'73 chrysler 105 surges at WOT then loses power

[Frank Acampora]

Re: '73 chrysler 105 surges at WOT then looses power

Re: '73 chrysler 105 surges at WOT then looses power

Rings are 2 degree taper. they have an up side and a bottom. The taper goes up. I usually don't bother gapping them anymore because my machine shop is very accurate on final hone and they are almost always in tolerance. I may be wrong but I think Chrysler specs for end gap is .006 to.016. If in doubt, err on the wide side.

Nice pistons, aren't they? Make the stock ones look sick. Wear safety galsses when you install the circlips. I find that installing on first by pushing it in the hole vertically then tilting it to match the groove works well. Orient the gap so it faces either the top or bottom of the piston when installed. Grease the needles and set them in the small end, position a spacer on the bottom and top, insert the wrist pin, then install the other circlip. Put one side in the groove opposite the notch, then use a small tool in the notch to bend in the clip and seat it fully.

Water temp sensor is variable ohm, depending upon temperature. That's how the gauge works--Voltage is varied by the resistance at a specific temperature. I don't know what value ohms should be cold. Do you hqave a gauge or a buzzer. They are different. the buzzer uses a bimetal switch on the head near a sparkplug while the gauge is a sensor mounted on top of the head. Bimetal switch will usually be a straight cylinder covered with plastic. It has a terminal sticking out of the potting compound and a screw attaches the wire. The base is 5/8. The sensor will be a brass screw-in with the center screw terminal using a nut.

 

[spool]

Re: '73 chrysler 105 surges at WOT then looses power

Re: '73 chrysler 105 surges at WOT then looses power

Rings are 2 degree taper. they have an up side and a bottom. The taper goes up. I usually don't bother gapping them anymore because my machine shop is very accurate on final hone and they are almost always in tolerance. I may be wrong but I think Chrysler specs for end gap is .006 to.016. If in doubt, err on the wide side.

Nice pistons, aren't they? Make the stock ones look sick. Wear safety galsses when you install the circlips. I find that installing on first by pushing it in the hole vertically then tilting it to match the groove works well. Orient the gap so it faces either the top or bottom of the piston when installed. Grease the needles and set them in the small end, position a spacer on the bottom and top, insert the wrist pin, then install the other circlip. Put one side in the groove opposite the notch, then use a small tool in the notch to bend in the clip and seat it fully.

Water temp sensor is variable ohm, depending upon temperature. That's how the gauge works--Voltage is varied by the resistance at a specific temperature. I don't know what value ohms should be cold. Do you hqave a gauge or a buzzer. They are different. the buzzer uses a bimetal switch on the head near a sparkplug while the gauge is a sensor mounted on top of the head. Bimetal switch will usually be a straight cylinder covered with plastic. It has a terminal sticking out of the potting compound and a screw attaches the wire. The base is 5/8. The sensor will be a brass screw-in with the center screw terminal using a nut.

They are nice indeed.
I already fitted 4 of the circlips.

I once copped a spring hose clamp directly in the eye and ended up in hospital. I know the imports of protecting your eyes! Had a small bleed but I recovered.

The clearance according to the ring sheet is 0.004" gap per 1" bore, so around 16thou sounds about right. Do these engines get piston slap due to the forged pistons or because it's a alloy block are they generally ok?

I was forced to go 40thou oversized as there was no stock of 30 thou. Given the scoring probably not a bad idea.

Just gotta wait for the rest of the parts I ordered from the states,

Usually the sensors are rated for x ohms for x deg, I'll work it out I'm sure, if not I'll fit a sensor I know the range of.


How long should one run 25:1 oil ratio after rebuilding?

 

[Frank Acampora]

Re: '73 chrysler 105 surges at WOT then looses power

Re: '73 chrysler 105 surges at WOT then looses power

I usually assemble the engine with a good dose of TCW-3. I coat the cylinders, rings, and pistons by hand before insertingand pour some on the bearings. Usually, this makes the engine difficult to turn over and start for the first time. However, It seems to me that heated and used TCW oil is "thicker" than virgin and thus oil that has run through the engine will protect it better.

