Replacing a VP DP-A with DP-SM drive.

Hi All,
I purchased a 1990 Marlin Chinook boat with a bad 4.3 carbureted engine. There is water in the oil, and a rod knock. It has a good DP-A drive in it, but repairing/replacing the 4.3 was getting costly. A 190 Hp 4.3 on a 4000# boat is probably going to be under powered in any case. I contacted the local Volvo Penta dealer, and they only suggested replacing the whole package with a new one for 17K.

I found a 2000 5.0 Gi package with a DP-SM drive complete for what it was going to cost to repair the 4.3. The engine is complete, has good compression, and appears to have been loved by its owner. This puts me ahead with fuel injection, and 250? HP. Except for the transom, it should be a bolt in job. While everything is apart, it is a good time to replace some seals, gaskets, and hoses. I am no expert on outdrives, but I would imagine that it could use some love, new hoses, bellows etc.

My question is that I see that there is an adapter plate made by VP to go from the 290 cutout to the DP-SM. They also make one that is to adapt a DP-A to a 290 cutout. I thought that the DP-A used a 290 cutout? At $800 for the adapter, this is not something I want to trial and error........
Thanks in advance,
Doug

What is the condition of your transom core? If questionable, and if you need to replace the core material, you may be better off to do that and to extend it inwards as to allow for the smaller cut-out required for the DP-SM drive.

However, the AQ series drive (the DP-A) is a much better drive.

No gimbal suspension.
No gimbal bearing.
Main suspension fork and pivot tube geometry.
Fixed geometry between engine and stern drive.
All steel drive coupler. (not a rubber hub coupler)
No annual engine drive coupler alignment check.


.

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jetdoctor said:

The DP-A drive that is attached to the 4.3 is actually in nice condition, and does not appear to have been left in the water for long periods. It also has CD trim/power steering. The problem is that it has a 2.30 gear ratio.
I believe that the 4.3L reduction should have been 1.95:1

I do not know whether it would be economical to change the ratio of the DP-A, or whether the 5.0 will bolt up to it.
Changing a gear set can be very expensive.
The gear set alone will run you about $1,800+ or so. Then you have set-up time (6 to 8 hours) and new bearings to factor in.

The 5.0L SBC rear flange is the same as the 4.3L flange...... so the 5.0L SBC will bolt up to the 4.3L flywheel cover (bell housing in the auto world).

The DP-SM came as a package with the 5.0 GiPWTR. The engine/drive was removed from a 24 SeaSport that was bracketed, and had an outboard installed. All of the controls, and wiring came with the package. I need to strip off the anti fouling paint to verify the ID plate, but the DP-SM should have the correct 1.95 ratio. I also have a set of D4 props which should be in the ball park.
Keep in mind that the prop set must be correct for through hub exhaust.

I am not sure what the best solution will be, but I am certainly open to suggestions. The 5.0 is going in regardless of which drive is used.
What do you recommend?
Doug, I much prefer the AQ series over that of the later gimbal system drives.
As mentioned.....
No gimbal suspension.
No gimbal bearing.
You would have main suspension fork and pivot tube geometry.
You would also have fixed geometry between engine and stern drive.
All steel drive coupler. (not a rubber hub coupler)
No annual engine drive coupler alignment check.

and I forgot to mention....
no through hub exhaust.
no gimbal ring upper pivot issues.


If I owned that boat, I'd be looking for a DP-C or DP-C1 system.


​

Click to expand...

In case any one else is wondering what this thread is about, here is a drawing comparing the 3 cutouts that Volvo Penta has used over the years. Note that the smallest cutout is now standard for most makes of outdrive. I suppose that this is to accomodate repowering a boat that had another brand drive installed. My current DP-A drive uses the 290 cutout, while the DP-SM I also have that matches the 5,0 GI uses the smaller cutout. Many people felt that VP made a step back by going to a gimbal shield copied from OMC who copied it from Mercruiser.
The way to deal with this is with either an adapter plate, or by repairing the core. After the hole is glassed over, a new hole is cut.
Cheers,
Doug

Rick,
What is the difference between the DP-A, and the DP-C drives? If I decide to go that route, would a 1.95 DP-A(C) lower bolt up the the DP-A upper that I already have. Those are on Ebay for $3500. The 3 gears to change the DP-A to 1.95 are $2200. Do you have a line on a DP in 1.95?
On the other hand, VP seems to still be selling DP-SM drives. While they may not be optimal, I would imagine that they work.
In any case, I should be able to sell whatever I do not use. Compared to what I see up for sale, what I have is beautiful.
I probably need to get cracking and pull the engine out so that I can evaluate the transom condition.
Cheers,
Doug

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jetdoctor said:

In case any one else is wondering what this thread is about, here is a drawing comparing the 3 cutouts that Volvo Penta has used over the years. Note that the smallest cutout is now standard for most makes of outdrive.
Yes, the smallest cut-out is for the Gimbal suspension drives.
Today that would be Merc and Volvo Penta only. (OMC's last production was end of 1993)

I suppose that this is to accomodate repowering a boat that had another brand drive installed.
Volvo Penta initially designed the SX and DP-S as to better gain market share. With this cut-out, the boat manufacturers could now fit either Merc or V/P stern drives.

