Dhadley, how far on heads....

[walleyehed]

When I rebuilt my powerhead last spring, I used a sierra gasket set, and I'm sure the head gaskets are std.<br /> Because of my altitude, I've kicked around the idea of planing the heads...???.....<br /> Do I want to have this done, or should I find thinner gaskets, if available?????<br />I know a thicker gasket is available but haven't run accross "thin" gaskets. If I plane the heads, how far could I get by with??? (wiseco pistons). <br />Oh yea, 97' crossflow 115hp Jonny...

 

[rodbolt]

Re: Dhadley, how far on heads....

hello<br /> there are some high altitude modifications availible if needed. dont mill the heads. you would have to take atleast .04 to .06 to see any compression increase. now that you have an increase in compression you have to use more air/fuel to cool it. there are some mods to help high altitude but shaving the heads is not one.<br /> good luck and keep posting

 

[ledgefinder]

Re: Dhadley, how far on heads....

The website screamandfly had a thread on planing crossflow V4 heads a while back (try searching their archives).

 

[walleyehed]

Re: Dhadley, how far on heads....

OK, I wasn't too clear I guess on this.<br />Since the early 70's we've been running (setting up) the V4's for 4000ft and above by going .003-.005 leaner in jetting, advancing timing 4-8 degrees, and running a minumum of 90 octane in these because of the timing advance (on the cross-flows). Most people at sea-level do not understand the lack of O2 here, running the same C.I.D., we lose 12-15% of the available power just being here.<br />Planing the heads is just one item we never done to a factory new engine as part of the set-up, and yet there are semi-high comp heads, and straight high comp heads to be run with the same pistons. I was wanting to get around buying new heads by planing if possible. I've done the port work, and the polished exhaust. It pretty well will put the hurt on a 120 looper (stock) now, on a very simular boat.<br />I will check screamandfly, I haven't been there for awhile, so I'll try and catch up.<br />Thanks for both of your replys, but I'd still like to here from Dhadley, as I know he has done all that COULD be done to the crossflows right up to the point of coming apart.....

 

[AUGIDAWG]

Re: Dhadley, how far on heads....

What kind of port work did you do?<br /><br />If you have raised the exhaust port, (changed the port timing) you will need to mill the heads to get the compression back.

 

[walleyehed]

Re: Dhadley, how far on heads....

I squared the ports, taking small amounts between webbing.....did not go "higher".<br />I raced snowmobiles for yamaha for years and porting is a minor task if understood.<br />I've had very good luck with this on several engines now. I just need to figure out where I'm at with heads???

 

[Dhadley]

Re: Dhadley, how far on heads....

What do you mean "up to the point of the motor coming apart"? I crossed that line many times! Lol!<br /><br />Seriously I am not a fan of cutting the crossflow heads unless you have a "commercial head" that has the large lip. Even then I would only cut it to the point that it matches the "recreational" head. For added power I would rather switch heads to an earlier set which has the different chamber configurations. That changes the swirl pattern which produces the power.<br /><br />Sorry about taking so long to answer -- Im away from my office this week.<br /><br />Good luck!

 

[walleyehed]

Re: Dhadley, how far on heads....

Thanks, and no problem....I know you can't be there every minute of the day.<br />I've got a pair of semi-high comp heads that match my piston tops I think I will try.<br />These are the ones that have some filler (Factory) around the standard oval. I'll put them on and see how much clearance I've got and go from there.<br />Thanks for the reply! <br />Kenny

 

[wilde1j]

Re: Dhadley, how far on heads....

Your power is down even more due to altitude ... the rule of thumb is 4%/1000' above MSL. My father had a marine business in Santa Fe, NM (~6800' MSL) and most lakes there were at 5000' or higher. The best you could expect by rejetting was about 80% of nominal HP. Most mfgrs would ship motors already rejetted, but we changed a bunch of sea level motors which moved into the area.

 

[R.Johnson]

Re: Dhadley, how far on heads....

KennyB: When you squared the ports , you said you squared them between the webs, what about the outside on the outside ports? The reason I ask is I have a 1973, 135 that has the tuned exhaust laying around the shop I would like to rebuild. Did you make any changes to the exhaust tuner, or should this be left alone? What about intake ports? I've got a 15.5 ft. Checkmate I want to run this on.

 

[walleyehed]

Re: Dhadley, how far on heads....

R.Johnson, my experience with intake ports has been to leave them as is, unless you are changing the entire induction system, such as carbs, intake manifold work and what-not. I would also recommend you leave the casting marks in the intake ports as the "roughness" acts as a turbulator, better mixing of fuel/air mixture.<br />There are alot of rough areas in the exhaust port areas that can be smoothed up, and you can take "a little" at the webbing in each direction, left/right, but you have to be careful in that area, because if you take too much of the webbing, what portion is left can bow slightly and cause a high wear area very quickly. the outside 2 ports (either side) can be taken a little farther, but you still want a nice round, although smaller radius, corner.<br />You want these as uniform as you can make them, and finish with crokis(?) cloth on a dowel with a slot, in a dremal, and by hand where needed.<br />Edit: I polished the bubble-back exhaust chamber to a mirror finish, and it takes quite a few hours to get it all.

