Mopar Gen III Hemi COMP CAMS Thumper Cam Specs Incorrect?
I've been working on a 1998 Dodge Dakota Gen III swap for about a year now. Its a street-truck build on a budget. 2007 5.7L, fully rebuilt with stock 3.92 bore, MDS delete, Mancini drag-pack style intake, 750 demon vac secondary carb, Hemi 6, and 44RE, toughened up with a shift kit, HP clutches and steels, 8.25" rear rebuilt with 4.56 gears and track-loc) Goal is around 400hp at the crank.
I apologize for the insane length of this. But, it's a long story.
I purchased and installed a Comp-Cams Thumper Cam. (112-700-11)
First, I know the Thumper probably has a little too much overlap for the single plane. But, the specs looked more attractive to me than the Comp-Cams Stage 1 NSR cam, It is a budget build and I was focused on reusing as much as possible including the valve springs. I thought the Thumper the better choice of the two Comp' 'no springs required' cams available for my build. I'm sure there was a better choice out there elsewhere... But, that's now beside the point.
My problem:
The cam card for this cam is not correct. Also, the intake closing point was/is not listed on their website specs for this cam. The card states an intake closing event of 81 degrees ABDC?!
When I degreed the cam I was getting 66 degrees, which makes sense for a 'street' oriented cam. I am using a stock chain setup and it installed at 112 degrees. (the 2 degree advance could just be bad resolution from the small degree wheel) 66-2=64 degrees (see below)
I called COMP twice and two separate associates told me: 'The cam card is correct.'
Look: intake open + 180 degrees + intake close = duration (as long as all numbers are referenced at the same valve lift)
24+180+64=268 This IS the advertised duration @ .006" on the card.
If you do the math @ .050" you get 37 degrees Intake close. That also makes sense.
24+180+81=285? That duration isn't even listed on the card.
I am confident the cam will work fine because I trust the measurements I took when degreeing the cam. But, the fact they won't admit their numbers are possibly incorrect is driving me nuts!
Either the 81 degree intake closing event is wrong: (waaaay too late for a street cam)
Or, some other number(s) is/are incorrect.
I explained the the two 'experts' at COMP that I thought it was a typo, and they insisted once again it was correct. One of them also tried to tell me it was because 81 degrees was measured at .050"?!!
I then explained to him that I had based my build, including head gasket thickness, raised shift points, tire size, and gearing based on the power-band of this cam which I chose first, (and calculated the intake closing point before purchase) and I was concerned that if 81 degrees IC were correct, I would have no dynamic compression.
I was then told by the associate at COMP that I was "OVERTHINKING IT..."
I have since emailed COMPS 'cam selection experts' about the issue and have not received a response in over 14 days.
Does anything they told me make any sense?
PLEASE LOOK AT MY MATH and let me know if I messed something up.
I am getting the feeling if you buy from COMP CAMS you are probably on your own as far as legitimate technical help.
Please help and let me know your thoughts.
I've been working on a 1998 Dodge Dakota Gen III swap for about a year now. Its a street-truck build on a budget. 2007 5.7L, fully rebuilt with stock 3.92 bore, MDS delete, Mancini drag-pack style intake, 750 demon vac secondary carb, Hemi 6, and 44RE, toughened up with a shift kit, HP clutches and steels, 8.25" rear rebuilt with 4.56 gears and track-loc) Goal is around 400hp at the crank.
I apologize for the insane length of this. But, it's a long story.
I purchased and installed a Comp-Cams Thumper Cam. (112-700-11)
First, I know the Thumper probably has a little too much overlap for the single plane. But, the specs looked more attractive to me than the Comp-Cams Stage 1 NSR cam, It is a budget build and I was focused on reusing as much as possible including the valve springs. I thought the Thumper the better choice of the two Comp' 'no springs required' cams available for my build. I'm sure there was a better choice out there elsewhere... But, that's now beside the point.
My problem:
The cam card for this cam is not correct. Also, the intake closing point was/is not listed on their website specs for this cam. The card states an intake closing event of 81 degrees ABDC?!
When I degreed the cam I was getting 66 degrees, which makes sense for a 'street' oriented cam. I am using a stock chain setup and it installed at 112 degrees. (the 2 degree advance could just be bad resolution from the small degree wheel) 66-2=64 degrees (see below)
I called COMP twice and two separate associates told me: 'The cam card is correct.'
Look: intake open + 180 degrees + intake close = duration (as long as all numbers are referenced at the same valve lift)
24+180+64=268 This IS the advertised duration @ .006" on the card.
If you do the math @ .050" you get 37 degrees Intake close. That also makes sense.
24+180+81=285? That duration isn't even listed on the card.
I am confident the cam will work fine because I trust the measurements I took when degreeing the cam. But, the fact they won't admit their numbers are possibly incorrect is driving me nuts!
Either the 81 degree intake closing event is wrong: (waaaay too late for a street cam)
Or, some other number(s) is/are incorrect.
I explained the the two 'experts' at COMP that I thought it was a typo, and they insisted once again it was correct. One of them also tried to tell me it was because 81 degrees was measured at .050"?!!
I then explained to him that I had based my build, including head gasket thickness, raised shift points, tire size, and gearing based on the power-band of this cam which I chose first, (and calculated the intake closing point before purchase) and I was concerned that if 81 degrees IC were correct, I would have no dynamic compression.
I was then told by the associate at COMP that I was "OVERTHINKING IT..."
I have since emailed COMPS 'cam selection experts' about the issue and have not received a response in over 14 days.
Does anything they told me make any sense?
PLEASE LOOK AT MY MATH and let me know if I messed something up.
I am getting the feeling if you buy from COMP CAMS you are probably on your own as far as legitimate technical help.
Please help and let me know your thoughts.
