Can anyone confirm (reasonably) that 1970 2v heads are all open chamber? I’m already assuming also that there are no external markings to indicate chamber design.
I believe the 1970 351C 2v heads were open chamber, but the 351W 2v heads were closed chamber
As always, thanks for the insight. I only hope the author’s suggestion to recycle open chamber head’s is not a valid recommendation.
1 Like
I have zero personal experience with the open chamber heads, but understand they actually have more torque at the low end which is nice for a driver. But the motivation to use the open chamber design was to meet emissions standards rather than to improve performance. That’s probably why they get no love. I’ve also heard they are more prone to pre-ignition spark knock.
I may have to keep my eye on Australia’s FB Marketplace. Shipping might be prohibitive though. 
Hmm, California is close than Australia; $600 a pair.
Like I don’t have enought to do already!
1 Like
Here is some interesting info.
1 Like
Interesting it was thanks for sharing. I was reading a “back & forth” diatribe on the subject, I believe on the 351C forum and no one had a convincing argument - two conflicting theories, ending in a stalemate. This one at least explains the reason for “yes”, but “no”.
All US-cast 2v port Cleveland style iron heads are open chamber regardless of the year, or whether they were installed on a 351C, 351M or a 400. The closed chamber Aussie 2V heads are off their 302C.
The DIY Ford site has a bunch of errors.
1 Like
Hi there, it’s has been my experience that the 351C 2V engines were all built as “open chamber” in the U.S. However, the 351C 4V closed chamber heads were offered in the U.S. from about late 1969 to 1971, or maybe 1972 with the Boss 351 engine. As a general rule, there’s a marking cast on the heads that will have a number located at the upper left corner of the cylinder head which will have a 2 or 4. Additionally, the 4V heads will have number 4 , meaning 4V. But if there’s a dot present, too ( 4*), it indicates it a closed chamber head.
Help this helps,
Mark
Cleveland head identifiers are actually:
4 with dot = open chamber
4 = closed chamber
I’ve read both the dot signifies open chamber 4V heads and that it signifies closed chamber heads. It doesn’t appear to be a definitive characteristic.
Well, it does look like there are examples of both open and closed chamber heads with the dot. I didn’t know that. I do believe that all 4V D0AE Cleveland heads cast in 69 and 70 were closed chamber.
Our ‘71 convertible has closed chamber 4V heads, and they are marked with both 4 and the dot.
Saw an episode of Roadkill Garage and the hosts repeated the rumor that heads with the 4 and the “cannonball” (their term) were all closed chamber. They pulled the heads and they were open chambers…..
1 Like
So some comedian in the production line says “watch this, I’ll blow their minds *chink” -
1 Like
lol - probably not too far from the truth! Things were running pretty loose back in the day.
The “dot” was added to the 71 M-code’s D1AE-GA closed chamber 4V heads just after production started. I have seen several early June ‘70 cast examples sans “dot”, but everything after has it.
1 Like