Engine won't rev past 2800 rpm

Fresh 327F's, rebuilt carters, same props, port will rev to 3300 but starboard only gets up to 2800. Mechanical tachs and I haven't tried putting a digital tach on yet, probably my next move. Any other suggestions?

How old are your ignition distributors?
Have you verified that these are advancing correctly?

After you have thuroughly looked at the fuel delivery system, and at any other potentials such as correct over-all gear ratio, correct propeller, etc........, look at your ignition advance.
Make certain that the progressive curve is being offered as per your OEM specs, and that the total advance per correct RPM is being achieved as per your OEM specs.

Too often we set BASE or Initial advance, and look no further!

The progressive and TA are necessary in order for the engine to produce optimum power.

You can use a High-End digitally advancing timing light if you trust it and your skills.
Or..... you can use a standard timing light if the balancer is marked off up to approx 35*.

Keep in mind of how critical Marine Ignition advance is!
TA numbers that are too low, will hinder performance.
TA numbers that are too agressive, will/may cause engine damage!

BTW, you'll be looking for an OEM advance curve that will be similar to this one below.

With graph paper, you could plot out your existing curve (in incriments of 250 rpm or so) and post it for us to look at.

NOTE:
BASE or Initial advance will not be shown in the vertical scale. The scale will show only the progressive advance that is delivered by the ignition system. So we need to do the math in order to calculate the actual advance that the engine will see.

However, when strobing your timing marks dynamically, BASE will be included and seen.


This is an example only.

RicardoMarine said:

BTW, you'll be looking for an OEM advance curve that will be similar to this one below.

With graph paper, you could plot out your existing curve (in incriments of 250 rpm or so) and post it for us to look at.

NOTE:
BASE or Initial advance will not be shown in the vertical scale. The scale will show only the progressive advance that is delivered by the ignition system. So we need to do the math in order to calculate the actual advance that the engine will see.

However, when strobing your timing marks dynamically, BASE will be included and seen.


This is an example only.

Click to expand...

Thanks Rick, I will add that to the list of suspects. My advance plates are old and could be out of spec.

Dave

dcbullington said:

Thanks Rick, I will add that to the list of suspects. My advance plates are old and could be out of spec.

Click to expand...

Dave, is there a shop near you who would own/operate an old Sun, King or Allen distributor machine?
If so, they can run these up on their machine, and tell you what the progressive and TA are doing.
They should also be able to re-bush the housings if need be.

Note that most of these shops are set up for automotive ignition work whereby the curve and TA are not the same.
They'll need to see the OEM Marine specs and follow them.

Let the expense of this work be your guide.
If the over-haul cost approaches the cost of a new system, I'd go with new.

Perhaps look at Mallory's YLM624 AV VR system. If you have one RH Reverse rotation engne, the YLM624 BV .





I'd steer clear of any Hall Effect systems.




.

Rick,

I have looked at going that route what's holding me back is the mechanical tach drives. It's pulling the proverbial thread on the sweater......

Als, is there someplace I can get new rotor plates, springs and weights. I think these could use replacement as they seem worn and rusty.

dcbullington said:

Als, is there someplace I can get new rotor plates, springs and weights. I think these could use replacement as they seem worn and rusty.

Click to expand...

Post #5, first paragraph.
A good shop with a machine, and someone who can operate it, can over-haul these for you.

.

One more piece of info.......when the engines are in neutral the rpm's can go above 3500.