Conquest 32(39) Power??-gctid343848

[Guest]

Hi All,

I am new here. I have a Conquest 32' I just picked up at what I think was a good deal. It needs the starboard engine rebuilt. I am going to replace both with new long-blocks. (Volvo 350's)

My question, should I stay with the 350's or would it be a better fit to change to something like 383's ? I have been told buy the local mechanic that the drives wont handle the extra HP.

Any help and opinions would be great.

Thanks:

[itsabowtime2]

What's your budget?

[Guest]

Oh Ya its a 1981

[Guest]

I would like to stay under 7K I can get the 350's for 1475.00 each And I am going to undress the old blocks and redress the new ones. It is going to be about 2k to have them pulled and reinstalled.

[itsabowtime2]

Are you considering doing anything with the drives? In a boat that size a DP conversion would make a huge difference. I am sure Rick will chime in soon but I assume you have VP drives?

[Guest]

Yes they are Volvo Drives and yes it would be nice to upgrade to the DP drives but at this time it's not in the budget. I need to get the boat running and moved to Portland.

In less someone out there knows of a great deal on a couple of them.

[2850Bounty]

Which ever way you go, replace the PDS bearings while you have it torn down. Cheap and easy to do.

The person who told you that the Volvo drives won't hold up to 377/383 power, is uninformed.

The Duo Prop drives with 5.7's will do as much (or possibly more) for you than two 383's with single prop drives will.

The catch is the heavy hull. You need to get the thrust to the water.

If you build a pair engines, take a look at several of the SBC Q/E build threads in the BOC Vault.

The cost to do this is peanuts (comparatively speaking), and with a heavy hull the benefits are well worth the efforts.

No other major internal changes need to be made.

The 377/383 will require some additional internal work, but is unrelated to the Q/E.

You still want the Q/E as it becomes even more important for the Marine 377/383.

Edit;

The Duo Prop lowers are expensive...... even good used ones...., especially the more popular 1.95:1 ratio.

If you were to build a pair of 377/383's, you may be able to use the 1.78:1 ratio, which are sometimes less expensive and sometimes easier to find.

.

[yachtman]

There are lots of different ways you can go. I think that the 383's will be tough to keep with in your budget done correctly unless you have a bunch of the right parts laying around.

There are other things you can do to 350's that cost little and give alot of power.

Make sure you do as Rick suggests and use the correct pistons. Many off the shelf manufacturers wont use the correct pistons. Are you closed or open cooling system?

Yes you might be a stretch on the 383 with the ourselves you have but Rick would know more about that than I. You can build 350's properly with all the power those drives can handle and less money than 383.

Do a search for fordm he did 383's on his 3250 he might have some cost info for you.

[Guest]

Rick, You seem to be very negligible about these Volvo systems. Am I going about this right in thinking to just install a new long block? The starboard engine has water in the oil. when doing a pressure test on the closed cooling system it failed. I was told it has a blown head gasket but I suspect a bad head. this engine has about 1400 hrs on it. The port engine runs good and has about 2200 hrs on it. I was thinking it is a good idea to do them both at the same time. I was thinking to go with new distributors and maybe hi rise manifolds. and new exhaust manifolds and risers. Are you familiar with superior engines there in Portland?

To upgrade to the DP drives is it just the bottoms that need to be changed or the whole drive?

[2850Bounty]

ssanderson69 wrote:

• 1 wrote:
• Am I going about this right in thinking to just install a new long block?
• I was thinking it is a good idea to do them both at the same time.
• I was thinking to go with new distributors.....
• ..... and maybe hi rise manifolds.
• Are you familiar with superior engines there in Portland?
• To upgrade to the DP drives is it just the bottoms that need to be changed or the whole drive?

• 1 wrote:
• There's quite a bit to this in order to do it correctly, and yet it can be very simple.
  
  The trick is in the understanding of the differences between automotive and marine loads and how this affects the build design.
  
  So if these long blocks offer the correct piston and cylinder head selection, along with camshaft profile, etc.... then yes, that would be a great idea!
  
  If you match year designation, your tin wear will transfer over also (should they come w/o).
• Yes. Note that with the Volvo Penta both engines are Standard LH Rotation.
  
  No Reverse RH Rotation with V/P, so that will save you a bit of hassle.
• Lots of choices for Ignition Distributors.
  
  These must be Marine so that the progressive advance curve and limit are correct and that they offer ignition protection against fuel vapors.
  
  No Automotive type ignition distributors should be used here!
• A high rise manifold would not be as suitable for your SBC Marine application. A fairly standard dual plane intake manifold would perform better.
  
  Many use Edelbrock's Aluminum Performer with the Closed Cooling systems.
  
  If raw water cooled, it is best to the Marine aluminum intake w/ the bronzed lined coolant cross-over, or a cast iron intake.
• No, sorry, but I do not..... they may be very good.
  
  I do know that I'd be most comfortable using a shop whose techs have present or past experience with cruiser type boats that use the SBC engines...... not necessarily street performance experience ONLY!
  
