Dual IDF Tuning - 36HPVW

[txoval]

The engine is brand new...it's very hard to increase compression much more on a 36hp.

The carbs can be made to work...worst case as I see it is moving to a set of 36DRLA's which several others have used successfully with milder engines.

I need to get the exact specs on the cam, but I doubt Matthew (Aircooled Research) would grind a cam requiring 9-1 compression for a 36hp engine. It's his Stage 2 cam...I could be wrong on the comparison to a Super 90 cam.

[Alstrup]

Yes. The easiest way to increase cr is actually to bump the displacement, or install domed pistons. But the late model 1200 domed piston only increase cr with about 0,4, so not worth it. The next step is je I guess. Then we are back at increase displacement pricewise.
1200's with dual 36'es can work well. No problem.

[Danwvw]

Well the DRLA 36's only go down to 28mm for venturi's but the newer DRLA 40's DRLA's show 26mm venturi's available, And the 356A carburetors the Zeniths 32 NDIX, I believe have a 24mm venturi available: S-90 and other 356 cam profiles, My VW engine with the Webcam 118 vs the engine with a W-100 profile Compression on these engines is around 8.5:1.
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1960 Beetle And 1679cc DP W-100 & Dual Zeniths!

[esde]

Fwiw, I have just installed a sync link, and it is pretty much a genius piece of kit. I went up to visit Tim and pick it up as he's only 30 minutes north, and I bet he'd be up to help make a set for you. He's got some nice cnc machines, and has done several custom brackets for the cables, etc. IF the linkage is some component of the problem, the sync link is the answer to at least that much of it. You're in good hands otherwise..
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modok wrote:
Bent cranks are silent but gather no moss. I mean, ah, something like that.

[modok]

the cam specs, according to the site are
Big lift
Long duration


Is this mcdonalds?

One time at Wendy's the young lady asked me how many fries I'd like, so I said 75. i counted them, it was not far off!

[Danwvw]

http://www.webcamshafts.com/mobile/automobile/volkswagen/volkswagen_36_hp_8v.html Who knows what the lift is on that Air cooled Research Stage 2 camshaft is though?
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1960 Beetle And 1679cc DP W-100 & Dual Zeniths!

[pupjoint]

may not be relevant, would a Berg linkage fit your requirement? i have tried CB, CSP, Berg and the latter is by far the best in terms of throttle response, staying "in sync" and full throttle no issues. even when i remove the linkage for other repairs, i put it back and it is dead on unlike the cb setup. csp piece i could not get full throttle, not sure what i did wrong. i am on DRLAs

a mate of mine just got the new VS linkage and seem pleased with it.

[txoval]

I'm afraid the Berg linkage will be too wide. My manifolds are close to the fan shroud and the 36hp engine is already narrow.

I had to shorten the CB hex bar over 1.5" to fit. Shortening the Berg linkage would not be easy. Originally it was my first choice.

I'll email Matthew to get the specs of the Stage 2 cam. I remember a post in the Vintage Speed forum a few years back that mentioned it was similar to the S-90...but I may be wrong.

[txoval]

I did get feedback from another Samba member with my setup...he's running 55 idles and 115 mains.

I ordered 57 idles and 120 mains, so we'll see where that puts me.

[txoval]

At .050 lift was 230 deg on 108 deg centers, and .330" lift. At .040" (which is more like the Porsche checking height) it measured 235 deg on 108 centers.

[modok]

Seems reasonable. That should be ok

[txoval]

I'd like to thank everyone for their help!

New jets arrived today (57 idles and 120 mains). Placed them in there and the spitting/popping is gone. Revs smooth from idle to full throttle. At full throttle I saw what I would call "splashing" at the top of the carbs...more like a mist. Is this from the 120's being too rich? It didn't pop...just curious

Now, I think I'm a little rich at idle, so the fine tuning begins. 50's are too lean and 57's are too rich. I was able to find lean best idle...so maybe I'm wrong

[66brm]

Sounds like reversion are you running any stacks? Looks like a fuel fog over the carbs
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Aust. RHD 66 Type 1
Aust. RHD 57 Type 1 Oval

[txoval]

No stacks during this...but I do have a set...short ones

[sled]

velocity stacks are very good at containing fuel standoff, as well as directing airflow more efficiently, use them.

do your stacks match the upper bore diameter? they should.
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drive your split.

[txoval]

Unfortunately no, they are bigger...does anyone make/sell stacks for the smaller bore of 36's?

I guess I could if comes down to it.

[sled]

John @ aircooled has them in 1" and 1-5/8". The height of your aircleaner elements determines which you can use, but he 1-5/8 would be preferable.

I forget, do you have a wideband on this thing yet? You will be chasing your tail somewhat until you can see your real-time AFR.
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drive your split.

[txoval]

My exhaust has the port(bung) for an O2 sensor, but I do not have a wide band.

Openings in the top of 36IDF's are ~37.8mm...my velocity stacks have an ID of 40mm. Mine are the same that John sells for 36/40 IDFs.

Dellorto-UK does sell a "custom" velocity stack for 36 IDFs with a 38mm ID, but they are definitely proud if them...$20 each

[txoval]

So with my setup/airflow, only being 1200cc, will that change the standard AFR's?

With 57 idles, I'm sure my AFR at idle is lower than 14.1...unless I'm misunderstanding again

[57BLITZ]