Lost 110 HP!!!
 

Last summer I was having ignition break up at 4500 to 5500 rpm about a month after installing my new motor. The motor was purchased as a long block without the intake manifold installed, as I was putting on the intake and fuel injection system (MassFlowEFI) from my previous motor. The only change to the FI system was larger injector (42 lbs) for the increased displacement and a custom tune done on a Dyno Dynamics chassis dyno. The motor is a 8.2" deck height Dart Sportsman Big bore block measuring 363ci, with AFR 205 CNC ported heads, solid roller lifter, a custom Jones cam and 13/1 compression. This is a track only car and I run 112 octane fuel. After tuning the motor made 488 RWHP naturally aspirated.

Then the issue with the ignition presented itself within a month of the dyno day with no track time. I had to deploy so I was unable to fix the issue until this past week, so the car has sat for 14 months. During trouble shooting I replaced the coil, plugs wires, plugs, cap/rotor and installed a ignition box (Mallory). The issue ended up being a intermittent ground.

Today I drained the tank put in 5 gals of fresh 112 octane fuel and hit the dyno. Disappointingly the car only made 378 HP at the same dyno shop and same tuner that I have used for years. A/F ratio was right on the money at 12.5, base timing was at 10 degrees and all advance was done thru tuning (as it was before). I also did a compression check with a low of 240 and a high of 250 psi. This is my first solid roller motor and I neglected to adjust the valve after such a long period of sitting. I knew that they need to be adjusted often, but it slipped my mind to be honest.

Has anyone experience this much loss from miss adjusted valves? Or should I be looking some where else. Any help would be greatly appreciated. Thanks

You shouldn't have to adjust the valves that often. Once they were ran the first time on the dyno, they shouldn't have changed enough to make that much of a difference.

What did you set them at the first time? What are they set at now?

Closing the lash will increase the effective duration of the camshaft, thus making the engine believe the cam is a little larger than it is. You can usually gain/lose some peak hp/rpm depending on where the lash is, but 110rwhp isn't logical or reasonable.

You need to find out what other variables changed.

Brent,

I set them at .015 intake and .016 exhaust Hot as per the cam card. The car is at the dyno shop still. We are going to check and adjust the valves in the morning. Also we are going to see what the tune is doing.

I'm am at a loss of what else could have changed while the car sat.

Was the same dyno shop used both times?

Sorry, I see that it was....nevermind.

So you always look at what has been changed since the last time. In this case, plugs, wires, coil, etc.

Does the engine sound like it's missing? Dead cylinder? Firing order correct? Plug wires on tight?

Yes it was. They did recently move to a different shop and purchased a new dyno but there numbers have been very consistent from the old dyno to the new one as it is the same model with up graded soft ware. I would expect some difference but not this much.

Is the new one a Mustang brand?

It doesn't seem to be missing. I will check firing order and the wires tomorrow.

No its the same DynoDynamics dyno as before.

Well, just go through the basics tomorrow. Check the firing order, plugs, wires, check the oil as well...make sure there's nothing funky going on.

Brent thanks I am also going to check the filter tomorrow it has a remote Canton cartridge filter....Crossing my fingers that there is nothing IN the oil...Mac

It doesn't make sense that there is any damage since it came off the dyno last time with good numbers.

I would lean towards an issue with the parts that you replaced.

I am no expert!!!! but your compression test look great, 240-250 psig. My bet is the dyno is off, either this one or the original. It seams the only way you could experience a lost like that is with a valve opening or closing late, but it has to be closing with compression numbers like that. It will be interesting to hear what you find. Welcome back!!!!!!!

Mac,

I personally know that when you chip on of these Mass Flo systems, they will work for only a little while. The computer can't keep up with it or the computer doesn't reconize the chip anymore. If you have your old chip the car will run fine. For some reason the new programed chip is not effective anymore.

Bill

Think about fatigued valve springs, and sitting in the same spot for 14 months, especially on a roller cam. I use springs a max of 2 yrs, and after the first year, switch the intake and exhaust springs with each other. Then throw them away.

Well we found them!!!

After adjusting the valves, the car still made no power. We did find out that the timing was not advancing as it should. We set timing to 36 degree and disable the computer from advancing the timing and made 483 rwhp. Now we have to figure out why the distributor wont advance with the computer and chip.... Thanks all for the advise...mac

Good to hear. At least you have the problem identified.

I had a distance go nuts on Lilly and do the same thing , dropped off huger power numbers, changed dist and it came back

Engine and power
 

Like mentioned earlier I would talk with Mass Flow and see what they have to say. I know that when the computer has no power that it will have to start over or be re-programed. I would also check the spark plugs because I have seen this cause a lot of problems.

Good luck, Keith

I am almost certain that the issue lies in the distributor as the computer and SCT moduale are controlling the fuel just fine but the timimg will not advance. As a baind aid we have disconnected the spout connector from the distributor and set timing to 36 dergrees. It's not as easy to start but at WOT its great. We are going to swap distributors and see if it will advance the timing or it could be a wiring issue.... Thanks for the advice... Mac