13b-rotary-vw

O.K.

So I've just begun testing of my 13b-VW bug again with the new exhaust (I built) and I notice that when I hold it at about 3-4 grand in RPM's the header will rapidly glow to a bright red, almost bright enough to see in the day. I let off as soon as I start to see sparks coming of the pipes.

Here's the question. Are my pipes too thin (.065 stainless)???? Is my carb running rich (which is my theory)??? Is it just normal for them to glow like that??? How hot would they get under a load????

Aaron Cake

iTrader: (1)

My guess is too rich and not enough timing.

Celestial-Fc

run very hot

rxtasy3

iTrader: (2)

in my experience that problem has been a timing issue.

funkjaw

iTrader: (3)

First things that come to mind are timing and running too rich.

Sgtblue

iTrader: (16)

Shouldn't be glowing, but rotary exhaust is typically much hotter than a piston engine.

Even after you solve this problem, you may want check for anything at risk of being damaged from radiant heat. Heat-coating or header-wrap may be in your future.

13b-rotary-vw

Alright,

Going to switch carbs from motorcraft 2100 to 390 holley to see if there's a difference???

Timing should be dead on, atleast that what my timing gun says. My advance looks good as well but that's just eye ballin' it. I thinking some wrap just might be the ticket but DAMN those pipes get hot!!!AAAAHH...I'll get you guys a pic and maybe a vid ASAP...

Thanks for the help (especially to you Aaron) I will get this RX/BUG going...

rxtasy3

iTrader: (2)

the timing issue is that it's a tooth off, advanced or retarded. only dealt with the issue once so can't exactly remember which. like already mentioned, it shouldn't do that.

Kentetsu

Usually an indication of retarded timing, or running very lean (lean = hot/rich = cold). If the timing is correct, is everything routed correctly? Sometimes things get switched around by gremlins that sneak into your garage overnight.

Any signs of knock or preignition? How do the plugs look? They will be the best indicator of lean/rich.

You said "when you hold it at 4 - 5k", is that in nuetral or under load? If under load, I would suspect fuel system. If in nuetral, I'd start with ignition/timing.

As far as the thickness of the pipes, that could certainly be an issue. However, I don't know off the top of my head what the correct thickness should be. Maybe check Racing Beat and see what theirs are made with?

Good luck. Sounds like a very cool project.



.

funkjaw

iTrader: (3)

My friend had a problem on his 13bt where the downpipe would start glowing red... it turned out he forgot to plug in his leading coil lol.

rx7joes

Less fuel and more timing

13b-rotary-vw

WOW!!!

Do I feel like a true noob at this. Just found out my trailing and leading were firing at the same time. I took off the leading plug thinking that it wouldn't fire at all (during tis time I've been having trouble getting it to run smooth) and it purred like a kitten. So I'm guessing that my split may have something to do with it.

So my next question is:

What split would be good for a carbed set up???
I'm using an older distributor with the ignitors (can't remember the right name) with a carburetor. If carb specifics are nessesary, I'm currently running a motorcraft 2100 (1.21) I believe the CFM on that carb is 290, and I plan to switch to a Holley 390 CFM.

Should I just try to go by the stock timing or is there a better way to run it? Could this be the cause of my hot pipes problem? Please any info helps alot and thanks to all...

ImpartialMouse

iTrader: (2)

I'm kind of curious as to why running rich would be a problem? Is it because the fuel is igniting on the exhaust or something?

I have always heard running lean is a hotter and rich is cooler.

I understand he has the problem under control and this may seem off topic, but I'm just curious.

Aaron Cake

iTrader: (1)

Yep, basically. While lean mixture do cause high EGTs, glowing exhaust is almost always due to an overly rich mixture. The engine is literally spitting huge flames and unburned fuel out of the exhaust ports which are burning down the exhaust.

Kentetsu

Glad to see you are making some progress. First thing you need to do is find out why trailing/leading are firing at the same time.

Is it because you have both Leading wires plugged into only one of the rotors, and both of the trailing plugged into the other rotor?

Or, have you somehow ended up with one coil firing all plugs?

I would suggest that you unplug the trailing (top) spark plugs and just leave them right out of the equation for now, and simply focus on the leading (lower) plugs. Start by making sure that they are both firing. If they are, then set the leading timing according to the manual.

Once you get the leading sorted, then you can move on to the trailing. Make sure they are being fired by the trailing coil, and then set the trailing timing (this is done by sliding one of the vacuum pods in/out, not by turning the dizzy like you would to set the leading).

Good luck...

13b-rotary-vw

Update,

Put the holley on, but having trouble with it. I believe that it is intended to run as two individual carbs. Meaning that each half runs one rotor independantly (hope that makes sense) The racing beat intake I have clearly runs each port to individual engine ports. My problem is that I'm not sure if the carb I have was meant to run seperate chambers this way. I can almost say 99.9% that yes it does but ?????????? I'm going to take it apart again and hope I find something lodged in the idle circuit.

Oh yea, the problem I'm having is that at Idle only one rotor is firing. Don't worry though, i swithed carbs and it runs just fine. I also rotated my holly 180 and now the opposite rotor fires. ITS THE CARB. I hope I can get this carb working. I would also like to use it for a draw through system. Any one ever do a draw through using a 390 holley (kind of a rhetorical question) I hope I can do this someday, but one step at a time I guess...more later....