Some TLC for my QV

Yes:
While I can't say I'm the target customer for your more exact repros in 17", one useful bit of data I see missing is the rim width. At least in the US, that would help determine what tires would fit and what tires would most closely match the stock diameter.

7j and 8j are unfamiliar nomenclature for me here in the US.
ET51 seems to denote offset.

 

Urs.
Huh. You should absolutely pick whatever wheel dimensions you want for your project but my gut feel is that 7" width seems a bit narrow for a 17" rim. I fiddled with this a bit and did test fitments before going to 18s on my Mondial. Maybe I'm not accounting for the offset difference, but here are my thoughts

I believe the design goals you have are as follows (please confirm)
- Keep the stock look but in a larger, more standard diameter.
- Retain a similar overall tire diameter once mounted vs stock. For 220/55 VR 390, that was 25.1" according to my calculations. This means the speedometer/odometer will read correctly and won't require adjustment.
- Don't overdo the width so the wheels/tires stick out beyond the stock fenders like a Jeep or UTV.

Thoughts
Q: What tire size were you aiming for?
- To keep the stock 25.1" diameter, Tiresize.com says we are talking about 205/50R17 tires. Those are pretty tall and skinny and selection looks to be pretty sparse although the a few "high performance" tire choices (at least those common in the US) like Michelin PS2 are available. Curiously enough to me, these are pretty pricey compared to other tire sizes (even 18s).
https://tiresize.com/tiresizes/205-50R17.htm

- I think this cost/availability is much higher with a more common tire size like 225/45R17. They SEEM to fit 7" wheels so that might be a good choice as the rubber options are less than half the cost of the 205/50R17
https://tiresize.com/tiresizes/225-45R17.htm

- It should also be noted that most aftermarket wheels seem to be 17x8 or 17x9... but this is also accounted by a different offset (20-45mm), whereas you are sticking with +55.

- Looking at alot of the pictures I took on fitment (around https://www.gunn.com/mondialEV/37.jpg to https://www.gunn.com/mondialEV/45.jpg), I noticed that the stock wheels/tires bow out a bit more because of the metric tires taller sidewall. Going to a larger diameter wheel, the tire sidewall height (aka the aspect ratio) needs to be reduced to retain the tires overall diameter AND the wheel width is widened. If you enlarge the wheel diameter but keep the same width for the same outer tire diameter, you'll end up with a narrower tire.

- Unlike you, I no longer need to keep the stock diameter tire since I'm no longer using a stock odometer/speedometer OR stock ride height/suspension. As long as I can clear a big brake kit and the tires don't stick out beyond the fenders, I'm good. I originally went with 225x40R18 to go with my 18x8.5" wide wheels, but in hindsight I'll probably choose 235x40R18 tires next. They'll still fit on my rims but will offer an upgrade in traction b/c of the wider width. Visually, they'll also fill the wheel well better which is a more modern stylistic choice -- unless you are doing a safari build. In that case, go knobbies

 

I also have an old laying around that could be fixed...looking forward to see what is the problem on that one.Thanks for this input.

 

In theory, a wider tire would make it harder to turn but since you already adapted power steering, I think it may matter less for you. That's on my radar as a future project (why not) and I think the Prius power steering is what I'm thinking about. The parts are readily available and not hard to wire in from all the folks who have added it to their vehicles (you don't have to mess with the rack -- just the steering shaft).

As far as rubbin when you go wider, I haven't noticed any issues even when moving the wheel to opposite lock but the car hasn't moved under its own power (just pushed around). I'll need to test this further BUT I think the more shallow offset of my aftermarket wheels vs stock helps (+45 vs +55) which tucks them in a bit more. I can always raise ride height if necessary and/or dial in a bit of negative camber if necessary. I won't go for the "hella flush" look though.

Finally, as far as getting more power here are a few ideas (from minimal to terrible):
- Index spark plugs so the igniters face the intake valves (<1% gain)
- Remove the intake filter (another terrible idea for minimal gains)
- Straight pipe the exhaust (not great for the environments if you replace the cats with a downtube)
- Lean out the engine a bit (terrible idea, but more power)
- Fuel injector + EFI conversion -- which you probably won't do because originality (<10% gain)
- Forced induction. A supercharger won't kill the exhaust note (just add some whine), but again, originality.

