I had to have my bearing replaced due to an exploded oil pump drive assem. and the motor put down just shy of 407 at the rear before. The only things that were changed to the car besides the bearings was the timing chain and the addition of a more free flowing exaust (pretty much straight pipes now, Dynatech bullets with an X over, instead of just dumped at rear)
The motor is now missing almost 30 hp from a recent re-dyno. There was a heat difference from the first time i had it dyno'd from 76 degrees that day to 90 degrees on the 30 hp loss day. I realize that heat has a bad affect, but 30hp gone! with more free flowing exaust and royal purple in the motor i was hoping to at least put down the same numbers in spite of the heat.
I had a Cloyes True double roller on it before, and the local mechanic doing the bearing swap used a off brand heavy duty unit. I read in an article once that in high hp applications that timing chain brands can be off from brand to brand possibly explaining some of my hp loss. Also number 1 and 3 cylinder are running colder than the rest, i can't find any leaks and the plugs look fine so wtf.
Sorry this post is so long but I wanted to get everything i can out there, and you guys know how it is when you spend so much money and time on these cars and they don't do what you want. It can be so damn infuriating.
So what have a missed on 1 and 3, and should i buy another cloyes chain?
Thanks for being patient and any help given.

 

I'm confused- you said the exhaust is now more free flowing, but you also said before it just dumped and now you've got an X-pipe and mufflers on it If you went from dumped open exhaust to something like you have, I can see you losing some power in the upper RPM range......

 

ah sorry, i had the old exaust dumped before the rear into dynomax superturbo mufflers, but the cops made me change it to something that broke the body, so i had i had an x pipe put in and straight thru mufflers, there was no cats on either set-up all 3". I don't think the exaust played al huge part in power loss, i'm wondering if the timing chain has something to do with it is all

 

Timing chain causing 30 hp loss? I don't see that happening. You may also need to do more explanation than "I had to have my bearing replaced". That's not enough info.

 

damn me and my typo'ing ways. Sorry shoe, bearings. The entire motor was taken apart and put back together from the destruction the the oil pump drive assem. All the bearings were replaced throughout the motor. The pistons, rods, crank, cylinder walls, heads were all ok and left the same. But the only thing that wasn't reused besides the old gaskets and more importantly the bearings was the timing chain. The one used i think was call "American Std." er something, its a brand the local mechanic knew but i'd never heard of. The motor is your standard 383, Nu-Tek short block, Lloyd E. heads. If this timing chain was off a couple of degrees from the cloyes unit how much could possibly be lost from 2* to 4* of timing froma 470ish fwhp motor? And what should i check for those cold cylinders?

 

Heat should have little affect on dyno numbers that are SAE corrected. Are the numbers SAE corrected?

 

Depending on which way the cam is advanced/retarded, 4* can make a fairly big difference on an LE cam. Can you post before and after dyno charts?

I have the same concerns as FastZinTennessee about your exhaust. DynoMax STs are very free flowing. They are better than many "straight thru" mufflers. Could you reinstal the original system and re-dyno to eliminate that variable?

Were you measuring the temps on cylinders? If not, why do you think 1 & 3 were cold?

When the bearings were replaced, were all clearances measured? Was crank polished or reground? What kind of damage did you see on the journals?

Just for info, standard or HV oil pump? What kind of pressure do you see now?

 

Why didnt you degree the cam when the motor was out?

Did you rehone the block and buy new rings when you put it all back together?