Is a 235 cc head too big for a street 434 ??
 

I'm building a new small block 434 for the camaro and am still working on the heads.

We originally went with the Dart Platinum Pro 1's which is a 227 head. Well after waiting 6 months for the back order, they arrived... the first issue was there was a casting hole in one of the runners near the pushrod " galley". Darts response was "well you know you can just weld that up". That pissed me off to buy a brand new set of heads and have to fix them.

Then the second issue was the flow. They advertise 309 cfm.... the best we could flow them was 240 !!! Darts response was that they flowed them with their valves... fine.... we get one set of their valves and flow them again.... no change. I know the big thing is "wet flow" now, but come on..... 60 cfm difference ??

So the Darts are going back.... so now I need a new set of heads.

The car will be 99% street driven, manual 5 speed, 434 small block, Victor Jr intake, Dart block etc etc. We havent selected a cam yet because we wanted to get the heads nailed down first.

My engine builder is looking at the Brodix heads. I just saw some stuff about World putting out a Motown 235 cc head with a 72 cc chamber.

So is a 235 head too big for a street driven 434 small block ?? I dont want to get lured in by "bigger is better"

For the intended usage I'd say a 235cc would be OK but might be a little soft on the bottom even though they're feeding 434 cubes... but don't buy from World no matter how tempting things look from them. If you think your dealings with Dart were bad (I can't believe they'd tell you that!) then you haven't dealt with World yet!

You might also want to look into AFR 227s, good heads. Brodix heads are nice too.

kinda apples to oranges BUT,

My 425" ls1/7 hybrid has 260 cc heads. Should not have a problem with it being that soft on the bottom.Compression ratio, Localized port velocity and cam selection will play the biggest part in torque production on the low end.
There are tons of ls1 guys running around with a 250+ cc head on a 408.:_paranoid The factory l92's are around that size also.

I think a 235 will be fine on a 434" engine.

I don't think so, I had ProTopline 235's on my 434, and it ran great. I don't think I'd go any smaller than that.

Port size can't really be directly compared between 1st gen and LSx motors - port length, port height, valve size, and valve angle differences make the comparison not really useful.

235 CC would generally be considered quite large for a 434 street motor, unless you're going for higher RPM power peak (6500 - 7000). Even then, many engine builders will take the philosophy of using smaller ports. John Lingenfelter used to build 420 CID small blocks with heads in the 190 cc range, shooting for brutal torque and 550 HP or so.

If it was my motor, I'd think about the newest version of AFR 210s or 220s as a starting point. Call Tony Mamo over at AFR and tell him in detail what your goals are - he'll be able to make a recommendation on both heads and cam. I've used 3 sets of AFRs on different builds now, always with excellent results, and AFR's customer service has always been great for me.

Exactly what I was getting at only with more words. Heck, for street duty with a reasonable RPM cap in the 6400-6500 range I wouldn't doubt Tony would suggest their new 195 Eliminators, and I bet that 434 would make some mean torque numbers with them.

Wouldn't even give a thought to going with anything other than the AFR's!!!

I would go with the New 227 AFRS Realy a good head.

I kinda thought that may be the case, that's why I said apples--->oranges.:yes:

It is hard to imagine that 2 engines with similiar displacement could be that much different. Oh well, live and learn:yes:

not to hijack ur thread but i just ordered a set of afr's new 195's yesterday for my 355, from want ive read they really suppot engines more like a 210cc head with out losing the low end, for your app i would be trying to get a hold of afr's new 210's ....you'll get the hp and some mean torque!!!