loss of power 454 need advice

[CactusJack]

Another phantom power robber can be when the vacuum advance diaphragm breaks and becomes a hidden, rather large vacuum leak... if it has a vac advance, pull the line off the manifold and the cap off and suck the tube, see if the plate in the dizzy tries to move or if you just suck air..... I have been caught with that a few times

[southern safaris]

The fella at the engine shop reccomended mineral type 15-40 and lucas break in zinc additive , going to pull the valve covers and check things out this afternoon..... Hey maybe ill get lucky and itll just be a big dirt dobber nest up the tailpipe!

[southern safaris]

Already checked for vaccume leaks , havent been running vac adv on this one

[emmitt Kelly]

I ran into the same problem on mine...turns out the inside melted in muffler and collapsed on itself

before you tear into your engine...pull your mufflers and see if that is the problem...

regular mufflers can not take the heat ...

[southern safaris]

I had the plugged exhaust idea last night when i fired the ol cj7 up and a dirt dobber nest blew out the tail pipe thought id pull the flex off my muffs on the boat now and spin her up a bit when i get back to the shop

[emmitt Kelly]

Let us know how it goes...my airboat bud noticed my SuperTrapps seemed to not be flowing freely and before that had a set of Midas "their best" installed...really bad...I now have Morosso ...but I watch them closely I don't trust any of them for long term

[SWAMPHUNTER45]

It sounds like you did everything proper in the start up and dinosaur oil with a ZDDP additive is correct.
We use Rotella T and the Comp Cam 159 additive and have never had a failure on a side note.

If in fact it turns out to be the cam or lifters you need to have those valve springs checked for excessive pressure.

CUT THE FILTER OPEN if you see shards and flakes you know its bad news, at 10 hours fine bearing particulate and ring cut (dust or small specks) is expected but typically very small in size.

[southern safaris]

Gonna cut that filter too ! I notieced that suggestion earlier will do , thank yall and ill keep yall posted

[southern safaris]

It still sound like a bad power valve

Thought that as well but the holley demon dont use traditional powervalves that used to blow out. Not saying the principle doesnt apply so im gonna swap a carb and see though

[One Eyed Gator]

Find someone with an wideband O2 meter and check it out.

Also the cheap vacuum port plugs do not last long, make sure you use the silicone vacuum caps.

I pulled a card apart after have some issue and there was parts of the fuel line in the top portion of the float seat.

I just went back and read it was a 650 demon. I had 750 mighty demon new out of the box that had a handful of aluminum shaving in the top of each seat.

Also a demon has the easy idle circuit, which you adjust through the air cleaner stud hole.

Just a few thoughts.

[Rich Andrews]

i'll offer to eat the power valve if that's the problem here. What sign does he have saying its the power valve? I'm curious to know

[southern safaris]

Just got done with a few things ....

Pulled flex off mufflers = 100 less rpm hooked back up got my 100 rs back

Changed carb to q jet 750 no change up or down exactly same rpms turning wfo.... I was suprised no change in perf at all

Adjusted valves just for kicks and looked over springs n such all appeard ok but havent measured lift yet ... No loss or gain

Replaced plugs just for giggles no change

New fuel filters checked for water etc fuel looks ok

Going to rip the oil filter apart tomorrow check for debris and start maybe wondering if im losing a cam or lobes thats just where im leaning now if i havent listend to some advice given please dont hate on me yet still working through the posts and all thank you i never dreamed id get this much help i really appreciate it

[One Eyed Gator]

Do you have fuel pressure gauge on it?

[Deano]

To backtrack to Flying Fish's post(s) concerning the compression test.
More information please, about the results attained when you did that test.

Were the carb throttle plates held wide open during the test? If so, I agree
with his assessment that those numbers are probably low, given likely cam specs.

You said low and high on the weak side were 125 and 140 respectively. Ten percent is a large spread for new motor.
Were those results representative of the other side as well? or was the other side higher?

Actually, it may in your best interest to post the number you got from each cylinder, as there may be something to be seen in those results that is not otherwise ascertainable.

If the numbers were measured higher on the other side, that might be good news for the cam.

[southern safaris]

Deano , i will pull another compression test as no i did not have the throttle plates open (dont know where my brain was at) not my first rodeo there but i didnt do it..... And i only measured the portside bank thinking thats the side i had problems due to lower percieved flow and heat out of that side vs starboard side .... Nows the time i should be getting a little more accurate in my tests so i will pull them again and post findings , today im gonna be hit or miss around the shop my wife and i are expecting our first little one soon so between doctors visits and tests the next few days will be hectic but again thanks to all helping me out right now and will update w the tests as soon as i can !

