253 or 308 sorry guys plz help

[vks]

hey all sorry if this has already been brought up havnt been on here in a while , 253 and 308 heads are they the same? any commetns would be appreciated sorry again 2 drag sumthin on.
cheers vks

[SL/ENUT]

Yup, the same heads mate.

[vkhawkey]

the heads are different. 308 heads have bigger valves then the 253s. apparently when 308s heads are put onto 253s they perform less well because of the decreased velocity of fuel/air mixture going to the cylinder

[SL/ENUT]

Well all of the heads off a 253 and 308s that i have seen have the same size valves. Only the B cast, A9L and VL V8 heads have bigger valves.

[tigervh]

SL/ENUT is 100% correct, standard 253 and 308 heads are the same item, they have the same valve sizes and share the same GMH part number.

L34, Brock VC/VH, A9L, Black motor and beyond are a different kettle of fish though.

[defa]

i have a holden book which covers upto vl's and it says that 253 heads are different and you will get less power out of a 253 if you put 308 heads on it. i think they did say in the book that the valves were smaller. i will have to get the book back off my mate and look it up. i have another one here i will look in to confirm it.

[Cane_It]

less power in a 253 by running big valves, ? maybe on a stocker, but if you improve carby, cam and compression the bigger valves will be better

[tigervh]

i have a holden book which covers upto vl's and it says that 253 heads are different and you will get less power out of a 253 if you put 308 heads on it. i think they did say in the book that the valves were smaller. i will have to get the book back off my mate and look it up. i have another one here i will look in to confirm it.

I'm guessing the book you are referring to is the Max Ellery, How to rebuild and hot rod Holden V8, page 150.

The statement made is "Cylinder heads for 253 and 308 did not have large valves. It was only when the 253 was dropped that Holden produced heads with larger valves for production vehicles. Even though 5.0l heads with larger valves will bolt onto 253 engines, they do not perform, as they do not produce good torque due to head airflow and the engine will not respond to accelleration."

Hence SL/ENUT's origional statment is correct for red and Blue engines, for VK and beyond the valve sizes are different, which he stated in his second post.

[defa]

nah. that isn't the book. this is a book that runs you through different stages or power. i will get it back and read it again..
it did say for sure, that by putting 308 heads on a 253 it will deccease performance..

[defa]

i had a look in another book and it has confused me a little. i read it twice. the first time i read it that 253's decrease in power if 308 or l34 valves are used. then i read it again and had a better read and realised they might have meant the bigger 308 valves. in other words, they would be saying that stock 308 are the same as 253.
i am still not convinced so i will have to get my other book back..

[defa]

just looking on ebay and sooo many people can't be wrong and me be right. so i am giving up on this one. i must have just read it wrong..
one place i read it was in "building a tougher holden"

[A-TEAM AUTOMOTIVE]

wat does the b stand for on the b cast heads? sum1 told me b for brock

[SL/ENUT]

Tech they aren't "Brock" heads, these were cast buy Yella Terra, use L34 sized inlet and exhaust valves and most was used on Brock road cars. However some normal Holden Commodores with the V5H perforamnce engine had these too.