Runtz Problem

I have a 1951 ford shoebox that we have done a complete 12v conversion (except gauges and senders). We installed 3 runtz on the oil, temp and gas gauges. up untill a week ago they were all working perfectly, then all 3 of them gave out at the same time. I am still getting 12v to the input side of the runtz and checked all the earths, but i am not getting any voltage on the gauge side of the runtz.

Is it possible that i have blown all 3 runtz at the same time? i have them wired to the ignition switch the directly to the battery. The alternator charges the system at approx 14v, would this be enough to burn the runtz out?

Regards
Brett.

 

Maybe a power spike or surge zapped them, it sure sounds like they are bad. Did you build them or buy them already made?

 

Sounds like this may have been what happened. the alternator may have pumped out a bit higher than the 14 v and the runtz overheated and failed. When you replace them make sure they have a heat sink attached if possible, it will greatly extend their life.

 

How about English, the American version? WHat is a runtz?

 

runtz is a brand name, for a voltage reducer, used since the sixties to run 6 volt gauges on 12 volts.

 

That is the american version .It's just a voltage reducer I built mine from parts from Radio shack for about $7.00 a piece.

 

I bought the runtz from Speedway. Is there a simple way to splice in a surge protector? Apparently they can handle up to 20v or would it have been the amps that overheated them? I have been reading an article on building your own voltage reducer

http://www.jalopyjournal.com/forum/showthread.php?t=448038

has anyone had good results from these? or know what they are like in dealing with surges or spikes?

 

Thanks, never heard of it.

 

had this happen to a customers truck when he tried to jump start it backwards.

 

The Runtz need to be grounded on the tab, any chance the metal they are mounted to stopped being grounded?

I went with this piece, one does all the gauges: http://www.ebay.com/itm/12v-to-6v-v...r_Truck_Parts_Accessories&hash=item3f195b829b

 

Yes, a good heat sink is needed.

I kind of doubt it was an alternator spike, those integrated circuit regs usually have a wide spread of input voltages on the specs, yet still provide a stable 6v output even if it's 12v or 20 v.

Could be that the milliamp rating was a bit borderline for those brand of gauges?. Sometimes on ebay, there are special ICR's sold as surplus leftovers from very special uses, and if you get lucky like I did, there are some with over 3 AMPS output. I believe mine were 6V output at 3.6 or 3.8 A. Most others will be 300 to 500 MA, which is .3 and .5 A.

 

Just got word that we got them from shoebox ford. aparantly the best ones to use for a shoebox.

 

Just my $.02...In 1956 Ford went to the 12V system same as everyone else,but they kept their gauges 6Volt, right up to the mid 80's...believe it or not ..I ran into this over 20 years ago when converting a '51...The unit Ford used was called a Constant Voltage Reducer. It is a unit that is fastened to the back of the gauge cluster on all Fords. It is a small thing about 1/2"x1" the Hot wire goes in the + side and the - side feeds all the gauges at a time...with the original jumper wire on the back of the gauge cluster...Mac's used to carry this unit ..but now has an updated version 1 unit works for all the gauges...the part # is V12871..voltage Reducer...From what I have seen on here the Runtz unit ( as the younger ones say....****) So check out Macs auto parts..Oh by the way I am doing a 12V conversion on a '51 right now using the older style reducer that I have had for a couple years now...Hope this helps.
Jim

 

Jim, I used a brand-new new CVR from NAPA for years, but got tired of my gauges visibly swinging as the CVR pulsed. Cheap Hecho en China part, and believe it or not, over $20 now. A Ford part from the boneyard would be a better bet, they last forever.

 

Hi, just to cap this thread off, the 51 ford in question is fixed.
Yes all 3 runtz's from shoebox ford blew. dont know if it was from a voltage spike or overheating.
We built 3 voltage drops using this info http://www.jalopyjournal.com/forum/showthread.php?t=448038.
When we pulled the shoeboxford Runtz's apart we found they use the same components but are smaller and have no heat sink and were visibly blown.

So i absolutely recommend building your own according to the Tech article.

Peace

 

Thanks for the update ...

 

We just had she same thing happen to a 50 merc that Bryan lowered and rewired to 12 v . Your not alone

 

I used one of these on my pickup got it at O'Reillys. Told them it was for a 64 Falcon.

 

Right on... Paul, that's it!!! Didn't know O'Reilly's could get that...Thanks
Jim

 

NAPA sells them too, for about $25. Hecho en China, they work but you can see them "pulse" at idle. P/N ECHIR1 (Echlin Instrument Regulator-1)

 

From what I remember, the IVR that Furd uses, has an average DC voltage output of 5 volts. So if you have the reducer of your choice set to 6 volts, your gauge may not be accurate.

 

I have the eBay type regulator that's adjustable, and have played with settings from 5 to 7 volts. It really doesn't make any difference to speak of. The Ford gauges aren't real accurate. It really doesn't matter if you have 30 or 35 psi oil pressure. Gas gauge needs to be more accurate, tho!