Low perf. heads

[three_deuces]

Just wondering if anyone has tried to have them milled in an attempt to fit bigger valves? Or are 583 & 690 heads the only option as far as big HP goes?

[Ronnie Russell]

Depends what you mean by "big horsepower". The small heads will accept 2.19 intake valves and with some basic port work, they can produce good street power. Stainless valves and screw-in studs are good upgrades also.

[three_deuces]

400 to 500 HP. Sorry, should have been a little more specific. A 454 stroker with 11:1 or 12:1 compression is plannned. So, those numbers certainly aren't out of reach.

[Ronnie Russell]

three deuces, I have just completed such a motor. The 817s will accept the 2.19s but Im not sure about the 333, 379, etc. We have plenty of guys here who have used them so they will comment. The 409 with 4 in. stroke should make 450 hp, even with modified 817s.

[three_deuces]

That helps. 817 heads sure are a lot cheaper compaired to the 583/690 heads. Has anyone ever tried to modify the 379 heads? That's what my 348 came with. (1960 Block) Probably would be a waste of time since the ports wouldn't allow for the flow needed.

[models916]

Good street heads. Support 400 hp and 6,000 rpm. Not so go if you are racing.

[three_deuces]

The 817's I can understand, but 333 heads? Same valves as the 379's. Is there something special about them that I'm missing?

[Ronnie Russell]

three deuces, There has been much speculation as to whether 379s and 333s are the same heads as 817s , only with smaller valves. I keep thinking that with all the knowledge on this web-site that someone would measure port volumes of all the heads and post for all to see. Skip Fix has a flow bench and no doubt he has the equipment needed to measure port volumes. How bout it , Skip??? Sure would be better than ----" well, Ive heard this, or Ive heard that". Skip, give us some facts. :dunno

[three_deuces]

Maybe a search is in need. I'll let you know if I find anything. :D

[three_deuces]

Search didn't reveal a thing. :mad: Just casting numbers and valve sizes. :bang Are port volume numbers for 348-409 heads really that obscure?

[models916]

I beleive the 333 is the 817 with smaller valves and exhaust rotators. Intake port has the small turbulence inducer in the floors for torque. Not that big on flow volume, but velocity on the street at mid lift is where it's at. Just a good cruiser head if you use cut back SS valves and a correct angle serdi valve job. Just my seat of the pants in a heavy car opinion. Yes test them all. We could all use the data.

[W Head]

three deuces, I have just completed such a motor. The 817s will accept the 2.19s but Im not sure about the 333, 379, etc. We have plenty of guys here who have used them so they will comment. The 409 with 4 in. stroke should make 450 hp, even with modified 817s.

Ronnie, I built a set of 333 heads and took 2.19 BB Manley stainless and cut the valve head down to 2.10 or 2.08 (can't remember for sure-been too long ago) and used 1.80 stainless exhaust. That is as large as you can go on valves for 333 heads. Did some porting and they worked real good. I used these heads to drop compression for the street, has 11 1/2 to 1 pistons.

W Head
59 El Camino 348-3,2s
59 Impala 409-2,4s

[three_deuces]

So, in theory, you could do the same to 379s because they share the same valves? :scratch

Did some porting and they worked real good.

I was always told that you couldn't port 348-409 heads. I guess my sorces were wrong! :takethat

[Tom Kochtanek]

I recall a previous thread that got around to this subject, modifying smaller heads with bigger valves. Fatride had done some work on his 379s atop to the 409, with 3x2s. Now he is doing some benchwork on the big heads. I recall he had some words of wisdom in terms of what to do / what not to do :).

And I recall there are some limits if you are using these on a 348? Has to be a big valve/big lift cam/small bore thing with these "near flatheads" :). Probably less of a clearance problem with a 409, especially the blocks I get, all needing .060" or bigger to clean up the years of corrosion...

Good luck and keep us posted. If anyone gets around to conducting "the big flow test", we should all contribute our heads, don't you think? Ship 'em directly to me, especially some built ones, and I'll see what I can do... :) :) :). No need to supply return address...

Cheers!

TomK

[Bungy]

You don't need to flow these heads to find out if the ports are the same. All you have to do is look at them. I have all three (817,333,379) if you put them side by side, you can see the 333s and the 817s have the same size ports. The 379 heads have smaller ports. Of course the flow numbers will probably differ some but just by sight that's my finding. So in conclusion, go with the 333 heads over the 379s.

[models916]

Check out the little bumps (333) in the floor of the intake ports. About the size of a pencil eraser, raised about 20 thou. and angled. Spos'd to make low RPM low lift torque. Not on the big heads. Might have to feel for them, don't grind them out.

[three_deuces]

Hey guys. Check this out! I was flipping through my Show Cars catalog last night thinking "Yeah, i need that, and that, blah blah blah..." Then I came to their little book of numbers section. Well, in the 409 head part, they show the flow for that casting! :doh

Here they are:
817 - stock = 215 CFM : 2.19/1.72 valves = 230 CFM
333 - stock = 180 CFM : 2.19/1.72 valves = 230 CFM
690/583 = 260 CFM
379 = ???

