Hi guys, I'm here with a question that I thought I knew the answer to, but it turns out I may have been wrong.

I know there are open chamber heads with the 2V sized ports and valves. These are the heads that came stock on all 351M's, 400's, and some 351C's.

I know there are closed chamber and open chamber heads with the 4V ports and valves, that came on 351C's.

And I know there are closed chamber 2V heads that came on 302C's in Australia.

I always thought though, that there was another kind, 351C heads, that were 2V sized, with closed chambers, and with the SAME SIZE COMBUSTION CHAMBERS as the 4V closed chamber heads.

Does anybody know if there are 2V closed chamber heads other than the smaller chambered 302C heads? I was always under the impression that there were.....

Thanks for any info, AleX

 

351C-2V, 2.04 int 1.66 exh. with 76.2cc combustion chamber(open)

351C-4V/CJ, 2.19 1.71 62.8cc. 71 CJ, the only year it was produced, 4v porting and valves with 2v combustion chamber.

351 Boss and HO, 71 Boss and 72 HO heads same with exception of combustion-chamber size. the Boss is smaller at 66.1cc and HO is 75.4cc. Both head used stamped-steel, pushrod-guided, adjustable rocker arms and 4V-size ports and valves.

The 2v size and closed chamber are the aussie head. Same closed chamber as 4v but with 2v size valve.

I know it's confusing me too some time !

 

Well that's what I always thought, but I found out recently that the Aussie heads that we always talk about, with the 2V sized ports and valves are actually 302C heads, and the chambers are actually 58 cc, not 63 cc like the 4V.

I'm wondering if a 63 cc chambered 2V port and 2V valve sized head exists, as I always thought it did???

 

What compression are you shooting for ?

 

None with these heads right now. I'm gunna slap on some open chambers and a conservative cam to try to get a quick functional engine to test the rest of the truck out for a few weeks.

After that though, depending on how it drives of course, I maaay want to upgrade to closed chamber 2V's (after selling the 4V's), but I pinged pretty bad with the closed 4V's I had on there 2 months ago and a SCR of 10.3, so smaller chambers are the laaast thing I want, even with all the other stuff I'm going to change.

 

Ford Australia made heads for the XA Falcon GT which have 2V intake ports and 4V exhaust ports

Ford Falcon XA GT Technical Specifications

Check it out Mark.A think you know every thing

I bought a set of heads off one of these but cause we have unleaded fuel now I have to lower the compression cause it pings it bloody heads off. shorten the cam duration and change a hole heap of stuff it goes on and on but it will work

 

While the closed chamber heads do raise compression, they are also meant to help to some degree with pinging as they promote better combustion due to a better flamepath(?). Can some-one confirm this? I believe I saw this on a T Meyer post, (but don't hold me to that), and i will stand corrected if proven otherwise. maybe it was for better compression. I suppose you're trying to get a US based alternative to importing a set of aussie heads and then opening them up to 4v valve size anyway, and still retain closed chamber heads with out the import cost?

 

Walling, wow, I had no idea anything thaaat weird existed! That's really interesting at the very least, I'll have to read up on how they performed, but thanks for the info. Goodluck on getting that running smooth, I know exactly how that goes..... Message me when you're done if you remember, I'd be interested to hear how the torque is with those hybrid heads. I was honestly pretty disappointed with my 4V setup, even with how much I tried to torque up the rest of the motor.

And Miffy, the closed heads reduce pinging by creating more turbulence in the chamber than the much more round chambered unobstructed open heads. That motion in the chamber helps keep hot spots, and extremely high pressure zones (both of which can cause the mixture to detonate before the spark sets it off) more averaged out. They also raise compression of course compared to open heads, with their smaller chambers. And no it's not the cost of importing that's the issue, I'll have to import any 2V closed chamber head, and I'm actually wanting to switch back to a 2V setup, not turn 2V's into 4V's. I just had 4V closed heads, and was pretty disappointed with them like I said.

