318 Engine Bits

[propellerhead]

Hi guys. In the early stages of a resto on my 15.5' clinker skiboat (late 60's, make unknown, not a Lewis). Has a 318 engine with raw water intake. I'm after some advice and looking for bits:

- Exhaust exits thru homemade copper headers where the water is injected about 1" from block down each individual pipe. I like the simplicity of this setup but have been told it injects too close to the exhaust port & could get water uptake into cylinders. What do you reckon about retaining this setup?
- If above setup sounds bad, anyone got a pair of 318 water jacket manifolds or other type?
- What do you reckon about installing a heat exchanger? Is it really that beneficial to block longevity? Can get a Chrysler heat exchanger from Marine Direct for $610. Does anyone have one sitting around?
- Does anyone have some pictures of how they have plumbed their engine with either old style water injection or water jacket manifolds and heat exchanger? Trying to visualise where all the bits go!

Thanks, Nick.

[propellerhead]

Exhaust manifold question: have since had a good look & think. Rolco type wet exhausts seem the tried & proven way to go so will keep an eye out for these, or if anyone wants to sell a set in the next year or so? One thing however is that the lower 2 exhaust ports on my engine are very close if not on the waterline - probably because of the big, fat Chrysler engine in my little boat! Which probably explains water in the oil when I first got the boat - no elbow in the system to stop it! I feel risers/elbows going north after exiting the Rolco exhausts, then dropping down to the waterline or just below at the transom is the way to go. Comments much appreciated here...

Heat exchanger question: would like to go down this path as I will run the boat in the salt at times. I have found plenty of info. in past board posts. Also exchangers appear standard on all the American boats - Chris Craft etc - in fact the major US motor companies all appear to have produced complete engine units with wet exhausts and heat exchangers bolted to the blocks. I find it strange that brand new ski boats with big dollar engines have raw water cooling. But maybe I'm missing something - probably simplicity. Again, comments much appreciated...

Cheers, Nick W.

[Greg]

G'day Nick

Looks like the experts are away, so I'll put in my two penneth.

Were the headers on the boat/engine originally? If so, they probably haven't done any harm, otherwise they would have been removed. If the pipes drop away (down) from the head, there is probably not a lot of chance of water entering the cylinders, particlularly when the pump is only operating when the engine is. One inch is close, probably just maximising the amount of pipe being cooled. Does it inject straight in or is it angled to spray down the pipe? Water cooled manifolds take this danger out of the equation, but you have to go and buy them (extra expense) and it will probably mean new/rehashed exhausts through to the transom to suit them. The direct injection was the cheaper (but still very effective) way of keeping things cool up there.

I don't know a whole lot about heat exchangers. I believe the biggest benefits are keeping salt water out of your engine when operating in that environment and giving you better control over the operating temperature of your motor. Again, I don't think they were all that popular purely for the ease of raw water cooling and again, the expense. Many of these old boats were fitted out by your typical backyard mechanic and cheap but effective was the way to go. I don't know that you would need a Chrysler specific heat exchanger if you decided to go that way. There are plenty of generic exchangers out there that would suit. Brian B. might want to comment after having done some research recently into heat exchangers.

I think there's a couple of schools of thought on plumbing engines (raw cooling water systems). I have seen engines where the water is sent to the exhaust manifolds for preheating prior to entering the engine block. This removes the supposed cold water shock when water enters the engine. The water then exits the block and passes through the exhaust manifolds and is then sent overboard via the exhausts. Others send the water through engine oil cooler (when fitted) for preheating prior to entering the engine, then from the engine to the manifolds and then overboard via the exhausts. Others are just straight into the block, then out through the exhausts after passing through the manifolds. I'm sure there are other set ups as well. The cooling water is usually injected into the exhaust pipes immediately downstream of the manifold.

If your cylinders are as low as you say, I would agree that elbows are probably a smart move. Plenty of people before us have found out the hard was that water is definitely incompressible and will eventually bend something.

Greg

[Bob Vic]

Hi Nick - there is some sound advice therew from Greg. For what it is worth I recently did a 318 as a mid mount in a 1964 Lewis. I decided to use a set of Rolco risers - these bolt straight up to the exhaust manifold. They are expensive to buy new, but you can sometimes see them on eBay with a manifold attached (rarely a 318 manifold) which makes them a viable proposition. With regard the heat exchanger I am not a big fan of using them in a ski boat. I reckon your engine will wear out before it rusts out. There is a neat Rolco thermostat unit that will help to keep the temperature in your engine about right. It is designed for inboards and I have one both Rebound and Turbo Fire. My experience is that they operate quite well.

As you delve into your set up more, you will quicly learn that there is no right or wrong way, but a way that works best for your set up.

Good luck.

Bob

[propellerhead]

Thanks heaps guys - that's the exact sort of advice I was after. I have to do the hull first - strip, degrease, rebuild etc. etc. so will have a year or two before the engine gets done. In that time I'll keep an eye out for a couple Rolco exhausts & risers as suggested. Yeah a 318 is hard engine to gets some bits for, but it's in there so will stick with it...

The original exhausts are a tribute to backyard Aussie mechanics & I think they deserve cleaning, framing & sticking on the wall - honestly!

Greg when the boat was at rest the outside water came into the main exhausts to just under the rear engine ports. Wondered why it was so bloody hard to crank over - must have been trying to push 20 litres of water Raw water is prewarmed thru the sump then into the water pump housing.

Bob I think I'll take your advice about the heat exchanger - a lot of extra expense for an already old engine. If/when I rebuild it, I'll have another think.

Bob one more question - I assume the risers still separate the exhaust pipe & water jacket until they drop down again? Sorry 'bout ignorance, just haven't seen these first hand yet (have to get along to a meet).

Cheers! Nick W.

[Bob Vic]

The risers have a water jacket around them just as the exhaust manifolds do. The risers are cool to touch externally. I'll see if I can find a pic of these and post it here.

Bob

[mccaughd]

Hi Nick,
I have rebuilt my 318 for my boat before i did the hull. If i can be any assistance please let me know, but it sounds like i have the same questions as you.

By the way, were are you located? I have a vague recolection your in SA. If so, drop me a PM as it sounds like we are doig very similar restoration projects.

Regards
Damien

[propellerhead]

Hi Damien. I'm up in Grafton NSW. Will be asking lots of questions along the way so would be very keen for any help I can get, and give, along the way. Cheers! Nick W.