1978 Chrysler 85HP Powerhead Swap

[topgun3690]

.....continued from WinnerCougars "Post your performance numbers" thread....

 

[jerryjerry05]

Good luck!!!
Remember , there are no stupid questions(just stupid answers )

 

[topgun3690]

Jerry, did u see my response in that other thread? Was asking about finding out why that bottom cylinder went bad.....it didn't get hot....that bottom port cover was leaking, causing lean condition....possible carb running lean....am thinking that by replacing the PH and rebuilding/cleaning the carbs should fix that problem? Anything else to look for as to WHY the damage occurred? Don't want to do all this work for nothing, not to mention $$$.

 

[Nordin]

Topgun sometimes it is hard to find out why one cylinder went out.
But as you say lean mixture is a good spot.
Clean the carbs and set the air fuel mixture screw at about 1 1/4 turn out.
Set the timing at 30 dgr at WOT.
Use good TCW-3 two stroke oil and do not run the hell out of the engine.
From my experience sometimes a cylinder just fail and I think it is because the engine have been used for many many years and the material in the rings and pistons just break from fatigue.

 

[topgun3690]

Glad to hear from you sir.....thanks for the great advice.

 

[topgun3690]

Nordin....do you know the torque spec for the PH attaching nuts and hex bolts? My factory manual gives the value for the 4 nuts that hold the spacer plate on from underneath as 270 in lbs......but nothing for the outer fasteners.

 

[Nordin]

My factory service manual 3-4 cylinder engines OB 1565 have no special value for those bolts, but all 5/16-18 160 in lbs and 3/8-16 270 in lbs.

 

[topgun3690]

270 in lbs looks good then......thanks. Just wanted to be sure since these are what holds the PH to the motor leg.

 

[jerryjerry05]

Why a port cover leaks.
One TINY TINY cough, or a huge backfire and what ever cyl the backfire was on will probably blow the gasket.
The only way to see that is loosen the packs/coils and hold a cigarette or propane torch around the cover and see if the smoke get sucked in or blown away???
Some bad cases the gasket actually gets blown out and is hanging there.

 

[topgun3690]

I plan on doing the starter fluid test as part of routine maintenance after this debacle......it's quick and easy to do......no mess.

 

[topgun3690]

racerone......could you post your cyl head refinishing procedure? Thanks.

 

[topgun3690]

I have a sheet of glass, 220 up to 1200 grit silicon carbide wet/dry paper......work it in a figure eight pattern....is wet or dry better?

 

[jerryjerry05]

racerone......could you post your cyl head refinishing procedure? Thanks.

It takes a lot to warp one of these heads so bad it won't work.
Piece of glass on a flat surface, then use a feeler gauge to see how much clearance is on the head, measure in a lot of places.

 

[The Force power]

I have a sheet of glass, 220 up to 1200 grit silicon carbide wet/dry paper......work it in a figure eight pattern....is wet or dry better?

To guarantee to get it straight would involve to apply equal pressure divided across the head (impossible by hand) this is only good to clean/de-burr the surface of the head preventing from sanding dips in it.
To "repair" a warped head it would have to be machined (if still possible)

 

[topgun3690]

Thanks Force and Jerry....going out to the shop today and will lay it on glass and see what it looks like. May use the paper to clean or deburr the surface only.

 

[topgun3690]

Update......have been working on this thing when I can.....am kinda slow but thorough. Have everything transferred over to the new powerhead except for the carbs. Will be rebuilding them next.....then Link and Sync and see what we got. Are any special tools needed for the carb cleaning/rebuild? Have 3 carb kits from Franz. Have never messed with the carbs on this motor.....had a Chrysler outboard guy but he is gone.

 

[Nordin]

No special tools to rebuild the carbs just clean out all channels, jets and nozzles.
Then set the float level right.
When turning the carb upside down the float should be parallel with the casting of the bowl edge.
Then adjust the float drop.
If you have Walbor carbs the drop should be 1,00-1,08 in between the float lower edge (the edge facing away from carb body) and the bowl edge casting.
If you have Tillotson carbs the drop should be 1/16-1/32 in between the float lower edge (the edge facing to the carb body where the main jet is) to the main jet perimeter.

 

[topgun3690]

They are Tillotson....have a factory manual but sometimes they assume you know more than you do. The reason I asked was because I read another thread about carbs and the guy said you needed a "special" tool to remove the valve seats? Thanks for the info Nordin.

 

[jerryjerry05]

They are Tillotson....have a factory manual but sometimes they assume you know more than you do. The reason I asked was because I read another thread about carbs and the guy said you needed a "special" tool to remove the valve seats? Thanks for the info Nordin.

What the heck is a "valve seat" ?? Maybe the needle/seat? Most that I've seen the seat isn't removable?? If it is it will have a slot across the top like a screwdriver slot.
Seat repair: sometimes with a solid needle there's a teeeeny tiiiiny o-ring in the bottom of the seat???
Or the needle with the rubber tip has developed a small groove in the rubber allowing it to leak. Those solid seats stand a better chance of repairing than the other with the tiny o-ring.
I think FrankA repaired some with using a puller on the seat but ended up breaking the base of the carb?

 

[topgun3690]

"What the heck is a "valve seat" ??" My bad! Meant to type needle seat. Thanks jerry.