Loosing RPM's 1984 454's - RESOLVED (Long Story)

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dwarren

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Well, as stated in previous threads, I'm struggling with some intermittent issues on both my 84 454's with only 478 hours on them. As per previous threads, both engines were pulled out and "checked" prior to me buying boat. Shafts, struts, cutlasses and stuffing boxes are new and/serviced. Distributors look almost new (old mallories points and cond), fuel system(s) new including a "rebuilt" on the port side.

Two major (not life changing but annyoing) issues.
1. Both motors have had an issue where after cruising along just fine at 3100 RPMs, I have to come off plane for one reason or another. Then, as I go to power back up, one of the two (and it does alternate lately) won't climb above 2600 rpms.....in most cases, after a few minutes of me cursing and messing about, all of a sudden, it will climb up to proper RPM and run just fine all day. I can smell the exhaust getting very rich when it happens on either engine.

2. On one motor, the one with the rebuilt carb, after cruising for a bit (assuming the above didn't happen), and I go to back in to a slip or idle around a bit in a cove, the idle falls out and it stalls. It doesn't happen every time (only when the wind is whipping and I'm squeezing into a slip much too small for my boat with expensive boats on either side ;-)). It always starts right back up and then just goes away after a while. This is a real oddity as it only happens on the way to go somewhere and never when I'm pulling into my slip (go figure).

My thoughts are this.....

As I'm only going by what the broker and last owner told me, both engines were completely checked out when pulled. I can state for a fact that all fuel lines, fuel tanks, RACOR (just replaced) are all new. the port side carb (that stalls) was rebuilt and looks brand new. It seems like there were a lot of extra distributor parts including coils (which are new on both motors btw). Kind of makes me suspect they were chasing this down.

I'm thinking of replacing the distributors with electronic just to completely isolate for that being an issue (and let's face it, it's a good preventive maintenance that yields some serious efficiencies). I'm nervous doing this as I'm no ignition expert but have done this in the past.

I've read almost every thread (chris's from 2013 was captivating) and think this is the best start to troubleshooting this. Given his issues with a rebuild, I'm thinking maybe sending out for another one and replacing so I know it's new.

What are the general thoughts on brand/type of distributor? I was thinking the delco EST kit. I'm assuming I need to buy an RH and LH? And....check me here, I determine RH by looking from front of engine correct?

Input appreciated, I'm not going to rush into this as basically, the boat is running great 90% of the time so I'm in to listening to any and all input........

RESOLVED - I had a mechanic actually go down to check out engine. I relayed that I felt it was the secondaries not opening up correctly as the port side kept getting stuck at 2900. He called me later and basically stated that I had low compression in both motors across the board (90's). Even with that, I wasn't convinced that all of a sudden my boat didn't work right. Second issue I had with diagnosis was that he did not do a leak down and was already writing the engines off. I had already ordered new Voyager EST's so figured I'd wait and see if that had any affect. I changed out the port side with no affect. The engine would not get above 2900 to 2950.

Very depressed and defeated, I limped back to my slip. I made a call to Yacht Services (Todd Brice) and asked if his team could give me a second opinion. I dropped off the boat yesterday thinking best case, new heads for both engines and a ton of money, or....worst case, new blocks for 12 tons of money....that I didn't have on a boat where the motors were pulled recently and supposedly checked............

So....not in my best fantasy did I think I'd get a call later that day (figured it would be at least a week) that all was fixed and it's good to go.......compression was at 115 give or take a couple of percent and the issue was carb and timing. I had only asked him to look at the port side but he checked both engines and got everything back in line. The carb issue.....as I had stated to first mechanic.....the secondaries were not opening.....

The boat is over propped of which I'm going to rectify over the winter but all in, he got it running better than I ever have seen with these engines. Yes, the WOT is only 3800 but that's due to the oversized props (which I didn't know about when I splashed).

Moral of this long drawn out story......always get a second opinion and always go to the person(s) you trust. I have been with Yacht Services in the past with two boats (kept both there for some time) and now he's got a customer for life. Going to haul there and keep the boat there from now on.

Talk about relief.......
 
I had several 1984 454's in our marina that had rusted spark advance springs in the distributors, replace all with electronic distributors and 12 volt coils, problem solved. All same problem as yours before replacement.
 
Thanks Jim, I think that's where I'm gonna go. Any idea on best model/type?
 
I think I used Prestolite it's been years since I changed them. The auto parts store in town had a sale.
 
This is only a summary of what I've read here:

In one of the brands, the newer model version doesn't burn a component out if the Key is ON with Engine NOT Running

DELCO VOYAGER seems to be the Gold Standard in replacement ignition systems
 
In order to solve the advance problem you have to replace the whole distributor.
 
