Mucci

Does seat reaming for oversized valves also include boring out the aluminum its set in? Wouldn't the bottleneck still be the air tract?

I saw IE sells +1mm oversized valves that work with the stock valve seats, they just needed to be reamed out. 

On the M10 heads, do the seats overhang the intake/exhaust tracts? I'm curious how much of a difference reaming out the stock seats would make, especially if the seats are flush with the air tract. 

Pic to better describe:

I have a million other things to buy for this car that are higher priority. I'm really just curious

Straight to the 44's on a stock M10?

Is there some sort of calculation to help choose the correct size motorcycle carbs for a sporty daily driver?

Also, is there a reason you went with the individual cable Mikunis vs. a linkage bank with single cable?

Ahh! Great info AVG! Thanks for that. 

Even more questions...

- Can you even setup a DCOE 40 to have a 40mm venturi? Or is the 40mm number just the carb body diameter and not the actual air flow orifice measurement? In a bike carb, since they're fixed, a 40mm carb = a 40mm final airflow passage. Sounds like this is may not be the case here.

- What is the importance of the resonance against the closed intake valve? ...aside from the killer sound.

edit: After re-reading that a bunch of times I now understand the benefit / driveability of sequential 2-barrel carbs. Throwing DCOE 45's on a stock motor is like trying to suck up a pea through a paper towel tube. 

I now see the issue with trying to choose what size motorcycle carbs to run. Since you can't swap venturis you're stuck with what you got. 

I've always wondered what the purpose of these double velocity stacks are on Yoshimura carburetors. Is this a way to run a larger diameter venturi (greater flow at WOT) but get more velocity at partial throttle (driveability)?

5 hours ago, Andrej said:

 

There's a chart in Pat Braden's Weber book that at least gives a starting point. It will vary somewhat depending on the application, but it's at least a rough guide.

 

 

FWIW, I've run 32 and 34mm venturis on the street, and I've driven cars with 30 and 36mm. They can all work, but have very different characteristics at the extremes. For bike carbs with fixed venturis I suspect you'd just have to do some experimenting to find the best arrangement.

Based on that graph it looks like main Venturi size for a 500cc cylinder that revs to 6500rpm would be about 38mm. So would you not be doubling that be running a 38/38?

Ahhh yes, I hadn't considered that a single cylinder is pulling at a time. All makes sense now. 

So if you were running a motorcycle carb bank, one per cylinder, you'd still likely want them in the 38-45 range depending on engine mods.

What's this talk about fixed vs non fixed venturis? Are the Weber venturis replaceable in the DCOEs? What exactly is that doing? Off the top of my head I would think increasing air speed and therefore pulling more fuel? How is that helping tuning?

3 hours ago, Andrej said:

Lots of variables to consider: displacement, cam profile, rev limit, and desired RPM for peak power, to name a few. As noted, 40 DCOEs use venturis in the throats to dial in air flow. They are easily tuned for a wide variety of engines and usages.

 

The big advantage of sidedrafts is that the air flow path is short and direct, both ideal when you want high RPM peak power. Far better IMO to use two sidedraft carbs with smaller venturis than one with an intake that significantly reduces the advantage of that direct path into the cylinders.

I understand the advantage of side draft carburetors. Motorcycle carburetors are also side draft. 

I don't understand how you would choose throttle body size if you wanted to use motorcycle carbs. 

3 hours ago, TobyB said:

suckety suck suck suck.

 

On a pair of DCOEs, each cylinder sees a 40 mm throttle body with an (x) choke.

or pi(40) mm each.  125 square mm at the throttle plates, we'll say.

With a 32/36, each cylinder sees a 32 and a 36 mm throttle with (what, a 28 and a 30?) venturi.

215 square mm. at the throttle plates.

 

So really, a 32/36 is more carb than a pair of 40's. 

 

45''s only net you 140 mm, 

whereas a 38/38 is good for 240

 

48's are only good for 150mm,

but a 40/40 is a whopping 250mm.

 

And a single 40 is no less than a pair.

 

t

it's all in the manifolding.

 

 

I didn't understand a word of that. How would 4 cylinders pulling through a 36mm and a 32mm orifice be more air flow than 4 40mm orifices?

