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914World.com _ 914World Garage _ Tach hack
Posted by: jeffdon Feb 27 2010, 12:13 PM
Ok, so I want to fire the engine today on the test stand for the first time. I understand that I need to run it for 20mins at over 2500 rpm for cam/lifter break in.
I dont have a seperate tach, so what would be the min hook up to run long jumpers to the car, and use the in-dash tach?
Posted by: underthetire Feb 27 2010, 12:20 PM
one wire from the coil on your test engine to the tach wire on the car. Turn key on. Or, borrow a dwell meter. They all have tachs in them.
Posted by: jeffdon Feb 27 2010, 12:27 PM
one wire from the coil on your test engine to the tach wire on the car. Turn key on. Or, borrow a dwell meter. They all have tachs in them.
Since the battery is out of the car, I would also need to run power and ground to the car, right? Tried hooking my battery charger to the battery connections in the engine compartment, and the tach goes to about 4 k all on its on when i turn the ignition swtich. WTF??
And one more question...i got a brown wire and black/purple wire...i think the black/purple is the tach lead. Right?
Posted by: underthetire Feb 27 2010, 12:36 PM
Car is not here to look at the wire color, but sounds right.. Also, battery chargers directly to the car without a battery are a bad idea! Chargers are not a good regulated power supply without a battery, they can get too high, and, they will put a lot of electrical noise in the system. This burns out stereos, gauges, and relays. If yo don't have a meter yet, run down to Newark and spend the 35 bucks for the automotive meter at HF. It shows dell, tach, voltage, ohms, etc. You will need a meter anyway if you own a 914.
Posted by: BigD9146gt Feb 27 2010, 12:37 PM
been some time, so someone else chime in here. make sure you ground the tack (brown wire) too. and the black/purple is the tack wire (so long as its hooked up correctly in the engine bay as well) 
Posted by: underthetire Feb 27 2010, 12:41 PM
here
http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=95670
Posted by: jeffdon Feb 27 2010, 01:25 PM
Thanks all for the advise....
Seems like i got a bigger issue. Trying to turn it over to build pressure, and the starter will not turn it over with the plugs in. Compression is only 8.5:1. On the plus side, i AM getting some oil pressure with plugs out, but only about 5 psi.
Posted by: ahdoman Feb 27 2010, 05:35 PM
Before you try to fire it you should pull all the plugs and turn it over to get oil circulation. If you used assembly lube it's a lot stickier than oil. The engine will labor at first but will turn easier when it gets oil circulation. Also, do you have an oil light and pressure gauge hooked up? When your turning the engine over without the plugs in look for the oil light to go out. You probably won't get significant pressure until it fires. Oh, and make sure your fuel pump is off if your just turning it over for oil circulation.
Posted by: jeffdon Feb 28 2010, 12:49 PM
Like i mentioned, turning it over without plugs i am getting 5-10psi oil pressure. Damn thing wont turn over with plugs. I suspect my starter may be below par. Thinking i might get an early 911 starter, as it looks like they have almost double the power.
I just hope i do not have a bearing thats installed wrong. Pretty sure I dont. Anyone know how much torque it would take to turn over an engine with new bearings, new pistons and cylinders? Without plugs, that is.
Posted by: underthetire Feb 28 2010, 01:29 PM
Like i mentioned, turning it over without plugs i am getting 5-10psi oil pressure. Damn thing wont turn over with plugs. I suspect my starter may be below par. Thinking i might get an early 911 starter, as it looks like they have almost double the power.
I just hope i do not have a bearing thats installed wrong. Pretty sure I dont. Anyone know how much torque it would take to turn over an engine with new bearings, new pistons and cylinders? Without plugs, that is.
Sounds like a classic wire/connection problem. What are you using to try and turn the starter? jumper cables with a battery, or did you get the proper cables for it?
Posted by: jeffdon Feb 28 2010, 02:04 PM
Like i mentioned, turning it over without plugs i am getting 5-10psi oil pressure. Damn thing wont turn over with plugs. I suspect my starter may be below par. Thinking i might get an early 911 starter, as it looks like they have almost double the power.
I just hope i do not have a bearing thats installed wrong. Pretty sure I dont. Anyone know how much torque it would take to turn over an engine with new bearings, new pistons and cylinders? Without plugs, that is.
Sounds like a classic wire/connection problem. What are you using to try and turn the starter? jumper cables with a battery, or did you get the proper cables for it?
Jumper cables. Think properly cabling it will make that big a dif?
Posted by: underthetire Feb 28 2010, 02:07 PM
Like i mentioned, turning it over without plugs i am getting 5-10psi oil pressure. Damn thing wont turn over with plugs. I suspect my starter may be below par. Thinking i might get an early 911 starter, as it looks like they have almost double the power.
I just hope i do not have a bearing thats installed wrong. Pretty sure I dont. Anyone know how much torque it would take to turn over an engine with new bearings, new pistons and cylinders? Without plugs, that is.
Sounds like a classic wire/connection problem. What are you using to try and turn the starter? jumper cables with a battery, or did you get the proper cables for it?
Jumper cables. Think properly cabling it will make that big a dif?
Huge difference. And remember, it's always the ground.
Posted by: jeffdon Feb 28 2010, 02:21 PM
Allrighty, off the FLAPS for some proper cabling.
Posted by: underthetire Feb 28 2010, 02:22 PM
Allrighty, off the FLAPS for some proper cabling.
And keep it as short as you can. That helps as well.
Posted by: ahdoman Feb 28 2010, 02:27 PM
Pull the battery from the car and use as short as cables as possible. I also used my battery charger which has a "quick start" setting to help with the juice. It took quite a bit of turning over with the battery before everything finally loosened up. It will labor a lot in the beginning but you should be able to hear the the engine begin to turn over easier. At that point you're OK to put the plugs in and try to fire.
Posted by: jeffdon Feb 28 2010, 03:18 PM
Well son of a gun. That did the trick.
VIELEN DANK!!!
Posted by: markb Feb 28 2010, 06:13 PM
So it's running?
Posted by: Al Meredith Feb 28 2010, 07:03 PM
I always put a direct reading guage on a new engine and turn it over to build oil pressure ( with out plugs) and get 20PSI on a new engine.
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