[jmbjs]

Hi folks,
I am working through electrical problems on my engine test stand. A jpeg attachment of the schematic I used for the engine stand from hotrodders.com is included.
The only changes to the schematic was dropping the ballast resistor (HEI ignition) and addding a relay switch for the electric fan. I have checked, rechecked, and even had my wife go behind me and verify that it is as the schematic says with the exception of the above mentioned changes.

-The battery ground is to the block with a good connnection.
Should I have it grounded somewhere else?
-Alternator is ground from one of the small extending bolts to a ground on the block.
Is this correct?

Now, my problem: I keep blowing the 30 amp fuse from the "BAT" lug on the ignition switch to the starter "BAT" lug. As soon as I turn on the ignition switch it blows...Fuses are not that expensive, but I will soon have to stop and sweep the floor!

What is causing me to blow the fuse(s)(s)(s)(s)(s)(s)(s)(s)(s)(s)?!!!!

Any help you can provide would be most appreciated!

Jason
DE OPRESSO LIBER!

[whitecloud]

When you turn the key on you are sending power to the fan, fuel pump, and distributor. Since the fan and pump are fused circuits, I would guess something isn't right with the distributor wiring. Remove all the wires from the ign. terminal at the switch and try again. This will verify the ign switch is ok.(if the fuse doesn't blow) Then reattach each wire one at a time and test again to determine which circuit is grounding.

[jmbjs]

Just returned from the parts store...We tested the Petronix Flame Thrower distributor module and found that it was bad...That module was new. Comparing my Petronix coil to several new stock GM coils, it read the same. So, I got a new one with an extra one to boot. Would a bad module cause the blown fuses?...

I will take the sytem down to bare minimum and replace the wires one at a time, see how that goes...

Thanks,

Jason

[whitecloud]

After taking a closer look at your diagram, I have a feeling the distributor wiring is incorrect. I don't understand how you can have two circuits for "crank and run". I'm not familiar with the setup you are using. Evidently you are supposed to have 12V for cranking and that should be wired to the start terminal on the ignition switch. After the engine starts, the power should go thru the ballast resistor which reduces the voltage, and that should be wired to the ignition terminal on the switch. Take a look at the diagram supplied by the manufacturer, you may be damaging the module.

[T-bucket23]

Your diagram seems to be missing a ground from the dist, are you sure that black wire isnt supposed to be a ground.

[steve392]

jmbjs,

That diagram is from my setup. I drew it, and I see you mentioned that you got it off this board...No problems with you using it, but did you see the comments to this diagram by Docvette? I'm think you did, because I believe he was the one that mentioned the relay for the fan. (I did not go back and check the post, but that is what I recall.)

I have a Vertex electronic distributor that needs to be hooked up as shown. I got that part of the diagram directly from the Vertex instructions. This diagram for your setup may not be correct...

The distributor is grounded through the distributor body to the engine block. This setup works fine for me, with no blown fuses, but if you have a different type distributor, you may have something mis-wired. Please follow the wiring instructions that came with your distributor or module.

[docvette]

Originally Posted by jmbjs

Just returned from the parts store...We tested the Petronix Flame Thrower distributor module and found that it was bad...That module was new. Comparing my Petronix coil to several new stock GM coils, it read the same. So, I got a new one with an extra one to boot. Would a bad module cause the blown fuses?...

I will take the sytem down to bare minimum and replace the wires one at a time, see how that goes...

Thanks,

Jason

Doc here,

IF this is a Stock type GM in Cap Coil type, and is connected as per your drawing, REMOVE the Black wire from the power (IGN) and replace the fuse..

Turn it back on and see if the fuse does not blow..IF not, you had the Ground of the Dizzy on the IGN line..And yes, that will trash a module.

If you have something DIFFERENT , refer to your installation diagram as per the Black wire..

Doc

[vicrod]

The GM HEI distributor needs 12 volts to start and run. That's it.
The ignition switch (ign.) terminal post must be hot when in the start position.
If not a wire is needed from the I terminal post on the starter to the distributor.

vicrod

[jmbjs]

Steve392,
I appreciated you posting that schematic on the website. Although it was slightly different from my needs, it has greatly helped me to understand the basic wiring required to power an engine. My wife and I, through this website figured out what we needed. I read closely the recommendations that DocVette made when he suggested using the relay. I made the few suggested changes to the wiring, installed a new module, and she fired right up! Now I just have to dial her in.
Once again, I really do appreciate the knowledge that you guys/gals provide. This engine stand is a project I took on out of the frustration of cramming a newly built engine into a vega and it failing (although I'm not sure why the engine failed. Anybody interested in trying to help me figure out why?). I vowed that I would never do that again without getting the engine right. I figured that I needed to go back to the basics of an engine, with no distractions of shifters, transmissions, rollbars, etc...I tried to go to far, too fast, so that's why I built the stand, back to the basics, and I have learned a tremendous amount. All of my information comes from this website, a bunch of books, and occasionally, other websites. As long as you guys keep giving the quality advice, I will continue to read, and occassionally ask questions. My son and I were very proud today when that engine came to life.

Take care,

Jason

*My favorite saying: Experience can be expensive!

[docvette]

Doc here,

KEWL!!

Glad to hear it' Roared to life!

GOOD JOB!

Keep us updated on progress..

Doc

[steve392]

Jason,

Glad to hear it worked out for you.

Steve

[jmbjs]

Hey folks,
just wanted to update you on the engine test stand and sbc 350 engine...attached are some pics of the finished stand. I simply took a engine stand with cast wheels, re-enforced it, extended the front to accomodate the radiator, fuel tank, dash and battery shelf. I used the shematics that Steve392 posted (with some adjustments and a new control module) and the engine fired right up. I soon found out she was running real hot. I shut her down to see what I could do. She sputtered, kicked and coughed after I shut the key off, but finally gave up...
I discovered the fan was not blowing in the right direction, changed the polarity and squared that away....
I have learned to be patient and not keep cranking on it hoping the late night fairies have fixed the problem, so back to the books...
Oil pressure is 50-55, firing is good, but when I looked at the carb getting it up to 2200+ for the 20 minute break-in, the carb seems to be dumping a LOT of gas down her throat...The fuel pressure was between 5-6...
I have NOT set any timing other than the intitial timing. The rest of the procedures for timing have been a grey area to me. So, for the next 2 weeks I will be cracking the books, reading this forum and learning about setting the rest of the timing...the engine will not crank till I learn and understand the fundamentals. You guys have been more of a help than you will realize. I'm sure there are also others out there that read a heck of a lot more than they post, and I'll bet they appreciate the expertise as much as I do.

Take care,
Jason
De Oppresso Liber!