 

[R.Johnson]

Re: Dhadley, how far on heads....

KennyB: Did you do your ports with a mill, or by hand? Did you make any changes to your exhaust tuner, other than polishing? What type of boat, and prop are you running, and where are you at, performace wise. Winter is really setting in, and I need a project.

 

[Dhadley]

Re: Dhadley, how far on heads....

A Checkmate, huh? Ther's a really neat series of articles coming out in either Trailer Boat or Bass & Walleye -- maybe both -- about a little Checkmate and a V4 Evinrude.<br /><br />Keep an eye out for it.

 

[ledgefinder]

Re: Dhadley, how far on heads....

What's the story with running the filler blocks inside the tuner? In theory they should be important to the pulse tuning, but I've read here and elsewhere, at times, that in practice the Xflow V4s run better without them. Any comments?

 

[R.Johnson]

Re: Dhadley, how far on heads....

Dhadley, or KennyB: My idea is to build the lightest engine I can. 1973, 135, 1979 1 3/8 carbs from a 140, with rubber stuffers, fiber reeds which I have. I have taken out the rear seat, and built in gas tank. Replaced front seat's with #5 units, and run on a 6gal. can. I had a tonneau cover made to cover rear of boat up to the front seats. I wii rebore engine just enough to clean up, and run Wiseco pistons. I have a 24" Raker repitched to 25". Dhadly! looking forward to that article, I'm sure it will give me other idea's, what RPM did you run those cross flows? I'm the kid who still makes his own toys.

 

[walleyehed]

Re: Dhadley, how far on heads....

R.Johnson, If you're going all out on an engine rebuild for extra-high performance, Dhadley is the man to answer those particular questions.<br />As for how I ported mine, I measured an equal distance from outside, in, for a starting point, and from there, used a bore mic to stay as close to equal in demensions as I could. the final smoothing was done by hand.<br />RPM max on my engine has been about 6500RPM, and I haven't let it go any farther...that was with a modified 13X17 Stainless. My boat is a deep-V starcraft, and really doesn't do well above about 49-51MPH, as it wasn't made to go that fast anyway. I'm running 6 inches total set-back and 3.75 inches high. I'm running an older OMC RAKER, 13.5X18" thats been modified with a little more cup. I can turn this about 5900RPM., but I'm dealing with high altitude issues so I feel I'm doing very well with this set-up, thanks to the help of Dhadley.<br />Just before the super-cold hit here, I ran 2 days in a row at the 'Bluff's and got a chance to run against a simular boat with a little more ponies.....18ft crestliner with a newer Johnson 130hp. We started from idle in gear, and I had to pull back halfway waiting a few seconds for him to plane. At that point, I just left the hammer down and started to trim-out to usual position (boat attitude)...I just walked away like he had a problem. When we got back together, he said the 115 on my cowl was not accurate, no way. He thought I was jerkin' his chain. Had to be bigger, he said. I finally got him close enough to read the data plate to convince him, at which point he noticed the set-back and heigth of the engine....I told him "thats the key" right there.<br />Want high performance....Dhadley is your man...I just followed his lead on my set-up. The engine is my work, but the set-up credit goes to him.....

 

[Dhadley]

Re: Dhadley, how far on heads....

We found that on a typical ski boat that leaving the exhaust filler blocks out we gained almost 200 rpm. Once you get the Boyesens in there its just a matter of set up to get your rpms. We ran a cross flow with stock ports (stock "as produced") and ended up at 7400 rpm. That was not on a ski boat -- that was on an Allison (pad bottom). We found a bunch of power in the intake manifold. We cut the "wall" out between the intakes and used some late model 1 1/4" carbs. You have to seal up the base side of the carbs to do this. Its kinda hard to explain but if you look at the base of the carb there is a passage there that goes to atmosphere. Obviously you have to seal that off once the intake wall is removed. We just filled it with epoxy.<br /><br />We were using the later model gearcase with a Bob's low water pick up and nose cone. Using the earlier gearcasemight be interesting which it is shorter to start with. We were also using the later model intake so you would have to look real close at the 73 to see about making it a plenium manifold. The earlier one -- in theory -- should be better since the runners are shorter (puts the carbs closer to the "signal").<br /><br />walleyehed -- Im glad youre having fun playing with those who have bigger decals. We used to run our Super Stock V4 aginst the Stock V6's. That was fun!<br /><br />Good luck guys and have fun!