Delco sounds like the way to go. Do I need to be concerned about engine rotation or, as with my last retrofit, do the 454's distributors both still rotate same way?
 
You just need to keep the plug wires in the order that they were on the old cap and the rotor pointed at the same wire. Remember you have to replace the whole distributor. There are kits they sell that just replaces the points that won't fix the advance.
 
quote:
There are kits they sell that just replaces the points that won't fix the advance.
Click to expand...


I was not sure if Delco Voyager is the only one that converts to breakerless AND totally electronic advance control.

So Jim, thanks for clearing that up.

Just looked at Pertronix replacement distributors and saw that they incorporate mechanical advances. Didn't think they did. I suppose installing brand new distributors, even with mechanical components, might extend the life of the ignition, out to the remaining life of the engine.

I don't think I've ever heard anything bad about Voyager.
 
If you don't replace the distributor you still have the advance that isn't working right now so the old advance would not be stable. If you use an additional electronic advance I'm not sure the advance would ever be right.
But I don't know what the Delco system is so maybe the have a way of freezing the old advance system. That system works with fly weights that are controlled by RPM and springs in my cases the springs were rusted and some broke but the weights would still move but not change the advance right be would change it somewhat. If on yours the weights still remain without being frozen in place the the advance could wonder.
 
My only point is replace the whole distributor, distributors are mechanical you can't get away from that. I don't care what brand you use. The ones I used were on sale and the 12 volt coils and the new distributors were like $170.00 for each engine.
 
The Delco Voyager EST kit includes a whole new distributor which has only electronic advance , not mechanical, plus a good matching coil and high quality plug and coil cables.
Some other "electronic" distributors still have mechanical advance , just no points or condenser.

And yes the RH/CW (opposite) rotation engine as viewed from the flywheel end does require a different Voyager kit # than the standard rotation engine kit, and it costs about an additional $100.
Some have suggested the only difference in the LH and RH engine distributors is the swap-able oil pump drive reverse-bevel gear at the bottom of the distributor.
That may or may not be the case for these Delco ESTs since the advance is programmed, but I was happy enough to pay the extra $100 to ensure all worked well, which it surely did.
You still need to set base timing in Timing Mode, then return to Run Mode

I found these Voyager EST distributor kits worth every penny but you may have luck as well with others, especially if they, like the Delco, do not use mechanical advance or ballast resistors.

* But... if you think your engine issues may be due to rusty/sticky mechanical advance , why not just lightly oil that mechanism and exercise it a bit to fully free it up... if in fact it is sticking? Then check (adjust?) initial timing and check total timing at up to a little over 3000 rpm with a strobe.
That's simple enough as long as advance springs and pins are intact. Mechanical advance is effective if maintained.

After checking the centrifugal advance, I'd suggest a good full tune up , then carefully adjust the idle mix screws( with idle speed screw backed off) for highest idle manifold vac readings on the carbs if Rochester Q-jets.

Just because carbs are "rebuilt" doesn't mean they are fine-tuned for your engines yet.
 
Thanks Sandy, I'm pretty confident that both engines have both been recently tuned, I believe that the Delco is the best choice as well. I've gone that route before. Thanks for the refresher on the RH/LH discussion. I knew there was something that had to change to use the same and I agree, the extra hundred is no biggie in the grand scheme of things. I just think these old mallories are tired and figure if I replace, just another thing I won't have to think about again any time soon. Thanks for all the input.
 
Here's another idea. On my Silverton I was having similar intermittent problems. After much effort I came accross a mention of problems resulting from the fuel shut-off valves that were used. If yours is similar, you may have a fuel line from each tank coming together to a common set of valves, with a cross-over valve between them, to allow both engines to run from 1 tank or both.It seems that these valves will leak under SUCTION allowing air to enter the fuel system, eventually starving an engine. Simple fix to try is to eliminate these valves; connecting the fuel lines together directly, and then introducing a new, proper fuel shutoff valve there, or elsewhere in the system.

When I did that, the problem I had was solved.
 
Still don't understand why the motors were pulled out? What was done to them when they were out.
 
quote:
Originally posted by Gregory S

Still don't understand why the motors were pulled out? What was done to them when they were out.

Click to expand...


Sorry for delay. They pulled engines to refurbish fuel tanks and lines. Issue is back again and now seems like it's no longer "intermittent". Port side won't go above 2800 RPMS. I have to believe this is distributor related as I believe that's when mechanical advance is supposed to deploy. I'm going to order the delco's and just bite the bullet.

Any quick instructions/tricks to replace them? I've done it before but it's been a long while.
 
You have to "play" the twist on the drive gear on the bottom of the distributor. Either get the engines to TDC first to make sure you know where the original distributor was pointing.
 
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