Corroded head Atomic 4

[lenjonsen]

Hi guys,

I am new to this forum and the Atomic 4 engine. I recently acquired a 1977 Catalina 27 from a customer that I traded some work for the boat. It has the Atomic 4 motor that was seized up when I got the boat, but after soaking the pistons for about a week in Marvel Mystery Oil I got it turning over. It had no compression in the number 3 and 4 cylinder, so I removed the head and found the intake and exhaust valves for those cylinders stuck open. I put some MMO on the valves, but the exhaust valve for the #3 cylinder won't budge! A bigger problem was the condition of the head. It has corroded through in a few spots. I want to replace the head, but have concerns about how the block might be. Can the head corrode through and the block still be okay? It looks okay from what I can see but thought I would get some expert advice here. I have included some pictures of the engine and head. Thanks!

[joec43]

Check the studs from the head you removed, if the thread is good (I think someone suggested more than 3 threads, on mine there was at least 5 on all that came out), the theory is the block is good. (barring any other issues).

Although Don sells some used heads, I went with the new aftermarket, and it has treated us well.

Although your block is scary to look at, it will clean up great with some elbowgrease and cleaners.

I'm sure someone with more experience than I will step in, mine was a 1969 that blew a headgasket halfway through a 6500 mile trip.

When I removed the head, it was so corroded that a screwdriver pushed right through it in once spot. The block was solid, with lots of threads.

Now the trip is finished, I have removed the engine, cleaned it up, painted, and am making ready for the next trip, details on the blog.

Good luck, get the manual, take lots of pictures, and label all your baggies.

Joe
potogold.wordpress.com

[hanleyclifford]

It is possible for the head to be corroded thru and yet the block be OK. As you clean look for small cracks especially near the corners of the block surface. Welcome to the forum.

[ArtJ]

Can' t the block threads be replaced or repaired? I thought that Moyer
sells helicoils or the like to do this with.

[edwardc]

Can' t the block threads be replaced or repaired? I thought that Moyer
sells helicoils or the like to do this with.

The problem is not the threads themselves, it's with the thickness of the block. Once the block thickness corrodes down so thin that there are only less than 4 threads left in it, there is a high likelyhood that the threads will strip and the stud pull out when attempting to torque the head nuts to 30-35 ft-lbs.

The repair collar can repair stripped threads, but if the block is too thin, the collar doesn't have much to grab onto and it too can pill out.

[sastanley]

Art...Ed explains it pretty well, but I'll add some more. My understanding is the studs extend into the water passages in the block. As the water passages slowly corrode from years of raw water cooling, so do the ends of the studs...the 'number of threads' can help indicate how much of the cooling passages have deteriorated (from the inside out) and whether the block is still serviceable.

I had 4-ish threads when I did my thermostat housing upgrade last spring, so I am saving up for the fresh water cooling kit..especially now that Tom at Indigo has engineered a kit with the electric pump. I can't even buy the parts for what he is selling his ready-to-install kit!

len - I think your motor isn't looking too bad. Pulling a head stud or two and counting the threads may help determine the condition of the block. You may want to get the valve grinder kit from Moyer to address the sticky valves..I know that my #4 cylinder had sticky valves in it and the P.O. left the spring compressor & the .316 valve guide grinder on board for me.

Call Ken in the parts dept. and help send his kids to college!
Here is my quick list for you so far:

• MMI A-4 service manual (aka. the bible)
• MMI aftermarket head
• two head gaskets
• valve grinding kit
• valve cover gasket
• lots of other little gaskets and stuff

Great pics & welcome to the group!

[keelcooler]

Our blocks hold up pretty well unless water has been able to stand for an extended period of time in a combustion chamber. Looks like number 3 had water in it. Check for corrosion pitting lower inner wall. The head, manifold, thermostat housing and side plates rot out all the time.

I feel that draining the water jacket during the winter and not filling w/ antifreeze allows air to accelerate internal corrosion. Excessive stud thread wastage can give you some indication of internal block corrosion. Keeping in mind the stud alloy is not as robust as the block material.

[Jesse Delanoy]

For what it's worth, I have a rebuilt engine with a MMI aftermarket head, and it's just fine. I'd much rather have a new aftermarket head than a used OEM part.

[lenjonsen]

Thanks a lot guys for the advice! The treads on the head studs are in pretty good shape. I can get the studs to tread in to the block without any problem. The exhaust valve for the #3 cylinder is stuck pretty good. I tried tapping it down with a hammer, but I was afraid to hit it to hard. I don't want to bend or break it. Also, the plate on the left of the motor for the water jacket looks pretty rusted. I think water from the corroded thermostat housing was leaking down the side and on to it. I plan on buying the manual, after market head, gaskets, and new head studs and nuts. I would also like to do the fresh water cooling conversion. Is there something you can use to flush out the block?
Thanks again!

[67c&ccorv]

Thanks a lot guys for the advice! The treads on the head studs are in pretty good shape. I can get the studs to tread in to the block without any problem. The exhaust valve for the #3 cylinder is stuck pretty good. I tried tapping it down with a hammer, but I was afraid to hit it to hard. I don't want to bend or break it. Also, the plate on the left of the motor for the water jacket looks pretty rusted. I think water from the corroded thermostat housing was leaking down the side and on to it. I plan on buying the manual, after market head, gaskets, and new head studs and nuts. I would also like to do the fresh water cooling conversion. Is there something you can use to flush out the block?
Thanks again!

Bad idea - use a hardwood block or dead blow hammer with non-marring surface...GENTLY!

[ArtJ]

Just curious, what does a dead blow hammer look like?

[sastanley]

Art, it looks kinda like a rubber mallet, but it has lead shot inside the head (probably not really lead anymore) to keep the hammer from bouncing, hence the term 'dead blow'.

len - Yes...diluted muratic acid (I can find it at Lowe's) is a good block flusher, but you really need the engine running for that. Vinegar helps break up some crustys too..a lot of people do a muratic acid flush every couple of years, and vinegar flushes in between.