35mph @ 3200 WOT - 4 cylinder Chrysler

Arawak

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Aug 27, 2010
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Finally splashed my rebuilt 1988 Bayliner 17' today.

Was very gratified to see that she gets up on plane easily, and has about 5mph more than before (wet foam), but now that I have a tach I see that it maxes out at about 3200 rpm, at which point she's doing 35mph according to the GPS. I think this means it has too much pitch, does this seem reasonable?

The FrankenChrysler was built by an older fellow who used to own a Chrysler dealership, out of several motors. The lower unit is aftermarket I think, and takes Merc props, I was told. So, I'm not sure how to tell what pitch/diameter prop I have, and what I should try.

Or am I barking up the wrong tree entirely?

Behold the FrankenChrysler...

bZB_rOC6XWRSknuwTfEJqh8fiUNDSsQX0awa932vbdw=w1258-h943-no
 

jerryjerry05

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Nothing Franken about your motor.
It's all Chrysler.
You neglected to mention the HP???
If your getting 3500 and 35mph I'd check the tach.

The prop on there???
The shaft coming out of the lower is a Chrysler prop shaft.
Look up a 1979 100hp and check out the gear housing.
The prop looks like a ???? Who knows.
Someplace on the prop is a # look close.
 

Frank Acampora

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That is a stock one piece lower unit. The prop, however appears to be from the old two piece lower unit and re-hubbed to fit the 15 spline one piece drive shaft. This lower unit uses the same spline count and diameter as Mercury outboards BUT the casting is 1/4 inch smaller in diameter. THUS you can use some Mercury props and ALL one piece Chrysler props. You can also use Force props. There is NO DIFFERENCE in performance between closed hub props and thru-hub exhaust props.Since Chrysler designed and produced the one piece lower unit in 1978 your engine can date from then up until 1984 if it is original paint.. HOWEVER, the hood is earlier and no telling when the block was made. If it is original white it can be anywhere from the late 60s up until1984.

If you are topping out at 35 and it is a 100 or 105 then the speed is about right and check your tachometer. If it is a 120 or 125 up to a 140--and you don't know because it is a parts assembled engine--then speed is a little low. Check compression. The 100 and 105 used small venturi WB carbs. Some 120s used small WB carbs. Some 120s and all 125-140 used large venturi TC carbs.

Post a good photo of the head and one of the carbs.

That prop SHOULD have the pitch stamped on the hub, between two blades. It will be nominal 13 inch diameter and it appears to be a higher pitch like 19.. A big 4 cylinder engine on a 17 foot hull should swing a 17 or 19 pitch prop.

HOWEVER: While that prop is a Michigan prop it is not as efficient as the stock props. Buy
or borrow a nice used aluminum prop to test and if the pitch is correct buy a stainless prop. You should see a jump of a couple of MPH with the stainless.

The engine appears to have a newer power TNT pump. HOWEVER the original leg did not have power trim as evidenced by the tilt lock in the photo. GET rid of the tilt lock. It is no good for towing and if you do forget about it you will damage something if you try to tilt the engine. Either get a transom saver or search ebay for a stock trailering bar that fits into the transom clamp holes.
 
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Arawak

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Wow, you guys are pure gold!

So, the story, as I remember it (and subject to be wrong) is that the block is a 105hp, and the head + pistons are from a 135hp. Bits and pieces came from various other 4 cylinder Chryslers motors. Murray rebuilt the motor as a project but AFAIK it was never run on a boat after rebuild. He advised i run the oil a bit rich for the first few tanks. This is what I remember from my friend who was the intermediary.

So, as requested, I went and took a bunch of photos, which are below. The nutshell...

Tach is brand new but it's an ebay cheapie (no name)
Prop is stamped 13x17
The carbs are Tillotson TC-5D -- I think those are from a 135HP and match the head.
The TNT pump is brand new as of last Wednesday.
I do have a transom saver, it is normally in use. Will remove the lock as advised.

Last year I had to reset the timing (long story). I followed the instructions posted on this stie, and think I got it right. But maybe I didn't...?

Also, the carb linkage was disconnected when I put the motor back on. Just noticed the two buttertfly valves and not synced. Per comments from Frank on other threads I have left the carbs alone as I wouldn't know what I am doing without guidance.

But it seems that this motor is essentially a 135hp, and should have no trouble with the prop that's there?

Now the photos:

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s4TdPVNZvDtpHYl6p17z4hobZ29hpxCdd4x7urz_OdU=w1258-h943-no


Y1fLirKxMnMHh1_4tCjxPEhFSE_I9f4KBav2UdpAeK4=w708-h943-no


LZ_wRE2uRatC2udC8yN42qIo_w4nqNCwIa5wWV_BdzE=w708-h943-no

AFSdX0nDaEsy_sWSeVYCWhMmnHqp9yYHPhiwXlnRZNU=w1258-h943-no
 
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Arawak

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Oh, one other thing I forgot to mention. The motor started losing power at the very top of the throttle. So I wasn't actually wide open.
 