I personally run a couple of six gallon tanks through the engine as a break-in. That translates to two quarts of oil run through it. This gets enough oil throughout to protect it. I vary speeds but keep the engine at 3/4 throttle or less until break-in is done. The exception is during on-the-water timing, but that is only for a very short period--just enough to check my setting.

I don't think you need to worry about piston slap in these engines. Pistons have a full skirt and a relatively tight fit in the bore to maximise crankcase suction and compression

 

[spool]

Re: '73 chrysler 105 surges at WOT then looses power

Re: '73 chrysler 105 surges at WOT then looses power

That's a good idea. I was going to use engine assembly grease ( moly graphite based lube )

Sorry frank I'm not really following / familiar with your measurements. The Chrysler manual says 25:1 for break in. So break in is very short on these motors?

Should I perform break in on the water or in a barrel? I've heard many different theories. I used a high load moderate rpm technique for the last car engine I built.

I will triple check the for blockages this time =/

 

[spool]

Re: '73 chrysler 105 surges at WOT then looses power

Re: '73 chrysler 105 surges at WOT then looses power

Ok some sad news,

Apon boring cylinder 3 one of the deep scores turned out to have a 1.5" long crack in it
I'm forced to sleeve the cylinder, I looked at a replacement block but that worked out to be a bit hard to source. *sigh* my pockets feeling the strain

The crack must have been from overheating.

 

[Frank Acampora]

Re: '73 chrysler 105 surges at WOT then looses power

Re: '73 chrysler 105 surges at WOT then looses power

That's why you bore first, then order pistons.

Now the good news: Any early three or 4 cylinder block will swap in, from 85 to 140 HP.

If you can get the ignition, then any late Chrysler from 79 on and Force engine from 90 to 125 and possibly 150 up to 1994 will swap in. So you are not limited to finding an early Chrysler block

 

[spool]

Re: '73 chrysler 105 surges at WOT then looses power

Re: '73 chrysler 105 surges at WOT then looses power

That's why you bore first, then order pistons.

Now the good news: Any early three or 4 cylinder block will swap in, from 85 to 140 HP.

If you can get the ignition, then any late Chrysler from 79 on and Force engine from 90 to 125 and possibly 150 up to 1994 will swap in. So you are not limited to finding an early Chrysler block

Oh well, The crack was only found after boring, I'm having a sleeve installed in cylinder 3 and continuing with the rebuild. It's the cheapest and quickest option as summer is fast approaching.

All my goodies have arrived now (gasket sets, water pump kit, misc broken parts)

 

[Sabbath]

Re: '73 chrysler 105 surges at WOT then looses power

Re: '73 chrysler 105 surges at WOT then looses power

Hurry up and fix this. We need to get our boats on the water.

 

[spool]

Re: '73 chrysler 105 surges at WOT then looses power

Re: '73 chrysler 105 surges at WOT then looses power

Hurry up and fix this. We need to get our boats on the water.

I will Sabby, waiting on the engine block to come back from the builders.
Summer is just around the corner now too!

This boat is starting to burn a hole in my pocket.

 

[spool]

Re: '73 chrysler 105 surges at WOT then looses power

Re: '73 chrysler 105 surges at WOT then looses power

Ok so i got the block back from the machine shop. I've installed the conrods to the new pistons and i'm gapping the rings

i calculated the correct piston ring end gap to 0.34mm (about 0.0134") it appears the rings once installed in the current bores have 0.44mm gap at the top of the bore (0.0173") thats about 4 thou difference. Could this cause premature engine damage such as piston slap?

at the lower section of the bore the gap is smack on 0.34mm, i found this a bit weird. It is consistant across all 4 cylinders.

Should I be worrying about this? Frank i'd value your input here

 

[Frank Acampora]

Re: '73 chrysler 105 surges at WOT then looses power

Re: '73 chrysler 105 surges at WOT then looses power

Nope! The only time you would run into trouble is if the ring gap was too tight. Then, they would jam and score the cylinder and possibly break when they expanded with running heat. .44 mm at the top of the bore will cause no problems.

