RHS cylinder head advice!

[67 gt]

Hi all looking for some advice,first a run down on my 318 that im building its a LA 74 block,which is Zero decked,40 up ,torque plate was used in the honing process,main bearing caps were lined honed, ARP mains bolts,balanced,steel crank 10 under on mains and big ends,scat i beam rods with the 7/16 arp bolts used & with bushings in the small end to accommodate the full floating pistons KBs 167s pistons,Moroso windage tray,new std pump with stronger relief spring as im using std sump.The cam is a comp cams 270s solid,Duration @ .50"lift 224, valve lift 468,lobe sep/110,comp solid lifters,pushrods and pro mag roller rockers,1406 Edelbrock vac secondary carb.Now some advice needed on these cylinder heads im looking at they are the RHS 62cc with the 192 intakes,162 exhaust stainless valves,10 degree retainers with locks.Springs will be the comps 901 singles with dampers,Are these heads the large port design or small port?as i have the LD4B manifold which i would like to use and i have the headman block huggers ceramic coated small port,could these items still be used?would these heads be a bit of a over kill due to the larger size valves.The car wont see a drag strip but will be opened up on occasions but mainly cruzin.Running a 904 havent decided yet on converter,with 3.55 rear end gearing.Any advice would be appreciated.Thanks in advance

 

[lil red]

the port size on the LD4B are smaller (273/318) than the LD340 (340/360). I used an LD340 intake with my RHS heads and found the ports matched up damn near perfectly and I did very little port matching (actually better than my old x heads)

I used a set of 90's truck shorty headers (magnum) on my LA engine express (because of the exhaust configuration it was the best fit) and found the exhaust ports lined up alot better - the RHS heads are a magnum desisn.

alot of guys here run LA style headers - I think they use magnum gaskets or trim the LA's to fit - not sure

theres alot of knowledge here and fellas running these heads and im sure they'll chime in with their experiences

 

[C130 Chief]

You'd have a better port match with an LD340 or Performer RPM. I think the block hugger headers will be your limiting factor. I would run a garden variety 1 5/8" long tube header and 2 1/4" duals.

The bigger valves on the RHS heads will help with low lift flow. Mopar used these valves on truck 318's. Larger valves will make a small cam seem bigger, but you have a fairly mild cam to begin with.

You'll probably want a converter with a 2500-2800 RPM stall speed. 3.55 gears are probably about the tallest I would go with that cam, 3.91's would really wake it up. Look for a low gear set for your 904 when you rebuild it. Don't rule out an A500/42RH swap and 4.10's.

 

[moper]

I think I'd replace the intake rather than re-use. There should be some sort of 340/360 port intake available over there and even a stocker would be an improvement over the LD4B. Otherwise it sounds like a great build.

 

[67 gt]

Thanks mopar and the rest on your input,what would be a good, Edelbrock duel plane manifold to use with this combo,reason why i want a duel plane is because I'll be doing alot of cruzin and to get that good bottom- mid range power.I want to achieve around the 10-10.5 compression which is quite achievable with the 62cc heads,they might need some some light machining and right compressed head gaskets to get to that mark just so it will give this little motor some bang!

 

[C130 Chief]

Edelbrock Performer RPM would be the best choice.

 

[67 gt]

Thanks Chief !