351 cleveland question

[74bronk]

are the tops of the pistons normally "raised" and have slight impressions for the valves "stock" or is that a "high performance" piston?

 

[wdbowers]

what year engine is it. the later engines had dish top pistons even with 4v heads.

 

[Madgyver]

Flat tops With valve reliefs came stock with the earlier motors. D0AE

 

[bmc69]

What Mad said. If your pistons have a raised area above the block deck then they are aftermarket "pop ups" and very (very) high compression pistons for a closed-chamber Cleveland. "Back in the day" CRs as high as 13:1 were not unheard of..when the stock CRs were in the high 10s and low elevens anyway. The 1970 Cleveland 4V had a stock CR of 10.5.

 

[74bronk]

What Mad said. If your pistons have a raised area above the block deck then they are aftermarket "pop ups" and very (very) high compression pistons for a closed-chamber Cleveland. "Back in the day" CRs as high as 13:1 were not unheard of..when the stock CRs were in the high 10s and low elevens anyway. The 1970 Cleveland 4V had a stock CR of 10.5.

the guy that gave me the block said he was getting 14:1 coppression

 

[74bronk]

what year engine is it. the later engines had dish top pistons even with 4v heads.

1970 block according to engine casting numbers
DOAE-L
OE21

 

[bmc69]

Have you confirmed that heads are closed-chamber '71 or earlier? Those heads, with domed pistons, and you are talking some evil compression.

 

[74bronk]

Have you confirmed that heads are closed-chamber '71 or earlier? Those heads, with domed pistons, and you are talking some evil compression.

how can i confirm the "closed chamber" heads? the guy that gave me the engine block said he had 14:1 compression....

 

[bmc69]

See pics below. The Aussie closed chamber same as early 4V US closed chamber...the early US 351C-4V closed-chmaber head shown in second pic all by its lonesome. Can't miss an open-chamber head..completely round and domed.

 

[74bronk]

See pics below. The Aussie closed chamber same as early 4V US closed chamber...the early US 351C-4V closed-chmaber head shown in second pic all by its lonesome. Can't miss an open-chamber head..completely round and domed.

the pic with the side by side it is the one on the left.

 

[bmc69]

the pic with the side by side it is the one on the left.

Really? Too bad then. Those aren't worth more than 75 bucks a set for good castings...if that.

 

[ugly74]

Really? Too bad then. Those aren't worth more than 75 bucks a set for good castings...if that.

really? open chamber heads aren't worth shit? I polished my chambers so they don't ping, and with a little port and bowl work, they flow angry amounts of air.
I know the M heads are crap, but I thought the open chamber heads were still worth somethin

 

[bmc69]

I know the M heads are crap, but I thought the open chamber heads were still worth somethin

Uh...hello..you didn't know that the only real difference between what you call "M heads" and the original 351C 2V open chamber heads is the Thermactor porting in each end?

There are only effectively (as it relates to the chamber geometry, runner volumes and valve sizes) 3 different US Cleveland heads. The 4V closed chamber heads, the 4V open chamber heads, and the 2V heads (all open chamber).

Not a thing 'wrong' with the 2V heads you are talking about..they are still massively better than any head evern put on a wheezer in term of flow potential. And I've polished many of those (and 429/460 heads..same design) until I could see myself in the gleam; an 'old school' treatment that really works.

 

[ugly74]

and there is a difference in the exhaust port as well. in the M head, there is a big ol water jacket around the exhaust valve guide right down in the pocket. The M head will not flow near as much as a C 2V head. (not without a lot of grinding and welding anyways)
I could take pics of the heads I have to show ya the difference there, if you like

 

[Madgyver]

You could use flat top pistons in open chamber heads. That should give you about 9.0 or 9.5 to 1 CR.
Any head is a good head. Lol

 

[bmc69]

and there is a difference in the exhaust port as well. in the M head, there is a big ol water jacket around the exhaust valve guide right down in the pocket. The M head will not flow near as much as a C 2V head. (not without a lot of grinding and welding anyways)
I could take pics of the heads I have to show ya the difference there, if you like

No need for pics...I have plenty of both flavors here at the shop and been building both for...dag..over 30 years now. Ick..getting old.

That difference is quite minor..as it turns out, and not that hard to compensate for. But I do like the early castings better for not having the Thermactor ports. Not enough to pay much for them..;D

In recent years, practically all I build are the Australian Cleveland 2V heads which I consider the best of all worlds; close chamber..2V valve size..no Thermactor ports..