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Author Topic: baseline jetting for 40 DCNF's  (Read 2215 times)
Glauco
Hero Member
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Posts: 511



« on: April 21, 2023, 11:36:55 am »

Hello,

I'm looking for a good baseline to start my jetting to go from IDF's to DCNF's on my 1641.
engine specs are:
mahle P&C
scat cw crank
scat connecting rods
Scat 170mm pulley and lightened flywheel
stock heads with the "how to hodrod a vw" port job and SS valves. oteva springs and titanium retainers.
Engle FK65 with 1.4 rockers (rather 1.5, lift measured out at 12.95mm)
MSD 6AL ignition
S&S 1 1/2 header with S&S DQP

running good on the IDF's, rev limiter is set on 6300 and I have the feeling the engine likes to go there, even with the fk65. But I have a killer set of 40 DCNF-12's on DDS manifolds and linkage I'm dying to use.
they received a full overhall and I did the berg mods, including the snorkel for the float bowl.

what would be a good baseline? I was thinking to go with
28mm vents, possibly 26/30 or 28/32 Berg style venturies
200 Air corrections
- 125 mains
- 50 idles

I was thinking to use the 50 Idles because of the very large pump jet cam that is in it now. not sure on the pump jet size.
I have a set of 26mm and a set of 32mm vents as well, 26 would be to small I presume, might try the 32's later in the tuning stage as well//
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Lightning
Newbie
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Posts: 17


« Reply #1 on: June 30, 2023, 22:43:02 pm »

Hei,

have an engine spec. fairly close:
stock 1585cc
mahle P&C
stock crank
stock connecting rods
CB serpentine pulley
stock lightened flywheel machined for ignition pickup
stock heads with my own port job, app 9:1, SS valves, stock springs and retainers.
Stock cam with 1.25 rockers
MegaJolt ignition
Memminger Sebring replica exhaust

40 DCNF's in original state expect cold start system blocked
28 vents
145 main jets
F24 emulsion tubes
210 air correction jets
052 idle jets
port matched Scat manifolds

Runs pretty well with a slight flat spot mid range. Easily scares unsuspecting BMW's when lights turn green  Cheesy
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Glauco
Hero Member
*****
Posts: 511



« Reply #2 on: July 05, 2023, 11:07:22 am »

thank you for your input, I might try that combo.

I installed an AFR-meter just to make sure I wasn't doing anyting wrong and I had to bump up to 55 idle to get it right.
also changed the 200 air for a 180, but now it's a little too rich, so might change back to 190 or 200 just to doubble check
or I install the 220's I have and try a bigger main jet, also a possibility

Glauco
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