[GRX]

This is exactly what I went through when building the 400 for my '69 GTO several years ago. Eventually ended up going with the 670's with TRW Powerforged flat top pistons. 8 valve reliefs with beveled edge.
These would seem to be the modern equivalent : http://store.summitracing.com/partde...5&autoview=sku

Final compression was about 10:1. Which was managable with 93-94 octane with some timing adjusments. Cam overlap surely affected this as well. This is not to say that I didn't have some detonation going on like Skip said in post #12. Never had my engine Dyno tested.

[GTOGreg]

While my stock original 400 WT with 670's was running seemingly fine on 91 octane plus 100 octane (50/50, sometimes even 25:75 mix to get 93-95 octane), I'm not taking a chance with my rebuild. Having Dave at SD work his chamber mod and then I'm looking for anywhere from 5-9cc's to come from a piston dish. Lastly I'm going to get the block zero-decked.

[Tim john]

I just purchased ROSS pistons through Butler, dished 10cc for a 9:5 compression in a 67 WS engine with 670 heads for my original H.O. four speed car. Jim told me this will be fine for a street driven car on pump gas, he will be receiving the 670 heads this winter for flow and port work, nothing exotic just upgrading for the street. My car is a 13 second car in the 1/4 mile so it is not setting any land speed records but it will be a robust engine for the street without any spark knock. The ROSS pistons are a work of art, just beautiful ! and another plus was they (pistons) were 200 grams lighter than stock each so I now have 1,600 grams less rotational weight on the crank which is a huge benefit for wear and tear on the bottom end. I also went with Eagle H beam connecting rods and total seal piston rings (file fit). Everything will be balanced (rotating assembly). Block square decked as well.

Tim john---

[BILTIT]

Originally Posted by Tim john

I just purchased ROSS pistons through Butler, dished 10cc for a 9:5 compression in a 67 WS engine with 670 heads for my original H.O. four speed car. Jim told me this will be fine for a street driven car on pump gas, he will be receiving the 670 heads this winter for flow and port work, nothing exotic just upgrading for the street. My car is a 13 second car in the 1/4 mile so it is not setting any land speed records but it will be a robust engine for the street without any spark knock. The ROSS pistons are a work of art, just beautiful ! and another plus was they (pistons) were 200 grams lighter than stock each so I now have 1,600 grams less rotational weight on the crank which is a huge benefit for wear and tear on the bottom end. I also went with Eagle H beam connecting rods and total seal piston rings (file fit). Everything will be balanced (rotating assembly). Block square decked as well.

Tim john---

I agree, the ross pistons are nice!

[Hillard]

I know someone running a 455 + .030, flat top pistons, mild cam,and 670 heads. He runs fine on pump gas. His secret.........water injection. He swears by it.

[Lloyd-TX]

Open those chambers up a bit - PROPERLY. Zero deck the block. Have someone help select a PROPER camshaft. Careful tuning, including advance curve and carburetor and it'll run fine on 93 octane with no spark knock or detonation.

My advice is NOT to used bevel edged or eight valve relief pistons. More downsides to those than benefits, such as reduced quench, more edges to hold carbon (hot spots) and poor burn patterns. Most efficient would be custom, two valve relief flat tops or reverse deflector deals, but those are custom, made to order and big $$$.

Once again - ZERO deck that dude and do NOT use a thicker head gasket,

[Tim john]

I have an original Edelbrock water injection unit from the mid-70's called "Vara-jection. I removed this back from my car in about 1979 or 80 and it is currently up in the barn loft, it did work but I was not a fan of putting water into the cylinders, I was paranoid of hurting my pistons but no damage ever occured and I ran it for two summers. I ran the water line into my center tri power carburetor through the chrome lid, it just killed me to drill a hole in that original lid even back then. I just had AIH chrome in Iowa fix the hole and re-plate this very same lid last month after all these years. I am going with dished pistons now as stated above, back then I was looking for an easy, cheap way out to stop the spark knock, parts and cars are too hard to come by today for gadgets so I will pay the price for quality ...gladly.

Tim john---

[Hillard]

I have done a little research about water injection and have found nothing bad about it as long as it's done properly. Some say they have taken the engine apart after years of using it and it looked like it had just been steam cleaned. It needs to be a fine mist. You have to use the correct pressure and nozzles. I'm not recommending it, I haven't tried it myself (although I'm thinking about it), it's just another idea. fwiw.

[GRX]

Originally Posted by Lloyd-TX

Open those chambers up a bit - PROPERLY. Zero deck the block. Have someone help select a PROPER camshaft. Careful tuning, including advance curve and carburetor and it'll run fine on 93 octane with no spark knock or detonation.

My advice is NOT to used bevel edged or eight valve relief pistons. More downsides to those than benefits, such as reduced quench, more edges to hold carbon (hot spots) and poor burn patterns. Most efficient would be custom, two valve relief flat tops or reverse deflector deals, but those are custom, made to order and big $$$.

Good advice Lloyd.
Feel I need to clarify my last post .... my intention was to point out a possible solution for those without the funds or means to get custom pistons, or have the chambers on their 670 heads machined.

With above said ... for my next 400 build I will probably open up the 72cc chambers on my 061 heads and use a proper set of flat tops. For those who don't know, the 061 are basically 670's with open chambers. If you see a pair of these rare heads grab them! Most likely they will be going cheap because of the press-in studs. Very easy fix for a competent shop.

