81 250 smog head
- Thread starter Mbauer1
- Start date
What is the casting number? E0 or E1?
If it is one of these, you have one of the more desirable heads. Largest stock valves and hardened valve seats.
You will have to mill the head to decrease the volume (62cc) and get the CR back up.
Just plug the extra holes in the head.
If it is one of these, you have one of the more desirable heads. Largest stock valves and hardened valve seats.
You will have to mill the head to decrease the volume (62cc) and get the CR back up.
Just plug the extra holes in the head.
congrats and yes absolutely you can use it on your 200! The 81 head is about the best of all the Log heads, at a minimum to use it on your 200 will need to CC the combustion chambers to find out the chamber volume and then Mill it to get the Compression ratio up to where you want it. There are also other things you can do depending on what performance level you are planing on. Good luck 
If you mill it a bunch and make a block plate for the EGR port it should work fine. The late heads have ~62cc chambers, and head gaskets these days are thicker than the originals. If you mill about .060 off it that should compensate for the thicker head gasket and bring your combustion chamber size down to around 54cc and keep your compression ratio from dropping.
Mbauer1":2n5w0bd9 said:
Its the Monarch Granada head, 1980 model year if it is indeed a 250. Some have no number where the E0 or E1 should be if its a service replacment. One guy here showed one like that...would take a while to find the photos.
Should be blue color; 81'S were only 200's, either Gray or Ford Blue until the last made in late 1983.
Great cylinder head. It flows really well, and, if you want to reduce the problems with heat build up, use the EGR. EGR uses gas to cool the combustion chamber tempuratures so that Nox doesn't form.
If you don't want to use AIR, EGR, and an air pump, I'd consider welding a Port Divider in.
The 22 to 26 thou stock D8 head gasket is a good one and will keep your compression at 8.6:1 with a stock head on a 200.
If your running a 250, then consider taller pistons if its in your budget.
The log head had all its bugs worked out in its slow, and somwhat cash starved development. The log head really just needs valve lift, and porting around the long side radius, with a three angle grind and the recomendations the Falcon Six hand book gives.
Although his head is a D8 head, Crosley has an excellent direct mount coversion he did with a bridge port.
/viewtopic.php?f=1&t=56639&p=440076#p440076
He ended up with 205 flywheel horspower based on his quarter mile times, but used a Clay Smith 274 degree cam, and a 500 cfm Holley 4412 to get it. .
Comapred to the Aussie Crossflows at 425 thou lift, the later log heads at 450 to 490 thou lift can make the same air flow numbers, over 145 cfm at 25"Hg. That's enough to flow 205 hp if you have enough cam duration and lift. IIRC, the valve to piston contact only happens when duration is above 230 thou at 50 thou lift, so you should be okay. The 255 pistons are a good option for the 250, but the compression ratio on a 250 can skyrocket when the head is planed.
