Head Cracking

Lately there have been several instances of people having a hard time finding 2.3 OHV heads that do not have cracks. Even otherwise well running cars have cracks.

I'm curious because the same plant, and the same basic techniques were used to also make the 200 head, is it also prone to head cracking, and have no outword signs of a crack?

The six cylinder heads never crack unless they have been

a) repeat overheated or

b) run on low octane unleaded with a high compression ratio.

c) frozen in the winter (the front of the block tends to crack, not the head!)

d)The exhast manifolds tends to crack, but I've not seen cracks on the head

The HSC has its head bolts fully inclosed rocker cover. It is rather like the Aussie cross flow in that manner. On the 144/170/200/250 log heads, there is a huge support area of iron in that integrated manifold.

A very, very common failure point on cast iron Cleveland, Windsor and alloy V6 heads with the sled fulcrum rockers is the casting plug drains where the sand is removed from the water jacket. It is very common for cracks to apear during magnaflux or zyglo tests. In many instances, cracks are not terminal, but most prudent machinists biff them and get another set. Alloy can be repaired, but iron isn't nearly as easy to fix becasue the welding or plug process can propagate cracks. A good welder can fix iron heads if they are confident the cracks aren't major stuctural items.

My original 200 head was cracked and i didnt even know it. i was driving it around without any probs. i took it to the machine shop to clean it up and he told me it was cracked. I then went with a late 70;s 250 head. but i guess its possible for them to crack and not even know it...

Only place I have seen a 200 head cracked was on the carb opening, kind of weird.

this is kinda hard to explain, but the tap towards the front top of the head where the manifond bolts in cracked off on mine before i even got the car. theres no bolt in there now but the manifold still stays sealed in that corner.

I've seen the "ears" where the manifold bolts on broken many times. Other than that, nothing. That's an easy fix anyhow. MIG'd a couple studs in, and voila problem solved.

wallaka":1ic7xn8i said:

I've seen the "ears" where the ex. manifold bolts on broken many times.

Click to expand...

Every late model head I have seen has nowhere near enough material in the ears.
One head I have, the ear is so thin there's only three threads in the top part of it!
I drilled through the center of the old bolts and tapped it to 5/16"