Thread: Coolant in cylinders; fresh 400 sbc build

Tweet

Originally Posted by NTFDAY

Not if they don't have steam holes drilled in them.

so with no steam holes I can have coolant going directly into the cylinders?

The water out of the block will find some place to go

Originally Posted by NTFDAY

The water out of the block will find some place to go

Guess I'll find out when I pull the heads back off

Originally Posted by NTFDAY

The water out of the block will find some place to go

Yep, and if it can't go, it will generate a hot spot where the gasket can let go or pre-ignition/detonation can begin.

How can I identify the heads?

Well – here’s my two cents worth on what may be your problem. The 400 block starts life with a 4.125 bore (verses a 4.00 for a 350). You didn’t say if the block was bored but if it was, the bore would now be between 4.155 and 4.185. In any case, the head gaskets for a 400 typically are sized for a larger initial bore size and they have steam holes. The 400 block requires specific head gaskets with matching steam holes (Fel-Pro PN 17031).

The 350 heads are intended to be used on a smaller bore and they do not (in their stock form) have steam holes. 350 head gaskets do not have steam holes. Many well intended hot rodders have put 350 heads on their 400 blocks in anticipation of upping the compression ratio with the smaller chambers only to have a real disappointment in a very short time if steam holes were not drilled and proper gaskets not used.

When using heads without steam holes, the pressure immediately builds and more often than not, compromises the gasket. When that happens, water in the cylinders is common. I think you’ll find the gaskets have been compromised – as evidenced by compression being significantly lower in #2 cylinder.

I’d recommend pulling the heads, making sure you have steam holes and correct gaskets and reassembling.

Good Luck,
Glenn

I said the block was stock. Never been machined.

Originally Posted by jerry clayton

I got a blank post Jerry

OK--couldn't get it to post but do have a pic in my gallery of the steam holes in a 400 block---however these have been blocked as is sorta common mod for some guys---you can see how the one hole is cracked over to the head bolt hole and toward the cylinder however this block has been sleeved because of the crack into the wall---hope it gives you an idea of what to expect or look for. It is the first pic that comes up.

If anyone would like to post it to the thread I would appreciate it---Maybe Looey can take care of it.

Thanks

Jerry

Originally Posted by jerry clayton

OK--couldn't get it to post but do have a pic in my gallery of the steam holes in a 400 block---however these have been blocked as is sorta common mod for some guys---you can see how the one hole is cracked over to the head bolt hole and toward the cylinder however this block has been sleeved because of the crack into the wall---hope it gives you an idea of what to expect or look for. It is the first pic that comes up.

If anyone would like to post it to the thread I would appreciate it---Maybe Looey can take care of it.

Thanks

Jerry

Post the pic in PhotoBucket and copy the URL. Then reply and click the "Insert Image" button at top of window and paste the URL

Block before assembly

So did you look at the photo in my gallery?

I know that the photos can be posted here and I'm not going to do photobucket--too many pics of my stuff are by magazine phtogs and copywrite type stuff can be involved whereas just posting on a single post is ok

Originally Posted by jerry clayton

So did you look at the photo in my gallery?

I know that the photos can be posted here and I'm not going to do photobucket--too many pics of my stuff are by magazine phtogs and copywrite type stuff can be involved whereas just posting on a single post is ok

Yeah, I see that. I'll look real close at the block this weekend when I get time to pull the heads off.