I recently did a few mods to my 23hp MBLT, thin head gaskets and stainless valves from PVT, and rev kit from ECCarb with a 30 degree key and stainless rods and spring shims. Set valve lash 1/4 past TDC compression stroke at .005 and checked it 5 times. Engine starts up ok when cold but doesn't turn real strong. Next I took it out for a run ran great until I shut down to take a break and it could barely turn over past a certain point in the cranking. I had to let it cool down for while before the starter was able to turn it over enough to start.

-Checked valve lash again-Good
-Checked for resistance in the drive-Good
-2 gauge power and ground cables going to batter
-New battery 2 months old
-turns like a dream with spark plugs out

Weak Starter? or Compression issue? too much timing advance?

Bad battery?
Id have it load tested.

Forgot to mention, Theres a buzzing at the starter or solenoid when it hits the tough spot in the stroke when starting. Solenoid is new but the terminals get super hot when it hits this point.

Sounds like a bad ground / bad connection, or bad battery.

Hot means weak connections. 30 deg works ok when u have stock compression. With the thin headgaskets you may need to back off timing a few deg. Also a stock cam has a compression release. Many aftermarket cams dont. If you have a cam.. ive heard you can buy hi torque starters also.. start with solid cables, good connections and a hot battery first

No cam. (yet). I guess i'll start with getting the battery tested. It's a 65 group 610 CCA auto craft gold that fits my F150 that I got for a free replacement because the first exploded(this tells me they could be crap) .The cables are good.

Prebuilt battery cables or you built them yourself? You can check for a voltage drop both at the battery and at the starter connection. If you have a large drop at the starter, but almost no drop at the battery, it could be the cables. If there is a large drop on both side, could be battery. As noted above, have it load tested. Cables can look fine and still have issues.

all new connectors. I'll put a meter on some stuff tonight.

Prebuilt, hydraulic crimped lugs? Something you put together and smashed with a hammer or pair of pliers? Soldered?

A big v crimp tool a buddy had for marine diesel work.

Always solder those connections when possible. Not saying that's the issue or it isnt, just never leave something like that crimped when you have solder available.

Hydraulic crimper is the way to go. Seen a lot of solder connections go south on those big lugs. Most people fill the lugs up with molten solder then stick the wire in, and that's it. If you are gonna do it that way, you have to keep the heat on it for a while and likely add some more solder to make sure it's completely soaked through the wire and is making a solid connection. Even then, I've seen the solder joint come loose inside the terminal and cause some really hard to troubleshoot issues. Another way is to drill a hole in the top of the lug (ring side), then crimp the terminal, then fill the lug with solder through the hole. Hydraulic crimper is still the best option. It basically makes a cold weld and completely fuses the copper wire to the lug.

This is what the inside looks like after a lug has been crimped with a hyrdraulic crimper. This shit aint' ever coming apart. I won't solder anything 8 gauge or larger ever again.

Ok, that's new.

Not really.

I bet somebody's gonna be getting a new toy.

Already ordered.

you will love it

I've used one of these for years without issue. Mainly because it's easy to carry and you only need a hammer to operate it

https://m.lowes.com/pd/Lincoln-Electric ... ol/3467237


I often go back and solder the crimp though. But in most cases I don't think I'd need to.

Bad cell or weak battery. I've had the same issue on a modded 35. Went through 2 replacement batteries before I got smart and bought a good one. Now I have no problems regardless of how hot the motor is or how cold the weather is. Cranks right over.

As has been mentioned check all connections going to starter and your grounds as well for corrosion. I've had it on customers boat where I checked and cleaned all the connections and it still wouldn't crank right. I started checking voltage drop and found what cable it was. I eventually cut enough coating away and about 2' down the cable there was several broken wires and it was corroded as hell. But, looking from the outside you would have never seen it. A good multi meter are worth there weight when trouble shooting.

FYI if you crimp then flow solder into the connection, proper cleaning paste and rosin core solder. Never use acid core or plumbing solder for electrical connections. And also a good heavy wall shrink boot/wrap also prevents the elements from having too much of an effect to your connections.

You ain't gonna flow any solder into that connection I posted a pic of.

That's basically what it turns into. That was a piece of high strand count 4 gauge wire and just a plain jane copper lug. Crimped, then cut open.

update:
-connections good.
-battery good at 663 CCA.
-new solenoid because the old one was only putting out 10v when turning the key and the other post directly to the battery was getting almost 13v.
-I opened up the starter because the motor is old and it looked like crap so I cleaned it up, brushes were fine. Still started week. -
-Blew up the starter last night and ordered a new one.

I hope that fixes it.