New 482 Tunnelport wont rev

[Smokin427]

We have tried everything and are totally stumped. Built a 482 Tunnelport in a 56 Ford and trying to get it going. It will not wind above about 5200 and takes forever to get there. Has no power at all. Does not miss just feels like a small 4 cylinder. We have checked all the obvious stuff such as:
Timing and advancing (New MSD ingition, 16 initial 32 total (it is advancing))
Rods at .0025 and mains at .003, Took only 32 lbs torque to turn it over, Compression is 190 to 200 on all, Battery turns it over easily so nothing is frozen,etc. Carb is a new HP850 and seems to be working just fine, No vacuum leaks as far as we can tell. Plugs look good, Cam is an Isky custom grind solid lifter cam and set with the dot on cam gear facing the 0 on the crank gear. It is only .540 lift, ~242 @.050 and had plenty of valve to piston clearance. Even checked it with open headers in case the exhaust pipes were somehow blocked but it makes no difference.Had problems with using shell lifters and longer pushrods with the pushrods binding in the intake port tubes but replaced them with std solids and std length 3/8 hardened pushrods and there is no interference now. It has roller rockers also. The engine is not making any wierd noises, it just does not want to accelerate !
It is absolutely blowing our minds !
Has anyone ever experienced anything like this and if so, do you know where we might look next ?

[Gaz64]

Hi there, "dot to dot" is a little antiquated for valve timing accuracy.

Did you check the cam timing with a degree wheel and dial indicator etc?

I have never trusted any other method to time cams, and others will agree.

[Argess]

I've only had "low revs/low power" for two reasons:

1/ Timing gear was off by 2 teeth......I didn't do it....a Machine Shop did it on a Chev 350 for a freind's boat. I just helped diagnose it. Never-the-less, I have caught myself one tooth out after a doublecheck on timing gears. As above, a degree wheel works wonders. And you can check it with a dial indicator and degree wheel and only have to remove the passenger side valve cover and the crank front snout bolt.

2/ Overly advanced ignition timing...the enigne will feel like it's fighting you...or overly retarded timing, and it will feel ...shoot,, i don't know...LOL...but I bet it will be sluggish.

EDIT: Oh, there's a numebr 3, but I'm sure it doesn't apply to you. Again, in a boat (which is always under load), I couldn't get over 2800 rpm. Felt like a rev limiter was in action. Turned out to be worn wire-tip sparkplugs. Once I hit a certain load req't, the plugs wouldn't fire. I went back to stock style plugs and never a problem since. But I'm sure that's not your problem...just an interesting tidbit.

[Woodz428]

I would lean toward the cam timing, I always degree a cam when installing so that I know the machining/manufacturing tolerances didn't thow them off. You can do a pretty accurate check with a valve cover off, but count on removing the front if it is off any. Use the cam card to check accuracy. Too tight of a valve adjustment can create similar issues as well.

[tcrist]

I had a similar issue one time on a bone stock 327 Chevy. The cam gear actually cracked and was flexing, changing the cam to crank timing.

Terry

[Tom Kirkham]

Originally Posted by Smokin427

...Timing and advancing (New MSD ingition, 16 initial 32 total (it is advancing))...

Sounds like your cam timing is a tooth off. Very easy to do if you are installing a timing chain while the engine is still in the car. I did it it my 67 Mustang in while I was in High School...And WOW did it run better when I fixed it.

This is probably not your problem but...
Your total timing is a little bit retarded. Typically FE should be about 36 degrees. Also at what RPM is the advance all in?

[PatBuckley]

If all else that has been suggested fails, check to make sure you have sufficient grounds to everything.

[cobra427hp]

Only time I've seen this problem a customer had always timed Chevy's and didn't realize Ford number one is on opposite side of engine.

[olddog]

My first thought was the valves were too tight, but the compression looks good. Maybe a leak down would be a better test than compression.

Put a vacuum gauge on it. I'm guessing if the cam timing is off, the vacuum will be very low.

Spark plug wires (firing order) can be off. Certain plugs can be swapped and not cause a back fire. With a high durration cam you may not notice a couple dead cylinders, by sound. That sure does kill the power. I suppose a few bad plugs or wires would do the same. Have you pulled the plugs and looked to see if any are wet?

[Smokin427]

Pulled the timing cover this afternoon and thank goodness we found the problem. The crank gear has a ton of markings on it inner and outer markings. Somehow we got the wrong one and the cam was about 20 degrees advanced meaning the exhaust valves were opening way too soon on the power stroke and all the power was going out the exhaust pipes. We have reset the gears properly and will put it all back together in a couple of days. Thank you all for the good advice which lead me to go ahead and pull the cover even though we were sure it was on correctly. I cannot wait to see how this new 482 Tunnelport feels in this sweet little stock looking 56 Club Sedan.

[Jerry Clayton]

the high cranking compression numbers is a clue that the cam is way advanced,, however consider yourselves lucky that you didn't bend the valves