Poly heads on LA block...HOW did you do that again?

Ok, first off I am starting this thread just to clear the air about this conversion. 20 years ago, I had all the pieces to build a poly head 360, including a Poly 2X4 intake. I never put it together because of one glaring problem, the water transfer passages in the block deck surface.

The poly block deck has 2 bosses above the 3rd cylinder back where the water flows up from the block into the cylinder heads. The head has corresponding holes in that area. On the LA block, these bosses do not exist. So even if you put a blanked head gasket on, there is nothing for it to seal against.

I have seen posts about people actually doing this swap, but I've asked and never got a definitive answer about HOW the transfer passage issue was addressed. One guy said "just don't worry about it"... Well, hopefully the photos I've attached will explain why you have to worry about it.

First photo shows the Poly 318 block with the bosses and head gasket. Second photo is an LA block deck. Last photo is the poly head deck surface. The arrows show the location of the 2 holes that are above the edge of the deck on the LA block. I know the holes in the head can be brazed shut and redrilled, but no one mentions this.

I'm probably not going to go there again, but this seems to come up every so often; so I'd like to get cleared up exactly what's involved in making this swap work.

If you have actually done this, how did you solve the transfer passage problem? Not interested in "I know a guy who..." info... Thanks.

 

Plug the holes in the heads maybe?Realy is that the only problem?I didn't think this was even posable!

 

You call those water transfer holes. Why? Look at how small the openings in the head gasket are. You think any appreciable flow of water will take place there? Looks like it's used to bleed air or steam. otherwise flow is up from the block into the head along the exhaust side through the larger openings then out to the water pump like most engines. But I must admit I have never built either an LA or a poly (both are engines I respect).

I predict plug the holes in the heads will eventually be the correct prescription for your polyhead fever.

 

I did a bit of poking around on the net and came up with this guy ... Gary Pavlovich. Apparently "the" poly engine guru. Here is his email add [email protected]


I am guessing he will be able to answer your question. Good luck


I took this from another site:
"Gary Pavlovich, located in Lakeside/Santee, CA 92071 helps members of the 1962 to 1965 Mopar Mail List with technical data and parts source information to help in their Poly 318 or Poly Stroker build. Contact Gary Pavlovich at his email"

There were comments on other message boards regarding Gary being THE poly guru. I realize you are only talking about the poly heads, but this guy just might have some answers or possibly point you in the right direction for answers.

 

I believe Gary is a member here. I know of him through Don Dolmetsch, who I'm also hoping will weigh in on this one.

It's not so much that I need the answer. I'm hoping to get the be-all, end-all method for anyone else who is thinking about doing this.

 

Haven't seen a post from Don in quite a while. Probably best to PM him.

 

There's discussions on the subject on the Australian www.moparmarket.com Forums. You can go one way, but not the other with the head swap.

 

if they are not really needed, why not just tap the heads, install plugs and have them machined level? I've never seen poly heads on an LA block, but I have seen a couple 408stroked poly's.

 

That's how I'd do it, but I'm still interested in hearing from the guys who've run this combo. It's got potential to be a really nasty small-block setup. The poly is actually a pretty good cylinder head, even with some service issues...

I know you're out there....

 

service issues?

 

Well, sometimes you have to go that route, ya see I know a guy that has such a combo in a Duster/Demon. I'll send his phone number in a PM.

Gary P and I have discussed this swap but I don't believe he has bothered doing one since big cranks are available that render the 360 package a bit moot.

Gary

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Not the easiest things to get the rockers off of. Putting the heads on with the pushrods in place can be fun.

 

Oh yah, forgot about the integral rocker stands, been a while since I had one apart.

 

I'm a fan of the poly head I'm sure we are talking a one off cam because Of the different valve arrangement. Poly ieieieie LA eiieeiie

 

That's why I read through the thread...I though the valves weren't in the same places.