More BBF problems

For reference my base set up info for the new engine: Stock 460ci D1VE block with stock dished pistons and ported C8VE heads running MEI 1.8 roller rockers and Ferrea CP Valves (2.19/1.75) with Comp springs/retainers/keepers etc. It runs Stealth 8012 intake, a marinized Holley 80531 (850CFM with vac secondaries), and a Comp Cams 34-251-4 (dur: 236/244 @ .050, .565/.560 lift [.598/.593 with 1.8 rockers], and 110* duration) with Hyd. Comp cams lifters. It now has a Petronix billet dist, MSD coil, and Taylor 9mm wires. Exhaust is unfortunately still exiting through the old stock logs. This all powers a Sidewinder 18SS with a Berkeley JC pump and an aluminum “A” impeller and Hyd. Place diverter. A big thanks to Paul Kane of HIGH FLOW DYNAMICS and Brett Powel of PFC ENGINES for all the help getting this set up put together. It definitely has the potential to do its job!
Now for the problem(s):
We took the boat to the Taylor boat roost at Table Rock Lake a couple weeks ago. While there I had an intermittent engine cut out problem. It seemed as though it would run out of fuel at a constant RPM every so often. The last long run it appeared as if the RPM level to cause the problem was decreasing and it could be caused by a full throttle burst. I checked the float levels, fixed a fuel leak problem (gasket leak in the top of the secondary bowl), and looked for any debris in the floats and filter. Took the boat back out and found a serious bog trying to come up on plane (over 2800-3000 rpm). I don’t know if the cut out problem was solved as I couldn’t accelerate through the bog/miss. It was the last day of the roost so I put her back on the trailer and came home.
Last week I pulled the cap off the stock prestolite distrib. to check the rotor/cap condition and found a destroyed advance spring lying next to the old Petronix ignition system. I was unable to find a direct replacement for the spring so I used an HEI kit and tried to match the failed spring and replaced the rotor and cap. When tested I couldn’t get the damn thing to idle or run without intermittent backfiring and stuttering/dying. I figured the failed spring had bounced around and took out the hall sensor so I replaced the distrib. with a new billet Petronix set up today. I set the base timing at 14* with total advance set at 34* @ 3000-3500 RPM. I went through the carb again looking for crap and to check both 4.5 power valves and all passages. No problems were found with the installed power valves but I replaced the power valves with 3.5 units due to a measured 4-5” vac at idle and installed a fuel pressure gage. I also found and fixed a problem where the secondary’s power valve was being held open by the quick change jet block. I replaced the NGK “V-Power” plugs with some Champion “plain” ones and increased plug gap to .045.
Back to the lake. With the timing bumped up from 10 to 14* and the new distrib. the idle quality improved a lot and I didn’t have any problems with the intermittent cut out of the motor as at Table Rock in the whole day of testing, but I came up against the bog though not as severe. The bog was at its worse as the secondaries began to open. It acted the same even if I held the secondaries closed. Changing secondary springs had no effect on the bog. Neither did limiting total advance to 30*. I bumped the secondary jet size up about four sizes figuring I had done early tuning with the blocked open power valve and stepped up the primary jet size one notch and decreased the plug gap back to .035. I did see some improvement with a drop in the primary power valve back to the 4.5 and a slight improvement when I did the same for the secondary power valve. I didn’t notice any change going from a blue pump cam to the orange one, or changing the orange from position two to position one (trying to get a bigger shot where the bog seemed to be at). I couldn’t get a 50cc pump conversion today. Though one will be on order very soon, I’m not holding my breath for it to fix the problem either.
The fuel pressure showed some bounce early on but seemed to level off between 4.5 and 5.5 at anything over idle, but I didn’t run the engine at higher RPM’s for any significant time while on the trailer at the ramp. I was by my self today so I couldn’t check the pressure on longer speed runs off the trailer.
As it stands now I have a bog, stutter, miss on acceleration (hard or light) through the 3300-4500 range that it will eventually fight through, an occasional stutter at nearly constant RPM within that band, and decreased top end power by about 2-400 RPM.
I don’t know where to go from here. Nothing that I’ve done seems to get things moving towards where the engine should be. I have seen 5000 RPM with this engine back in June when I was first trying to set it up so I know it’s capable of about 400HP but can’t get the lower end stuff ironed out to get back there.
Does anyone have any idea of my vac readings are within an expected range (4-5 at idle, highest at about 10-12 mid throttle, and nearly 0 at full throttle)? I’m seriously worried my cam timing is off. I had to set it at 6* retarded to get it dialed in with the CL method.
It is subjective, but it seemed like the heads and valve covers were hotter today than I’ve noticed before. It’s one of the reason I richened things up and backed down the total advance today. I did shut it off at the end of a long full throttle run to get a look at the plugs, and beyond a moderate amount of flakey white/grey deposits on the ground strap there was no noticeable color to the insulator (top, middle, or bottom). I’m jetted at about 80 primary and 85 seconday at this time so there is a potential I have been heading the wrong way with the jetting, but since I’m not sure at this time I would rather heat up the manifolds with too rich a mix than the cyls too lean. My valves should be able to hold up for this trial and error testing, but I don’t want to push thing too far or cook a piston.
I’ve stopped short of checking the cam timing since either the motor or interior has to come out, but as things drag on I’m getting closer to it.
I’m open to suggestions at this point. What am I overlooking, not doing, or doing that’s screwing thing up?
Thanks for sticking this ramble out, and thanks to any help you can offer.
Bones
http://images26.fotki.com/v895/photo...SCN2666-vi.jpg (http://public.fotki.com/Bones/misc/r.../dscn2666.html)

