273 crank in a 318

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Wedgy

Wedgy

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Hi together,

I am building an engine for a friend.
It will be a 318 .03" over. I am having a nice looking forget crankshaft from a 1964 273 2bbl and will install it into the 318 block.

I will install Sealed Power cast pistons and don ´t know the correct weight for a nice ballance in combination with the 273 crank?

In the internet I could only find the weight for the 273 2bbl pistons only.

Can sombody tell me the piston weight including the weight for the piston pin, lock rings and piston rings?


Thanks - Wedgy
 
u need to to take 1 rod bearing, 1 piston worth of rings 'top/2nd/oil', 1 piston w/locks & pin, 1 connecting rod, 1 dampener and or flywheel & clutch ALong with the crank...to the machine shop thats balancing it.
 
Oh, and watch for the early 273 cranks, they have a smaller ID register on the back and will not 'without modification' accept the '68 & up torque convertor snout.

They are the same outer diameter however...so u can have them opened up.
 
The subject has come up in a couple of threads lately but I just wanted to make sure you are aware of it.

What converter will you be using behind the 318 with the 273 crank?
That early 273 crank has a smaller hole for the crank snout to fit into than later model engines had ('67 & later I think). So a converter used behind a 318, 340, 360 and later year 273's will not fit. Machining the hole larger in the back of the crank while it's at the machine shop for balancing is one option.


***Darn! 1wild&crazyguy beat me to it! lol***
 
hi, any good machinist can bore it out in a lathe., it 's easy to do. also, the 273 crank front and rear journals are solid, they have to be bored out for heavier piston and rods, so it will balance ok. I just had one done for 340 rods and pistons. no mallory was required. if your piston and rods weigh same as a 273, then you're probably ok. I would have it spun up though, just to make sure. also, the 68 to 69 273 cranks already have the larger convertor snout bore. just food for thought.
 
Hey, I'm not trying to steal this thread, but being as I have almost the same question, maybe you guys could answer it here.
Although I sold the car some years back, I still have the 318 out of my 67 Coronet. It's my understanding the 67 318 had a steel crank. I'm planning on freshening up my cast crank 340, while keeping the stock 340 rods and pistons. What needs to be done to put the steel crank from the 318 into the 340 and the cast crank from the 340 into the 318?
 
I have already machined the centering in the crank for the ´68 & up torque converter.

I just need the weight for the 273 2bbl pistons to match the old factory balancing. When I am installing the 318 pistons, maybe I have to machine the pistons to the 273 2bbl spezification????
 
Wedgy said:
I have already machined the centering in the crank for the ´68 & up torque converter.

I just need the weight for the 273 2bbl pistons to match the old factory balancing. When I am installing the 318 pistons, maybe I have to machine the pistons to the 273 2bbl spezification????
Click to expand...


I can't see why you'd want to match the factory balance job. Machining 318 pistons to a 273 weight? Where do you propose to remove the required mass from?
Getting the whole assembly balanced for the parts you actually have will yield far better results and isn't that expensive.
 
I second Anglia's idea- get all of the reciprocating parts balanced together (not just statically, but dynamically balanced). It will run very smooth, help make more power, and will be more durable. Unlesss you go "Cam Crazy!"
 
You are right, balancing is the better way. But in Germany it costs about 600$ to balance an engine. That is a lot of money :-x

The 318 will spin maximum 5000 RPM. I think the factory balancing is ok for this job.

I checked the 273piston weight in the past at another job.
But I just checked the piston and piston pin weight only.
Now a need the piston ring weight too, to get the compled weight.






Here you can see that the 273 2bbl piston pin is really heavy.

The piston plus the piston pin weighs 748g without the piston rings.

The Sealed Power cast pistons weighs 791g including the piston pin and the lock rings.
The Piston rings weigh 54g.

I heared that the ´60 318 engines used the same crank drive like the 273 engines.
 
$600? Hell no. You just haven't found the right shop. Most of Western Europe including here in the UK have similar labour rates for this kind of stuff. I paid less than $200 for my 318 stroker to be done last year and that was really tricky due to the light bobweight.

You can't machine the 318 pistons down to the 273 weight if the 273s are heavier to start with!

Wedgy said:
You are right, balancing is the better way. But in Germany it costs about 600$ to balance an engine. That is a lot of money :-x

The 318 will spin maximum 5000 RPM. I think the factory balancing is ok for this job.

I checked the 273piston weight in the past at another job.
But I just checked the piston and piston pin weight only.
Now a need the piston ring weight too, to get the compled weight.






Here you can see that the 273 2bbl piston pin is really heavy.

The piston plus the piston pin weighs 748g without the piston rings.

The Sealed Power cast pistons weighs 791g including the piston pin and the lock rings.
The Piston rings weigh 54g.

I heared that the ´60 318 engines used the same crank drive like the 273 engines.
Click to expand...
 
I believe they are the same weights as a pin and piston combo (thats a BEEFY heavy pin there!) see weights below (maybe I was wrong?) . 340 had heavier rods and piston that demanded the crank throws be lightened by a large hole drilled through the rod bearing end. PAW sold 318 poly forged cranks that were drilled to match 340 weights.
318 piston = 594g rod was 758g according to one website. Another says:


273 = 569 grams / 20.08 oz 4V (2V=530/18.7 oz)
318 = 592 grams / 20.89 oz
340 = 719 grams / 25.38 oz
360 = 584 grams / 20.61 oz

piston pin
273/318/340/360 = 154.6 grams / 5.45 oz (floater or press pin?)

If that is the case, you could alter the pin weight 154.6g by taking some out of the center if you need a lighter piston pack. I took a little off the ends in a press fit stroker piston to equalize the lousy MP stroker piston set weight spread. I couldnt find anywhere in the piston to shave almost 7g of Aluminum!
 
Yesterday I checked the total piston ring weight at the local speed shop. the rings are having a weight of 44,40g. all weights together we are having 795g. I found an old, used 318 std piston In my workshop. it is having a total weight of 800g, including the burned engine dirt. it seams to me, that the 273 and 318 crank/piston combination are the same. looks like the sealed power stuff is much too heavy. I will try to lightening the piston, piston pin and rod, to get the correct balance.
 
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