Wiring question on bench starting...

[RangRayy]

So before I throw the motor back in I want to bench fire it. Now I know why why why do it? Well I want to and I want to make sure all the kinks and bugs are gone before putting it back into the truck.

Now I know I need a 4g wire running positive battery to starter post. Along with a 10g wire from positive battery up to the HEI post. Grounded to the block off the battery.

How would I wire in a switch so it can be turned off? Just wire it in between the HEI and battery? Also a push button to start so I don't have to arch the starter.

Would something like I've drawn work?

 

[74 Shortbed]

That'll work..

 

[chengny]

I did that once - and rigged it electrically pretty much just as you show in your dwg. Do try to get the connection for battery negative cable as close as possible to the starter and use a big heavy fastener. Like maybe one of the bolt holes for the motor mount bracket - or one of those ground strap holes on the back of the head.

A couple of things that I learned from doing that - and they both have to do with the fact that you will want to bring the revs up. When you rev it up past idle:

1. It is going to be really loud. I am assuming the exhaust system will not be installed. I did it way out in the country so it didn't matter so much, but if I had done it in a residential setting...the law would have probably gotten involved.

2. I don't know how you plan to support the engine, but make sure it is rigidly mounted. At first I was just going to hang a 350 from a chain fall strapped to the garage joists. Then I started thinking about the torsional forces involved and what the engine would do when it was revved up. I had a scrap frame laying around - with no front clip - and decided to take the extra time to set the motor on the frame mounts. Turns out it was a good thing I did that. When the test run was over, I was curious to see what could've happened had it been just suspended from the falls. We released the mounts, lifted the engine and fired it up again. It twisted a bit when first fired up and then settled down when allowed to idle. But quickly increasing the rpm over say 2K was a different story. It wasn't a Chinese fire drill or anything, but that sucker really wanted to get off that chainfall. It looked like a horse being broken; it twisted in all planes but especially on it's rotational axis.

Bottom line; between the engine swinging dangerously and the unmuffled exhaust it would not made for a comfortable test run. It would have been a rush job and if anything were wrong it might have been missed.

Also, I don't read anything in your post that would indicate that a cam break-in is part of the plan. But even still, you might want to run a length of tubing or 1/8" pipe away from the engine and install a temporary oil pressure gauge. That will give you peace of mind that your oil pump is putting out sufficient volume and pressure. Nothing sucks like hearing a knock in a newly built and completely installed engine.

I didn't bother with running a temporary coolant indication. I just pulled the t-stat and used my hands to gauge coolant temp.

Have a fire extinguisher handy. I don't know how you plan to supply the fuel during the test run but keep the container far away from the action and make sure your gas line connections are tight - especially if you are using a remotely situated electric pump. Things can get a little hectic, and the last thing you want is one of your assistants having a Three Stooges type moment and tripping over the fuel line. With the exhaust open to atmosphere and the ignition secondary just temporarily assembled, there are many ways to start a fire.

For example, this:

You must be registered for see images attach

You must be registered for see images attach

You must be registered for see images attach

You must be registered for see images attach

You must be registered for see images attach

turned to this:

You must be registered for see images attach

You must be registered for see images attach

You must be registered for see images attach

in the blink of an eye.

It happened because I had the distributor cap open (and the gas supply to the carb disconnected) while priming the fuel lines. Those mechanical fuel pumps will pick up a suction from the tank and pack the entire system in a heartbeat. I had reached into the cab to crank the engine and was watching through the space between the hood and the cowling. It didn't take even two crankshaft revolutions when all of a sudden there was a strange orange glow coming from the engine compartment. The gas line had sprayed a mist over the manifold. So, with the distributor open and all that fresh engine paint...well you get the picture. By the time I was able to put it out (less than a minute), all that work was down the drain. It was all superficial stuff but it sucked to have to pull and re-finish it.

 

[74 Shortbed]

The safe way to run a motor outside of a vehicle is on a running stand.

 

[HotRodPC]

I always set the oil pan sump down in a tire and started them up. If you want to rap on it real good, I'd strap it down on both sides to something heavy. Starting them in a pick up bed is great, so you can strap to both bed sides.