I don't have a lot of time this morning, but I'm very suspicious of your idle vacuum. How carefully have you checked for vacuum leaks? The problem you have sounds like a fundamental one, not one that you're going to "tune" out of it. That carb should be close enough out of the box to run smoothly and provid eplenty of power, but I go back to the idle vacuum. That's a good indicator of something wrong. Try and backtrack through the changes you've made since it last ran best, and go through a process of elimination.
Just my .02
Edited to add...checking the timing on your cam might be a good idea.

I don't have a lot of time this morning, but I'm very suspicious of your idle vacuum. How carefully have you checked for vacuum leaks? The problem you have sounds like a fundamental one, not one that you're going to "tune" out of it. That carb should be close enough out of the box to run smoothly and provid eplenty of power, but I go back to the idle vacuum. That's a good indicator of something wrong. Try and backtrack through the changes you've made since it last ran best, and go through a process of elimination.
Just my .02
Edited to add...checking the timing on your cam might be a good idea.
I would have to agree,that seems very low vac. I have a similar setup and I have around 12" at idle. I would check the valve adjustment if one is not closing this would give low vac at idle. Why did you not run the cam straight up? The low vac would make that vac carb act up also.

I don't have a lot of time this morning, but I'm very suspicious of your idle vacuum. How carefully have you checked for vacuum leaks? The problem you have sounds like a fundamental one, not one that you're going to "tune" out of it. That carb should be close enough out of the box to run smoothly and provide plenty of power, but I go back to the idle vacuum. That's a good indicator of something wrong. Try and backtrack through the changes you've made since it last ran best, and go through a process of elimination.
Just my .02
Edited to add...checking the timing on your cam might be a good idea.
I’ve not chased down any vac leaks of yet. There aren’t too many areas for leaks besides the intake/head area and carb/intake area. All other ports etc on the intake are plugged with screw in plugs and the carb ports are capped with new rubber vac caps. I tried plugging the PCV system to see if it made a measurable change. It didn’t seem to affect the engine at idle anyway. I have been concerned with the intake to head sealing surface but the leak would have to be on the bottom of the intake and I would expect that a leak there would decrease blow-by that exits the valve cover breathers with the PVC system removed. If anything I worry that I have too much blow-by. The heads I bought were said to have only minor “clean-up” milling and the intake was new so I wouldn’t expect a problem, but I can’t say for sure that there is a complete seal.
My pressing project is to explore the leak angle more next test session. I haven’t felt this engine has ever performed to its potential, and I take credit for that. I assembled it and the problem is somewhere in that build. The carb was built by a company out in CO and was already modified from the factory build then further modified by me at time of install. With all the “customization” it’s actually back fairly close to the original Holley set up. The motor hasn’t had a time when it ran great across the RPM range. I’ve either had a problem off idle or now mid throttle. I’m the weak link in the build, so retracing my part is where to start so it’s looking more and more like I need to recheck the cam timing all the time.
Bones
http://images28.fotki.com/v1004/phot...SCN3310-vi.jpg (http://public.fotki.com/Bones/misc/r.../dscn3310.html)

