I wish they were 175cc.Hmmmm I thought X and J heads had 175cc intake runner?
Don't get me wrong. It's been awhile since I had one in front of me but is there a coolant passage between the valves?.
So unported la heads will flow 200cfm just by installing larger valves? Other than big valve X And J heads that do flow 200cfm but through alot larger port.
I did have alot of la 360 heads that were cracked and running coolant into the cylinder.
Guess I would have to see dyno and track numbers cracked vs non cracked. Of course this is if they are cracked between the seats. I have seen Utah awesome on there website dynoed a truck with cracked heads. Still never seen a magnum head leak coolant from the Crack between the seats
Cracks between the seat hurt performance because they leak shortly after forming and that's lost pressure and a burnt valve...because they grow.
Head gasket was fine, No I never overheated it. Cracks in the seat can slowly siphon out coolant..head gaskets that loose fire ring and combustion leak are what puts pressure into the cooling system.
150cc vs LA 2.02 155cc and 1.88 160cc
That easy, the pushrod pinch is near closed compared to the LA , that's 5 cc right there.
You try hard.Hmm okay so larger valve stock X and J heads flow about the same as stock magnum heads. Only with larger valves. I have a set of J heads that look like your magnum heads exhaust seats gone and intakes on the way out.
How many miles do your magnum heads have? I think indy still repairs the magnum heads 2-300 per head.
Volumetric efficiency has alot to do with getting as much air through a small port as possible. So 200cfm through a small port will make more usable hp than a head that does 200cfm through a large port.
Guess maybe it depends on what kind of hp you want to make over 400 and different or ported heads. Point of diminishing returns on valve size on a 3.91 bore is around 1.97" 4.02 bore is around 2.05 if I remember correctly. After those sizes the valve starts getting shrouded.
They flow close, close enough its splitting hairs. They have a bigger valve than the heads they flow more than=1.88 They are not an underdog head pulling ahead of the pack.Sorry I'm not trying to offend anyone. I like all mopars.
I'm just trying to figure out where people are getting thier numbers for calculating volumetric efficiency? And longevity? I'm not saying magnum heads are all that but out of the box stock with smaller valve they flow with the X and J heads with larger valves out of the box stock. So yeah depends on complete build like pistons compression, deck height ect... correct?
Sorry I'm not trying to offend anyone. I like all mopars.
I'm just trying to figure out where people are getting thier numbers for calculating volumetric efficiency? And longevity? I'm not saying magnum heads are all that but out of the box stock with smaller valve they flow with the X and J heads with larger valves out of the box stock. So yeah depends on complete build like pistons compression, deck height ect... correct?
I don't anyone here is trying to offend you. We're hungry for information. I have a set of "J" heads, a set of "Z" heads, and the Magnum heads from a 1998 Jeep Cherokee. I'm making a 408 for another project with the block, and don't need the cranks or heads. 113K total miles. I guess I'll move this to the for sale thread, so as not to invite the ire of the MODS.Sorry I'm not trying to offend anyone. I like all mopars.
I'm just trying to figure out where people are getting their numbers for calculating volumetric efficiency? And longevity? I'm not saying magnum heads are all that but out of the box stock with smaller valve they flow with the X and J heads with larger valves out of the box stock. So yeah depends on complete build like pistons compression, deck height ect... correct?
Also iam a little confused reading on the swap from La heads to magnum everyone is saying to use AMC style lifters because the magnum heads oil up through the push rods, since i have a LA Roller 318 block with roller lifters already i can just reuse my current lifters? or should i use the magnum roller lifters from the magnum block?
And i been reading that some had issues with the push rod hole in the magnum heads they had to open them up a bit.
Reading through this post hearing the pros and cons of the magnum heads and just wondering how fast some of you guys have gone with them. I’m honestly impressed with what I’ve seen out of a set on a friends engine. What do you guys think a 408 magnum engine with a hydraulic roller, flat top pistons, ported magnum heads with 2.05 intake valves, 750 alcohol carb, powerglide, at 3200 pounds. What do you think this combo would run in the 1/8 mile.