Can a 1974 Chrysler75hp block be used to rebuild my 1989 Force 85hp block? UPDATE!!!

[Frank Acampora]

Re: Can a 1974 Chrysler75hp block be used to rebuild my 1989 Force 85hp block? UPDATE

Reeds and VEE blocks are the same on all 3 and 4 cylinder engines. There is no power to be gained by changing them. Even if you modify the engine and put in the later square-tipped reeds which are supposed to be more responsive, you will not gain power. Supposedly fiberglass aftermarket reeds or Boyeson reeds do give more power but I have never tried either. I HAVE tried streamlining the Vee block openings and manifold passages with again, no increase in power. I have tried drilling holes in the reed stop plates to help reduce reed sticking from the oil and again, there was no difference in power. So save youself some work. Unless you port the 75 and increase compression, it is going to produce somewhere around 75 HP no matter what you do.

You can try opening the reed stop plates a bit. There is a different and slightly larger specification for the higher horsepower engines but again, your gain will be minimal. Port timing is the major factor in horsepower development.

 

[tater76]

Re: Can a 1974 Chrysler75hp block be used to rebuild my 1989 Force 85hp block? UPDATE

I thought you might say that Frank. Just for giggles, I happen to have reeds from a 75, 85, and 90hp, set them side by side and they are in fact identical. The main reason for swapping the 85hp plate onto the 75 is because it had fresh gaskets that were not messed up from removal (I'm cheap ok). The same went for the fuel pump, intake covers, head, etc. Remember, I am not trying to turn the 75 into an 85, just swap good/newer components to make the 75 a runner.

Well.... hit a snag this afternoon. I put the flywheel on, torqued it down, gave it a spin.... well tried to give it a spin. It would not move Pulled it to find the flywheel base was binding on the bearing cage.
You may be able to see it in the pics.

I think after I tear it back apart, I may have to shave the cage bottom flat. However, this is just speculation at this point. Anyway, I will post some more pics of what I find.

 

[Frank Acampora]

Re: Can a 1974 Chrysler75hp block be used to rebuild my 1989 Force 85hp block? UPDATE

I never told you it would be easy! At the beginning I told you the 75 block was higher. Nya-Nya! LOL. LMAO! ROTFL!

You either need to shave the top of the block to lower the bearing cage OR Turn the outside flange of the bearing cage so it sits deeper into the ball bearing recess in the block. Making it flat will not help. You MAY also be able to mill out the center of the cage where the flywheel center magnet is hitting IF the seal will let you go deep enough.

Since there is not a lot of meat on the Stator mount/bearing cage, My vote would be to take the extra effort and mill the top of the block.

Now you know why building a custom car takes so long! Always unanticipated problems that take time.

But on the positive side, I have a 90 that I want to convert from distributor ignition and your learning curve will save me time and trouble. Thanks!

 

[tater76]

Re: Can a 1974 Chrysler75hp block be used to rebuild my 1989 Force 85hp block? UPDATE

Glad I can help Frank, LOL! We truly learn from others mistakes huh? I think we have all been here, you know you get a project alomost all the way done, and DOH!!! didn't think about that :facepalm: but seriously though, the newer bearing cage has a drop that rides the bearing approximately 1/16", and another ledge approximately 1/16" so what if I have these milled flat and retain my spacer over the bearing? That would gain me another 1/16" or so lower. I have an extra cage (in the picture) to play with. I just hate to alter the block to the extent of not being able to put the original equipment back on, in case I decide to sell the block that is. Plus, I don't really want to pull the powerhead from the leg again (just put in new seals).

You can see in the pics the ledges that I am thinking could be milled to gain clearance. Also, If I did mill the bottom flat, and it was still too thick, I could take a 1/16" off the top side too. The only issue I see with this is the stator riding too high in the flywheel and possibly rubbing?

If you look carefully, you can see the space in between the cage and the block. This is the part that I think is causing me issues.

 

[Frank Acampora]

Re: Can a 1974 Chrysler75hp block be used to rebuild my 1989 Force 85hp block? UPDATE

I would not mill the bottom flat as the "plug" positively locates the shaft seal. However, I was down in the garage today and looked at a couple of mine. The seal sits low enough that you CAN mill the square section with the four ersatz bolt holes (first photo). After all, all you really need to clear is the trigger magnet, and I believe that the stator has enough space above it so it will still clear the flywheel. However, this is one thing I would double check by "mocking-up" before milling and final assembly.

 

[tater76]

Re: Can a 1974 Chrysler75hp block be used to rebuild my 1989 Force 85hp block? UPDATE

I thought the same thing Frank, it would be foolish to remove the plug, so I decided to try removing material from the top side.

So I spent ALL DAY on making this work!!! UUUHHHHHGGGGG!!!!!! phew! ok now I am better. Here is how I did it, pulled the flywheel to see where it was hitting on the bearing cage, pondered a bit, and gave my mechanic buddy a call. I went to his shop with the spare cage, and had him mill off 1/16" on top of the cage where the flywheel was binding. It took about an hour in between answering phones, and other customers. So back I went, installed the cage, installed the flywheel, torqued it down to 90ftlbs, spun it a few dozen times, removed flywheel, checked for rubbing.

