1700 head replacement: gasket question

Hello,

on the old heads, there are 3 thin metal gaskets or shims between cylinder barrels and the head. I pulled these out of the old heads.

The new head doesn't have these shims installed.

I read that I have to either 1)lap the barrel to the head (I've done this on

1600 plenty of times) or 2) match shims between cylinder barrel and case to the shims between barrels and head, to keep compression the same.

I understand how all of this works, but I am asking for advice from others who have replaced 1700 heads.

Should I remove all shims and lap heads to barrels, or buy a set of shims, and match the thickness between above/below shims?

I have a compression gauge. Should I spend the time to match compression, or just match shim thickness?

Jenny

It depends on many things.

First of all, the factory has released a technical bulletin that says the head shims should no longer be used, instead the cylinder tops meet the head directly. No mention of lapping the cylinders into the heads, but that's what I did. This bulletin refers to the 2 liter engine, but since the design is the same, I'd say it applies to earlier versions of the T4 as well. It also said to leave out paper gaskets from between cylinders and case.

Here's the bulletin:

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Your compression RATIO is what is effected by removing shims and gaskets. What ratio you want, depends on many things, like elevation and what grade fuel you intend to use, what deck height and combustion chamber/piston shape the engine has, etc. etc. etc.

For a stock engine, it is probably best to keep with stock specs. They were designed to run on average grade fuel, so if you are sure you can commit yourself to using high octane fuel, you can bump up the compression ratio a little.

A compression PRESSURE test on an old, worn engine will tell you what the pressure is THEN, but after you replace piston rings or do a valve job, it changes. And after that it will keep changing again, over time. The compression ratio however, will stay where you set it at.

Jan