Big Block Chev Cylinder Head Casting #s

[Z28SSMAN]

I have one 3993820 left from my '71 454

http://www.minuit10.net/EngineCode/c...linderHead.htm

From Chevelle Tech:

The 820 heads have the same runner size as the 049 and 781 heads. In fact all the big ovals have the same runner size so I dont get why the 049 and 781 are the holy grail of bbc iron heads. Anyway, the chamber size should be around 113cc compared to the 118-120cc's of the 049 and 781. One of the down sides to the 820's is there is a passage in the exhast bowl for smog. I think thats right, cant remember exactly but its something like that for smog stuff. Some of the 820's have a weird combustion chamber shape that unshrouds the exhaust valve but not all have it

If you are building a correct stock 1969 396 then you want closed chamber heads like the 063 or 215. I've got 063's on my 1969 427. If you use the 820's just remember that the stock 396 piston was designed for a 98-105cc closed chamber head so you'll lose a little compression.

[MR.hp]

802's, 049 and 781's do share some things but the chambers are completely different. 049 and 781 heads chambers are more like 990 sq. port heads. Some of the older heads like lets say a 265hp 396 were the same heads as your 454 on that Chevelle you have Glenn. Nothing wrong with them but the when you look at the chambers the low po heads the chamber wall by the spark plugs is flatter and the area around the exhaust valve is way more un-shrouded. The 049 and 781 flow better and are capable of supporting 850hp. I do remember I had a set of heads that I sold your buddy that had 265CC intake runners, the biggest of all oval ports. They worked pretty good but IMO the open chamber heads make more HP. All these years I was like you, Closed chamber heads are better as they engine has more compression, but at the top end the open chambers win. Edelbroke has made some heads that are 110CC and I guess they work pretty good but I am not willing to shell out 2K to find out.

The little 236 Peanut Ports heads I have make a ton of power and for this combo to go high 11's is better than I ever thought it would go with the stock size valve. At 7.8 Compression to 10 to 1 I am thinking the car would go mid to low 11's. There is one thing that put's this all in place, my Little 9.5 comp 358 still runs 11.50 in summer air and in my book still is a more impressive combo.

[Z28SSMAN]

Looks like the 802s are probably on mine now.
3909802 1966-67 396/427 Closed 109cc L-34/L-35 L-36/L-68

But the factory head casting that came off mine in '71 are 820 open chamber

[MR.hp]

Nothing wrong with 802's but I think that 454 would be quicker and faster with some 049 781 heads, but you like eating a sandwich going down the track and you don't need mustard in you lap.

[Z28SSMAN]

Since I already have an 820 which is a '71 head, I should find another 820 and dump the 802s? Or forget about the 820s and get the 049s or 781s?

[MR.hp]

Have a new set to or two to work with over the winter. Picked up a set of 360 PP heads with 2.19 and 1.88 valves that have 11/32" ferrea valves and all good parts. Just need porting. Also picked up a set of 401 BB Bowtie heads. Although these are sq. port heads these need only exhaust work, they have the chambers redone to get the cc's down to 108. Should make a ton of power on something.

[MR.hp]

Good news, just found out the 360 BB heads are good with no cracks. Just have to port them up and put them on the new short block. I guess I will try the roller cam with this project.

[MR.hp]

The 360 heads are all done just have to get them flowed. I redid the valve job as I do not trust others work in this area from past bad experiences. One interesting thing about these 360 heads is that their intake cc's were larger than the 236 heads I have on the car now. 2019 could be an interesting year, get ready boys racing time soon.

[Z28SSMAN]

What year had the 360s from the factory?

[MR.hp]

What year had the 360s from the factory?

Sounds like they were on 1990 SS 454 trucks from what I have read. They seem to flow more stock than my 236 heads I have on the other 454.