the car. Would like to know more about the car. Thanks.

 

All cars got the heat riser for the choke warm up. FI cars are the exception

 

Great looking car, I like Sunfire Yellow.

 

The only information you can get from the tags is that it's a 66 coupe yellow with black vinyl and the body was built by AO Smith on June 15 (K15).

 

Your car was built on Friday, July 1st, 1966 using an AOSmith body.

Why do you think that the exhaust manifold heat riser valve (which your car would have been built with) was the source of a cold start noise?

 

I've been told that the valve springs go bad regularly, and cause a bad rattle when the engine is cold. Was looking as that as a possible source for my rattle.

 

What engine do you have? How many miles are on the engine? When did this cold start rattle sound (in miles) and was it a sudden step change, or was it barely noticeable but is increasing over time?
What weight oil do you keep in the engine, what is ambient temperature when you do a cold start, and what is oil pressure at the start? What does oil pressure get to once warmed up both at idle and at cruising speed?
What does this rattle sound like to you? Have you (carefully) used an engine stethoscope to narrow down the location or source of the rattle? Does the frequency, tone, or volume of the rattle change with engine speed?
Has anything about the engine's performance changed coincided to the rattle?
Has there been any work done to the engine or accessories coincident or shortly before rattle?
Does the sound create a sense of concern for engine damage, or is it slight?

That's a start. I would start with basic troubleshooting before selecting parts to change out. Things that can cause an engine to rattle are too many to list, some of which are a 10 cent part and some call for an engine removal and overhaul.

 

On the '66 coupe, 327/300 cold engine, I get a rattle when starting from being stopped. The rattle only happens when I move from a stopped position, and when the engine is cold. Because of this, my first choice for this problem was the manifold heat riser valve because I heard about the spring being inoperable and causing a rattle, but when searching for the manifold heat riser valve, there is none. The car was originally a California K19 car, but the K19 gear was removed when the car was restored and sold on Barrett Jackson.
The rattle is aggravating as hell, and I was looking for advice from people who know more than I do. Appreciate any input from anyone.

 

Auto or manual? Any recent changes to the car? Did the sound appear suddenly or slowly and is it getting louder? Oil pressure?

Sound only when going from a complete stop and only when the engine is cold?

Just how loud is it and what does it sound like? Is it like sheet metal on metal?

 

Oil pressure is fine as are all gauge readings. It sounds like a piece of metal rattling around and disappears when the engine warms up.
Car has auto transmission and this just appeared a few weeks ago. Drive and runs great except for this aggravating rattle which disappears
after the engine warms up.

 

(If nothing else, I'm helping keep the ball in the air until someone here has the 'aha' answer)

Are your exhaust heat shields intact? Is one of them loose - as in the clamp rusted off or snapped? Are your exhaust down pipe to manifold nuts tight on the clamping rings?

Any way you can focus the location of the noise?

 

Based on your description...
I am interpreting this part of your description as when you let off the brake and begin to accelerate out of driveway, away from a stop sign / stoplight... Hope i got that right.
You didn't give any info about whether or not it stops rattling once you reach some speed, but i am going to guess the Rattle does stop.
Does it rattle only when starting to move FORWARD ? Or also Backward/Reverse ?

Rattles are tough to isolate and chase down because they can echo around and you're never in an ideal position to listen for them.
You also didn't give any indication about where it comes from but since you looked at Heat Riser, i am guessing Engine Bay or 'Up Front' somewhere.
>> This is a guess but i would look at transmission linkages

It could be some front end link getting loose, but since you also didn't mention any steering difficulties - so I doubt it.
There is a support arm for the Headlight Motor that has come loose on my '66 but that wouldn't fit the 'Rattles When Starting from a Stop' pattern

Play with a couple things like running the headlights up/down... Forward vs Reverse, If Forward - Only in First Gear or 1st, 2nd, Maybe even 3rd ?
Wiggle the Ignition Shielding, Exhaust hangers, etc and let us know more.

 

Noise only happens with a cold engine and when starting to move. Stops when it gets above 15 mph or when the engine gets warm. The problem is that I'm in the coupe driving when this happens, so I cannot pinpoint where the rattle is coming from. And it does not have exhaust heat shields, so that is a no no.

 

So the bounding conditions are limited to: 0-15 mph, cold engine, starting to move only?

Automatic, nothing recently changed, owned for years, otherwise runs fine, oil pressure good.

Any physically felt clunks, rattles, vibrations, or otherwise physically detectable feelings happen coincident to the rattling sound?

Is the rattle more of a buzzing tone, sheet metal tinny sound, or hard metal to metal clinking, or none of those?

 

The rattle sounds like metal rattling inside of metal and is definitely coming from under the hood. Problem is that to hear it, you have to be behind the steering wheel and moving, so I cannot lift the hood while the car is stationary. The rattle sounds like what I would imagine the loose spring in the heat riser exhaust vale would make, and that is why I looked there first, only to discover that there is no heat riser exhaust valve. Must have been removed when they removed the California K19 gear before selling the car on Barrett Jackson if there was a valve installed on the K19 cars to begin with.

 

Have you checked the flywheel cover