1967 Crysler 75hp cant make those high rpm's

[PeterW]

Hi all.<br /><br />Let me start by saying that I'm impressed by this site, it seems like there is a whole lot of know-how present here.<br /><br />Of course I have a problem to present to the guru's out there.<br /><br />Engine: Chrysler 1967 75hp, is this correct?<br />SN: 2052<br />Model: 75773<br /><br />I have just bought myself a new (used) boat with this engine on it. The problem is that it runs at idle and slow speed, but not when I try to give it some more throttle.<br /><br />This is what I've done so far:<br />I've "fiddled" around with the Rich/Lean screws in combination with shortening and lenghtening the gas rod to the carbs, to get the engine running "smoothly" at low rpm's. <br />When I push the throttle all the way up the engine seems to "dip" in rpm's before slowly building up rpm's to what I belive is a third of its potensial. However, when I push the throttle halfway up and manually push the carb gas rod it makes more rpm's but still not what I expect is high rpm.<br /><br />I have no way of measuring the actual rpm's.<br /><br />The middle carb is "leaking" drops of gas, any ideas on why?<br /><br />What is the consequenses of having the wrong firing sequence, and how do I determine which ignition cable should go to which cylinder? <br />Which is cyl 1, the top or bottom? <br />Which cable is nr 1, 2 and 3?<br /><br />The previous owner has changed/cleaned the carbs but not refitted/changed the gasket connecting the carbs to the engine. <br /><br />When examining the engine I noticed a fuelhose from the bottom of the lower carb not being connected to anything. After some closer look I located a suitable "nipple" on the underside of the air intake, and hooked it on there. What is the pupose of this fuelhose?<br /><br />What fuel should I use, unleaded/leaded 95/97/98 octane?<br /><br />I cincerely hope that someone can answer some, or all of my questions, and that I in return can use this new found knowledge to help someone else at another crossroad. <br />(And of course bring my chrysler up to speed )<br /><br />I apologize for my shortcoming in the English language, this is due to my Norwegian upbringing... <br /><br />Hope to here from someone soon.<br /><br />Best regards <br />Peter

 

[eurolarva]

Re: 1967 Crysler 75hp cant make those high rpm's

Hello and welcome to Iboats. The first thing you want to do is check to see if you are getting a spark on all three cylinders. Pull the spark plugs and look at the tips to verify that there is slight carbon on the tips. IF one is clean you could have a blown head gasket. The spark plugs for this motor are no longer availible which were Champion L4J. Use champion L82C if you can get them there.<br /><br />Low RPM can be from one or more cylinders not running or you could have fuel problems. The cheapest thing to do is to rebuild the entire fuel system. This is easy to do however getting the parts to Norway can be an issue. The fuel pump rebuild is 18-7806 fuel pump rebuild kit . I boats sells them and I believe they ship international. The rebuild kits for the carburators are 18-7037 carb rebuild kit <br /><br />That carburator leaking is not doing any good. My guess is all three of them need to be rebuilt. If you do this do only one at a time and do not mix parts from either carburator.<br /><br />IF you have the ability to do so get the compression tested before you spend too much money on this. That is a 37 year old motor and if the compression numbers are bad and you have to start rebuilding the powerhead it will be hard to find parts and pretty expensive. I am not sure how your octane works over there but 92 octane would probably work best and mix it with marine grade oil 50 to 1. If you have any more questions please ask.

 

[PeterW]

Re: 1967 Crysler 75hp cant make those high rpm's

Hello Eurolarva<br /><br />Thank you for the advice.<br /><br />The spark plugs currently on is champion L20V with a strange build. No gap to measure just a centerpoint and outer ring....<br /><br />I'll try to get the compression tested.<br /><br />The lowest octane we have here is 95, so I'll just have to go for that.<br /><br />Fuel system rebuild has been done to some extent by previous owner, I'll check how far he got....<br /><br />Is there a particular firing order on this two stroke engine, or is that irrelevant?<br />The reason for asking is that judging by the lenght of the cables it seems that the top/shortest cable is connected to number two7middle cylinder, and the mid cable is connected to the top....maybe I'm way off focusing on this?<br /><br />Anyway, thanks in advance and you will surely hear from me again, lol.<br /><br />Regards<br /><br />Peter

 

[eurolarva]

