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boatnut
04-08-2015, 01:09 PM
Actually this information is not exclusive to the H&M log manifolds that we are working with but could be appropriate for other situations also. We are working on our 1969 18 (which as you can gather from other threads now includes a tank change) with the goal of having it look like it did when it left the factory in 1969. So included in our work is going through the engine but with the goal of having it externally look like it did including all the H&M hardware, decals, etc. We are using the same engine as originally in the boat but internally we are making some changes to the 302 (hydraulic roller cam, stroke to 331, GT40 heads). However we want to keep the H&M exhaust manifolds. This is not about that decision, we know they are not the best manifolds, and that there is some loss of performance and risk by using them but they look so clean and are the essence of the H&M marined engine in our opinion. We have had some erosion of the aluminum in the manifolds going on where the exhaust flow/heat enters the ports of the manifold (for some reason it is more evident on the two rear cylinders of the engine). About 20 years ago I had someone build a little aluminum up on one of the ports to fill an eroded pit. This time we noticed the other manifold had a similar pit. When we checked with a couple of good aluminum heliarc guys, they did not want to fill the pit (maybe 1/8" deep or so) as they could not tell how much aluminum was left and they did not want to blow through to the water jacket. Our engine guy suggested checking on some of the places that do ceramic coating to possibly protect the aluminum from the exhaust heat. He said they are using more and more ceramic coatings on piston tops, combustion chambers, etc. as thermal barriers and to control (lower or increase) heat flow etc.

I then talked to several companies that did this type of coating. Most were involved with coatings for the aesthetics, such as external coatings on exhaust headers etc. But some were using the coatings for protection of parts like we were after. I ended up with Performance Coatings in Washington state and talked to Brad Gua (www.performancecoatings.com ). They have lots of experience with using these coatings for various reasons (primarily corrosion and thermal protection) on marine manifolds. When I described what was going on and sent some pictures to them, they said they were very confident they could stop the thermal erosion going on in our manifolds by coating the ports with a thermal barrier ceramic coating they use that is made by Techline Coatings. They said they could only clean and prep the aluminum a limited amount due to access but they were confident they could protect the area where we had the most erosion. We also had some pitting where the exhaust entered the two risers so the inside of the risers were coated also.

Attached are some pics that show the pitting on the manifolds and risers and some pics after the ceramic coating was applied. The cost to prep and coat all these ports was $200. The coating feels smooth and hard like glass.
819428194381946819488194981950

Our plan is to use these manifolds for a season or so and then remove one and try and determine if the ceramic coating is in fact doing its job of protecting the aluminum from the heat erosion. If it seems to be working we will stay with them. If the coating does not seem to be holding up we will consider changing over to a new set of aluminum or stainless manifolds (as you all know the choices for a small block Ford are limited). We do realize that blowing a hole between the exhaust passages and the water jackets could cause extensive engine damage.

Anyway, the purpose of this post is to share this "experiment" and provide some info in case there are others that are trying to save these manifolds. Ed

mattyboy
04-08-2015, 03:27 PM
have you sourced all of your HM parts for the rebuild ? The water pump parts are hard to find if you have a source from them please share they have been discontinued for some time and board members are always looking for them. There is also a HM hi po 271 k code motor on ebay original and complete re done by HM a few years ago it may be worth a look instead of reinventing the wheel.

If anyone has leads on the HM pump stuff post them up the chicken boat needs one

Scott Pearson
04-08-2015, 03:49 PM
I have one. Not going to come cheap.

boatnut
04-08-2015, 06:09 PM
Not sure how we moved from manifolds to water pumps but I think Depco Pump can provide some parts for these pumps. Go to their site and search on the Jabsco model that H&M used 11850-80 I think. http://www.depcopump.com/search.php?zoom_query=jabsco+11850-80
This url might get you there also. Good Luck, Ed

mattyboy
04-08-2015, 06:31 PM
Not sure how we moved from manifolds to water pumps but I think Depco Pump can provide some parts for these pumps. Go to their site and search on the Jabsco model that H&M used 11850-80 I think. http://www.depcopump.com/search.php?zoom_query=jabsco+11850-80
This url might get you there also. Good Luck, Ed

just giving some advice I just went thru a HM rebuild and I am helping a friend on another one, parts are hard to find and when you do find them they are big bucks . Just a heads up when you go to rebuild the old motor. we found a jabsco last year for 1800 bucks almost what a short block costs. thanks will give depco a call

mattyboy
04-09-2015, 09:35 AM
yes it is all coming back to me now after a call to Depco

the 11850-80 discontinued 16 years ago they have some parts the minor rebuild parts in stock ( basically the impellor and paper gasket) the major rebuild parts are no longer available a\but they "may be able" to rebuild if not totally shot .

