Best And Worst 351 Cleveland Heads

Episode 149 Manic Mechanic

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Jford@autorestomod.com

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400 cid.
Bellhousing pattern same as 429/460 (to allow use of already existing heavy-duty transmissions.
Main journal diameter increased by 0.25" to 3.00" for greater bearing surface area (incidentally, same as a 351W)
Crank stroke increased from 3.50" to 4.00" to gain 50 cid.
Deck height increased from 9.206" to 10.297" accommodate larger stroke
New intake manifold for wider deck.
Heads are identical in design to 351-2V, but have larger chambers to reduce compression, may also have air injection ports.
Different harmonic balancer and flexplate than 351C

351M
Same block as 400, but crank is back to 3.50" stroke.
Pistons have thicker compression height to maintain compression a 8.2:1 in the tall deck.
Different harmonic balancer than 400
Production of the 400 and 351M engines ceased in the early 80's, as oil prices began to sky rocket and federal EPA regulations became stricter. Ford turned to its Windsor series engines as the primary V8 options for passenger cars and trucks.

Cylinder heads from all 335 series engines will work.

US
Bad to Baddass
2V heads
351M and 400 heads are the oddly not the worst head on this list though the 78cc open chamber is a killer.
D5AE-AA

All 2V 351 Clevelands have the same 76cc open chamber 76cc
D1AE

4V Heads
1974 4V head. Possibly the worst head Ford ever plopped on a Cleveland 75.4 cc open chamber the same big ports as the older heads but with the added thrill of the same 2.04 intake valve and 1.66 exhaust valve as the 2V. A dead dog walking.

1971-73 Q code head. Honestly my experience with these heads is that they can perform well. 75.4 cc open chamber but with the big 2.19 intake and 1.71 exhaust valves, they can still get out of their own way.
D1AE-DA
D3AE-AA

1972 R code head. Same as the Q code head but with adjustable rockers.
D2AE-A

1971 Boss head. 66.1cc close chamber

1970-71 4V head. Closed chamber head with 62.8cc chambers. The head is quenched offering a better flame front that keeps the fuel cooler with high compression.

Aussie Closed Chamber 2V heads. Basically a US 2V head with closed chambers. Best of both worlds, quench chamber of the 4V with the port velocity and valve size of the 2V.

All 351 2V heads are marked with a 2 in the corner of the head.
All 351 4V heads are marked with a 4. Open chamber 4V heads are marked with a 4 and a dot.
All Boss 302 heads are blank (original use for these heads).
351 M and 400 heads are marked with an M.

Boss 302 heads are set up to run on a 302 block and have water passages in them. Boss 302 heads are unmarked but have a part number in the lifter valley and are always set up for screw in studs. If they are original the guide plates will have a C9ZE part number.