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Starter Solenoid Location

Joe

Well Known Member
This is an RV-8A QB fuselage firewall/wiring question. Grove brake reservoirs (not on the firewall), fuel injected (no gascolator and fuel primer solenoid), aft-mounted battery and master contactor.

I'm not working on firewall forward stuff yet but would like to mount my starter solenoid while I'm doing electrical wiring. DWG OP-11 shows a location for it but instead can I use the nutplates installed in my QB intended for the brake reservoir as shown in the image?

StarterSolenoidLocation.jpg


While I'm asking questions:

1. What's the purpose of the two pre-punched holes below and to the right of the temporarily mounted starter solenoid? Can I use either or both of them for the battery cable (aft battery installation) and solenoid control wires? OP-11 shows locations to drill holes for that wiring but I'd like to use one or both of these holes if they're not earmarked for something special later.

2. Can I mount my engine ground block/forest-of-tabs in the space designated for the original starter solenoid location? My concern is that I'll run into interference issues when I do mount the engine.

Thanks,
Joe
 
Here's my attempt.

Joe,

Here is what I've decided to try. I still have no idea what the "extra" holes are for. Any open holes will get filled with a rivet or screw when I'm finished, I guess. My cabin heat box will be on the right side, with the SCAT tubing running through the forward baggage compartment. I ran the solenoid control and indication wires through the Safeair unit along with the cable. All of the other engine sensor wires come through another Safeair pass-thru just above the solenoid (out of picture).

 
Hey guys. I am building a 7 and am not familiar with the 8 firewall. But if those are your starter solenoids don't you want to mount them upside down? The 7 plans show this and in general it is recommended so that you don't activate the solenoid by pulling positive g's. Something I just learned in my sport air electrical workshop. :).

Thx.
 
My cabin heat box will be on the right side, with the SCAT tubing running through the forward baggage compartment. I ran the solenoid control and indication wires through the Safeair unit along with the cable. All of the other engine sensor wires come through another Safeair pass-thru just above the solenoid (out of picture).

Thanks for your response, Jeff. If I'm interpreting your picture correctly, your solenoid is in the same position I'm proposing (i.e. it uses the brake reservoir nutplates). And your ground lug is in the general area I want to install mine in too. Just wish we had feedback on the possibility of interference when the engine is hung later.

BTW, the heater valve you see in my picture is installed in a 2-inch hole that Van's provided on my firewall. In fact, all the firewall holes you see in my picture came with the QB kit.

Thanks again,
Joe
 
Joe,
I think my firewall is the same as yours. I didn't like the position of the prepunched heatbox hole, so I just filled it with the Safe-air pass-thru. My engine is hung, and as of yet, I see no problems.....
 
Why mount the starter solenoid on the firewall?

I have a rear-mounted battery and I'm trying to figure out why I wouldn't want to install the starter solenoid in the back near the battery instead of on the firewall - anyone see an issue with putting it back there?

Advantages I see:

1) the long run of the fat cable will not be energized when not starting the engine
2) less stuff on the firewall
3) a bit more weight in the back

Thanks for any tips.

Regards,
Mickey
 
Joe,

My 8A battery is on the firewall in the standard right side position. I have a QB kit and my firewall was pre-punched like yours. I'm finishing up my FWF work these days (famous last words).

I used the three large holes for throttle, mixture, and carb-heat/alt-air (or prop pitch); the small hole may be intended for a Bowden cable, but I think I'll run electrical wires through that hole. My Bowden cables run through the firewall just below the throttle, mixture, and carb heat holes...

My Bowden cables operate (1) oil cooler butterfly and (2) the cabin heat valve, both of which you may wish to use and run through on that side, too.

Regards,
John
 
Mickey,

My battery on my 8 is mounted in the rear.

I have my battery master solenoid mounted in the rear on the battery tray and mounted my Starter Soleniod on the firewall to make a short wire run to the starter.

It seems to me less wires mean less line loss and more amps to the starter.

At least that is the reason I remember :confused:
 
battery solenoid in the back

Hi Jack,

Thanks for the feedback. The plans say to do it as you have done, with the battery contactor on the FW.

I wonder if moving the battery contactor to the back would not be better for the reasons I outline above?

Thanks,
Mickey
 
Optional Drawings

Suggest a set of Van's optional drawings:

OP-10 shows the electrical system block diagram (including the battery master on the battery tray for a rear battery setup in the 8).

OP-11 shows a basic wiring harness layout for the 8

OP-26 shows control cables

OP-27 shows the oil system

OP-29 shows cabin heat for engines with carb.

OP-32 shows the IO fuel system

OP-33 shows cabin heat for IO engines

OP-34 shows the firewall layout for the IO-360; the holes Joe is asking about are shown on this dwg and are for the brake reservoir fluid passthrough (inboard hole under the reservoir nutplates) and battery cable (outboard hole)

OP-34 shows the firewall layout for the O-320 and O-360.

There are others, but these are the ones I found most useful for my FWF layout.

Van's has done a pretty good job with these drawings; they really make sense once you hang your engine!

Good luck,
Mike
 
Last edited:
Mickey,

My battery on my 8 is mounted in the rear.

I have my battery master solenoid mounted in the rear on the battery tray and mounted my Starter Soleniod
on the firewall to make a short wire run to the starter.

It seems to me less wires mean less line loss and more amps to the starter.

At least that is the reason I remember :confused:

The problem is the starter sees the loss all the way back to the battery. But the starter solenoid should be on the firewall.
 
Optional Drawings

Where can I get these optional drawings? I went to Vans website and couldn't find anything about them

Mark,
Go to Van's web store and enter DWG OP in the search box. You'll pull up a list of the optional drawings. They're $3 each.

Mike
 
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