427 down on power

[Ron61]

Paul,

Does the engine pull well up to 3,000 and then just flatten out and start to miss, or is it sluggish getting up to 3,000 under load? Also when you are just running it under no load. does it act the same way? That # 3 plug really looks as if it isn't firing at all and if they just ran the engine to break in the cam and not under any load, then it must have came from them the way it is unless you have added or changed something. I believe in an earlier post someone asked you if you had checked the valve springs as some engine builders use a light set to do the break in run with and then put the heavy ones in for the dyno and testing.

Ron

[FatBoy]

Hi Ron,
It isn't right all the way from tickover, but it really runs out above 3,000rpm.
Paul

[jhv48]

Is the sound the same from both of your exhaust pipes?

Or is one more muffled than the other?

[Ron61]

I don't think this would really prove much, but if you disconnect both exhaust pipes and just run it through the headers, (VERY LOUD ) does that make any difference? I think you are going to wind up having to do that anyway as that # 3 plug and the symptoms you describe sound as if the engine may have to come out. My 69 Cobra with the 428SCJ that is bored .065 over and blueprinted doesn't even run well until it is over 3500 RPM. The peak power is at 6300. And I had a smaller cam put in to lower that.

Ron

[FatBoy]

Just a thought, I've run the coil leads (orange and black) alongside the distributor leads (green and purple). Could they be causing a problem with each other ?

Paul

[patrickt]

Originally Posted by FatBoy

Just a thought, I've run the coil leads (orange and black) alongside the distributor leads (green and purple). Could they be causing a problem with each other ?

ERA runs them down both sides of the engine to reduce feedback. So, before you pull the engine go ahead and separate them -- what have you got to lose? You've checked and disassembled your carb, checked the linkage, checked the timing and advance, checked the valve lash, checked the integrity of the fuel, checked the spark... and your car stil won't rev much over three grand.

There's still a possibility of exhaust obstruction, a bad MSD box, or something else that I can't even guess at. One last cheap test is to go out and buy a pyrometer and shoot it at your exhaust headers and see if there is a noticable temperature difference on them. Then, before I pulled the engine, I would put a new MSD box in and a new carb on. You do have the positive and negative feeds to the MSD box coming directly off the battery, right? Not the little "ignition on" feed, but the red and black power feeds. That's really important.

[FatBoy]

The black is bolted to part of the chassis i.e. earth,and the red is attached straight to the protected side of the main power fuse (Kirkhams have a main fuse behind the dash'.) Which is exactly how KMS say it should be done, so I can't imagine that is a problem.

Paul