Frank Acampora

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Well, it is a distributor Motorola ignition engine so that puts it prior to 1980 or 82. I forget exactly when Chrysler went to Prestolite ignition but it was right around that time. However: The distributor has the neutral interlock mounted on it so that does put the block or at least the distributor. earlier. The distributor is single wire so that means it is points and not electric eye. Be certain the points are set to .010 on a high lobe. It does have the big TC carbs so unless the P.O. swapped manifolds (I do it all the time) it is not a 100 or 105. It does not have two fuel pumps so it is not a140. The engine terminal board is mounted on the exhaust cover rather than the engine parting line halves and the wire loom is the old fashioned kind indication an earlier engine block.

If the carbs are not opening correctly that is part of the problem. Synchronizing them to timing is not difficult so you should follow the instructions in the video.

Going flat at full throttle is a fuel problem Check the tank pick-up, check the lines and quick-connects and if you haven't already done so change the fuel pump gasket and diaphragm. Don't worry if you can not find your engine listed. ALL Force 3 and 4 cylinders used the same pump up until Mercury started modifying the engine. Search for a 1989 or so Force for parts other than ignition.

AS I mentioned above, get rid of that prop. Look on ebay searching " Chrysler Force propellers" and buy a good used closed hub Chrysler prop. Don't settle for an expensive one. wait until you see one for less than 60 bucks or so. Some of these guys try to charge premium money for old props--over 100 bucks. I try to get used props for around 40 so if I need to sell one I don't have to rape the buyer.

That engine block was rated at the crankshaft so given all the variables, I suspect that 35 right now is respectable.
 
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Arawak

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Thanks again. I'm perfectly happy with 35 mph... that's as fast as I care to go on Lake Erie. My main concern is that I'm not abusing the motor. I wonder if the 12 pole tachometer I bought is really a 20 pole. I ordered this sparkplug wire tach to check the accuracy.

Found a prop on ebay, and will order the Sierra 18-7806-1 Fuel Pump Kit later today.

Will adjust the carbs tonight, and hopefully water test it again next weekend.
 

Arawak

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Thanks SkiDad, but it's actually pretty light now. 1275lbs from the factory... add batteries and gear, still not that heavy.

I found a 13x19 OEM, should be here in a couple days.
 

Arawak

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Frank, I went back to your excellent youtube video on carb synching and timing last night and synched the carbs.

One thing I noticed was that as I advance the throttle the distributor moved forward, but at the very top of throttle, just where it starts to die, the distributor actually moves back. I don't think it should do this, please advise.
 

Arawak

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Can anyone confirm whether the distributor should stop advancing and actually move back at the top of throttle? Thinking I have something incorrectly adjusted.
 

Arawak

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Here's a video to demonstrate.

[video]https://photos.google.com/u/0/photo/AF1QipNdlNj5cG3CeS-oXb34sPDh93JNcek4TbiSEGIS[/video]
 

Arawak

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Ok carbs synched and timing reset. Timing was a bit retarded, maybe 29 degrees. Set to somewhere between 30 and 31. I only put Shell vmax 91 octane in it, mainly because it's ethanol free, but hopefully that's a suitable grade of gas. Dunno what marine gas was back in the 70s before Chrysler dialed back to 30 degrees....

Mechanically, it looks like the distributor is supposed to move back at full throttle - that's a function if the angle of the control arm and I don't see how it could be adjusted. No idea what function that serves though.

Fuel pump kit and prop come Friday night, so Saturday I'll take her down to Lake Erie to test it out.
 

Frank Acampora

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That slight retarding at full throttle is correct. In fact, in the old days, autos routinely retarded timing a bit at full throttle to avoid pinging. They had a vacuum advance and when you put the pedal to the metal, manifold vacuum dropped causing the advance mechanism to retard. Typically, with a complex automobile carb. at full throttle the mixture is enriched for maximum power and timing is slightly retarded.. Now, the computer does everything. The simple Tillotsen carb has no provision for enriching the mixture at WOT thus the engine is run very slightly rich at all speeds except full throttle.

Your Chrysler has a strictly mechanical distributor advance with no correction so set the timing at wide open throttle. At cruise it will be a little advanced but this will give you slightly better fuel mileage.

Chrysler originally had timing set to 32 Degrees BTDC. However , I think it was late 70s- early 80s, because of low octane marina gas they changed the specification to 30.

Premium fuel is simply a waste of money and some of the additives might cause some trouble. Your engine will run quite happily on 87 octane 10% ethanol, especially if you have retarded the timing a degree or two.
 

Arawak

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Just got in from the lake. Motor ran better at the top end, but no major differences on the tach, maybe a couple hundred RPM more.

10 gallons more gas, and two more people, topped out at 33 mph.

It did run somewhat rough at lower mid speed... maybe 1200-2000 rpm. Seemed fine above and below that speed.

Low speed jets?
 

Frank Acampora

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Nope! It's just a Chrysler. They all seem to run rough at the transition between low and high speed.
 
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