Thread: 454 build up and a bit confused

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Hi, im a Kiwi building up a new engine for my 39 chev coupe, im just wanting to build a reasonably strong street motor not a balls out race motor, I have bored to +30 and have fitted a new crank, pistons are flat top "sealed power", cam is sealed power "torque" cam 1500-4000rpm. my problem is im confused as to what to do about the heads, the ones I have are casting no 346236 open chamber 113cc, I understand they have very small ports and were designed for low down torque, the manifold I have is to suit these heads. some of my mates say I should junk these heads and get the bigger oval port heads. should I stick with these or should I search out somthing else, cheers

Oval port heads are for lower end and rectangle heads are for higher end. If your cam is only good till about 4000 id either stay w/ those go w/ the 781 heads. Those are the best oval port stock castings.

Not to be a smartass, but do flat tops even work with open chambers?

your looking at max @ 4000 rpm i do not see why you want to look for a bigger head or use a 781 o49 casting they may help a wee bit but for the $$ and then bigger valves $$ you may not see big gains if a heavy car the smaller ports should work very good at low rpm the heads should work good as a TORQUE engine far from a sexy heads but will work fine. bigger cam or more cid and more rpm then a better head a open chamber will work with a flat top in marine use they used small port heads hi TQ cam and iron low intake and made 330hp so a better intake and headers wound not be hard to get 350 hp or abit more and alot of TQ if thats what you looking for ? what year block do you have the older heads will not work on mark 5 or 6 block

The engine dates to 1975, heads were what was on it and had flat top pistons in it, bore was std and worn so have bored out to +30 and fitted new flat top pistons, crank was also worn but also pitted on the journals so purchased a new "eagle" crank. im not intending to build a race engine so dont need heaps of compression, and the gas we get here is unleaded and 91 or 96 octane, thanks

Use the heads you have and have a quality 3 angle valve job and you are in business.