I haven't tried holding it at 4000 then flooring it. I tried 3000 because I figured every bit of advance should be in at that point.

I have no way to test WOT fuel pressure unless I install a remote guage. I'm running Champion RC9YC plugs. The Edelbrock instructions suggested RC12YCs and when i used those, it dieseled after shutdown. The 9s stopped that. When I tested the cranking compression in cylinder #6, I looked at the plug. It wasn't directly after a hard WOT run so the appearance may not help. It was the amber/tan color with no speckling or spots.

175 psi, 10.7:1, aluminum head, big cam, it should run on pump gas.

I have no way to test WOT fuel pressure unless I install a remote guage. correct. Get the correct tubing and attach it to a wiper blade or something so you can see it while driving. Of the 30 things you done in the last 3 days, this will be easy

The "9" plug should be good for your CR, you could try an 8, or a cooler NGK, but probably no help.

BSB, are you telling me that while the A/F ratio may look good on the guage, fuel pressure at WOT make a difference?
I'm hesitant to hold it at WOT because of the detonation. Each time I road test it, I only run it 2 seconds maximum when I hear it knocking.

I put the #86 jets back in the primaries of the 850. I still have the 3.5 PV in there along with #94 secondary jets. It actually idles better than it has in quite some time. It idles in gear for stoplights almost as smooth as it did with the 750. A/F ratios were also better than they have been, though a bit rich.
Of course it still knocked.
I am so confused by this. I even came home and poured in 5 gallons of 100 octane unleaded I bought as a last resort. I still had about 5 gallons of 91 in the tank, so I have to guess the mix would result in a 95 to 95 1/2 octane rating. It ran exactly the same. During the first 4 miles I drove easy, thinking I'd need to use up the 91 octane in the fuel line and carb. Once I hammered it, it knocked at the same point it had before. The timing is at 17/31.

I'm curious about the fuel pressure @ WOT theory. If I'm doing 2500 rpms at 55 and floor it, it knocks. If I sit idling at a stoplight then floor it, it detonates even with the tires blazing. I would think that the fuel bowls are pretty full if I'm just idling. I don't mean to discount anyones ideas. I am just trying to understand.
Speculation time again:
*What are the chances of the cam having some manufacturing defect? With adjustable valvetrain, each rocker arm gets adjusted to spec. *What if one or more lobes were ground wrong? I only tested cranking compression on one cylinder. Tomorrow I'll check them all.
*Another idea: I degreed the cam and it came in exactly at the 106 number called for on the cam card. Lets say I was wrong and it was off 4 degrees one way or another. Would that make this much of a difference?
*With fuel as high as 95 octane, what possible reason could cause an engine to spark knock if the A/F ratio is right and the fuel pressure is @ 5 lbs or more?

I wonder if you have the same head gasket problem my buddy had with his 496 eddy heads and fel pro gasket??? fire rings hang in a bit and burnt right off. he was running 110 and still some detonation now with the big bore fel pro gasket he runs straight 94 big big difference???

He needs to find someone that has a good e85 carb put the timing back where it should be quit playing games,
he will keep going till he has a motor that will need total rework, either to much detonation , to much heat take exhaust valves out and take tension out a set of rings,
but keep trying something will give sooner or later!
need more than 5 # of fuel pressure , should have 7-8 going to carb!

Don't recall if this was mentioned or not but did you verify that your timing mark for TDC is accurate?

Kevin

I verified the timing mark when I degreed the cam. I was happy to see that it was correct.

I doubt this is causing your detonation now, but demon carbs have a reputation for being full of fine aluminum shavings ootb. That could be part of the problem you had getting the a/f ratio dialed in and why it improved when you cleaned out some of the passages with carb cleaner.

