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Author Topic:   No Power with new motor
posted May 23, 2004 12:03 PM
I just put in a new motor two weeks ago and the dang thing just will not pull out of the corners. I race the IMCA hobby stock class on a 3/8 mile track. I have only ben able to turn this motor 6100 where as the old motor was consistently turning 6800 to 7100. The new motor seems to run fine but just can't keep up down the straights. Any suggestions please not making the A really ***** .

posted May 23, 2004 09:48 PM
what the difference in the two? different heads or cam ?

posted May 24, 2004 07:28 AM
Here is some more info. The old motor had I beleive a MidwestMotorsports hobby stock cam in it with 487x heads. The new motor has an Isky cam but i don't no what the numbers are on it and the heads are a 487. I can try to post more info but it may take a few days.

posted May 24, 2004 11:03 AM
do have any reason to think it's fuel starvation or iginition related. how do the plugs look?

are you having a handling problem in the corner that you did not have when the old motor was in this car?

any type of engine hesitation problem coming out of the corner?

are you running the same final gear ratio as with the other motor?

check your timing.

compression test the cylinders to make sure your valves are adjusted correctly.

otherwise, i guess it's cam related. cam could be incorrectly degree'd or the power curve is different from the previous cam.

posted May 24, 2004 07:35 PM
You should get the exact specs on the two cams before you look anywhere else. If they are not relatively close, I would think your answer likely lies there. Cam selection can make a huge difference.


posted June 03, 2004 01:05 PM
487x heads have a 10cc larger intake runner than the 487, but I doubt that's the major source of your problems

posted June 03, 2004 05:30 PM
99 is right with these little 9-1 imca motors the cam is the key to making power if you look at it the only thing different on everybody's cars is the cam

posted June 11, 2004 09:48 AM
Headers play a big part in this problem. Headers do not make as much back pressure as do manifolds. Your problem is in your cam shaft selection and the valve overlap. Call you cam company and tell them the specs of your motor and stress to them (open headers). I will bet they tell you that you have the wrong cam.

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