Early 348 heads 791

[Jeffrey Osstyn]

I have a set of non water jacketed heads, around spark plug, has anyone ever had a problem with these? I know GM only used them for one year then added the water jacket around the spark plug, anyone know why they did it? Overheating, cracking, detonation? Should I not use these heads, the block I have has the holes for the water passages, they were plugged with set screws it appears.

 

[Don Jacks]

Yes there were some issues with overheating/cracking,but some ran fine without any changes.I would suggest that a lot would depend on the level of your planned build.If you're planning on a little extra hp,then find a set of 333's or 817's.The venerable old 379's will also work,but the smaller ports will limit your power,even with bigger valves.Any of the above heads will allow you to open up the cooling holes in the block.

 

[62impala409]

Oldskydog did us all a big favor when he posted a bunch of Service Bulletins a while back. This one pertains to the cooling in the cyl. heads. We need to remember that these engines were also used under severe conditions in big trucks. Leo http://www.348-409.com/forum/threads/spark-plug-cooling-tsb.21411/

 

[Jeffrey Osstyn]

Thanks for the quick reply! I am planning to use a tri-power setup so I need to use the 348 specific heads, as I can't find anybody that makes a 409 tri-power intake, which would allow the Edelbrock heads to be used. 817 heads would be out for this reason, trying to locate a set of good used heads is becoming a challenge, ran two sets through machine shop and came out with one good head. Will try again.

 

[Don Jacks]

Jeffery,817's ARE small port heads,and will bolt up to the tri power intake.They are upgraded versions of the high performance 1147 high performance 348 head,just more plentiful,cheaper to find.The 333's are late 348-409 truck heads with the same larger ports,just smaller valves,and a small combustion chamber,and can be bought for around 300 per set.With work,these small port heads can support nearly 500 horsepower.

 

[Jeffrey Osstyn]

Not doubting what you say, but one thing I have found out so far dealing with the 348/409 I get LOTS of input from people and as you may imagine they all offer their side of the story, which don't always agree. Case in point, The Chevy 348/409 book by John Carollo states that the 817's are 409 only. He lists 348 heads, 409 heads and 348/409 compatible heads. Actually the cylinder head I.D. info chart connected to this website also lists 817's as 409 heads. So here I am at another crossroad, which way do I go? Thanks for the response on my question, every bit of information helps.
http://www.348-409.com/cgi-bin/heads/csvread.pl?&page=1

 

[Don Jacks]

While they are correct in stating that the 817 is a 409 head,there are three types of 409 heads.Type 1,the 333 late 348 and 409 truck head,type2 the 817,340 hp[commuter]engine.Type 3,the 690,and 583 high performance head.The first two types are the small port,like all 348's,and 348 manifolds bolt up like they belong there.The type 3[690,583] are the large port,large valve,high performance heads,and the intakes for them are different,and will not easily work with the small port heads.There seems to be,in some circles,an assumption that all 409's are the same.Since both 348's,and 409 heads have the same bolt pattern,and deck height,these parts can be used on either engine,as long as the manifolds for the heads are the same.The difference for what you're trying to do has everything to do with port type[small port vs large port],instead of 348,or 409 cubic inches of displacement.

 

[Jeffrey Osstyn]

O.K. Thanks! So if they list a p/n for the 348 AND 409 these would be a small port head and it will have to be used with a small port intake? I guess a better way to state this is: These following p/n heads are large port type and have to be used with large port intakes 586, 690, 817, and 583, and can be used on either a 348 or 409 as long as they are paired correctly with the intake. Would that be a correct statement? In my case I need to avoid these.

 

[Phil Reed]

586 and 817 are small port heads.

 

[Don Jacks]

The 817 is a small port head,the 690,and 583's are large port heads,the 586 is rarer than hens teeth,but also a small port head.If you find a set of 586's,you just won the lottery.The only ones worth more are the z-11 heads.

 

[64ss409]

Don, you have a typo on the 690 head.

 

[Jeffrey Osstyn]

O.K. so maybe I should have asked what will NOT work with the tri power manifold? I gather the 690 and 583 are the only ones that will not work, due to port size.

 

[Jeffrey Osstyn]

What are your thoughts on the early non water jacketed heads [around spark plug] # 791?

 

[Ronnie Russell]

I use them for ballast on my engine crane.

 

[rstreet]

I use them for ballast on my engine crane.

Now that is right funny Ronnie!
Robert

 

[1958 delivery]

I use them for ballast on my engine crane.

Tell us what you really think about those

 

[Clyde Waldo]

I use them for ballast on my engine crane.

It's true - he does - there were three on his engine crane for ballast when I was there a couple of years ago.

 

[CDNpontiac409guy]

What are your thoughts on the early non water jacketed heads [around spark plug] # 791?

If you have a genuine early 58 348 block ( without holes ), and a good 58 car... use 'em
Otherwise... they're ballast.

 

[Rickys61]

If you have a genuine early 58 348 block ( without holes ), and a good 58 car... use 'em
Otherwise... they're ballast.

I have a '58 engine with 791's in my 61... It was in the car when I bought it in '95... I've never had the heads off and I haven't had any problems with them. I drive it a lot.. For a mild build they probably would be fine, but there's definitely better small port heads out there....
Rick

 

[rstreet]

Clyde what did you drop causing Ronnie to try to bend over and pick up. I have another Ronnie picture somewhere I need to post
Robert