  These are the guys who will know the subtle differences between the Auto and Marine SBC and will understand the value of the Quench or Squish, and will know how to build it correctly.
  
  Either that, or you provide the build specs, and have them perform the work accordingly.
  
  I'd think that many shops would do more automotive work than marine.
• Just the lower unit is replaced. It does involve a critical shimming procedure... takes about 30-35 minutes for calculating the shim value...... very easy to do.
  
  There should be some info in the Vault re; adding the DP lower unit and the shimming procedure.

A few notes and fyi's;

Piston selection (flat top, fully dished or partial dished w/ quench area) influences cylinder head chamber volume selection, and visa-versa in order to create the squish or quench effect, yet keep the C/R where it needs to be. The quench or squish principle applies to any engine that uses a wedge area within the combustion chamber.... such as the SBC, SBF and some of the Chrysler V-8s.

This can be important for use in a Marine application..... especially for heavy hulls such as yours.

IMOO, you'll want to steer clear of the full dished pistons when you have the option to do so. This is why building your own works so well.

Stroke dimension plays an important role in this also....... (377/383 for example).

A 5.7L with F/T's and 76cc chambers puts the C/R about where we want to be, and gives us the quench w/ the correct deck height and head gasket.

A 5.7L with full dished and 64cc chambers puts the C/R where we need it, but offers ZERO quench or squish possibilities. :thumb

A 377/383 (3.750" stroke) with F/T's and 76cc chambers does NOT pencil out the same as does the 5.7L (3.480" stroke). The C/R will likely be too great with the added stroke!

Then there's connecting rod length.

The hot rod guys prefer the longer rods, but as you know this shortens the effective piston skirt area. We want to use the shorter rods and keep the longer skirt area.

(has to do with the greater and more continuous engine loads)

A good piston supplier can provide you with just about any style, dimension, pin offset, pin height, skirt length, dish volume, material grade, price range, etc. piston.

You could spend over $1,500 per set, or you could spend a more modest $200-250 per set for a good Hypereutectic grade piston of the correct dimensions that offer the Quench or Squish effect.

Then there's camshaft profile..... best to contact a good supplier directly and ask for their help.

So you can begin to see how these little changes can make a quite a big difference.

Jeff H's 383 stroker thread that's linked to in the Vault, may interest you.

I don't think that Mike Emm's thread is linked to. I'll see if I link us to that thread.

(both of those threads pertain to the 377/383, but the Q/E idea can be used for any SBC)

Dave M (aka Yachtman) also has a thread on his twin engine build where he incorporates the quench or squish effect. He is very knowledgeable on camshaft profile, so pick his brain some.

I don't know if I have a link... perhaps Dave can link us.

There are also several cylinder head castings to steer clear of. There is a thread in the Vault that mentions this.

Also, you can have your local library bring in Dennis Moore's [COLOR]"#0000FF" wrote:
Small Block Chevy Marine Performance[/COLOR] book.

NOTE: Marine Performance.... not High Performance!

Tons of good info in Dennis' book..... well worth reading.



.

[Guest]

2850Bounty wrote:

• 1 wrote:
• There's quite a bit to this in order to do it correctly, and yet it can be very simple.
  
  The trick is in the understanding of the differences between automotive and marine loads and how this affects the build design.
  
  So if these long blocks offer the correct piston and cylinder head selection, along with camshaft profile, etc.... then yes, that would be a great idea!
  
  If you match year designation, your tin wear will transfer over also (should they come w/o).
• Yes. Note that with the Volvo Penta both engines are Standard LH Rotation.
  
  No Reverse RH Rotation with V/P, so that will save you a bit of hassle.
• Lots of choices for Ignition Distributors.
  
  These must be Marine so that the progressive advance curve and limit are correct and that they offer ignition protection against fuel vapors.
  
  No Automotive type ignition distributors should be used here!
• A high rise manifold would not be as suitable for your SBC Marine application. A fairly standard dual plane intake manifold would perform better.
  
  Many use Edelbrock's Aluminum Performer with the Closed Cooling systems.
  
  If raw water cooled, it is best to the Marine aluminum intake w/ the bronzed lined coolant cross-over, or a cast iron intake.
• No, sorry, but I do not..... they may be very good.
  
  I do know that I'd be most comfortable using a shop whose techs have present or past experience with cruiser type boats that use the SBC engines...... not necessarily street performance experience ONLY!
  
  These are the guys who will know the subtle differences between the Auto and Marine SBC and will understand the value of the Quench or Squish, and will know how to build it correctly.
  
  Either that, or you provide the build specs, and have them perform the work accordingly.
  
  I'd think that many shops would do more automotive work than marine.
• Just the lower unit is replaced. It does involve a critical shimming procedure... takes about 30-35 minutes for calculating the shim value...... very easy to do.
  
  There should be some info in the Vault re; adding the DP lower unit and the shimming procedure.

A few notes and fyi's;

Piston selection (flat top, fully dished or partial dished w/ quench area) influences cylinder head chamber volume selection, and visa-versa in order to create the squish or quench effect, yet keep the C/R where it needs to be. The quench or squish principle applies to any engine that uses a wedge area within the combustion chamber.... such as the SBC, SBF and some of the Chrysler V-8s.