I mainly work on motorcycles and always see modern carb banks on Craigslist for like $50. Generally the 4 bank setups are around 32mm for a 600cc motor. 

This has made me consider carb body diameters vs. displacement and how much of a leap it is to go from a Weber 38/38 up to four 40mm throttle bodies like the dual DCOEs. How does a leap that drastic even work? How is the logical next step not a SINGLE DCOE 40?

Is throttle body area not tied to displacement? I would think if you're doubling the throttle body area you would need to double the displacement but that obviously isn't true. What's going on here?

What's the second hole for inside the pocket? There are rubber grommets on both but I only see the need to use one to route the wiring. 

How can I tell? I know its got at least 2 colors on it right now. Currently maroon but blue underneath. 

Can I just drill a new hole or is there a nut back there? It's hard to tell. 

I just mounted a used replacement fender on the car and went to put the OEM US turn signal back on and the holes don't line up. I spent a good 20min trying to get both screws to thread but they just won't. One is always about 4mm off center. Were there different mounting holes for different years?

The interior is mostly gutted aside from the dash. I haven't yet stripped the roof (and the previous owner flat blacked it) but you can see just behind the sunroof it's bubbling up. I'm not sure yet how bad it is under there. 

58 minutes ago, Simeon said:

30 minutes with a DA sander and some #80 discs would sort any of those roof panels out. 

Mine looks decent from the top, but on the underside it's flaking off in chunks. This is why I ask.

19 minutes ago, 7502 said:

The aroma of Tacoma has this one : https://seattle.craigslist.org/tac/pts/d/tacoma-1974-bmw-2002/6943897800.html

 

I asked about that passenger side turn signal but got no answer?  Maybe I can buy it off you????? 

He's not willing to part it and $1200 is a lot for a roof. I'd feel bad chopping it from a decent shell. 

I'm looking for a sunroof model ideally. 

2 hours ago, Kingryan86 said:

509-216-8176 I’m in Spokane Wa 99216. 

Is the headliner taken out? Can you see what the underside looks like? 

52 minutes ago, 2002iii said:

Check This out

Unfortunately all the panels look decent except the roof! Looks like the paint is flaking and rusting.

That does look like exactly what I need but 11 hrs one way is quite a hike.

Thanks, I sent him a message.

Might be interested in the chassis. I'm in Portland. Sent you a PM.

29 minutes ago, Conserv said:

 

I suspect the benefit of the re-skin method is that you don’t alter the structure of the vehicle or have to worry about alignment. From what I’ve heard, it’s more expensive, so presumably more time-intensive.

 

I wonder if your car had one or more plugged sunroof drains and thus accumulated water in the sunroof tracks and roof reinforcements.

 

Is that Taiga metallic paint, or Mintgrun paint? Either way: two desirable colors!

 

Regards,

 

Steve

 

I was thinking the same thing. I bought it as an ugly runner that someone definitely dumped a bottle of bleach into - I had assumed due to some sort of water leak / mold issue. This pretty much confirms that.

What once was Taiga shall return to Taiga! On top of aerosol flat blacking the exterior the previous owner also reupholstered the interior bright red and bondo'd up all the trim holes. There will be much restoration in this project...

6 minutes ago, Son of Marty said:

If your donor roof has a sunroof be careful adding reinforcement in the A pillar as the sunroof drains need to go down the pillar and there's not much room to do it. 

Ah yes, good point

Although it does appear to be mostly just the skin that's affected, chopping the full roof at the pillars seems way easier. Having to drill out and reweld a million spot welds then grind them all smooth looks like a real pain in the ass. What's the benefit to doing that? 

I just saw some neat structural tips in a YouTube video where the guy sliced the outer pillar skin at one spot then the inner about 4" lower. He did the inverse to the donor car that way your weld seams aren't on the same plane. He also made a sleeve that fit inside the pillars and welded through to it a couple inches above and below the main weld. Thought that was neat. 

Here's my infection. The driver's side inner structure looks good but the passenger side is rusty. I wonder if the drip rail was clogged up over there. Or maybe a bad seal?