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1/2 Fresh water cooling To full upgrade help

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bob61

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Right now 86 AQ225 with fresh water cooling 1/2 system Block only.

Im in the process of a complete motor rebuild (350 so its not going to be 225 any longer it will be whatever) with new manifolds. Manifolds are Not purchased yet..

I was wondering how do I convert the system I got now to a full system Block and Manifolds.

I believe my heat ex changer is large enough for the task 4 x 26. Basic 4 hole exchanger 2 for the AF 2 for the raw water

Cooling the riser is the easy part.. What do I need to do to get Anti freeze running though the manifolds :confused:
 
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bob61 said:
1....... Im in the process of a complete motor rebuild


2....... Right now 86 AQ225 with fresh water cooling 1/2 system Block only.

I was wondering how do I convert the system I got now to a full system Block and Manifolds.
I believe my heat ex changer is large enough for the task 4 x 26. Basic 4 hole exchanger 2 for the AF 2 for the raw water
Cooling the riser is the easy part.. What do I need to do to get Anti freeze running though the manifolds :confused:
Click to expand...

1........ Bob, please see this thread and begin reading at post #7.



2...... Bob, the AQ series GM V-8s were fitted with "Half" Closed Cooling Systems only.

Here's some info and the why:


The OEM Manifold's coolant supply would be the FWD-most port within the manifold.
The coolant return would be via the AFT-most port in the manifold (this port is typically closed off, and serves as the drain port).
The OEM Volvo Penta exhaust system, and/or any A-Market OEM replacement system, is not ported large enough for a Full System application!
IWO..... the ports would be too restrictive for a Full Closed Cooling system!

A non-existant Spacer/Riser would become blocked off between itself and the manifold.......... IOW, underneath the spacer/riser.
The non-existant Spacer/Riser would also become necessary for the supply of "spent" seawater to the exhaust Elbow..... since this Elbow is NOT ported!


The Down-Angle of the exhaust Elbow, and it's alignment to the Y-pipe bends, prevents a Spacer/Riser from being used.
But that is not all!


Also, a Heat Exchanger that is set-up for a "Half" system would require modification in order to work for a "Full" system.


In other words........ without changing to entirely different exhaust manifolds, exhaust Elbows and modified Y-pipe...... and without changing or modifying the H/E, it can't be done.



.
 
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Thank you Rick for quick reply

Ive read that post a couple years ago And I got real lost.

Been reading or should say brushing up on that thread in post 10.
And im still lost... is .038 the the head of the nail quench point?

The motor is a old 3970010 block turned out to be a 2 bt main the builder will be keeping it as stock as possible it will need to be bored .?0 over..guessing 30 over with 3932441 heads (76cc 194 150) he'll be putting hardened seats in.




Cooling

The old manifolds & Y- pipe will not work 100% understode

Thank you
Bob
 
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The motor is a old 3970010 block turned out to be a 2 bt main the builder will be keeping it as stock as possible it will need to be bored .?0 over..guessing 30 over with 3932441 heads (76cc 194 150) he'll be putting hardened seats in.
Click to expand...

Bob, a 5.7L (3.480" stroke) can use single valve relief flat top Pistons with the 76cc chamber cylinder heads........ (Not the 64 or 65cc)!
This gives us a suitable static C/R for Marine Cruiser use.

Your machinist can work with the piston deck height and compressed head gasket thickness as to create the .038" Quench dimension!




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Cut Volvo Y pipe about 2 inches above the merge. Connect exhaust (4" ports on MERC 5.7) to a 4 to 3 reducer, then to a 72degree elbow and down to the Volvo Y pipe. I did this and ran it for a couple of months. Not satisfied w/ engine performance. Measured pressure in exhaust manifold line and it was over 6psi waaaaay over max spec. Ended up running out thru the transom w/ shorty fiberglass mufflers ( NJ antinoise regs) Got an additional 450 rpm @ WOT out of the engine.
 
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kingsfisherman said:
Richardo,
how close does the Merc. manifolds and risers line up to a VP Y-pipe?
Click to expand...
Not sure..... perhaps take some measurements!


sandkicker said:
Cut Volvo Y pipe about 2 inches above the merge. Connect exhaust (4" ports on MERC 5.7) to a 4 to 3 reducer, then to a 72degree elbow and down to the Volvo Y pipe. I did this and ran it for a couple of months. Not satisfied w/ engine performance. Measured pressure in exhaust manifold line and it was over 6psi waaaaay over max spec. Ended up running out thru the transom w/ shorty fiberglass mufflers ( NJ antinoise regs) Got an additional 450 rpm @ WOT out of the engine.
Click to expand...

Just a thought...... use the later 95mm Double Exhaust relief Y-pipe, and DO NOT use the exhaust bellows with the internal back-flow-prevention-flapper.


.
 
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