replacing manifolds on 5.7

[uwish]

Hi
I have a 1990 5.7 alpha 1 set up and the exhaust manifolds have failed so I'm repairing the engine and need to replace manifolds, can I use the newer dry joint style? do they bolt straight on with no modifications?
is there any thing tips/tricks I need to look out for when buying manifolds?
cheers Ben

 

[alldodge]

You should have the one hose feeding the manifold from the bottom, if that is the case they should be plug n play. You will need the restrictor gasket with the hole. Note the hole goes at the highest point of the manifold which is usually the front

 

[alldodge]

BTW you can also go for aftermarket performance manifolds like GIL, EMI, and others

 

[Scott Danforth]

try to stay away from GLM or other imported manifolds unless you want to machine the castings flat to make them work. Osco and Barr are good aftermarket choices for stock, or as AllDodge indicated, there are plenty of performance ones out there.

 

[Fishermark]

What are the aftermarket performance manifolds? Are they generic versions of the dry exhaust type manifolds? The Mercruiser dry exhaust system is a great manifold system for salt water.

 

[uwish]

Ok thanks so if I only have the one hose going to bottom on manifold I can replace my old non dry joint manifolds(upper and lower) with later dry joint ones and it's a bolt over job? Also were online that ships to nz is a good place to buy parts? Head gasket,water pump,thermostat housing ect? Cheers ben

 

[alldodge]

Ok thanks so if I only have the one hose going to bottom on manifold I can replace my old non dry joint manifolds(upper and lower) with later dry joint ones and it's a bolt over job? Also were online that ships to nz is a good place to buy parts? Head gasket,water pump,thermostat housing ect? Cheers ben

Yea its simple remove and replace.

As for shipping to NZ (been a long time since I was there, pretty country) I would PM achris and see if he can advise. achris lives in Australia

 

[alldodge]

What are the aftermarket performance manifolds? Are they generic versions of the dry exhaust type manifolds? The Mercruiser dry exhaust system is a great manifold system for salt water.

The performance are GIL, EMI, Stainless marine and others. They will all work in salt but I would be getting the all stainless for salt or the coated ones

 

[Scott Danforth]

What are the aftermarket performance manifolds? Are they generic versions of the dry exhaust type manifolds? The Mercruiser dry exhaust system is a great manifold system for salt water.

they are designed for the go-fast crowd. Performance exhaust systems are designed to extract every ounce of power from the boat. most are either anodized aluminum or stainless. some have a dry break at the manifold/header, others incorporate the riser into the manifold.

most are designed to be in salt water and not need constant replacement like iron lumps do. While more expensive than a lump of iron, they pay for themselves by year 5 or 6 when iron needs to be replaced again

As AllDodge indicated, EMI, GIL / Hardding, CMI, IMCO, and others. think of it as tuned headers for your boat vs low dollar cast iron hunks.
http://eddiemarine.com/emi-thunder-exhaust
http://www.custommarine.com/
http://www.cpperformance.com/products/exhaust/gil-exhaust.htm
http://www.hardin-marine.com/c-1328-exhaust-systems.aspx
https://www.imcomarine.com/

A set of EMI Thunder manifolds with stainless risers for a small block will be about $1100. A set of CMI E-tops will be $2300

There is also HiTek out of Australia http://www.hitekmarine.com.au/

 

[Volphin]

I can vouch for the HiTek product. Very well built and very light.

 

[uwish]

Thanks for help so far, I was kinda hoping for a "summit racing" style except for mercruiser parts ? If there is such a place

 

[alldodge]

Thanks for help so far, I was kinda hoping for a "summit racing" style except for mercruiser parts ? If there is such a place

The marine market just isn't large enough for a full time summit type shop. They make stainless style but cost a bit more

 

[Scott Danforth]

if you are in fresh water, there are a variety of aluminum manifolds you can get these in hard anodizing for salt water application. you just have to look around.

 

[Bondo]

Thanks for help so far, I was kinda hoping for a "summit racing" style except for mercruiser parts ? If there is such a place

Ayuh,..... Search up parts for "Off-shore" type boats,.....

Off-shore only forums might be worth a visit,....

 

[uwish]

Sorry should have been more clear I have found a new set of dry joint manifolds in my city I was just wanting to order water pump, and gasket set pulse a thermostat housing from somewhere over seas as the parts prices here mean they should be made of gold cheers

 

[uwish]

Ok so I have had a bit more of a look. My thermostat housing also needs replacing. raw water cooled, From the research I have done online this thermostat housing is no longer available or made (16413A3) it has been superseded by this part number: (87290A23).
Now the original thermostat has 4 hoses(not total just that go to exhaust manifolds), that go, 2 to the bottom of the exhaust manifolds and 2 to the risers(I'm assuming both dump out the riser into exhaust) , so my question is if I'm replacing my exhaust manifolds with the newer dry joint style any they only have the bottom feed into the manifold(or do they have the provision for the hoses into the riser)? do I need to buy the thermostat housing with the 4 water hoses for the old style manifolds seen as I don't need 2 of the hoses anymore?
what thermostat housing would be suitable for engine now? thanks again for your help hope this make sense

 

[alldodge]

Can you supply your engine serial number so we can look up the engines configuration?

 

[uwish]

Yep no probs oc877150

 

[alldodge]

There were 3 designs used during your model and below is the old (design 2 yours) and new (design 3). You will need to replace your thermostat housing with the new design (860256A3). Both use the same water pump, but in the pic note the circulating water pump hose is on the opposite side. You will probably also need the new hose going from the power steering cooler to the thermostat. Can you post a pic of the front of your engine ?

 

[uwish]

ok thanks, engine is in pieces sorry most of it is at my engine reconditioners so no photos sorry , with the diagram's how you say that the water circulating pipe is on the opposite side, is that not because the diagram for the "old" set up is standing looking at "front" of motor and the "new" diagram is looking from the "rear/side", meaning the pipe is infact on same side?
also the new design thermostat is two water pipes short compared to the old design, the pipes its missing are for the exhaust manifolds by the looks of it(into the risers)?
so if I switch to the new thermosat design will I have to delete two of the water feeds in exhaust(I'm guessing the two that go into the exhaust risers and just leave the bottom feeds into the lower part of the exhaust manifold?)
this brings me to my next question, just for my understanding of the system that I have (design 2), the water system has 4 "dumps" that in turn blow out the exhaust, these are the water feeds into the bottom of the lower manifolds(1 each side) and also the risers(also 1 each side)?
and inturn this changed on the later systems because they only had 2 water "dumps" (into lower exhaust manifold 1 each side) is this correct?