I would have to agree, that seems very low vac. I have a similar setup and I have around 12" at idle. I would check the valve adjustment if one is not closing this would give low vac at idle. Why did you not run the cam straight up? The low vac would make that vac carb act up also.
I did recheck the “lash” on the rockers. I’m running a hyd lifter set up with MEI Mid-lift rockers. I have the preload at about a half turn in from “zero lash”.
I set the cam at the advertised centerline to dial it in. It’s not that I wanted to set it to 6* retarded, it’s just what it took to dial the centerline to where it was meant to be. I do second guess my measurements as it was my cherry busting set up. Though the degreeing to CL is fairly cook book in method I won’t say I couldn’t have screwed it up somehow. It’s looking like I need to pull the intake and check sealing angles and check the cam timing. I need to eliminate the likely areas I could have gone wrong before I make a bunch more changes on the carb etc.
Bones
http://images28.fotki.com/v977/photo...SCN3301-vi.jpg (http://public.fotki.com/Bones/misc/r.../dscn3301.html)

All I can say to what you just posted is that it soulds like you've got a good handle on the situation. With your open mindedness and what sounds like some decent knowledge, you'll find the problem. Again, my guess is that it'll be something fundamental, staring you right in the face when you finally find it.
I used to use an old trick for checking intake leakage and vacuum leaks. With the engine running, spray some carb cleaner around all the sealing surfaces. (Berryman works best for some reason) If your idle changes, there ya go. You can even spray it through a breather into the crank case. If the intake is leaking underneath, you'll know it.
Nice looking build, BTW.
Keep us posted.
On cam timing, make sure of a couple things. First, make sure you have a true zero timing set, and not a retarded one. (My guess is you already know this)
Second, make sure you have an accurate TDC mark. Without this, you're guessing.

Maybe your choke is going shut?

I had almost the same same problem with mine and chased it for quite awhile.My fuel pressure was about he same as what you are at.I bumped the the fuel pressure up to about 9-10 psi and it made a tremendous difference,it idled better and definetly made a difference in top end.Fords like alot of fuel.

Do you know anyone that can loan you a different carb, like a 850DP with out a choke to try? If not set float level to max and fuel pressure at 8.5-9 psI. and see what happens.
Have you checked the timing at the lake while running at 3.500 rpm's ? Get a friend to drive the boat and watch the timing at running rpm's.
Lastly check for those vac leaks with the carb cleaner.
Sleeper CP
Big Inch Ford Lover

It is subjective, but it seemed like the heads and valve covers were hotter today than I’ve noticed before. It’s one of the reason I richened things up and backed down the total advance today. Bones
http://images26.fotki.com/v895/photo...SCN2666-vi.jpg (http://public.fotki.com/Bones/misc/r.../dscn2666.html)
If the heads were hotter my guess would be that the distributor is retarding. Pull it out and check the pin at the gear:idea: Our engine has wiped out a few dist. gear pins in the past and you can feel it in the boat when it starts to go.
Also on the carb, make sure that the float adjustment hasn't bottomed out or been crushed at the top. That happened to me once, huge bog when the throttle was mashed down. just an idea?
Also make sure the fuel lines are not collapsing, but this sounds more like an engine prob. but you never know.
Hope you find the answer here somewhere.
Sleeper CP