They also state the 230 CFM will support 450 HP. 260 CFM will support 525 HP. Go Fig! Could this be the end to our little discussion if 333 and 817 heads are the same? :dunno

[Mr Goodwrench]

just remember the 333 heads have smaller valves in stock for than the 817's

[models916]

There is no mid lift numbers. I had a CFM of 196 with stock size SS valves for the 333 from a friend years ago. (Stone Valve Job) Mid lift data was good on the truck head. Torque producer not HP. Serdi 3 angle valve job and back of head shape and contour makes a lot of difference in flow across the lift.

[models916]

333 truck head has 817 port size, 379 valve size, turbulance inducers in the intake floor, small L88 type of combustion chamber. Valve size needs to be balanced with the entire head. Look at the new Chevy Vortec head with small valves/big flow spectacular torque. Originally a truck head, til' the hot rodders found it. I think Chevy built that head (333) to make torque in the trucks. I have been told by early years racers not to mill out the small chamber (mill 20 ok), but to use a piston to increase the compression lost by it. Chevy made the combustion chamber in the head to make power. If they wanted to lose compression, it's just a piston cut. C Harvey told me the 333 head can make over 400 HP with the right cam and piston design. If you are just drag racing its wide open and 1320. Not much low rpm matters to be concerned with. 333 head is not a strip head. I drive on the street from light to light, I don't need a race head or cam. Then again for $400 you can add 200 HP with NOS and only use it if you need to. All in all you need to build a package. Head cam pistons carb to work together and for how you drive. 600 HP at 6500 rpm isn't going to do you any good in a street car with 3:73 gears going to cruise night. 500 fp torque will.

[three_deuces]

Drag racing never came to mind with my 348. Just a good cruiser that COULD stomp the he!! out of any 4 banger. A lot of people in my age group(24) seem to think those pieces of crap a cool these days. I can't stand them!:takethat If I wanted to drag, I would go do what everyone else does. BB 572 Crate engine! :beerbang I do have something in mind as in what would be a good over all package. The only thing that had me confused was the heads. Hence why I asked. :D

[models916]

348 is limited for valve size because of the bore size. Worry about the valve job and back cut on the valves. Match port to the gaskets you are going to use and pocket port if you are brave. Valve guide area should be raindrop shaped, big side into the air flow. A stock 348 with a modern cam and 3 angle valve job runs strong. Doesn't need a lot of work to run on the street.

[models916]

The notch helps the 348 but it needs more. I like a notched 409 block for 690 heads. A lot depends on the valve job and how the air comes off the valve and into the chamber/block.

[61409]

Three Duces, I just built an engine with 817 heads. Stroker, 296 cam, 2 fours, etc. Anyway the engine dynoed 485 hp and 547 torque. As you see, I don't believe you have to have 290 heads to make good horsepower. By the way, Curt Harvey said if I had used pump gas instead of race gas it would have made over 500.

[three_deuces]

Wasn't trying to imply that you had to use 690 heads. Sorry if I made it seem that way. I have taken what everyone has said into consideration and think I have a pretty good game plan as to what I'm going to do now. Tell me what you think. :)

Tri-Power Manifold, ported and polished
333 heads fitted with 2.06/1.72 SS valves, ported and polished
12.0:1 Ross forged stroker pistons
Isky 284/284 duration Roller cam and lifters

[jim_ss409]

Three Duces, I just built an engine with 817 heads. Stroker, 296 cam, 2 fours, etc. Anyway the engine dynoed 485 hp and 547 torque. As you see, I don't believe you have to have 290 heads to make good horsepower. By the way, Curt Harvey said if I had used pump gas instead of race gas it would have made over 500.

That's a strong engine!:beerbang Is this the cam you used? http://www.iskycams.com/productdisplay.php?productnumber=396296&sku=1972&hdwt=31101&loc=101&dealer=no I was also wondering if you used the Offy intake?

[61409]

Jim, That is the cam I am using. Also I am using Offey low rise manifold with a one inch spacer.

[Loafer409]

Three Duces, I just built an engine with 817 heads. Stroker, 296 cam, 2 fours, etc. Anyway the engine dynoed 485 hp and 547 torque. As you see, I don't believe you have to have 290 heads to make good horsepower. By the way,




Curt Harvey said if I had used pump gas instead of race gas it would have made over 500.


Why:dunno Can you explain this....

[tripowerguy]

You only want to use as much octane as needed to prevent detonation any more slows down combustion and you lose power. :) Roy

[jim_ss409]

485 hp and 547 torque is a ton of power. That thing should really go.:beerbang

[models916]

What RPM did the torque peak? How flat was the curve? Sounds like a good engine.

[61409]

Peak HP 5100. Tq. 4000=450 4400= peak tq 4900=510 We pulled it to 6000 but wasn't making much at 6000,418 hp and 372 tq

[SSpev]

what stroke??? 427 or 454??? Over bore??

[61409]

454 stroke, 30 over.