big block help

[snc4life]

need some advice im building a 454 for my truck and the machine shop swears up and down i need to run some 366t heads punched out for bigger valves on it he's got me about 90% convinced what im wondering about is the intake and distributer im not fond of this spacer idea or swapping out my new dist for another new one ....anyone every run this head combo any feed back would be great im trying to find a intake that bolts on with no spacers and uses the short deck dist or do i just scrap it and go with my 781 heads and a good slug to get the comp ratio up????

[b454rat]

I wouldn't go with the 366 heads, they are small ports, and will run like a bastard to about 3k RPM then fall flat on it's face. If you never plan on going over that RPM, then go with those heads. I'd go with the 781 or 049s. My old truck had a stock 454 with 781s, 4-speed, 4.10s with 35s, thing was a blast to drive. Had all kinds of power, and would pull to 5k.

With either of the heads that I mentioned, you have the ability to get more out of the motor down the road. Those 366 heads, they are just a waste of money doing anything to them.

[STOCKISH]

I agree, those heads are no good. I had a 454 .030 over that made over 500 horses with flat tops, 781 heads and a good cam and intake/ carb.

[raws67]

sounds like the machine shop needs to get rid of some 366 heads.

[SSC's76]

Originally Posted by snc4life

need some advice im building a 454 for my truck and the machine shop swears up and down i need to run some 366t heads punched out for bigger valves on it he's got me about 90% convinced what im wondering about is the intake and distributer im not fond of this spacer idea or swapping out my new dist for another new one ....anyone every run this head combo any feed back would be great im trying to find a intake that bolts on with no spacers and uses the short deck dist or do i just scrap it and go with my 781 heads and a good slug to get the comp ratio up????

I dont know what you plan on doing with the truck so I cant comment to much on those heads other then they should have a more closed chamber but depends on how ape crap they go with the valves and open the chamber up its hard to say. You do not need an adapter. You can use tall deck heads on a short deck engine with a short deck intake with no issues. The heads are the same so no need to order the adapters or a different intake. Now back to the heads. Closed chamber heads are great on a BBC those would be the heads found on the bastard tall deck HD engines. I have used tall deck closed chamber heads in the past as cheap performance heads had large valves stuffed in and ported the crap out of the runners. They work well but you need to put in a lot of work to open them up. Newer Vortec BBC heads have a smaller chamber and bolt right up to a older BBC intake just need to swap the valve train to adjustable rockers. Nice of GM just to drill a few extra holes to allow one to use a carb intake or a TBI intake and a vortec intake all on the same set of heads with no mods.

[snc4life]

the truck is a 78 swb with a th400 no stall and 342 gears im going to run air so i not going crazy with the cam the shortblock is 30 over with flat tops as for the machinist he goes pretty hard on every thing, he's done 3 sb's for me and all of them where great....i have to supply the heads so he's not trying to dump his junk on me haha....he's done this 366 head alot and he said he is very impressed with the result but my expirence with the 366 is in my old 3 tons more torque then ive ever seen but at 3k flat on there face maybe i should go ahead get them done and if i don't like them its not hard to swap them out i hate doing things twice and then have useless set of heads hangin around

[Alex1]

781's, period.

[snc4life]

Originally Posted by SSC's76

I dont know what you plan on doing with the truck so I cant comment to much on those heads other then they should have a more closed chamber but depends on how ape crap they go with the valves and open the chamber up its hard to say. You do not need an adapter. You can use tall deck heads on a short deck engine with a short deck intake with no issues. The heads are the same so no need to order the adapters or a different intake. Now back to the heads. Closed chamber heads are great on a BBC those would be the heads found on the bastard tall deck HD engines. I have used tall deck closed chamber heads in the past as cheap performance heads had large valves stuffed in and ported the crap out of the runners. They work well but you need to put in a lot of work to open them up. Newer Vortec BBC heads have a smaller chamber and bolt right up to a older BBC intake just need to swap the valve train to adjustable rockers. Nice of GM just to drill a few extra holes to allow one to use a carb intake or a TBI intake and a vortec intake all on the same set of heads with no mods.

thanks for the info
so after all that work on the closed chamber head would they still fall off early or would they pull all the way through?

[SSC's76]

Originally Posted by snc4life

thanks for the info
so after all that work on the closed chamber head would they still fall off early or would they pull all the way through?

Last set I used was on a 402. These heads were worked I'm talking a lot of hours were spent on these heads and it had 2.25 and 1.88 valves stuffed in. Like I mentioned you need to work the bowl a bit and open up the chamber or the valves will be shrouded so you will loose some compression but no to much. The engine had 0 breathing problems seemed like hitting the 6k rev limiter was almost as instant as hitting a light switch. It only had a comp 274H cam which isn’t that aggressive for a street BB.

[Damien]

Originally Posted by SSC's76

Newer Vortec BBC heads have a smaller chamber and bolt right up to a older BBC intake just need to swap the valve train to adjustable rockers. Nice of GM just to drill a few extra holes to allow one to use a carb intake or a TBI intake and a vortec intake all on the same set of heads with no mods.

The vortec 454 heads will work on an early block?

[SSC's76]

Originally Posted by Damien

The vortec 454 heads will work on an early block?

Yep they bolt right on and the big block chevy heads are drilled for every intake manifold so swapping a late mod fuel injected chevy bb into an early veh is simple. There is a slight difference in the shape of the coolant passages head to block when using these vortec heads on an early BB it it isnt a issue but the other way around you can have some problems with coolant leaking into the lifter valley.

[sierra4x4]

For the application that you have I would say go with the 366 heads but make sure that you do get the closed chamber ones. I just built a 454 for my k20 and I used 366 heads and put 454 valves in them(206int,1.72ex) so that the valves arn't shrouded as bad as they are with larger valves. The heads that I used had 235cc intake ports with 99cc combustion chambers. All I did was a little bit of bowl blending. When picking heads for my engine I found peanut ports to have 205cc intake ports and 781's had around 265cc ports. So I chose the 366 heads becouse in a 4x4 I wanted to have lots of low end torque and I figured the smaller ports would help with that and yet they still make excellent mid range power all while increasing the compression. I am very happy with the combination it makes awsome low end torque and will pull to past 5500rpm. I'm sure 781's will make more top end power but you will loose low end torque with the larger ports and lower compression.