This can be important for use in a Marine application..... especially for heavy hulls such as yours.

IMOO, you'll want to steer clear of the full dished pistons when you have the option to do so. This is why building your own works so well.

Stroke dimension plays an important role in this also....... (377/383 for example).

A 5.7L with F/T's and 76cc chambers puts the C/R about where we want to be, and gives us the quench w/ the correct deck height and head gasket.

A 5.7L with full dished and 64cc chambers puts the C/R where we need it, but offers ZERO quench or squish possibilities. :thumb

A 377/383 (3.750" stroke) with F/T's and 76cc chambers does NOT pencil out the same as does the 5.7L (3.480" stroke). The C/R will likely be too great with the added stroke!

Then there's connecting rod length.

The hot rod guys prefer the longer rods, but as you know this shortens the effective piston skirt area. We want to use the shorter rods and keep the longer skirt area.

(has to do with the greater and more continuous engine loads)

A good piston supplier can provide you with just about any style, dimension, pin offset, pin height, skirt length, dish volume, material grade, price range, etc. piston.

You could spend over $1,500 per set, or you could spend a more modest $200-250 per set for a good Hypereutectic grade piston of the correct dimensions that offer the Quench or Squish effect.

Then there's camshaft profile..... best to contact a good supplier directly and ask for their help.

So you can begin to see how these little changes can make a quite a big difference.

Jeff H's 383 stroker thread that's linked to in the Vault, may interest you.

I don't think that Mike Emm's thread is linked to. I'll see if I link us to that thread.

(both of those threads pertain to the 377/383, but the Q/E idea can be used for any SBC)

Dave M (aka Yachtman) also has a thread on his twin engine build where he incorporates the quench or squish effect. He is very knowledgeable on camshaft profile, so pick his brain some.

I don't know if I have a link... perhaps Dave can link us.

There are also several cylinder head castings to steer clear of. There is a thread in the Vault that mentions this.

Also, you can have your local library bring in Dennis Moore's [COLOR]#0000FF wrote:
Small Block Chevy Marine Performance[/COLOR] book.

NOTE: Marine Performance.... not High Performance!

Tons of good info in Dennis' book..... well worth reading.



.

And one more thing...as Rick would be so inclined to mention... NO CHEAP CHINESE BEARINGS! I just got a newly rebuilt PDS adapter which I will be using for my repower. The cost difference between low grade Chinese made bearings verses high quality electric motor grade bearings amounted to $15. Consider it cheap insurance...because if the PDS bearing fails, the engine needs to be pulled. Or better put, you pay $15 to save $1500.

[2850Bounty]

Well said, Ed! And both Ed and I like BBQ'd Pork and fried rice!

ssanderson69, there is a dedicated thread on this topic in my Vault thread.

Edit:

Anther thought to share with you.

No doubt some of these men will give you the talk'n to about the full dished pistons and how GM has been using these for years in both auto and Marine.

This may very well be in defence of the full dished piston.

Ask this person to explain the evolution of the full dished piston, the evolution of the SBC cylinder head combustion chamber volume and runner volume....., and what took place in the '70s during the rush to better control emmissions.

Then ask them to explain Ignition Induced Detonation pertaining to Marine engine loads.

Then ask what combats Marine load Detonation most effectively!

That ought to do it!

Why GM could not have mirrored the wedge, yet kept the dish to control C/R, is beyond me!

The cost would have been peanuts! Perhaps no real cost at all!

OK... off my horse now!

.

[Guest]

Was going through the same decision process and when I spotted two DPs I snapped them up. I am now 1/2 way through the conversion (so many projects so little time!). Hope to have her back in the water in 6 weeks and will let you know how it goes.

It will be very interesting to compare the performance.

Good luck!

[2850Bounty]

nmuir wrote:
Was going through the same decision process and when I spotted two DPs I snapped them up. I am now 1/2 way through the conversion (so many projects so little time!). Hope to have her back in the water in 6 weeks and will let you know how it goes.

It will be very interesting to compare the performance.

This is certainly unsolicited, but please make sure that you replace your PDS bearings in each flywheel cover. With these not yet installed, it's a piece of cake.

Buy these from a major bearing supplier, and save yourself some money. You'll get the exact same bearings that you would through Volvo Penta, but at a fraction of the cost. Likewise with the four seals.

There is a link to a PDS bearing replacement thread in the BOC Vault.

.

[Guest]

2850Bounty wrote:
This is certainly unsolicited, but please make sure that you replace your PDS bearings in each flywheel cover. With these not yet installed, it's a piece of cake.

Buy these from a major bearing supplier, and save yourself some money. You'll get the exact same bearings that you would through Volvo Penta, but at a fraction of the cost. Likewise with the four seals.

There is a link to a PDS bearing replacement thread in the BOC Vault.

.

Thanks Rick. Yes that is one of the jobs on the list - based on some BOC forum browsing the recommendation came out load and clear!