[CactusJack]

It sure sounds like the cam timing being out for some reason is highly possible?

Is the person that built the motor near you? It would be good to let them look at it, they might have overlooked something.

While you are at it, make sure the TDC pointer is right with the mark.... if the harmonic balancer outer is slipping on the rubber, you might have your ignition timing right by the mark and pointer, but if the mark aint where it is supposed to be, the ignition timing might actually be way off? While you have #1 plug out for the compression test or leak down, find TDC with something like a plastic drink straw thru the plug hole onto the piston and when you get the piston right on TDC, confirm the pointer and mark line up.

[southern safaris]

Cactus, i did verify tdc , ive never trusted the stock pointers .... Ive found too many slightly off or if parts are echanged with wrong models and years not everything is just right , and no the engine builder is too far away to be of help and after some heated debat on the engine in the past when the order didnt come through as promised ive about lost faith in any hopes of them standing behind thier warranty , even if i have to replace cam/lifters etc, id be ahead eating that , about the only way i would ship it back was if the bottom end is an issue (rotating assmbly or such) and then itll be a roll of the dice im affraid,

[southern safaris]

Do you have fuel pressure gauge on it?

No i dont have one plumed in but you made me think... Just to see im going to pick one up in town today and put it inline and see if im getting pressure during all rpm ranges or if it drops under load ... Im running an electric running through a mech as well but ive done this before with good results

[southern safaris]

Pulling the cam and putting a mic on it isnt out of the question i just was hoping it wouldve been something id overlooked , ill still run the comp test and a few things first maybe some of the smarter than me engine fellas here can read more into the numbers before i pull it down thanks agin

[glades cat]

Deano , i will pull another compression test as no i did not have the throttle plates open (dont know where my brain was at) not my first rodeo there but i didnt do it..... And i only measured the portside bank thinking thats the side i had problems due to lower percieved flow and heat out of that side vs starboard side .... Nows the time i should be getting a little more accurate in my tests so i will pull them again and post findings , today im gonna be hit or miss around the shop my wife and i are expecting our first little one soon so between doctors visits and tests the next few days will be hectic but again thanks to all helping me out right now and will update w the tests as soon as i can !

That explains the reduced power. An expecting mother and the duties involved will bleed horsepower from the strongest of stallions.
Octane booster for the engine…Geritol for the steed.

Hey man, many blessings for your family.

[odcjohn]

compression is key what was each cylinder also timing is set where at wot

[southern safaris]

Thanks glades , sitting in the hosp right now i needed that !!!! Lifes about to change for sure i better start mixin that octane boost in my v8 drink every mornin to get my motor goin on all 8 cy.......

[southern safaris]

compression is key what was each cylinder also timing is set where at wot

Going to re run the comp test and post #s and full advance is 32*

[Deano]

First of all, Congratulations on your pending arrival
When my son was born, it was among the best times of my life.
This may go without saying . . . but I will say it anyway.

If your lovely bride is as close to delivering as it sounds, I would encourage you to abandon your concerns with this engine and use your available time, energy and focus on the much more significant happenings in your life. When it is years up the road, the less distractions you have now and the clearer your memory is later, the better it will be for everyone. At that point, you will only remember this engine (if you do) as a distraction to your first son's birth.

All the help you have here, will be available later when you get that far.

God Bless You and your expanding family.

[southern safaris]

First of all, Congratulations on your pending arrival
When my son was born, it was among the best times of my life.
This may go without saying . . . but I will say it anyway.

If your lovely bride is as close to delivering as it sounds, I would encourage you to abandon your concerns with this engine and use your available time, energy and focus on the much more significant happenings in your life. When it is years up the road, the less distractions you have now and the clearer your memory is later, the better it will be for everyone. At that point, you will only remember this engine (if you do) as a distraction to your first son's birth.

All the help you have here, will be available later when you get that far.

God Bless You and your expanding family.

Well said my friend .....


Thats some advice i will take and keep focused on , not to make any prior posts by everyone not important but reality check was in order, its easy to get distracted in a very materialistic world and look past the truly important things .... Hell thats why i left south florida and moved out here to the country , i love the simpler way of life ,,,and the glades and the south fla waters that where my home started disappering and getting so overcrowded we decided to get back to simple and try a stint out here amongst family n friends.... Sorry for the rant but you got me thinking and re evaluating the important things , thank you