the 11850-0711 was the replacement but not a direct replacement some adjustments need to be made this pump is also discontinued now

the lovejoy and spider can be found with some searching the HM pulley might be a tad harder to find.

there is a 11850-0711 used on ebay now for 800 bucks

http://www.ebay.com/itm/Jabsco-11850-0711-Engine-Cooling-Pump-/281597206119?pt=Boat_Parts_Accessories_Gear&hash=item4190805e67&vxp=mtr

again just some input from someone who has gone thru it , before you invest time and money that may be wasted.
I have come to the conclusion that originality is nice but it doesn't make sense to redo a 45 yr old boat to make it last another 45 yrs and put 45 yr technology back into it. Parts are hard to find now what will it be like in 5 yrs never mind 10 yrs.
Most board members know the chicken boat an all original 71 it sat on it's lift last year trying to source HM cooling parts.An original boat is neat but a 45 yr old classic tearing up the lake is much neater. It is one thing to build a museum piece and then have it not running because of lack of parts and it is another thing to build a running enjoyable piece of history that will last and run another 45 yrs.

I am not going to go the original route again as far as power and drive are concerned, been there done that . modern power from now on.

just my thought good luck on the project.

boatnut
04-09-2015, 12:13 PM
yes it is all coming back to me now after a call to Depco

the 11850-80 discontinued 16 years ago they have some parts the minor rebuild parts in stock ( basically the impellor and paper gasket) the major rebuild parts are no longer available a\but they "may be able" to rebuild if not totally shot .

the 11850-0711 was the replacement but not a direct replacement some adjustments need to be made this pump is also discontinued now

the lovejoy and spider can be found with some searching the HM pulley might be a tad harder to find.

there is a 11850-0711 used on ebay now for 800 bucks

http://www.ebay.com/itm/Jabsco-11850-0711-Engine-Cooling-Pump-/281597206119?pt=Boat_Parts_Accessories_Gear&hash=item4190805e67&vxp=mtr

again just some input from someone who has gone thru it , before you invest time and money that may be wasted.
I have come to the conclusion that originality is nice but it doesn't make sense to redo a 45 yr old boat to make it last another 45 yrs and put 45 yr technology back into it. Parts are hard to find now what will it be like in 5 yrs never mind 10 yrs.
Most board members know the chicken boat an all original 71 it sat on it's lift last year trying to source HM cooling parts.An original boat is neat but a 45 yr old classic tearing up the lake is much neater. It is one thing to build a museum piece and then have it not running because of lack of parts and it is another thing to build a running enjoyable piece of history that will last and run another 45 yrs.

I am not going to go the original route again as far as power and drive are concerned, been there done that . modern power from now on.

just my thought good luck on the project.

Well I certainly understand your position Matty. It might be less costly if all time is accounted for to just put a mercruiser pkg in our '69 and move on. However our engine, drive, water pump, manifolds etc. were all working when we tore it down and we want to resurrect the magic that this simple power train and overall boat had and is. The 302 marined by H&M is classic in its simplicity. Hopefully (and I understand your point) we can continue to enjoy that and can manage the risk involved. In cars and boats and planes, keeping the old stuff usable and viable is more difficult that switching to current technology but much more elegant and rewarding to some of us. At least we are going to give it a try. But, thank you for your advice. When the pain exceeds the gain we will cop out and put an exciting Mercruiser V6 package in the boat and just take it out of the "classic" category :).

I had a different experience talking to Depco Pump, they have all the parts for rebuilding the Jabsco pump used by H&M unless they need a new shaft or a new end plate. Those they can make. The major parts kit is available but pricey at 200., they are going to rebuild our pump and assuming it does not need a new shaft the price will be approx. 300. (includes new bearing, all seals, wear plate, impeller, etc.). It is costly but bronze marine pumps are just costly. Dan in the service dept at Depco is very knowledgeable of these pumps and likes to restore these old parts. I probably should move this info to a new thread to facilitate others finding it.