1972 Heads on a 360

[Spider]

I am pretty new to AMCs and I'm trying to learn some things before my 74 Javelin 360 4spd sells. I originally thought I had a pair of 390 heads because I decoded the valve cover tag and it said they were from a 1968 390 head. But now I took the vavle covers off to install 1.6 roller rockers and found the heads were had a number 72 on bothe which appear to be the year. Here are all the numbers off the heads "72" by itself on both heads, then there is a "L-6" or "9-7" if I read it upside down(in the same place on the pass. side is "11-2"), finally the last number is the same on both heads is "3216090-1" or the "9" could have been a "8" I tried to clean it but still couldn't tell.

The other question I have is with these new roller rockers the motor is running worse, it seems that the timing is off even when it is at 0 degrees, I have retarded it and advanced but still seems to miss once in awhile. With roller rockers should I upgrade another part of the motor, I have a Holley carb that is at least a 600, seems to be a race carb because it doesn't have holes the choke. I have a points distributor would it help if I switched to electronic ignition or could the problem be with my distributor. I have replaced the points maybe the distributor is bad. Also it seems that when I get to higher RPM it just flatens out like it's has nothing left, but it didn't do this before I put the roller rockers in. I am lost this car used to be fast but now it feels like the motor is bogging, I lashed the rockers liked it said. I am going to try and get numbers off the carb to find the CFM maybe it needs a rebuild too. I would appreciate any help, thanks everyone.

[Spider]

Ok I have figured out that the heads are 1973 360 heads, so I am thinking the motor is probably a 1973 as well. The rockers I put on are the Comp Cams Magnum Steel roller tip 1.6 with comp cam push rods and comp cam 3/8" studs. I lashed them correctly and then re-lashed them after running the car for a couple months and there is still a ticking lifter, I am pretty sure that because the car sat so long the lifter is gummed up. When the car is warming up before the oil warms up and the pressure drops the lifter doesn't tick, but as soon as the pressure drops to normal the lifter starts ticking. I am out of money so the lifter will have to wait.

My main problem is when I am driving the car and I give it alot of gas it flattens out, like the carb is choking out I'm confused, sometimes it backfires like it out of time but its at 0 degrees. Here is everything I have done to the motor, first off I flushed the motor with kreen, then I changed the oil pickup, rebuilt the oil pump, new plugs, wells wires, wells cap/rotor, wells points and the guy also had a bunch of extra vaccum lines running back and forth in the intake manifold(so I capped some of them off except for the vaccum advance in for the distributor). Besides the motor I also put a new clutch kit in it including, pilot bushing, throwout bearing, pressure plate, clutch plate and I had the flywheel refinished. There is also a slight vibration problem I am working out right now, someone said it may be a cracked pilot bushing. Thanks for anyone who helps.

[Spider]

ok another update I ran the carb numbers and found out I only have a 450cfm holley, I have a carter 600cfm AFB that I want to put on it to make sure it isn't running lean at higher RPM and giving me that problem. I have also adjusted the timing by ear instead of with the light and it is now about 4 degrees advanced. I'm going to start with the carb and see what happens.

[RGBJavelin]

It sounds to me that someone probably put the factory chrome valve covers from a '68 390 AMX maybe? I would think you would want the newer heads rather than the 1968 ones. sure they have less compression, but they flow much better. 70 and up 360 and 390, as well as 401 heads are all the same with respect to year.
Now for the drivability issues, 0 degrees advance is a little retarded ( no pun intended), keep advancing your timing by ear untill you start to get detonation under load, then tap it back a hair.
Check out those vacuum lines, capping them off is not the answer. Figure out what they are for, you might be disabling something that needs the vacuum to function, or maybe you have the fuel evap line plugged, causing a vapor lock condition? Also, check where you are getting your distributor vacuum, ported or manifold?
You could always throw the original 1.6 ratio rockers back on and see if your problems are still there, but if you did everything right and adjusted them correctly that doesn't sound like the problem. I don't know for sure, let me drive it! :D LOL
Hope this helps, good luck!

[Spider]

Thanks for the advice, I ended up selling the car for $2,000 to a guy in California. He took the motor apart and had it checked, turns out the block had a hairline crack and the head was cracked leaking coolant into the cylinder. This guy took the car and in about 4 months time it had been painted, new interior, new motor, tires, rims etc. The car looks awesome, I am so glad I sold it to him he gave the car exactly what it needed. Thanks again for the help.