I assembled a remanufactured engine from PAW (289, .030 over) and installed an Edelbrock Performer cam. I checked all the crank and rod bearing tolerances and all were consistently right in the middle, and end play was good. I also checked piston ring gaps and they were good. When I installed the cam it slid in ok but when it was in I tried to rotate it and it seemed very tight. I installed a bolt on the end and used a breaker bar to turn it and although it did rotate it sure seemed like it took too much torque to turn it. Since this was the first engine I assembled from scratch I went ahead and completed the assembly and installed it in the car. Now when I try to start it, the engine cranks but I can hear the starter really straining to turn the engine and the engine turns over a lot slower than it should and does not fire up. I have spark and fuel and I was sure I had the #1 piston on TDC on the compression stroke, but I swapped it 180 just to be sure and got the same results. The battery and starter are both new so my suspicion is that the cam is too tight and dragging the rotating assembly down where it cannot get enough momentum to fire. Could it be my cam is too tight? Any ideas? I appreciate any advice. As it stands now, I’m thinking I need to take the engine out, tear it apart, clean it and reassemble it again.Cam too tight in rebuilt engine?
- Thread starter Blu-Steel
- Start date
I assembled a remanufactured engine from PAW (289, .030 over) and installed an Edelbrock Performer cam. I checked all the crank and rod bearing tolerances and all were consistently right in the middle, and end play was good. I also checked piston ring gaps and they were good. When I installed the cam it slid in ok but when it was in I tried to rotate it and it seemed very tight. I installed a bolt on the end and used a breaker bar to turn it and although it did rotate it sure seemed like it took too much torque to turn it. Since this was the first engine I assembled from scratch I went ahead and completed the assembly and installed it in the car. Now when I try to start it, the engine cranks but I can hear the starter really straining to turn the engine and the engine turns over a lot slower than it should and does not fire up. I have spark and fuel and I was sure I had the #1 piston on TDC on the compression stroke, but I swapped it 180 just to be sure and got the same results. The battery and starter are both new so my suspicion is that the cam is too tight and dragging the rotating assembly down where it cannot get enough momentum to fire. Could it be my cam is too tight? Any ideas? I appreciate any advice. As it stands now, I’m thinking I need to take the engine out, tear it apart, clean it and reassemble it again.
iskwezm
10 Year Member
Stanger007
Founding Member
When you rotated the cam, were the lifters sitting on it? IIRC, every cam I have installed in the past I could turn with my hand (slight resistance) when it was sitting by itself in the cam bearings all lubed up.
Wes
Wes
were the cam bearings straight?? is the cam straight
I believe so. The cam is brand new (although I know that doesn't necessarily mean it’s straight) and went in and turned easily until it was fully in. Once fully in it became tight. I suspect some clearance issues at the rear.
I didn't have the lifters in when I noticed it was tight, but it was all lubed up. I definately was not able to turn it by hand like you described and had to use a breaker bar. Based on your description I think mine is way too tight for some reason. Thanks.
it could be any of the 5 bearings that support the cam, not just the rear one. as for the tightness, the bearings could have a high spot, the journal could have a high spot, the bearing clearance could be to tight, the cam might have a slight bend in it. it is also possible that when you installed the rear cam plug you had too much sealant, and that is causing a drag on the cam.
jake2582
New Member
ratio411
Founding Member
One of the cam bearings is not installed perfectly square, or one of them has a burr on it.
The cam should turn very freely within the bearings.
The cam should turn very freely within the bearings.
jasonn
Founding Member
Yep, it should turn very freely. I had the same problem when I built the 408. But my cam would not even go into the block! I took it back to the machine shop that installed the bearings. ( I also had another cam just to put in and try, which did the same thing). He checked all of the clearances and he found one was very tight. So he took them out and measured the thickness. One bearing was way too thick. Just a bad set of bearings was all. Pressed in a new set and it was all better. Although ratio411 is correct. Probably more common that a bearing has a bur or was pressed in a little crooked. In any case, do not run the motor that way.
Iamdiffrnt
Member
Don't leave the cam in there until you have the problem fixed. Had a similar issue on my 351w back when I was 18. Didn't install the last bearing straight (the cam was tight, but I could turn it with the gear and some oomph). Ran the car anyways and broke 2 cams. Thought the first one was just a junk cam (JC Whitney, 3 pieces), so I bought a name brand one and flushed another $200 dollars down the toilet (Erson, broke in half). Moral of the story, if the cam don't turn nice and easy, fix the problem!
Thanks everyone for the great advice. Now I'm glad that I couldn't get the engine started. You all really helped me to narrow down my search, and I do have an old cam that I'll try just to see if it slides in and turns like it should. If it doesn't I'll know for sure it's the bearings. Thanks again
I just wanted to give those of you who helped me with an update on my engine, and provide a tip for others if they have the same problem. I found and fixed my problem; it was the #2 bearing. I took my engine back out of the car, disassembled it and called PAW. They said they usually fit the cam to the bearings but since my Edelbrock Performer cam was on back order they used a different cam to test fit it. So, they told me to do what they do when they match a cam to its bearings. Install the cam dry, spin it with a wrench about 3 turns and then remove it. If there are any high points on the bearings they will show up as shiny spots. Then they polish those spots down with emery paper. So I did that and sure enough, a nice shiny spot was on the #2 bearing. I polished it up, cleaned up all of my parts and reassembled the engine and put it back in the car. It fired right up and ran fine for the cam break in period. I gotta say, the PAW kit is just fantastic. In addition to the great machine work, they dynamically balanced the crank, and balanced and matched the piston and rod assemblies to each cylinder. As a result this engine runs really smooth. Thanks for the great tips everyone.