 

How exactly do you "index" spark plugs? I've never heard of that either. I understand that it means pointing the electrodes a certain way, but since the spark plugs thread in, how do you get the electrodes point the correct way?
Album

 

I first learned to index spark plugs as a neat project to tweak on my 24 Hours of Lemons crapcan racecar (powered by a 5.0L Ford Windsor engine). I can't say it really improved performance (because i had zero interest in dynoing the car) but it was an interesting thing to learn about (much like tweaking your own ECU tune using an Moates Quarterhorse EEPROM replacement module + Binary Editor).

There's a whole rabbit hole of ideas about the optimal placement of spark plugs but the gist is as follows:
- Mark the electrode position on the outside of each spark plug with a sharpie
- Decide on where you should position the spark plugs: towards the intake, towards the exhaust, or halfway between.
https://www.moroso.com/media/wysiwyg/PDFs/HRDP-200200-QUICK.pdf
https://www.spoolstreet.com/threads/spark-plug-indexing.4701/#post-66500
https://www.motortrend.com/how-to/how-to-index-spark-plugs/
- This is easiest with the heads off but when you tighten each spark plug in place, you'll find the tight spot to put the index mark in different points. Try one plug. If it doesn't work, try another one. With 12 plugs, I found it wasn't too hard to find the "right" plug for each cylinder. Number them w/ the sharpie. I used copper plugs on my lemons car so this was only a few dollars to buy extras which became "race spares"
- There are companies that also sell shims which you'd use to set the right position for each plug by adding a shim or two for each plug position.

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As far as a well setup k-jet system working as well as a modern EFI system using bosch injectors, I'm not so sure. While the fuel injection point (into the manifold above the intake valve) may be the same between a modern EFI system and the original kjet/jetronic/whatever system, I'm betting the fuel misting/atomization isn't nearly as good as with a garden variety bosch injector. The precision in the amount squirted with this distributor setup simply isn't there.

Its machining work + EFI setup, but others have done it. Passing local certification may be a challenge though.
https://www.***********.com/threads/qv-efi-conversion.37577/
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One more bad idea came to mind. In CA, things have to be a bit more stealthy as well because even an engine "sniffs clean" on a dyno, all fuel/intake/exhaust parts must have a California Air Resources Board (CARB Executive Order #). This means aftemarket turbos/superchargers are often verbooten unless the mfg paid for emissions testing AND for a CARB #). What some people do THOUGH is instead of bolting on a turbo, they'll opt for engine work instead and install a stroker kit). Of course, you'll need to upgrade the fueling/EFI to take advantage of the added displacement BUT its entirely possible. For these engines, swapping out the injectors for larger models AND a stealthy reflash of the stock ECU is good enough.

In Urs case, he's clearly not shy about spending money/effort on the Mondial: if he ever has to rebuild the block, why not resleeve it for slightly larger pistons and/or swap the crank to get more displacement?
- There seem to be folks here in the US who say resleeving with liners containing larger bores + stroker crank (or a 360 Modena crank) you can get to 4L.
- You'll still have to deal with an increase in fueling demands over stock but with a proper EFI, that would be entirely possible. Others have done this without drama. While I doubt just cranking up the fuel pressure on the stock K-Jet system would adequate to cover all driveability situations with a larger displacement engine, a similar technique was done with adjustable fuel pressure regulators and old turbo engines after they cranked up the boost and/or swapped to a larger turbo which shoved more air into the engine. This was popular with turbo-brick era volvos and mostly worked because a turbo charged engine would still operate pretty similarly to a stock engine when off boast whereas a bigger displacement engine (4L vs 3L) would be much leaner. I certainly wouldn't stop you from trying to make increasing fuel pressure to the k-jet work

 

Not to hijack your thread, Urs, but the spark plug index thing is quite the rabbit hole indeed!
I think I'll just hang a small vial containing some soil from Enzo's grave from my rear view mirror and call it done!
Alden

 

Alden - hot rodders have been indexing spark plugs forever - To get the electrode in the right orientation, you use washers...I've never done it - it's for folks trying to get that last bit of HP out of their engines:

https://www.summitracing.com/parts/mor-71910?srsltid=AfmBOoo1kOH8xrRAY2BeaxlY_HUg1H_wqsV0_czVer2bfF5WPnfV2TCEBY8

 

Nice work, as usual. What paint did you use to refinish the ashtrays? Mine could use the same treatment.

 

Sure they were powdercoatet initially? I redid mine as well and just sanded the surface a bit and used an ordinary matte black spray can in 2-3 layers. Works since three years.