Im having a 350 longblock built for me at a local performance shop. I vouched to go with the hsr intake instead of a modded tpi. we are shooting for a shade over 400 hp at the crank. it will be 24lb injectors, double roller timing set, new crank rods and bearings, and a 228/235 cam but he said he might go a bit more agressive cam with the intake change, flat top pistons, and 9:1 dynamic comp ratio. my question is he offers aluminum heads as a $550 add on over the cast 1.94-1.50 heads with him blending the bowls and port matching. is that a realistic hp number to hope for with cast heads or should i be looking into an upgraded head. He claims that by machining the valves deeper it fools the motor into thinking it has better heads and will be more responsive than with the 2.02-1.60 heads, and that his modified iron heads will flow close to 250 cfm. I just want to do this right the first time so the car is done and im not going back and spending even more money because im not happy with it. thanks for all the help.

 

Its also a hydraulic tappet motor...

 

Which block are you using...? A 2pc rear main seal, hydraulic flat tappet block?
There are better options, but you didn't state what this build is gonna cost as a whole...

In my opinion, Aluminum heads are better than iron heads 90% of the time, unless you have to run iron heads for a racing class or something. But not all aluminum heads are comparable... I think what you have to think about is intake/exhaust port flow and combustion chamber design among other things. Did the shop tell you what casting # iron heads that they were gonna use....? or which Aluminum heads they would upgrade to?
The HSR is a great intake as a whole and will Rev much easier than any TPI, but that cam duration is already pretty steep on a 350, maybe not for flat tappets.... (been running rollers along time) and you might have a hard time tuning your EFI. I thought that my HSR with 211/219 idled poorly and needs more PROM tuning

Just something to think about..... Hope others can chime in.

 

:i agree:

What heads?

You can pick up Darts for ~900, AFRs for aroudn 1200. It would be hard for me to go no-name (if that is what this is for 250cfm, I wonder if these are GM heads) when you can get 280cfm out of the box. This isn't including Brodix either which usually has good heads.

 

It is a 2pc rear main seal because im reusing all the trim i can off the 305 that came out of the car (oil pan, timing cover, ect). They gave me a core on the 305 block and are using gm blocks and heads they have in stock i am not sure on the casting number of the heads or which aluminum heads he would upgrade to they do deal the big name aluminum heads afr, trick flow, and dart. Their website just says gm 76cc castings rebuilt inhouse. And it is a hydraulic flat tappet block as far as i no because the upgrade to roller would be $700, and price including the intake, fuel rails, and gasket set is $3500 and will come as a shortblock pistons, crank, and rods installed and the cam degreed and heads portmatched to the intake...sorry if that isnt enough but thats all i know for now...

 

Bummer they don't have a roller block for you. The cost to go roller block over flat tappet is maybe 0-50-150$ for a used 350 roller block. If you decide to go roller in the future you have to worry about cam endplay, cam buttons and super expensive lifters (I have em, I know.) You end up spending about 700$ to do it later. I would think if you can sub in a 350 roller block it shouldn't be 700...

I don't know what rotating assembly pieces they are using either. What intake are they using too?

I'm guessing the heads are 128s with that many cc's. I can't remember off the top of my head but that would be my guess you would be better off going with 113s if you can get them (well ported they'll hit 280cfm) or go with a vortec head/manifold setup.

I suppose it all depends what you want out of it though.

 

Holley stealth ram intake. were hoping for 400-425 at the crank, this is with headers no cats and no emissions. Just wondering what you guys have seen with similar setups... and if i really need to go to the aluminum heads or if it will be a fun competitive car with ported cast heads like the shop claims it will be.

 

Sounds good to me. Abit more compression would be nice with aluminum heads but you should have 400hp with that 350 with that cam and intake if the heads are somewhat decent ~240+ cfm

 

thanks for the fast replies... but do u think the upgrade to aluminum heads will be enough difference over the ported factory heads to justify the extra cost...

 

Depending on the type of head you get with and the amount of work on the iron heads. The weight savings alone is nice to have. But comparing a mild port stock iron head to an aftermarket brodix/dart/AFR head, the difference will be substantial.

 

It really depends on what you want to do, and only you know that.

I know I was using cleaned up aluminum GM 113s. Looked into having them ported and decided to go aftermarket instead. But I was already at that point and I really wanted to have some nice heads on the build to support the changes I have and plan to make.

However if you just want a good street thumper with decent power that isn't all out crazy, it may not be worth it. It is all in what you want out of it.