I never got all critical on the wiring. You want to shut it off, just pull the hot wire to the coil off the battery and it shuts off, crossing the solenoid with a screwdriver is no big deal either. Hook your Negative to the alternator bracket, your starter cable, and a 10gu hot wire to the Coil is all you need.

 

[MikeB]

Also, I don't read anything in your post that would indicate that a cam break-in is part of the plan

Same goes for doing a pre-lube before start-up. And if it's a flat tappet cam, be sure to use a break-in oil, or at least a break-in additive to prevent cam/lifter failure. And vary the engine speed from 1500 to 2000 RPM for 20 minutes or so.

You must be registered for see images attach

You must be registered for see images attach

 

[RangRayy]

1. It is going to be really loud. I am assuming the exhaust system will not be installed. I did it way out in the country so it didn't matter so much, but if I had done it in a residential setting...the law would have probably gotten involved.

Yeah just headers but I did think about rigging up the exhaust but that's slot more work. I've seen and read many and I mean many opinions on stand starting and not on a run stand. There are plenty of videos out there with people doing it and not having an issue. I am afraid I'd be the unlucky one to have something go wrong. So I may just put it back in the truck and hook up the trans and all the wires I will need along with the exhaust. That way all I have to do is rig up the speedo and I can drive it again.

It's not a fresh rebuild and I opted to not install a new cam at the moment. I just freshened up the block with some cleaning and paint and put new gaskets all around. So no cam break in.

Since I ditched the tbi and ECM I installed a manual oil pressure gauge behind the intake. And it is hooked up right now and I was using it while priming the block. But with my drill I could only get psi readings of 37-40.

 

[chengny]

Anything approaching 40 psi would make me happy - especially since the bearings are not new. To prime the system before a break-in, I use an old modified distributor chucked up in a 1/2" Milwaukee Magnum drill motor. And, even with all new bearings, 35# is about the max I expect to see during the pre-prime.

I have never measured the drill's rpm while it's turning the oil pump, but I would guess it is about 300 - 400. If the engine's normal idle speed is 800 - and since the cam/distributor shafts are rotating at half crankshaft speed - that would seem to simulate normal operating conditions.

But (and I don't know why this happens) when the engine is finally fired up and idling normally on it's own, the indicated oil pressure always jumps another 10 - 15 psi. It probably has something to do with the fact that, during the priming operation all the journals are sitting stationary within their bearings. Then, when fired up, and the journals start spinning, an oil wedge develops in each bearing. That wedge restricts the flow-through rate of oil at each bearing. All those restrictions add up and - when taken together - they increase the total system pressure? IDK.

But in the end, pre-priming is more about flow than pressure anyway. It's main purpose is to purge the oil passages of any air and have them packed (full of oil). That helps ensure that oil flow across the bearings is established as quickly as possible at the initial start. Priming isn't really necessary in your case. But since you changed all the gaskets, it is a good practice. It allows you to identify - and deal with - any external leaks before the engine is put into service. It is also a useful diagnostic tool - for gauging oil pump performance and bearing condition.

 

[RangRayy]

But in the end, pre-priming is more about flow than pressure anyway. It's main purpose is to purge the oil passages of any air and have them packed (full of oil). That helps ensure that oil flow across the bearings is established as quickly as possible at the initial start. Priming isn't really necessary in your case.

Well at first I wasn't getting any oil to the passenger head until I got the tool that has the bushing similar to a distributor. I did hack up an old one but I don't have a 1/2 drill... It was easy to rent the tool from autozone and go that way for now.

It took some time but I finally got oil to all rockers. Then I noticed INTAKE #5 was dry. I rotated the block twice but still nothing. I know it's all in the timing and how the holes line up. Maybe I just missed it each time I rotated the crank?? I really do not want to have to pull the intake off and replace a lifter. But I guess it's easier out on the stand than in the truck.

Also I opted to prime it because it has been sitting since November with the pan off and almost completely drained of oil. Figured it would help.