At this point I found that there was still a small amount of rubbing, so rather than drive another 20 mins to get it shaved further, I broke out the file and carefully/skillfully shaved it down another ten thousandths or so. Then I repeated the install of the flywheel, torque, spin, remove, check. I did this 5 more times until it was not rubbing at all!!!!!! (should have driven the 20 mins). However, we have success!!! everything fits, and moves as it should. Plus.... I got it mounted to the boat!!!!

Now, I am not familiar with this type of mount, so is it acceptable to use the wood (see pic) for fill in? I want to do this right, as I now have way to many hours in it to halfast the mounting.



Tomorrow I wire, plumb everything, drill mounting holes, and try to fire it

 

[Frank Acampora]

Re: Can a 1974 Chrysler75hp block be used to rebuild my 1989 Force 85hp block? UPDATE

The wood is not necessary at all! In fact, it is probably worse to use it. The "tits" on the transom clamps are there simply to ease installation. You hang and center the engine, then use a bic "C" clamp or pony clamp to bring the transom clamps tight to the transom. Using a long 1/2 inch bit, drill through the top of the two top holes, through the transom, so the engine can be raised one inch without re-drilling. Use 1/2 inch stainless bolts with brass nuts if you can find them. Put the bolts through from the engine clamp side and put an extra thick 1/2 inch fender washer under the nuts. Use 3/8 bolts and nuts again in the top of the group of two.

Those transom clamps tend to corrode and split open right at the bolts from the contact of two dissimilar metals. Therefore, liberally coat each bolt with silicone RTV and squeeze a good bit into the holes too.

Remember to insert the steering cable before mounting the engine. Sometimes it is damn near impossible afterward.

 

[tater76]

Re: Can a 1974 Chrysler75hp block be used to rebuild my 1989 Force 85hp block? UPDATE

DOH!!! guess what I did... bolted the motor without the steering inserted :facepalm: Oh well, on the other hand it is running!!! Yep it fired right up with no major issues. Now, I am at a stopping point where I need some advice. I set the timing to tdc, (lined up the single lines) fired it up, put the timing light on top plug wire, checked it out. The mark was over an inch to the right when facing the carbs! I then turned the adjuster screw until the tdc mark on the flywheel lined up with the block. Is this where it should be at idle? I read your sticky, did all the adjustments, I just want to make sure I get it right.

Ok, I screwed up another thing too :facepalm: I start the motor, run it, turn the key to shut it off, and it continues to run. It did not do this upon the first few times of running, so I am at a loss here. I know it is likely something I hooked up wrong, but where do I begin to troubleshoot this?

Thanks again for all the support on this project, and for keeping the laughing at my absent mindedness to a minimum I will try to post a vid of FrankenForce2 running.

 

[Frank Acampora]

Re: Can a 1974 Chrysler75hp block be used to rebuild my 1989 Force 85hp block? UPDATE

Now, come on--How many times have I said that timing is set at WOT, 30 degrees before TDC. Timing at closed throttle or idle is a function of WOT and can not be changed. It will not necessarily be at TDC. So now re-do the timing at WOT to be certain it is correct.

Remember that the wiring is different on the later electronic ignition. Blue is jumped to ground and white and blue are attached to the "M" terminals on the switch. Basically, to stop the engine you must ground BOTH white wires, one from each CD box, otherwise the engine will continue to run on one or two cylinders. Yes, they will run like that.

 

[tater76]

Re: Can a 1974 Chrysler75hp block be used to rebuild my 1989 Force 85hp block? UPDATE

True True, I should have known better. Timing these motors has made me nervous for a long time now. I am a very visual learner and reading directions often makes me second guess myself. Now if I could only afford to drag my boat the couple of thousand miles to your place Frank, you could visually show me how to set it up LOL

I have read all the threads I could pertaining to anything timing, and am wondering if I am making this harder than it needs to be. If I get the motor fired up, put the timing light on it, open throttle up all the way while checking the mark orientation, then adjust timing one or the other direction as necessary to reach 30 degrees? and to be clear on the timing marks, I have a cluster of 3, little, big, little, and one single mark a few inches to the right. My 30 degree mark is the far left little mark right? Sorry to sound so uninformed, but I want to be dead sure of my work here.

 

[Frank Acampora]

Re: Can a 1974 Chrysler75hp block be used to rebuild my 1989 Force 85hp block? UPDATE

The group of three to the left (looking from inside the boat toward the engine) is 32, 30 (big), and 28 degrees from left to right. The single mark to the right is TDC. You can static time the engine by removing and grounding all four plugs, setting the handle to WOT, and cranking the engine with the ignition key on. Static timing should be 28 degrees. That is, the 28 degree mark should line up with the block pointer when the light (clamped on top plug wire) stops it.

 

[tater76]

Re: Can a 1974 Chrysler75hp block be used to rebuild my 1989 Force 85hp block? UPDATE

See, glad I asked I would have been off 2 degrees. That is the most clear explanation I have heard yet. I will set the timing, but I have to wait for a water test. I had to order a new impeller, and the lower is going to the shop tomorrow to get the skeg repaired. Maybe the end of next week before I get the final results.

Thanks again for all the help Frank and Lucas, I will post a vid when I get it out on the lake.