Torque & HP Open Discussion

Thought I would repost these photos over here.



Still planning on doing some basic flow tests but I think that won't happen until January when I get a little free time. It will take me until then to complete the refurbishing of my HM manifolds anyway.

The new heads shipped yesterday so I'm anxiously waiting for them to arrive. I'll post some pics and flow data once I get it then start pulling things apart after the first of the year.

I did pull my hiteks and commanderstyle the other day if anyone wants them for testing purposes let me know.

So heres a newB question for ya. When purchasing a cam can I get any cam advertised or is there a rot specific note I need to look for, or a specific place I should call, or a magic troll to put under my timing cover?

Comp cams can grind you one also. I think any specs other than stock will have to be custom ground.

Joe,
I would love to try the manifolds but I have a big problem. Our lake is down about 25' now due to the drought. Tree tops are starting to poke up in various places so there's no way I'm taking the Nautique out. I would love to do some testing but can't until we get some serious rain! It's not looking good for this summer!

Matt

Thanks guys!!

Holy holes there magicman!!!

Funny you bumped this Waterdog, I finally got some time this weekend to gasket match the intake to the new heads. Needed to remove lots of material but they came out pretty good. The factory port castings are not very uniform and even if they matched up good enough they could use to have some of the casting lines removed so I've cleaned up as deep into the ports as I can get. I still have some drum sanding to do but the heavy work is done. Took about 4 hours to do the intake.

Exhaust manifolds are coming back from the machine shop later this week after having all mating surfaces machined. I'll gasket match them next. Biggest problem I see there is I don't think I'll be able to open them up enough to match the ports on the heads so the exhaust is still somewhat of an issue.

Needed to remove almost an 1/8" of material


Partially completed port matching

79nautique wrote: Allen taper the cut when you do the exhaust, The flange is thick enough and it's much better to have a transition than a flat wall, think of it as adding a chamfer all around. Depending on how much needs removed and how deep you can go will drive the angle.

That's the plan Chris, problem is I'm switching over to Holman Moody manifolds and they are water jacketed all the way down to the block so there's just not much material fro removal and I'm concerned about cutting through. I'll go as far as I dare and then taper. Thanks

Lousy picture but all I have here on this computer. The arrows indicate the area on the bottom of the manifolds where the ports are water jacketed all the way to the head. Although I'm not sure how much I will have to remove yet I'll have to be careful, that's all.



The thickness of material between the bolt holes and the port "should" allow for a fair amount of opening but the stock ports on the HM and PCM manifolds are so much smaller than on these heads that I will have to settle for a happy medium. These ports are really designed for a nice set of headers but I'll make it work.

MaddMarxx wrote: Alan..Those heads look great, your Boat is going haul butt with them on it, What do they cost? And are you going to run the same Cam you are using now?

Mark, You can buy them assembled from Summit for less than $1000 but I got them bare through Cam research and had him do some porting and we milled them to get my compression up. He then did a 5 angle valve job and matched the springs to my cam. The porting wasn't mandatory but he talked me into it and I'm glad he did, he does very nice work. Take a look at the area around the valve guides compared to stock heads, it's amazing how much work went into that area to get it looking that nice. These same heads are available in aluminum if you want to go that route.

I am staying with the cam that was in the boat, after installing the 1.7 roller rockers it will be at .488 lift. If I was starting from scratch I would change the cam out but I think this will be a runner as is.

I wish I had them in front of me to take a look as I'm going from memory, I should have them back this weekend but you're probably right. I tend to be over-cautious with first time projects so I'm sure I'm over planning something that's fairly routine. Thanks for the help, I'll post some better pictures once I get going on them. I have the polishing just about done too, they certainly don't look like the above photo anymore.

Well it's 2009 and time for everyone to get back to working on solutions to worlds most pressing issues like the massive deficit of 60 mph correctcrafts, so we better get this thread back on the first page. I took the opportunity to measure the exhaust ports on a couple manifolds over the holidays and thought I would share the results for reference. On the hiteks   the opening is approx 1.29 inchs x 1.53 inches high the runners are big and smooth but have some dimpleing for the bolt heads. On my pcm manifolds that are ported as far as I would consider safe the openings are more peanut shaped. The port ended up about 1.45 high and near the top and bottoms 1.28 wide, however near the mounting holes they neck down to about 1.18. The runners are fairly smooth but restrict down quite a bit after the interface due to mounting bolt head dimples.

Alan, How big are the ports on the Rhs heads?

eric lavine wrote: I think some work could be done to get some good clean fresh air in the engine boxes, it gets pretty hot in there and air is pretty restricted and i personally dont think the engines breath enough...thats me though, dollar for dollar it is cheap to get more air in the compartment

While that might be an issue in some of these boats, particularly older examples it is not an issue in my 83, I have run it down the lake with no motor box and saw no significant change in performance, just louder and scarier.

Joe, I think as you are running, the wind over the windshield creates a vacuum, so i dont think it would help with the cover up or down.
I was more on the lines thinking of forced fresh air from the front of the boat...it just seems the little venting they have now doesnt matter

What's the logic in using the HM manifolds? Are they proven to flow better?