340 Motor with 360 heads?

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getdusted

getdusted

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I am in the middle of restoring my 1970 Duster "340" and after removing the motor and taking it apart, it looks like 360 heads were put on, apparently the crankshaft and rods are lighter than original because the balancer has been drilled out. I was told that this was a numbers matching 340 when I bought it but obviously I was lied to. Is it common to put 360 heads on the 340 and what are the pros and cons? Is there a name for doing this? Does this make it a "stroker"?

Also, the car has 4 caliper disc brakes in front, was this standard on the 340?Where can I find replacement drums for the back? I found new cross drilled rotors for the front and pads but am a little worried about finding replacement drums for the back.

any help?
 
What makes you think they are 360 heads ? Do you have the casting bumber for them ?

The block could still be numbers matching even if the heads were changed. Theres no Vin number on the heads. Just on the block.

Strokers are motor that have had the crank shafts stroke changed.
 
ok what makes you think you have 360 heads? are they J castings? no a change of heads don't make a stroker.

balancer sounds normal. can ya post some pictures of what you have?

4 piston disc brakes were an option.

what size drums are they? may be able to find them around.
 
inside, under the valver covers "360" is stamped in between the pistons.
I am not positive but I would assume that meant they were for a 360?
ALso, the intake manifold isnt a perfect fit, the heads seem too large for it. Whomever owned this and worked on it before me seemed to have thrown everything together half@ssed. Lots of bolts, hand tightened, nothing in the steering column was connected, the dash was thrown in and not even hooked up, I can go on and on.
 
Gimme about 20 minutes, I will take pics. THanks for all your help.
 
Back in the 1970s, I heard stories of people putting 360 heads on their 340s to get hardened valve seats due to elimination of lead from gasoline. I don't know if this is true, but I heard of it, none the less.
 
They are probably later heads but I wouldnt worry about it. There isnt really any difference in flow.
 
The "360" on the head doesn't make them 360 heads. You'll need to find the casting number on the head to find out what heads they are.

Also, the 340 and 360 shared the same casting numbers on the head. When the 360 cam out, they used 1.88 intake valves with the same casting numbers (head) as the 340.

Auto Zone has drums and discs, pads and shoes.

When you say the balancer was drilled out, it leeds one to assume you mean the balancer has holes drilled through it.
 
heads.jpg

the heads


hole.jpg

the drilled balancer


fit.jpg

the manifold seems smaller than the heads
 
I cant find any numbers on the outside of the heads, I looked where they should be and nothing is there?
 
that head can be a J head. i believe J heads came witht he 360 cast there also. look between the spark plugs. is there a J, U or X ? the casting number should be along the runner somewhere under the valve cover. may have to take the rocker shafts off to see it.

heads.jpg






thai is a crank not a balancer. and its normal to have been drilled.

hole.jpg




that is an edelbrock intake. should fit fine. what doesn't look like it fits??


fit.jpg
 
It may just be the gasket that is a little wrong. In the center of the heads, there is a space where intake doesnt cover. It doesnt affect anything but just looks off.
 
getdusted said:
It may just be the gasket that is a little wrong. In the center of the heads, there is a space where intake doesnt cover. It doesnt affect anything but just looks off.
Click to expand...

thats the heat cross over. its fine. the gasket looks to be a felpro. they are made to fit many years. looks to fit fine in your pic.
 
THanks for all your help. I am just learning as we go. This is my first complete rebuild.

Does anyone know what the stock spec sizes were for the rear brake drums? or should I move this question to another section?
 
Yes, absolutely right. Felpro. I ordered the complete gasket set.
 
Joe's correct, The heat cross over never gets covered up completely.
 
The balancer has stock drill marks, it's fine.
The intake gasket is fine. That upsidedown "U" shape is OK to be seen like that.
Early 273's and 340's are the only engine to come stock with mechanical pushrods that you have.

The casting number may also be under the head where the 2 center runners meet by the intake. Once you remove the head, you'll see them.
 
The set of J heads I have say 360 on them. They are on 70 340 motor. Like what was said before the 360 cast in them doesn't mean that is the engine size. The pictures you of the "balancer" isn't the balancer. That is a picture of one of the crank throws and holes you refering to is how the factory balanced the crank. Yes an aftermarket intake has been added to increase the performance of the engine. My j heads have 2.02 intakes and the exhaust seats were not the hardend ones. I know because they were replaced with hardend seats and all new exhaust valves.
 
AdamR said:
Joe's correct, The heat cross over never gets covered up completely.
Click to expand...

ok. duh on my part. I just never know what to expect with this thing. EVERYTHING seems to have been thrown together on it. Fortunately, we have fixed everything. All that is left is finish the motor and tranny, then its light'em up time.
 
From the pictures, it looks like the crank has the normal factory balancing holes drilled in the counter-wieghts. The balancer may have similar holes for balancing. Rumblefish360 is correct in the the 360 cast into the head doesn't mean that the heads are from a 360. You have to look at the 7 digit casting number to determine exactly which heads that you have. The "J" had 915 for the last 3 digits. There is a large "J" cast into the head between the spark plug hole pairs. These heads came with either the 1.88" intake valves or 2.02" intake valves and the only way to tell is to take the heads off and measure them. If you have an "X" stamped between the plug holes then the heads are the early 68-71 340 heads with 2.02" intakes.

When you said that the intake didn't fit the heads, what did you mean by that? Which Edelbrock intake is on it? I did notice that the rocker arm adjusters are out quite a bit. That would indicate that either the block or heads, or both, have been cut or that the pushrods are a little too long for the application. You need to check that the cup part of the pushrods aren't hitting the underside of the rocker arm during it's movement.

Ken
Edison, NJ
 
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