924Board.org

[Octane]

Well it's been a long, tiring, and often times frustrating journey since I parked my 924 and put it up on jack stands last fall. Until this point it was a mostly well sorted and reliable bone stock 924 N/A that I was daily driving at the time with very little issues. However like most of us, it just needed a little more power.

Engine bay before, nothing to see here...


So I yanked the I-4 out of there and started figuring out what I was going to do...



I had planned to install euro pistons and possibly a camshaft, but after pulling the valve cover and oil pan everything was so clean and showing so little wear that I decided to leave it alone for now. I paid $250 for a set of euro pistons and would have had to pay another $300 for rod bolts just to take it apart, plus rings, circlips, wrist pins, main bearings etc. so I decided it wasn't economical to do it. However I did find a set of Solex C-40 DDH carbs with manifold for the 924 that I bought for $120 on eBay.



The carbs fit with little headache and modification and were supposedly already set up for the car at a fraction of the cost of Webers.

So once all that was done and the engine was back in, had some trouble getting it running initially but eventually did thanks to forum member DOCO for coming out to help me with it. Turns out I had the distributor mounted in the wrong position... but here's the engine back in, all hooked up and running.



I had initially set it up temporarily for the throttle to pull across from the top. Ideally it has to pull straight down for it to work and I'm still waiting on parts to do that one day soon. The first month of driving it I was unknowingly not even getting full throttle. It felt pretty good but mostly the same horsepower as before and not much else. I spent a bit of time tuning the carbs and timing but wasn't getting anything special. It wasn't until yesterday when I re-did it that I am now getting full throttle (or at least 9/10) that I was really surprised at the power it's putting out. Complete night and day difference from how it was before with CIS. Realistically it is probably at most 10 hp more but it's that little bit that counts. A little hesitation on the bottom end that I'm working on but then it just pulls hard from there.

Costs:
Solex C-40 DDH carbs with manifold, used - $120
Generic 8-12psi fuel pump & fittings - $80
Fuel line, clamps, etc. - $25
Misc. bolts, brackets, etc. - $25

Total cost: Under $250
Performance gain: Definitely noticeable, maybe 8-12 horsepower?
Fuel economy: To be determined, doesn't seem any worse so far.

I was really getting frustrated and starting to regret converting but at this point I couldn't be happier with it. Carbs still need some tuning as it's running pretty rich (including a sweet backfire every time I shut it off) and throttle to be set up properly but I can do that with time. For now it's running well and driving in this beautiful southern Ontario weather.

Bonus shots:










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- Brendan
1977 Porsche 924

[Rasta Monsta]

Bet it will really scoot when you get that distributor recurved.
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Toofah King Bad

• WeiBe (1987 924S 2.5t) - 931 S3

[avaconirl]

It just go's to show that you can't beat old tech at least you can play with it.
Well done and keep up the good work.

[the_mad_electrician]

Wow! I thought my carb conversion was cheap at around
$425 but damn you got a deal! I love my carbs so far and I like you still have a little tuning to do but the power does seem slightly better than CIS. The only question is, what's with the green? Planning on painting your car that color?
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81 924 N/A

2004 Ranger "Edge"

2005 Mazda 6

[Octane]

[931Owner]

Hey Octane! I remember reading your post about doco coming out to help you. I was wondering what happened after that. Thanks for the post and sure glad things are going well.

Not sure if they sell colortune where you are but for my old Rover 2200TC I used that to make sure the twin carbs were tuned good.
All colortune is, is a glass spark plug with a mirror so you can see what color burn you are getting in the cylinder (your air/fuel mixture). Great product.
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1980 Turbo
-too many cars and too many motobikes

[Joes924Racer]

I think hes waiting on the throttle linkage part, though its running.
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1979 porsche 924 Na
1980 porsche Turbo 931GT Replica
Have u ever driven a turbo.

[1055]

this is a cool conversion. im sure ill be picking your brain when its time to get mine running. I bought it already converted, but its a weber 2 barrel. do you have one throttle linkage running both carbs?
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77 924 w/Weber 2 barrel & dogleg 5.
99 Subaru OBS, EJ253 swapped.