Problems cranking a freshly built motor - Confusing me!.

Hi All,
 
So, for the last few weeks ive been pottering around in the garage rebuilding the engine for my project RS2000.
 
Whilst I am by no means a mechanic, i believe I am relatively mechanically minded. I have rebuilt quite a number of motors before (albeit not for quite a number of years), and have never had any problems.....untill potentially now.
 
I have put the engine back together now. The head is torqued down, and all timing gear is on. The block is 40 thou over. The cam is mild, and the valves are sightly oversized.
 
The engine was set to top dead center before it was put back together. Cam timing was done. No valves are hitting etc.
 
So today, i decided to give the engine a bit of a bench test (IE: crank it over without starting - whilst not in the car). So, I put the bell housing on, and bolted the starter in. I grabbed a fully charged battery, and my jumper leads. I hooked the negative to the block of the engine, and then hit the positive on the starter.
 
Now - from what I can see, the starter needs to be "powered up" in two stages. 1 - apply power to the throw terminal (causing the stater gear to throw out), and then almost immediately after, apply power to the drive terminal, causing the start to actually start turning (see below picture for repsective terminals, and the order the are being powered.
In other words, I power up point 1, then immediately after that, point 2.

The coil is not hooked up, and fuel pump is not it, so there is no chance of it starting.
 
OK - the here's where i start having problems. Then engine is cranking VERY slowly, and i cant work out why.
 
It sounds exactly like the battery is flat.
 
Here's a few points to note.
1) The spark plugs are not in, so the engine should turn over quite easily.
2) With a socket and breaker bar, I can successfully turn the engine over by hand. It is definately tight (as a new motor is), but i can turn it over.
3) Oil is being circulated through the motor. The rocker cover is off and i can see oil coming out of the rail supplying the cam with oil.
4) The battery is fine. I pulled it straight out of my wifes Lexus RX330 3.3L V6. It starts that no problems.
5) I bought the car as a project, so am unsure of the condition of the starter. It looks to be in good condition.
6) I could very well be operating the starter incorrectly.
7) When i first power up the starter motor (keep in mind the plugs are not in) the engine will turn, but if i then leave the terminals connected, the cranking will slow down. Kind of like the battery is going flat (which i know its not because i put it straight back into my wifes car, and it cranks her engine over no problems). Does this possible indicate as the starter heats up it degrades?.
8) If i leave the plugs out of cylinder 1, 2, and 3, and put my compression tester in cylinder 4, the cranking will basically hit a wall when it gets to cylinder 4. The PSI on the compression tester gets to about 40 PSI - way lower than it should be.
 
A few of my thoughts.
1) I was thinking it might be way I am powering the starter. Im just clamping jumper leads onto the terminals. Im not sold on this though.
2) I was thinking it could be a dodgy starter. I suspect it hasnt been operated for about 2 years. My understanding is it was working fine when the car was taken apart.
3) I'm pretty sure its not the internals of the motor. As mentioned I can turn it over by hand (yes its tight).
4) Discounted the battery.
 
So, I know i could continue troubleshooting, but i really wanted to throw it out to the forum, to see if anyone can let some expertise. Is it a dodgy starter, am i powering the starter incorrectly, etc etc.......
 
Now opening up to the masses.
 
Thanks very much in advance.
 
Dave

 
 

hi Matt,
 
Yeah its definately a way go to, however one of my reservations is, "IF" it is something to do with something mechanical, id rather know about it before the motor goes into the car to avoid me having to pull it out again.
 
I think tonight i might try it a little differently. Ill use the proper earth lead from the car and bolt it to the block, that way i know it wont be an earth problem.
 
Ive also got a few spare startes (that i picked up this morning) so ill try them as well.
 
The other thing I will do is what you have suggested, and try bridging different terminals.
 
Ahhh the fun.
 
Dave

ok - problem solved.
 
Had a read through some of the schematics i have here, and Matt, you were on the right track.
 
By providing high current leads to the positive terminal of the starter, and then a second lower current wire to the bottom terminal, everything worked as expected.
 
Happy boy now. This means i can put the engine to one side and start the body work.
 
Cheers,
 
Dave

Hi mates.  I was just reading through all of this and remember having the same problem years back with an engine I had rebuilt.  I remember resolving the problem another way though.  Cheers
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