And so it begins! 318 Poly to 360 LA Swap

[Birdman]

Hi, take a look at the Chrysler Power webstore https://cpwebstore.com/Poly for some very nice and pricey parts for the poly .
Obviously, one for the post corona period, if anybody's got any cash left.
Chris

[Cannonball]

That will have to be mega post corona the rate is stinkin and will be for yrs wont be much coming out of the usa now

[Birdman]

That will have to be mega post corona the rate is stinkin and will be for yrs wont be much coming out of the usa now

Very true, luckily I got some parts in January and sent via Ron Fenton

[Ray Bell]

How come it's considered the Poly is as heavy as a big block?

I remember weighing parts a few years ago and that wasn't how I found it to be. The heads are certainly heavier than LA heads and the block's a little heavier, but not enormously so.

Same crank, same rods, same timing cover, same water pump, same lots of stuff.

I think the Poly is discounted for a lot of assumed reasons which aren't really viable. A shame there's no current decent manifold available for it, that's true. A nice air-gap style manifold would be very welcome, otherwise I think the old Edelbrock is probably the best.

[Ray Bell]

Originally posted by Blue
The thing that rules the poly out for me apart from the rarity and cost of parts is the weight. Big block weight with small block capacity doesn't sound like an ideal place to start from. Pound for pound (£ as well as lb) a stroked 360 is a great option these days.

Let's put this to bed right now...

LA iron heads are 25kg complete with valves and rockers.

Poly heads are 28kg complete with valves and rockers.

That's 6kg difference in the heads - unless you buy alloy heads.

LA block is 77kg bare with caps.

Poly block is 83kg bare with caps.

These are real figures. 6kg for the heads, 6kg for the block, everything else is basically the same unless you're counting the original cast iron inlet manifold. there might be a couple more kgs in that.

I think you'll find that the big block crank on its own will make almost that difference, then you have a bigger and heavier block. Heads are probably the same.

Of course you can also stroke the Poly, some in America are running 408 cubic inches but you need a block with good cores to get it that big. You won't get that with a 318LA.

[mygasser]

[quote= Of course you can also stroke the Poly, some in America are running 408 cubic inches but you need a block with good cores to get it that big. You won't get that with a 318LA. [/quote]
a 318la will be at 396 cu in with a normal 60 thou' overbore and the same stroker kit you mention (4" stroke). finding a poly core is hard enough, let alone enough to check them all and find one that's thick enough for a 110 thou' overbore. just saying, and by the way i like a poly so no agenda
neil.

[Blue]

The poly in full stock configuration is usually listed at 600lb or so, I read someone weighed the iron intake at 56lbs. Maybe this information is incorrect Sure if you throw enough time and money at a poly you might get yourself a stout performer but with little aftermarket support it's hard work and unless you're trying to prove a point I really don't know why you'd go there is my take on it.

[deppmobile]

Back to the Plymouth! Lockdown project has been the resto of my Portafold, so now that's done, back to the LA!

Sump on, 727 refreshed and aiming to drop them in as one piece by the end of the week (as it's nice and sunny!)

[deppmobile]

Sorting out a couple of holes in the chassis leg way laid plans for the engine today

I reckon this wagon had lots of fun at the beach in its time considering how much sand came out of the chassis leg! It just seemed to keep coming!

Back to the engine tomorrow I hope

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[Pete]

Old car ownership is mostly about being tenacious.... and not quitting!!!!

[deppmobile]

Now I'm getting excited!

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[Pete]

Progress indeed!

[deppmobile]

And thanks to Duncan Watts who got some new trans seals in the post within an hour of talking to him!

[deppmobile]

And in! First time I've tried box and engine in one - surprisingly straight forward

Cripes it was hot.....

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[ScottyDave]

Bet you had a well deserved beer after doing that in this heat