It sounds like your machine shop got a slight taper with honing. This is common because the block has closed bottom cylinders.and the hone can not be run all the way through the bore. It will not cause a problem. In this case, closed bottom refers to the bearing saddles blocking the hone from passing completely through the bore, not actually closed like the bottom of a glass..

 

[spool]

Re: '73 chrysler 105 surges at WOT then looses power

Re: '73 chrysler 105 surges at WOT then looses power

Nope! The only time you would run into trouble is if the ring gap was too tight. Then, they would jam and score the cylinder and possibly break when they expanded with running heat. .44 mm at the top of the bore will cause no problems.

It sounds like your machine shop got a slight taper with honing. This is common because the block has closed bottom cylinders.and the hone can not be run all the way through the bore. It will not cause a problem. In this case, closed bottom refers to the bearing saddles blocking the hone from passing completely through the bore, not actually closed like the bottom of a glass..

Cool! So I should just be worried about less than a 0.34mm gap at any point of in the path the ring travels?

All of the rings are more or less already perfect, I just have to triple check everything before reassembly. I can't wait to be done!

 

[Frank Acampora]

Re: '73 chrysler 105 surges at WOT then looses power

Re: '73 chrysler 105 surges at WOT then looses power

I don't think you have anything to worry about. I would be concerned if ring gap was, for example, non-existant or if it were so small that rings would jam. Again, for example less than .006 inch or about .01 mm. So, assemble your engine and go have fun.

 

[spool]

Re: '73 chrysler 105 surges at WOT then looses power

Re: '73 chrysler 105 surges at WOT then looses power

I don't think you have anything to worry about. I would be concerned if ring gap was, for example, non-existant or if it were so small that rings would jam. Again, for example less than .006 inch or about .01 mm. So, assemble your engine and go have fun.

Don't worry about that i will have fun

Another question, How long should i run 25:1 2stroke mixutre for? ive got a 37L tank full with 25:1 already should I be fine to run 50:1 after that?

The pistons look pretty sexy with new needle rollers, Wiseco have almost turned making pistons into a artform!

 

[spool]

Re: '73 chrysler 105 surges at WOT then looses power

Re: '73 chrysler 105 surges at WOT then looses power

Ok well the assembly has been going well, Gapped and installed the pistons, installed the crank today and bearings

I was torquing up the conrod bolts when one snapped at less than 20ft/lb (22.5ft lb or 270ft/lb is what they should be tightened to)

now i have a thread stuck in my conrod. I'm lucky it failed during assembly rather than post. I think i made an error assuming they are reusable. I will be sending the con rod to a professional as i'd more than likley make a mess of it. worst case can i mix and match a new donor conrod? are they all balanced within the same weight? *sigh*

i wonder if arp make a replacement conrod bolt.

Does anyone know where i can get replacement bolts from?

EDIT:

http://www.crowleymarine.com/parts/1885.cfm
this looks like the right one, now just to wait another 5 weeks for the part to arrive

Ordered those bolts. They are for a 76 force 105hp which i believe is the same as my 73 chrysler in terms of conrods and pistons.

 

[stubtail]

Re: '73 chrysler 105 surges at WOT then looses power

Re: '73 chrysler 105 surges at WOT then looses power

You could take your bolts down to yuor local NDT shop and get a quick FPI (flourescent penetrant inspection) performed. If they are indication free, you would only then have to procure 1 bolt, maybe a used one (and inspect it) and maybe save several weeks. At any rate, good luck!

 

[spool]

Re: '73 chrysler 105 surges at WOT then looses power

Re: '73 chrysler 105 surges at WOT then looses power

You could take your bolts down to yuor local NDT shop and get a quick FPI (flourescent penetrant inspection) performed. If they are indication free, you would only then have to procure 1 bolt, maybe a used one (and inspect it) and maybe save several weeks. At any rate, good luck!