 

All good mate. good luck with the 2V's. The 1972 aussie XW phase 3 GTHO were officially the fastest 4 door sedan in the world. I can't remember specs, but that was how Ford Australia marketed them. Strangly enough the Aussie Chrysler Charger running a 265 six pack set up could beat it on the 1/4 mile and used to beat it on the shorter, twisty tracks in the aussie touring car series back then, but once they got big and long the HO was all over them. The only other thing that could touch it was the Holden (aussie GM) LJ torana XU1. It was only half the size of the Falcons but ran an inline 6 202 ci with triple strombergs(?) and went like the clappers. I believed that the HO's were 4V not hybridised, but again I will stand corrected on that.

 

G'day smiffy

As far as I know all you say is correct but we must remember we now use unleaded fuel and with the high compression will that change what type of cam would be required for street purposes. I have yet to purchase a cam for my project and I have so much conflicting info. I have also got a set of 4v closed chamber heads. I don't no which ones to use the hybrid open chamber 2v come 4v or just the straight 4v's I have flat top pistons and dome shaped pistons. So far I am leaning towards the dome with the closed 4v's I am told that should produce 9.9:1 ratio that should be plenty for the street.
Any way I am only thinkin of my self here goin of on a tangent

Also I apologise about the dribble causing so much angst in the other forum. I think popajon got his wires crossed it all really started with me being acused of smoking crack which I took to be VERY offensive.
I have cooled down now and arn't bothered by the offender he is the one with the problem.He's talkin out of his crack

I like you are new to this forum but am learning along the way

 

G'Day nothercrash

You arn't the first person I have heard say that

I know a bloke who spent a fortune on his 351 c only to find it was guttless under 3500 rpm but pretty good above that

After comparing a similar motor on the dyno did he realise that it was the 4v heads The other motor had these hybrid 2v's and was producing the same figures at 2200 revs. So I dunno wheather the unleaded fuel had something to do with it cause that is the major change we have had since these motors were designed. They worked perfectly back in 1971. Ford may have seen the writing on the wall back then and came out with these hybrids. Over here in OZ anyway.

 

As you are new I will (newer than me anyway) my build is this 400 (6.6) 268 DEH comp cam, 302 heads with boss valve springs and 4V valves opened up to the gaskets. Street dom single plane and Holley 725 (was meant to be 780) needs better ignition and headers and I'd like roller rockers, and probably better tweeking in the carby. goes well up top. I've tried to get contact witi popajon to cool it down with no luck, as he has been very reasonable from what I've seen and it would be a shame to lose some-one like that. the comments to you were completely inappropriate

 

Walling, how thick of a head gasket would you run with those domes, and how far are they down in the hole? I had flat tops (3cc valve relief) that were .077 down in the hole, with a .041 head gasket and closed chamber 4V's, and that made a static compression ratio of 10.3 or so, and that blew up....

I don't mean to question ya, but I would think with domes aaand the closed chambers, you would have a crazy high CR, and these heads didn't handle a borderline CR neeeearly as well as I was hoping they would have. Also, I don't know anything about the vehicle it's going in of course, but I would be leary of those 4V's on anything but a pure bred racer. I'd say go with your 2V's all day long, they really are a great head compared to so many other stock ones of the era, and in my opinion, the 4V's don't belong on a truck. I bought all the hype about them being just fine when you combined them with a nice long runner intake, a smaller carb, a moderate cam, and long tube headers, but I'd call even that set up all but gutless on my truck.

 

Yer the more I am hearin is to go for the 2v's I have yet to decide on a cam and was wonderin if you could compensate with a milder cam I dunno. I mean I could just go stock with the 2v's but then that would be boring It will eventually be a replacement motor for my xy ute pics in my garage. It has 2v heads 750 holley roller rockers and HM headers. I didn't build the motor so I don't know what cam it has Its not radical and it drives great down low. The ute is light compared to a truck so theres no comparison I guess.
When I finish the motor I am building I will swap em over and start again.

Do you remember the Sigerson cams I had a TQ 20 and I can't find out what grind they were

I had it in a 302c prity much stock but gee I really liked that cam it suited my purpose really well.

 

what sort of revs do you get up to? It all comes down to load too. One of the guys in the old home town was in the speed way. rebuilt a 302 (i think it was a windsor though) and put it in an old falcon wagon. Hopeless without a load, but with the sprintcar on the trailer it pulled like a schoolboy. It needed load to work.