My current DP-A drive uses the 290 cutout, while the DP-SM I also have that matches the 5,0 GI uses the smaller cutout.
Yes, that is correct!

Many people felt that VP made a step back by going to a gimbal shield copied from OMC who copied it from Mercruiser.
Yes, in my opinion is was a step in the wrong direction.

The way to deal with this is with either an adapter plate, or by repairing the core. After the hole is glassed over, a new hole is cut.
Yep!

Click to expand...

The original cut-out actually fits the 250, 275, and 285 as well.

View attachment 16839

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jetdoctor said:

Rick,
What is the difference between the DP-A, and the DP-C drives?
The DP-A is just about the same as the 290 DP. While it incorporates hydraulic trim/tilt, it still retains a version of the Reverse Latch, and it incorporates the SS Anchorage bracket that the cylinders attach to.
The C and later drives no longer use the Anchorage bracket nor the latch system.
The C lower gear unit's vertical shaft is now shorter and requires the long vertical shaft spline coupler.
The C transmission also uses a slightly larger driven gear angular contact bearing causing it to fit the C and later Intermediate housings ONLY!

If I decide to go that route, would a 1.95 DP-A(C) lower bolt up the the DP-A upper that I already have.
The changes that occurred to the C drive include the transmission, Intermediate housing, suspension fork, transom shield, hydraulic cylinders, etc.
With the correct shimming procedure being followed, all lower gear unit will interchange. In other words, if you go C, you need all C components minus the lower gear unit.

Those are on Ebay for $3500. The 3 gears to change the DP-A to 1.95 are $2200.
I don't know of any Volvo Penta tech that would change a gear set without also changing the bearings.
And don't forget the set-up time. This can be 6 to 8 hours shop time!!!!

Do you have a line on a DP in 1.95?
NO..... I am no longer active with repair work. If I did know of one, I'd certainly let you know.

On the other hand, VP seems to still be selling DP-SM drives. While they may not be optimal, I would imagine that they work.
In any case, I should be able to sell whatever I do not use. Compared to what I see up for sale, what I have is beautiful.
I probably need to get cracking and pull the engine out so that I can evaluate the transom condition.
Cheers,
Doug

Click to expand...

Doug, I put these images together some time back.
Hopefully they will help explain some of the differences between the AQ series models.

Rick,
Thank you for all of your expertise. It looks like the pre C AQ drives were made to kick up when hitting an obstruction, but had the dreaded reverse lock.
Right now, the plan is to drive on and evaluate what I have to work with. If a suitable AQ drive shows up, then it will be considered.
Cheers,
Doug

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jetdoctor said:

Rick, Thank you for all of your expertise.
You are very welcome.

It looks like the pre C AQ drives were made to kick up when hitting an obstruction, but had the dreaded reverse lock.
All of them incorporated a version of an impact release feature.
The early series used spring loaded latch hooks. Upon impact, the latch hooks will over-center and will release their hold on the set pin.

The latch hooks also prevented the drive from lifting while reversing. However, in order to tilt the drive up and out of the water, the latch hook release was created. This took on the name "Reverse Latch". But we tend to forget that it's primary function was impact release/protection.

The latch hook tilt-out release (disengages for tilt-out) was no longer needed for the 290 w/ hydraulic trim/tilt..... but the latch system was retained for impact release/protection.

The C and later hydraulic cylinders have an internal release, so they were able to do away with the Anchorage bracket and latch hooks.
That's part of what makes the C a much better system.

If your DP-A is in good condition, and is the correct ratio, go ahead and use it!

Click to expand...

.

Thanks Rick,
Unfortunately, the DP-A is 2.30 ratio. The 5.0 needs a 1.95 ratio. The 4.3 runs at a considerably faster RPM for a given speed vs a V8. The DP-SM that I have is the correct 1.95. Whatever I end up using, will end up in the best shape that I can get it.
Cheers,
Doug