High End Performance

I'm trying to piece together 100's of older threads regarding high end engine performance. Could somebody just quickly give their input on this:

My rebuilt 351 engine has about 22 hours on it. The Holley carburetor is new, all electrical components are new. Hoses, filters, gas related stuff new. I think the only original parts are the starter and alternator. Fresh gas, 89 octane in tank too.

At about 4,000 RPM's, I'm starting to run out of throttle fast. The tach reads about 4,250-4,300 TOPS, WOT with a new ACME 540. Listening to the engine and feeling what the boat is doing, my only conclusion is that I'm lacking sufficent fuel to the engine. I haven't checked the timing at high end yet. I've been reading stuff through out. What am I looking for the timing to be at 4,400 RPM's? The manual says no more than 30 degrees BTC. So does this mean 29 BTC is OK? Will adjusting the carburetor and timing cure lacking RPM's? The wacky thing is that when I have the throttle pinned, I'll be at about 3,800 RPM's then all of a sudden the engine adjusts it's RPM's to hit about 4,250. Everything else sounds and runs extremely healthy, except for the high 3,000, low 4,000 RPM band. I hate to repeat prior thread inquiries, but quick, short replies would really help.

Thanks,

Ken

It could be stuck advanxe or just plain wrong advance in distributer.or even sticky secondaries.

Munday

79nautique wrote: might even be too small of jets on the secondary side as well.

The secondaries on a stock 4160 wont have jets, only the metering plate.

Nutty, I dont think 4300 RPM sounds right. A stock 351w in a 2001 should be turning a 540 closer to 4600 RPM. From what I remember, Ken was turning his previous 4-blade 4100-4200 RPM, so the problem was there before the swap.

Thanks for the input. I'm not looking to push the engine beyond the factory specs. I'd like to be able to reach the maximum performance specs of 4,400 RPM.

The ACME is brand new and recently tuned. I have a Holley carburetor, which has 22 hours on it. It has "High Performance" stamped on the side of it, I'm not sure of the model number. Does an engine go out of original adjustment after the break in period? I haven't verified the timing since it was installed in late 2005.

Tim's exactly right, my four blade OJ wasn't spinning up to the max RPM range. I actually had OJ make adjustments to give me more RPMs, as I was spinning 3,800 max when I got it. Since the new "rebuilt" was installed, I've never reached maximum RPM, 4,400. It could be an adjustment that needs to make all the difference.

Ken

Tim,

I just shot an e-mail off to you and Brad about using my boat tonight. I want to grab my Dad's timing light and see what we have for settings. I can be the boat of choice for this evenings pull.

Ken

Ken I'm going through pretty much exactly what you are with our '88.

I couldn't get more than 4300 rpm with a 12" pitched prop. The stock 13" pitch brought me back down to 4150 rpm at WOT. I wouldn't be concerned with what the tach is telling me except that's at a GPS verified 38 mph. I've checked the throttle cable and looks like it's properly adjusted. Timing chain feels tight.

I will keep you posted although it sounds like you're attacking your issues sooner than I will be. Boat will probably hit the water next weekend for fuel pressure and timing checks.

Going down to TX to take a few sets behind Feelgood's BFN this weekend. Hopefully I can learn a few things from this thread when I get back.

I have an unknown EI conversion that uses a ballast resistor and an oil filled coil. Magicman's tuned 4160 is ready to bolt on for testing as well. Just put in fresh plugs and fuel filter.

Ken, I saw your email. If you get a chance, grab the List number off the choke horn. It should be somewhere around here:



Im assuming its a stock 351w replacement either from SkiDIM or Correct Craft, so it should be a 600 CFM 4160. The Holley tech line will be able to ID it for sure based on the List #.

Its quick and easy to dial in the timing. We can verify youre getting full advance- it sounds like the stock dist should be getting 20-24 degrees on top of the base (can anyone verify that number?). Based on what youre seeing though, Im with Chris and think there may be an issue with the secondaries. Beyond that, I couldnt tell you what to adjust.

Nautique2001 wrote: What about the accelerator linkage piece that opens the secondaries? Can that be adjusted to let more fuel in?

No. That closes the secondaries

Nautique2001 wrote: Tim, we also need to check the throttle linkage to ensure I'm getting max throttle.

always a valid check

Nautique2001 wrote: and turning the two adjustment screws a quarter towards the open position. Ken

wouldn't do that at all you do not have a rough idle issue and adjusting the screw will not effect off idle performance like your having.

Check the cable adjustment first to verify WOT at the carb, then move to the timing set it at 8-10 inital and then see what the timing is at 2500 rpm should be around 30 degrees after that you need to focus on fuel delivery and when and if the secondaries are opening.

Kevin, I'll be in the countryside area? electromotive diesel plant next week and I might be able to stop by and help you out if you want.

Nautique2001 wrote: Hollywood, Pretty mind boggling issue. The engine runs like a top until you hit the high 3,000 RPM band. I'm sure you feel the loss of throttle response like I do from 4,000 to about 4,300. I never thought to check the position on the throttle cable. I'm pretty positive the timing and carburetor adjustments aren't jiving. I think we'll start by advancing the timing a couple of degrees and turning the two adjustment screws a quarter towards the open position. I don't think the prop has anything to do with the lack of RPM's. I'll post something tomorrow. Ken

I just took a couple of pics. Not sure if this helps determine which model it is:

bkhallpass wrote: Sounds like Ken and Hollywood have lemons. Tell you what, I'll give you $2500 a piece for them, and I'll even get them back to CA at my expense. You can use the money for a down payment on a shiny new boat with all the power you need. Just trying to help a brother out. BKH

Brian, I'll trade you straight up!

Try not to drop the nut down the carburetor...

MM, you don't know the difference betwen a nut and a bolt? I would expect that from blondie but not you.

I also forgot to mention how much I like the looks of that annodized arrester. Classy.

LakeHoliday wrote: Okay, I just got this back from the folks at Holley (I really didn't expect to hear back from them so quickly): The List Number 75009-3 is actually a Holley Marine carb model 4160 600 CFM.

Nautique2001 wrote: MaddMarxx wrote: Try not to drop the nut down the carburetor... Ooops. Kidding... SAE J1223 75009-3 1195

Holley tech says its a marine 4160 with vaccuum secondaries, 600cfm (just like we thought).