[Lloyd-TX]

Originally Posted by GRX

Good advice Lloyd.
Feel I need to clarify my last post .... my intention was to point out a possible solution for those without the funds or means to get custom pistons, or have the chambers on their 670 heads machined.

With above said ... for my next 400 build I will probably open up the 72cc chambers on my 061 heads and use a proper set of flat tops. For those who don't know, the 061 are basically 670's with open chambers. If you see a pair of these rare heads grab them! Most likely they will be going cheap because of the press-in studs. Very easy fix for a competent shop.

Agreed - my advice is a budget buster, fo' sho'.

Refresh my memory - the 061 castings are what - '67 big car heads?

[JKrull66]

[QUOTE=Skip Fix]

Other option is opening the 670s chamber closer to a later 68 and up chambers. Tom Wilhite has a special Bridgeport cutter for this. That should get you the 10cc easy if you don't need a fresh rebuild. ()()()()

I have heard of this process, I have a set of 670's that I would like to have this done. Can the process be done on heads that are assembled or at least already have guides. Do you have any more info, Location, Cost, Contact info, Web site ?
Thanks JK

[dhallz71]

www.wilhiteautomotive.net

[dhallz71]

CORRECTION--www.wilhiteauto.net

[GRX]

Originally Posted by Lloyd-TX

>>>>>>

Refresh my memory - the 061 castings are what - '67 big car heads?

Sorry man, missed your post before. A couple PY members have had great success with the 061 heads after some modifications. Yes I think you may be right about them being installed in bag cars - with a 2bbl carb believe it or not. The ones I have came out of a '67 GTO w/4bbl but there is always the chance the heads came from another car.

Finding info on these heads is difficult. Found more info in these forums than everywhere else combined. Member Will has a ported set & has submitted some good posts on the 061 heads.

Originally Posted by Will

Seriously, the 061 heads are a little-known "possible" performance gem. They are only hampered by their lack of screw-in studs which adds about $150 to the price of rebuilding them for performance use. I say they are a "possible" performance gem because mine don't have a shortblock to go on quite yet and I don't know anyone else who's tested them to see what they'll do.

Here's what I do know about them: They use the 2.11/1.77" valves and are the first "open chamber" head Pontiac produced. The chamber design is very similar (hard to tell the difference side-by-side) to what was eventually used on the RAIV heads. The chamber has a more open design with a bit less quench area and a lot less valve shrouding than any of the other typical open chamber heads produced from '68 - on. The intake ports are shaped pretty much the same as the 670 heads in that they have a very tall short-turn radius which gives them outstanding low-lift flow. Properly ported they can flow great numbers as Phillygoat pointed out. Mine flow 273cfm intake and 185cfm exhaust at .550" lift and have excellent low-lift numbers as well. Not a whole lot of work had to be done to get those numbers.

The unique chamber design and the promise of a little extra power from a design the engineers felt was good enough for the RAIV heads is what convinced me to go with them. If you can swing the extra cost to convert them to screw-in studs they'll make a fine performance head.
http://forums.maxperformanceinc.com/...10&postcount=5
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

1967 # 061.

Nice, tall short turn radius, shallow chamber promotes good flame travel and almost no valve shrouding.
http://forums.maxperformanceinc.com/...4&postcount=17

Hope you don't mind me quoting you here Will. The way I see it, the more people who know about these largely undiscovered heads the less likely any more sets will be sent away for scrap.

Most sources I see list the 061 as small valve heads, but they obviously are not. Probably another reason they are so rare. Know I have seen a couple sets in swap meets that never sold because most see the press-in studs & keep on going.

[chiphead]

I've also got a set of 061s that I took off a 400 motor. Originally from a '67 Cat with 400 and 2bbl. Big valves, have all exhaust bolt holes, early accy bolt system, no EGR, push-in studs,etc. Approx 72-75 CC open chambers. Great heads as far as I can tell. Since I had a set of 670s I used them instead. Still have the 061s in storage. I think they are often confused with the '67 143 heads, which were used on the same cars and MAY have been small valve heads.

And Ive mentioned this before, I wouldnt modify a set of 670s if I didnt absolutely have to. They're a one-year only head with the 400 big valve size and later valve angle and closed chambers. As more people cut them to open chamber, an unmolested set will get very rare.

chip

[GRX]

Hi Chip. If you ever want to sell the 061's let me know ... < wink >

Sounds like you were in the same boat as me. I traded these 061's for a set of 6X-4's with customer (more on that in my other thread). Was tweeking them in my spare time at work when the 670's came along. The 061 have been sitting in storage half done ever since. Hopefully I will be able to finially use them soon.

[chiphead]

Yeah, since I was building a pump-gas 400, I used Ross pistons to drop compression with the 670s. Now in the low 9 area with static comp. But the engine revvs so freely with the long rods and lightweight internals. I'm using the SBC 400 1/16" ring pack relocated downwards on piston. In the future I can spray the motor and not worry about melting a slug or butting a ring.

chip

[Skip Fix]

You could also do it with a die grinder, but it would be moderate work. I would bet that would open them up just about right for pump gas and flat tops.

Mr. Wilhite has some pretty awesome old Pontiacs he and his wife race, one with an EFI Victor on it!