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Got back in town yesterday from taking the 401 to have the cam broke in and do a few dyno runs. I was a little hesitant about spending the money, but after thinking about how much I spent on building this motor, I kind of talked myself into as insurance that maybe some bad things would not happen.
A little background on the build. I picked up this 401 a few years ago and finally took it to the machine shop last January to see if the block, crank, and rods were rebuildable. When I first dropped it off, they thought that one cylinder might have to be sleaved because of rust. But, when they finally started boring, they found out it cleaned up and was fine at .030 over. I then contacted Matt about some pistons. He had a set of old TRW's on a shelf that were .030 over that we did a deal on. After going through ever cam profile I could find for an AMC and going back and forth if I wanted to spend the money to go with a roller, I finally decided on a Lunati 64502. It is advertised with a power range of 1600 - 5800 RPM. It has 220/226 duration at .050 and lift of .507 and .527. I liked it, because it appeared to take the most advantage of the large diameter lifter the AMC uses. Not too big on the duration, with some good lift. I figured this cam would work good with the Performer RPM Airgap, Performer RPM heads, and headers I wanted to run. I added some Lunati lifters, Edelbrock push rods, and Harland Sharp rockers to round out the internals. The 401 did not come with a timing cover and I wanted to keep the 360 intact for if and when I do something with it. So, I ordered up some overkill from Matt.
Last spring, I pulled the 360 out about the same time I worked a deal with my brother for a Edelbrock 750 he had in exchange for my Edelbrock Performer intake, Edelbrock 600 carb, and a player to be named later. I just swapped the Z & M HEI from the 360 for the 401. I had been planning on getting the Doug Thorley headers, but since you are not supposed to break in a new motor with new coated headers, I purchased some Hooker's since they have the same primary diameter and collector diameter. Sure the primarys are a little longer, but what the hay. I had on maybe selling the Hooker's after the dyno run and getting the Thorley's for when I install the motor, but as long as the Hookers fit with my other modifications, I think I will just run them for now.
I think that takes care of all of the engine stuff, so now for what happened.
My brother and I got to the shop about mid afternoon on Friday and between us and the guys at the shop (both employees and other customers), we spent the next three hours or so hooking up the engine and stuff. As a precaution, since the carb I had been sitting for over 10 years, they used a Holley 750 double pumper of theirs to do the break in and first few dyno pulls. We had everything just about square, when they noticed they needed some gas, so my brother drove down the road to get some more premium unleaded. He missed, but while he was gone, they fired up the 401 for the first time. I don't think it even turned over a full turn before it lit and took off. Wow, did it sound sweet!! He got back in few minutes and we watched as they check timing, oil pressure, tempratures and such while the cam was breaking in.
After breaking in the cam, they did the first pull. It peaked a 340 hp and 395 ft/lbs of torque. Not what I had expected, but then they explained that the nest day it would do better after cooling off over night. Saturday morning comes and the first pull makes peak numbers of 390 hp and 435 ft/lbs of torque. Alright, this is what I am talking about!! Then we swap on my carb and did some pulls. Since my brother never changed any rods or jets or anything, and it is looking a little rich, we decide to change the rods. We ended up with peak numbers of 392 hp and 429 ft/lbs of torque. And, it has a nice flat torque curve. This will probably be a good starting point once it is installed, but will need some more tuning since the dyno is 3000 ft lower in elevation than home.
All in all it was a fun experience. I had only seen this stuff done on TV. It sure made me want to build another one and see what it can do. But, I was real happy nothing broke or blew up.
Below are the numbers for the final pull and a graph of those numbers I made in Excel.
A little background on the build. I picked up this 401 a few years ago and finally took it to the machine shop last January to see if the block, crank, and rods were rebuildable. When I first dropped it off, they thought that one cylinder might have to be sleaved because of rust. But, when they finally started boring, they found out it cleaned up and was fine at .030 over. I then contacted Matt about some pistons. He had a set of old TRW's on a shelf that were .030 over that we did a deal on. After going through ever cam profile I could find for an AMC and going back and forth if I wanted to spend the money to go with a roller, I finally decided on a Lunati 64502. It is advertised with a power range of 1600 - 5800 RPM. It has 220/226 duration at .050 and lift of .507 and .527. I liked it, because it appeared to take the most advantage of the large diameter lifter the AMC uses. Not too big on the duration, with some good lift. I figured this cam would work good with the Performer RPM Airgap, Performer RPM heads, and headers I wanted to run. I added some Lunati lifters, Edelbrock push rods, and Harland Sharp rockers to round out the internals. The 401 did not come with a timing cover and I wanted to keep the 360 intact for if and when I do something with it. So, I ordered up some overkill from Matt.
Last spring, I pulled the 360 out about the same time I worked a deal with my brother for a Edelbrock 750 he had in exchange for my Edelbrock Performer intake, Edelbrock 600 carb, and a player to be named later. I just swapped the Z & M HEI from the 360 for the 401. I had been planning on getting the Doug Thorley headers, but since you are not supposed to break in a new motor with new coated headers, I purchased some Hooker's since they have the same primary diameter and collector diameter. Sure the primarys are a little longer, but what the hay. I had on maybe selling the Hooker's after the dyno run and getting the Thorley's for when I install the motor, but as long as the Hookers fit with my other modifications, I think I will just run them for now.
I think that takes care of all of the engine stuff, so now for what happened.
My brother and I got to the shop about mid afternoon on Friday and between us and the guys at the shop (both employees and other customers), we spent the next three hours or so hooking up the engine and stuff. As a precaution, since the carb I had been sitting for over 10 years, they used a Holley 750 double pumper of theirs to do the break in and first few dyno pulls. We had everything just about square, when they noticed they needed some gas, so my brother drove down the road to get some more premium unleaded. He missed, but while he was gone, they fired up the 401 for the first time. I don't think it even turned over a full turn before it lit and took off. Wow, did it sound sweet!! He got back in few minutes and we watched as they check timing, oil pressure, tempratures and such while the cam was breaking in.
After breaking in the cam, they did the first pull. It peaked a 340 hp and 395 ft/lbs of torque. Not what I had expected, but then they explained that the nest day it would do better after cooling off over night. Saturday morning comes and the first pull makes peak numbers of 390 hp and 435 ft/lbs of torque. Alright, this is what I am talking about!! Then we swap on my carb and did some pulls. Since my brother never changed any rods or jets or anything, and it is looking a little rich, we decide to change the rods. We ended up with peak numbers of 392 hp and 429 ft/lbs of torque. And, it has a nice flat torque curve. This will probably be a good starting point once it is installed, but will need some more tuning since the dyno is 3000 ft lower in elevation than home.
All in all it was a fun experience. I had only seen this stuff done on TV. It sure made me want to build another one and see what it can do. But, I was real happy nothing broke or blew up.
Below are the numbers for the final pull and a graph of those numbers I made in Excel.
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