Re: 1967 Crysler 75hp cant make those high rpm's

The chryslers did not start using L20V spark plugs till 1970. The manual says they should be L4J gapped at 030 inch. The firing order is 1 2 3. The fuel system may have been cleaned instead of rebuilt. My guess if it has been rebuilt the carburator that is leaking needs to have the float readjusted. I hope you can convert inches to metric. I believe the spec of the float upside down it 13/32 inches from float bottom(now on top because it is upside down) to carb bottom. If yours is set that way change it to 1/2 inch instead that should stop the leak. If not you probably have a bad needle valve or seat in that carb and will need to get a new rebuild for it.<br /><br />Also verify these things. When motor is running is choke all the way open? With motor off when you advance the throttles all the way do the carb throttle shutters open all the way but not go beyond all the way? Also has all the fuel line been changed? YOu might want to be looking for an air leak somewhere. Does bulb stay hard? Check the o ring on the quick disconnect to the fuel tank. If this is broken or rotted it could cause an air leak. I hope this is a fuel issue. Someone else will have to take you through the electronics part of this<br /><br />Do you have a manual?

 

[PeterW]

Re: 1967 Crysler 75hp cant make those high rpm's

Hi again.<br /><br />I've had the boat out today, and managed to get some more speed out of it by tweaking with the angle of the distibutor and length of the rod controlling the carbs.<br /><br />Also changed spark plugs, resulting in no apparent change in rpm's. But at least now I know they are the right ones (mental note to myself: check the gap!)<br /><br />I'll check compression tomorrow and decide wether to go ahead with rebuilding fuel line.<br /><br />I'm sure my problems are fuel related.<br />When going from no throttle to WOT the engine reacts somewhat "normal" at the start, but there is almost no change in engine reaction in the last 3/4 of the sticks movement. The engine then slowly, very slowly, builds up some rpm's. But its still in the very low rpm's. After some time (less than a minute) the rpm's drops slowly and then picks up again. Some times the drop is almost stalling the engine, but when I then throttle down and up again it picks up again. To me this seems to be fuel related, or?<br /><br />I tried the links you gave me, and the fuel pump kit is available but the carb kit is discontinued. Do you know of any other supplier for the carb kit?<br /><br />Thanks in advance.<br /><br />Peter<br /><br />PS. When changing the sparkplugs I noticed that the lowest cyl had a "lot" of oil on the edge of the plug, other than that they were all lookalikes with some soot on them....

 

[eurolarva]

Re: 1967 Crysler 75hp cant make those high rpm's

If you have a mercury outboard parts dealer there use this part number FK10005. It is their carb rebuild kit and has all the parts in it that you need to do one carb. These also have new jets which I would not mess with. Do a web search on the 18-7037 carb kit. It is a standard carb kit and is cheaper then mercury kits.<br /><br />If you do not do the carbs at least do the fuel pump. From the problems you are mentioning you may just need a new diaphram. If yours is old it could be stiff or brittle or even have holes in it.

 

[PeterW]

Re: 1967 Crysler 75hp cant make those high rpm's

<br /><br />Compression update:<br /><br />Top cyl: 120<br />Middle cyl: 120<br />Lower cyl: 0!!!<br /><br />Even I can smell that this is BAD!!!<br /><br />After I've had a moment to digest these disturbing numbers I removed the top (plate with spark plugs)<br /><br />All cylinders were marked by their age, <br />top piston had a sort of brownish color to it<br />middle piston had a black look from soot<br />bottom piston had a sort of oily look.<br />All pistons were rugged/had an uneven surface at the edge of the "curve".<br />All pistons had some sideways slack (1+ mm), but no slack inward/outward except for the bottom wich had some slack but not much (1+ mm).<br /><br />In the two top cylinders, when the piston was at the top, I thought I could see the piston rings, but not in the bottom cylinder. <br />This makes me wonder if the piston rings are broken on the bottom cylinder?<br />I then checked for scratcmarks on the inside of the cylinder but I couldnt se any particular marks.<br />What other explanation can it be for no compression?<br />One thing I noticed, that seemed somewhat disturbing, was that the three lowest bolts (for the top) was greasy with oil and residue on the tips. <br />Are they entering the inlet/exhaust channels?<br /><br />How big a job is it to replace the piston rings?<br />I know nothing about outboards and how they are constructed/put together!!!<br /><br />I've followed the interactive guidance to quote for a powerhead and ended up here: http://www.boatmotors.com/motorpart...urer=1&year=1967&state=dc&zip=&hp=&disp=&cyl= <br />My question is what does Core and Core First mean?<br />And does Powerhead include everything above the shaft?<br /><br />By Norwegian prices I've paid for the boat and gotten the engine for free, so I'm willing to spend some cash on this project but not a whole lot of it.<br /><br />Any feedback for me?

