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283 Manifolds

Posted: Fri Jan 01, 2021 12:58 am
by Peter McBratney
I am still rebuilding my 1961 Capri that has a 283 V8. It is getting close and I am about to trial fit the engine to make sure the shaft alignment is OK. I had the engine rebuilt about 15 years ago and it has been carefully stored since. It was preserved well and endoscope of the bores show no corrosion. However, the original manifolds were refitted at the rebuild and there is a fair bit of rusty surface visible at the exhaust bends. I am wondering how is the best way to check the manifolds integrity. I would be better to fix them now before the engine goes in. Can anyone suggest the best method? Thanks

Re: 283 Manifolds

Posted: Sat Jan 02, 2021 8:16 am
by Matt Smith
You can have them X rayed and a machine shop. It will show all the flaws. Thats the ultimate way. They are not that hard to find. To be double sure have your local Machine shop clean them and bake them and check for stuff then.

Re: 283 Manifolds

Posted: Sat Jan 02, 2021 6:15 pm
by jfrprops
as said they are not hard to find...get new new many problems with old manifolds when you can get replacements
John in Va

Re: 283 Manifolds

Posted: Thu Jan 07, 2021 8:09 pm
by Peter McBratney
Thanks for the advice.

My engine rebuilder just fitted the old manifolds without dismantling them so I have just pulled one off to look.

It is a 3 pass system on the 283 block. There is quite a bit of flaky rust in the gas chamber and some blockage in the water galleries. The risers look OK. I have not managed to locate anyone here that can x ray to check thickness and cracks.

I am wondering about replacing the 3 pass system with a 2 pass system such as available from Barr Marine (I found them on the web). I have not managed to find any new 3 pass manifolds on the web.

What are the disadvantages? Is this the usual remedy? Are there any alternatives?

Regards Peter

Re: 283 Manifolds

Posted: Tue Jan 12, 2021 10:55 pm
by rgmxk22
Since you're working on a 1961, I am thinking that you are talking about having the 1st generation 283, the flywheel forward design and not the later 283 F series engine. And on the flywheel forward model, the point of the 3 pass manifolds is for 2 reasons. The cooling water goes directly from the water pump to the rear of the exhaust manifold, enters one passage of the exhaust manifolds to help cool them since they are the hottest running part of the engine.

The water then makes the 180 degree turn at the flywheel end on the exhaust manifold, makes the return pass back through another passage in the manifold before then finally entering the block. This was done to pre-heat the water some before it entered the block, which is to help prevent thermal shocks in the cooling water and since this version of the 283, CC never used a thermostat in the cooling system, it helps with engine warm up and cooler weather performance. after the cooling water leaves the front of the cylinder heads, it enters the exhaust manifolds for the 3 pass to again help cool the exhaust manifolds.

So I would stay with the 3-pass set up if it was my engine. Also, from what I know, the CC style manifolds for the small block chevy all use the same manifold log (the main section of the manifold) so the water passages in the manifolds on original and orginial style replacements should be the same. It is the end caps of the manifolds that determine the cooling water flow through them.

Hope this info helps.

Ron Michael

Re: 283 Manifolds

Posted: Sun Jan 17, 2021 2:26 pm
by Delfing
Hi guys am new to the site put looking for a answer, looking for knowledge on the free flow NO THERMOSTE 283 ( fly wheel forward) engine, how does it get to operating temperature as there seems to be no restriction on water flow, two lines off the water pump to the manifold , through the manifold to the engine , and back to discharge into the manifolds, and out the exhaust,
is that it. 1963 Chris-craft holiday ski boat 20ft. my last build was a 1960 35 ft roamer ROX315.

Re: 283 Manifolds

Posted: Mon Jan 18, 2021 12:14 pm
by rgmxk22
As far as I know, Chris Craft never installed any sort of a "factory" thermostat on the flywheel forward 283. I have seen a few hints and rumors of an aftermarket thermostat unit was offered at one time, but I have never seen one installed personally. But as I wrote in my other reply in this thread,part of the reason CC directed the water from the water pumps on these engines to the exhaust manifolds first was to preheat cooling water before it enters the block.

So these engines tend to be a coldblooded engine since without a thermostat, if the cooling system is working right, no blockages with rust or dirt in the passages and a water pump in good shape (good rubber impellers or bronze gears with no wear on them) that is moving enough water through the engine, they run cool since the actual temperature of the lake water being drawn in by the pump will effect the running temp of the engine. Colder water in the spring or fall equals lower operating temps in the engine. And since nothing slows down the water flow through the engine, they run cooler than you would like during colder water operation of your boat. I know it seems strange that there is not thermostat to regulate water flow and the operating temp of the engine, but the system works well enough.

My family had a 1963 31' Sea Skiff with a pair of the 283 flywheel forwards in her and I worked on those engines for over 30 years and the lack of a thermostat wasn't a big issue normally. We would make sure that we always warmed the engines up well before leaving the dock to prevent the engines wanting to stall when put into gear. We also would make sure that the cooling water was flowing normally out to the exhaust pipes since we did have issues with the original bronze gear water pumps losing their prime once in a while and wouldn't start pumping, but we fixed that issue by upgrading to rubber impeller style pumps.

We also spent the time to get the chokes on the carbs dialed in the best we could to work with the cold running engines. So without a thermostat, they can be a little finicky when you start them up cold, but once they are warmed up, the lack of a thermostat was never a big issue for us.

But Chris Craft did solve the no thermostat issue on the later 283/327 F series of engines since they not only run a thermostat, but 2 pressure regulating valves in the cooling system to maintain something like 4 psi of water pressure in the cooling system. Along with adding a circulating pump in the cooling system to work with a raw water (sea water) pump, the F series engines operate more like a cooling system in a car where a thermostat will let the engine warm up to and maintain a pre-set operating temp.

Ron Michael