Thanks, but when torquing the bolts up i stepped it up slowly trying to avoid this,

i went from
10ft/lb to 15 -> 17.5 -> 19 -> 20

After 20 they seemed to start stretching, i stopped for a little bit wondering if i should proceed. i thought better i try for 22.5 like the manual says than leave it at 20 and possible end up with a piston exiting the block, I decided to try for 2.5ft/lb more, which is when one broke, the rest were at 20ft/lb i decided to untorque all of them at this point.

I do not trust the other 7 bolts as far as i can throw them and when i've invested this much time and money into rebuilding it i will not let a $3.50 part ruin the engine. I've already ordered the bolts i just have to wait

40 years of heat and stress has obviosly taken its toll on the bolts.

I just have to figure out how to get the thread out of the rod without unbalancing it.

 

[Frank Acampora]

Re: '73 chrysler 105 surges at WOT then looses power

Re: '73 chrysler 105 surges at WOT then looses power

It is not the bolt's fault, it is yours and the manual! Foot pounds is too imprecise a measurment and 20 foot pounds is too much. Con-rod cap bolts are torqued to 180 INCH pounds (15 foot pounds equivalent) unless they are 5/16 diameter which I am reasonably certain yours are not. Which manual are you using? Are you certain they were claiming foot pounds? 20.5 Newton meters equals 15 foot pounds so 22.5 Newton meters would be more in range.

The bolt will be a witch to drill but it is drillable with a new cobalt steel drill bit, slow speed, and lots of pressure. Then, because it is not corroded it should come out easily with an easy-out. If any is above the rod surface first try using a good pliers on the protrusing portion.

76 Force? Do you mean 86 Force or 76 Chrysler? Force brand engines were not made until 1984 and I don't think--but I could be wrong--that they made a 105.

While I have never seen the need and have never had a rod throw a cap, if it makes you feel more secure, use threadlocking compound on the bolts the way the engine came from the factory

 

[spool]

Re: '73 chrysler 105 surges at WOT then looses power

Re: '73 chrysler 105 surges at WOT then looses power

It is not the bolt's fault, it is yours and the manual! Foot pounds is too imprecise a measurment and 20 foot pounds is too much. Con-rod cap bolts are torqued to 180 INCH pounds (15 foot pounds equivalent) unless they are 5/16 diameter which I am reasonably certain yours are not. Which manual are you using? Are you certain they were claiming foot pounds? 20.5 Newton meters equals 15 foot pounds so 22.5 Newton meters would be more in range.

The bolt will be a witch to drill but it is drillable with a new cobalt steel drill bit, slow speed, and lots of pressure. Then, because it is not corroded it should come out easily with an easy-out. If any is above the rod surface first try using a good pliers on the protrusing portion.

76 Force? Do you mean 86 Force or 76 Chrysler? Force brand engines were not made until 1984 and I don't think--but I could be wrong--that they made a 105.

While I have never seen the need and have never had a rod throw a cap, if it makes you feel more secure, use threadlocking compound on the bolts the way the engine came from the factory

ohh dammit, i just checked my manual again, turns out i misread the collums its 170in lb, the main bearing bolts are 270in lb

can i mix and match rods? ie if i buy a new rod from another engine will it work?

 

[spool]

Re: '73 chrysler 105 surges at WOT then looses power

Re: '73 chrysler 105 surges at WOT then looses power

Ok well i rechecked the site i ordered from, definately a 1976 Force 105HP (Australian website that outsources from the US)

H1059H76D Engine code, Diagram looked identicle to my Chrysler 105 so i ordered the bolts

Its a Mercury bolt - Spec screw @5 Part no. 91012, I think its best i wait for the bolts as who knows if i've stressed the rest of them going to 20ft/lb.

I've got a colbalt drill bit set and a drill press. I cleaned the threads before installing the bolt too so it should turn right out. I've already tried pliers can't grip enough to turn it out. I'm sure i'll figure it out.