Thread: Coolant in cylinders; fresh 400 sbc build

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Ok I had my personal guru (who just happens to be a Master Machinist and Master tech) look at the heads and he said they have been angle milled and too much. That they would make great boat anchors. He also looked at my 305 heads and told me that he would use those since I am looking to make more torque. They cam off a 86 transam and are the H.O. heads with 68cc chambers and 1.84" valves. Casting number is 14014416. Looks like this will be the rout I am going to try

There are two schools of thought in regard to using 305 heads on a 400 – one says “with a ton of work, they can be used”. The other school says, “don’t use them..”

I’m in the second school – The steam holes are the least of your problems. The heads you have (14014416) are 58cc (not 68cc) and that’s a big factor. With your all stock engine and a .040” head gasket you’ll be pushing close to 12:1 compression ratio with these heads. Couple that with the small valves and relatively short runners (165cc/59cc) and you will end up with a dog that will only run on premium fuel - anything over 10:1 starts to be touchy with pump gas.

The 400 was designed for torque, but it still needs to breathe. Remember that an engine is really just a big ol’ air pump and the 400 was designed to move a lot more air through its stock heads than even HO 305 heads can supply.

Your “stock” bore 400 is 4.125” and a 305 is 3.766” – do the math and you’ll have .359” of cast iron hanging over the cylinder area. You’ll play hob trying to get 400 gaskets to seal so you’d have to use 305 gaskets and they do not have provisions for steam holes.

Probably not what you want to hear – but I think your frustration will be compounded if you bolt those heads on your 400.

Check out this thread from several years back:

using 305 heads on a 400 sbc

We really do want to help you here –go back to Tech’s post #45 and get the measurements let us help you determine what a good head would be for your engine.

Regards,
Glenn

Bigbzc------

When angle milling cylinder heads was a more or less common thing to do to raise compression so as not to need a large piston dome sticking up blocking the flame front---on a sbc they welded up those slots in the heads and then redrilled a hole to line up with the one in the block.

Now , shortly , since you seem to have a blockage of anything any of us have posted, I will be deleting my posts later tonight, and I would highly recommend that others do the same thing>

Ok, in regards to what you have all told me, we did a little more research and found that you are correct. A race engine builder told me that I would have to use racing fuel if I use those heads because of the high compression. Sorry that I have been stubborn about this. I just am over my budget and really can't afford new heads. I will get those measurements Tech wants tonight

I think all of you are doing a great thing trying to help this guy out. There's a lot to learn and that's all he's trying to do.
I agree he needs the proper heads for the job. He's learning and so am I.
Thanks. It's nice to see someone help.

Well…. It’s what we all want to do – help others. Sometimes it’s hard because we all tend to have our own ideas about what is the “best way” to do something. I know I do – however; when it comes to engine building, I listen up to Jerry, Pat, Tech and some others here as they’re a storehouse of knowledge brought about by a lot of years of hands-on experience. I’ve built my share, but I’m not a machinist and I want to keep learning until the day they lay me to rest.

Ask me how I know about steam holes and 400 SBC? Been down that road because I thought, “those tiny little holes can’t possibly be that important…” Well, let me tell you – they are! The machinist I was working with was gracious and gave me a “Heat and the Siamese Cylinder Block 101” lesson after hours in his shop and then he and I found a solid set of cores and he showed me the correct way to drill holes. You don’t soon forget those experiences and hopefully, when people come to CHR and have questions they’ll realize there is a lot of smart men (and brilliant women too - Barb!) who are passionate about what they know. Listen up, process the responses and make a decision. We’ll always support someone who wants to learn. Know-it-alls, eh –not so much.

Ok, the squish is .041" THe piston clearance is greater than .030" my largest filer gauge is .030 and it slides freely. these are also dished pistons

In case you didn't know, you can stack feeler gauge blades one on top of the other to make any thickness you want. How did you arrive at 0.041 squish? Squish is the piston deck height plus the gasket thickness.

Originally Posted by techinspector1

In case you didn't know, you can stack feeler gauge blades one on top of the other to make any thickness you want. How did you arrive at 0.041 squish? Squish is the piston deck height plus the gasket thickness.

Thought it was just the thickness of the gasket. Deck height is .036 so that makes squish .077

Originally Posted by Bigbzc

Thought it was just the thickness of the gasket. Deck height is .036 so that makes squish .077

Do you understand that 0.077" is pretty much unacceptable and that it needs to be between 0.035" and 0.045"?

Originally Posted by techinspector1

Do you understand that 0.077" is pretty much unacceptable and that it needs to be between 0.035" and 0.045"?

I'll try to measure it again. It is in the truck so it makes it very hard to measure. However, the thickness of my gasket after being torqued down (compressed) is .041" which according to your specs isn't giving me much to work with and I know there is more than .004 deck hight. Maybe we are misunderstanding each other somewhere?

Piston clearance????/how did you measure that???I know you said feeler guage but how?????

Originally Posted by jerry clayton

Piston clearance????/how did you measure that???I know you said feeler guage but how?????

Jerry, you must have a lot on your mind today because I know that sometime in the past 50 years of hot rodding, you've checked piston deck height with feeler gauges and a steel rule. I explained to this OP how to do it in post #45 and he is reporting back, saying that he has a squish dimension of 0.077" (0.036" piston deck height and 0.041" compressed gasket thickness).

OK Tech

I reread it---I was taking it that he checked piston to wall like above the ring land--I've had people do that before not understanding that the pistons are much smaller up there than the skirts.
Have a good week end

Jerry

Well, as I have said over and over, that the bottom end including the pistons is stock and that is the way I plan to leave it. This means that the pistons are dished, just the way they come from the factory. Now your telling me that this will not work which is why I'm getting confused on what you are asking of me. I do not plan on racing this engine and am not seeking 500 hp out of it. At most, it will be used to tow my rock crawler.