Take that carb completely apart and blow out all of the passages, ALL OF THEM Measure the size of the needles and seats, if they are smaller than .110 (the opening in the seats) replace them with bigger needles and seats Fuel delivery problems can and will drive you(and me) nuts After reading all of this post it reminds me of a problem I had with fuel delivery on one of my first car hauling trucks, it had crap packed up inside the fuel lines and fuel valve for switching tanks That problem almost drove me nuts back then Once you find these types of problem you learn what your made out of, you then know you can fix almost any thing Stick with this one, your going to figure it out

Hey, if it seems like I am getting desperate, its only because I am.
Dodgem got me thinking about head gaskets. The "fire-ring" in the common Fel-Pro head gaskets isn't exactly round. Why they made them in this silly semi-oval design is beyond me. I went outside and laid a new 1009 Fel-Pro gasket on the deck of a .030 over 440 shortblock I have. The engine in my car is also a .030 440 block so I figure it is a fair mock-up. The quench side is up toward the intake side of the deck and the "fire-ring" does sit very close to the edge of the bore. I don't know if it would actually enter the bore after the head is torqued down but it does sit close. I looked on the Summit site and saw these:

http://www.summitracing.com/parts/fel-1039

The bores in this gasket appear to be truly round. The bore size is much larger as well. The thickness increase would probably hurt quench a bit but lower compression about a 1/4 point.

THIS one looks a bit better:

http://www.summitracing.com/parts/edl-7325

It is .038 compressed so the quench stays the same. The slightly larger bore would add volume to the combustion camber like the Fel Pro .051. Both would result in a slight reduction in compression just from the volume increase.


I wonder though that if my cranking compression numbers seem fine, how would I know if I have a gasket failure like Dodgem was talking about? I'm not against pulling the heads, I'm just getting tired of chasing dead ends!

Epic thread.
Even though you got the demon to work better did you do any road testing with the holley?

Myself, I would do everything I could to prove it was or was not a particular system. Same results with a different carb would make me look at a different system. After you've checked fuel pressure as mentioned of course.

How sure are you the ignition is isn't failing when put to the task?

You may have mentioned either but it's hard to keep up with all the spins this has taken.
You'll get it eventually, just comes down to how much time and $$$ it takes.

Edit: Might be worth it to pull the heads just to make sure they aren't full of carbon build up.
Or one of those nifty borescope to peak around in there.

I drove it with the Holley 750 today. It detonated at the same point as with every other road test!

I'm unsure of how I'm supposed to plumb a fuel pressure guage to see it while driving. Am I supposed to remove the hood and run 4 feet of hard line over to the windshield?

I have a few ignition ECUs I can try to see if they make any difference. I am a big fan of testing free parts. I have a Rev-n-nator ECU that I tried last year. kinda funny...I pulled it because it made the engine knock MORE than with a stock ECU at the same timing settings!

Regarding carbon buildup: I guess it is possible, but I did have the engine apart in 2011. I've put about 3000 miles on it since then including 2 road trips of 1000 miles each. If and when I pull the heads, I'll have them ported while they are off. I've wanted to do this for years but always went cheap and skipped it.

Guess I missed the part about it being opened up in 2011.
That you got the same basic results with the holley would make me look elsewhere. Even though you got the demon to work better you still have the same base issue, pre det.
You mentioned you had different results with the revinator I might poke around in that area, ignition I mean.

Since you like 'free' (so do I), have you tried playing with the plug gap and see if you can change anything?
I know a lot of guys claim bushwa on messing with the gap but you'll never convince me otherwise.
Too many times have I seen performance issues clear up by moving the gap around.
And yes, I've heard every reason why it doesn't matter before anyone feels the need to correct my way of thinking.

Don't know what the fight is about either, it's 'free' to play with it and costs the same amount to put it back.
Guys will pull apart everything else, spend dollar after dollar then kick and scream about tightening or opening the gap .005.

E85 and E70 forgot you guys can get it at the pumps down there.


i hear you have to ask and or check yourself to see if you station actually sells E85 or winter E70 all year round???

But when he went 91/100 50/50 ish he should have been fine in my opinion??

Think part of the problem with the head gaskets is the combustion chamber design on a eddy head uncovers more of that fire wire.

Maybe why eddy sells a gasket with a bigger bore size??

You've tried a different cam, you've tried a different carb, still same problem.

Have you tried a different distributor?

Have you verified with a timing light that your distributor is really doing what the guy who recurved it said it was supposed to? Did the guy who set up your vacuum advance distributor set it up for the fact that you would be disconnecting the vacuum advance?

Did you set the initial, then rev it up to see the what the total is at a certain RPM?

Here's a crazy idea that won't cost anything. How about just hooking back up the vacuum advance you said you disconnected and see what it does with it hooked up? It will cost nothing and take a few seconds.

well you don't want to ad vacuum advance right now that adds more timing at light throttle.

At This point I would do an 8 cylinder compression test and go from there.

What did you set your valves at hot or cold??