femtnmax
Well-Known Member
Just received new Edel RPM LA heads assembled from Summit. Boy is the quality control lacking. Exhaust guide locations clear off the formed pad in the roof of the port, so you see the guide all the way down to the port roof itself. Also all the exh ports are offset to the left on BOTH heads vs the CNC finish for the port exit. So the exh ports kinda have a dogleg to the right just before the port exit. ONe exh manifold bolt hole is drilled thru into the exh port due to the port shift. All the machining when viewed from above is offset somewhat vs the casting.
I could run these edel heads, maybe trim the exh valve guides a little short in the ports so they don't heat up so much. Blend out the dogleg and accept the performance whatever it is, shouldn't change too much.
I'll tell you what...I'm building a 1400 cc engine for a 1979 Datsun 210 right now, has aluminum head with heart shaped combustion chamber...there is absolutely NO core shift or mis-drilling. The casting of the port walls, etc is thin, so the finished part had to be dead nuts on. This tells me quality alum heads can be mass produced.
So what to do....
this is not going on a race car build, no its for a street only car. I wanted the Alum weight savings and detonation tolerance, plus was switching to shaft rocker setup for reliablity...long road trips to shows out of state. So looked into the RHS heads. Internet said the RHS heads come in heavy at 62 lb each, compared to 50 lb for two alum heads, so I would be adding 74 lb by going to cast iron. I put the battery in the trunk, and with RHS I'd be dumping another battery weight back into the front again.
Engine combo is LA 360, with Ross forged flat top pistons; quench is 0.044 inch. Compression is 10.8:1 which works real well for my altitlude of 5000 feet. If I go cast iron heads (RHS) then combustion chamber volume needs to be 68cc to drop compression ratio to 10.0:1. I"m concerned this ratio is a little higher than with the alum heads (10.8 - 1 = 9.8ish), and I don't know if the cc's of the RHS heads can be brought up from 62 to 68 without too much chamber reshaping. Also the detonation tolerance of any engine drops with time/miles. I don't mind using premium pump gas, but you don't always get a good batch, and detonation shows itself real quick pulling mountain passes in my neck of the woods.
Any comments or suggestions welcome.
I could run these edel heads, maybe trim the exh valve guides a little short in the ports so they don't heat up so much. Blend out the dogleg and accept the performance whatever it is, shouldn't change too much.
I'll tell you what...I'm building a 1400 cc engine for a 1979 Datsun 210 right now, has aluminum head with heart shaped combustion chamber...there is absolutely NO core shift or mis-drilling. The casting of the port walls, etc is thin, so the finished part had to be dead nuts on. This tells me quality alum heads can be mass produced.
So what to do....
this is not going on a race car build, no its for a street only car. I wanted the Alum weight savings and detonation tolerance, plus was switching to shaft rocker setup for reliablity...long road trips to shows out of state. So looked into the RHS heads. Internet said the RHS heads come in heavy at 62 lb each, compared to 50 lb for two alum heads, so I would be adding 74 lb by going to cast iron. I put the battery in the trunk, and with RHS I'd be dumping another battery weight back into the front again.
Engine combo is LA 360, with Ross forged flat top pistons; quench is 0.044 inch. Compression is 10.8:1 which works real well for my altitlude of 5000 feet. If I go cast iron heads (RHS) then combustion chamber volume needs to be 68cc to drop compression ratio to 10.0:1. I"m concerned this ratio is a little higher than with the alum heads (10.8 - 1 = 9.8ish), and I don't know if the cc's of the RHS heads can be brought up from 62 to 68 without too much chamber reshaping. Also the detonation tolerance of any engine drops with time/miles. I don't mind using premium pump gas, but you don't always get a good batch, and detonation shows itself real quick pulling mountain passes in my neck of the woods.
Any comments or suggestions welcome.