 

[PeterW]

Re: 1967 Crysler 75hp cant make those high rpm's

Just wondering....<br /><br />I've been reading a lot of old posts, and a lot on carbon.<br /><br />Could it be that the piston ring on the lower cylinder is stuck <br />because of carbon and thus no compression?<br /><br />Just wondering (and hoping for an inexpensive solution) ;-)<br /><br />Peter

 

[scotiany]

Re: 1967 Crysler 75hp cant make those high rpm's

Did you remove the head also? Just wondering if you've got a blown head gasket. If so, it should be an easy fix. If it is, don't use any kind of sealant on the new gasket.

 

[eurolarva]

Re: 1967 Crysler 75hp cant make those high rpm's

YOu could replace the head gasket and try doing a decarb on the motor. IF you can find a head gasket they are probably about 30 dollars american. Seafoam is a great product which is made here in Minnesota however I am sure it is not availible over there. If it were me I would start looking for a new motor. Is this motor used in salt water? If so and it has not been flushed each time it has been used chances are it is on its last leg. You should try and find a newer motor that parts are still availible for. This is just my feeling on the subject.

 

[PeterW]

Re: 1967 Crysler 75hp cant make those high rpm's

Hi guys.<br /><br />Thanks for joining us Scotiany, the more the merrier...<br />Yeah I removed the head, previously referred to as the top.<br /><br />The gasket looks fine I reattached the head and did another compression reading, same numbers.<br /><br />From what I could see of the bottom cylinder, with the piston all the way back, the walls looked fine. <br />There was'nt any particular scratchmarks or stuff like that.<br /><br />What should the compression rating be on this engine?<br /><br />I've followed the wizard for a "new" powerhead and ended up here: http://www.boatmotors.com/motorpart...urer=1&year=1967&state=dc&zip=&hp=&disp=&cyl= <br />My question is what does Core and Core First mean?<br />And does Powerhead include everything above the shaft, including fuellines and the electric stuff?<br /><br />I know, you are probably right Eurolarva, I should be looking for a new motor.<br />But I really love it when the age of the boat and the motor match up.<br /><br />Please dont give up on me just yet, I love to learn new stuff and I'm really learning right now. <br /><br />Hope to hear from you guys again.<br /><br />Peter

 

[eurolarva]

Re: 1967 Crysler 75hp cant make those high rpm's

Just a guess here but core and core first I think means you have to give them your powerhead first then they send you the rebuilt one. I may be wrong here. Have you tried emailing Iboats?

 

[scotiany]

Re: 1967 Crysler 75hp cant make those high rpm's

In the Seloc manual, it says the compression ratio should be 145-155 psi.

 

[PeterW]

Re: 1967 Crysler 75hp cant make those high rpm's

Hi again guys.<br /><br />I think you're right about the Core stuff Eurolarva, I've checked about the fuelpump kit if they deliver to Norway and of course they dont. I'll check directly with Iboats on the Core stuff, I should have done that in the first place.<br /><br />About the salt water issue, I dont know. The guy who sold it to me had it in fresh water, <br />the motor came from a buddy of him he have had the motor stored in a barn for some years. <br />They are both inland guys<br /><br />Scotiany, if that is what the compression ratings should be on a brand new engine, is a 120 low or acceptable?<br /><br />Just a quick check, the head is where the sparkplugs are located right?<br />I'm wondering because the gasket didnt have the usual metal rings around the edge of the cylinder.<br />I tried to take apart the exhaust cover, on the left side of the motor, <br />but I gave up rather quickly because the two first bolts I tried broke right off.<br />Could this be a result of corrosion?<br />Is there any way to avoid breaking them? <br />I'm thinking WD40 or CRC5-65 might help<br /><br />Regards <br /><br />Peter

 

[scotiany]

Re: 1967 Crysler 75hp cant make those high rpm's

I think it's more important that the readings of all cylinders be similar. When rebuilding, use antiseize on the bolts. The Seloc manual says to get a heat source(not a flame source), direct it at bolt and attempt to remove with vice grip pliers. I suppose that soaking it with penetrating fluid wouldn't hurt either-after it cools down. If you're lucky enough to get cover off, make sure you check the water pressure relief valve.It most probably needs replacing along with its spring. GOOD LUCK.

 

[Wes Wyatt]

Re: 1967 Crysler 75hp cant make those high rpm's

I had the same problem with my 70 h.p. Chrysler .It took me about 2hrs to rebuild all three carbs with kits from NAPA. it was very easy and I've never done it before .The engine runs like new. I also replaced all the fuel lines just in case. Good luck..Wes