Baseline jetting question...

[gizago]

Just finished buttoning up a motor for my wifes '67 bug. Mostly parts i've had spare in the workshop, but should be a nice little combo-

1967cc
AS41 case, full flowed/clearanced etc
deep sump
CB 74mm 4140 crank
92mm mahles
Unitech rods
stage 1 clutch
13lb flywheel
Scat C35 cam
alu pushrods
single h/d springs
041 heads 40x32 (mild port job)
1.25:1 scat rockers with bolt ups/swivel feet
Treuhaft 010
Blue coil
Stock fuel pump
1"5/8 merged header with twin Q/P
9:1 c/r
40 IDFs on 5" manifolds

It will run on 97 pump gas (UK)

Any ideas on baseline jetting?
What emulsions would work best with this combo? They have F16s at the moment from memory
The IDFs have 28mm venturis in, which I will swap out, I was thinking 34mm vents with 145 main jets? It's not going to be a screamer with that cam, single springs and the 32mm exhaust valves on the heads.
Also, the heads have 1" 1/4 exhaust ports, is it worth opening these out to match the 1" 5/8 header?
And how much timing with the 010, ive only used 009s before.

Thanks in advance, Mat.

[dyno don]

Gizago, If you keep the 28 vents in ,start with 110 mains/115 Max. If you swap out with 34 vents in, start with 135 and I think that will be your best jetting on the mains. keep all other supplied jets the same as your requirements wont need anything more. The cam (scat C35) is close to an Engle 110  and I would suggest to you to NOT run the 1:25's unless you increase the spring pressure with duals however with those heads you will be very limited with your power output and duals will be overkill. I would suggest also to swap out the exhaust to 1 1/2 as the 1 5/8 with your combination listed is rather large and especially since the exhaust ports have already been compromised you will need more back pressure and I  would use a single "old school" muffler as it will help increase some of the low back pressure. Total advance should be set at 32 total. Hope some of this will steer you in the right direction.  Good Luck, Dyno Don

[gizago]

Excellent- many thanks Don.

[Phil West]

Hi Gizago,

I run a 1956cc with 40 drlas, C35 cam, 1.25 rockers in my van - I use dual springs.  I have an LM1 in there.  When not towing I have best results using 155 mains (note I am running the CB update kit), and it's a heavier unit!  So maybe something in the 135 to 145 area to start.
Cheers
Phil

[gizago]

Cheers Phil- ive got some 135s in another set of carbs so they will be my starting point. What heads/valve sizes are you running with that motor? What size air corrector jets are you using?

[Phil West]

Soz for the delay been engine building - they're Scat pro street with duals, valves are 40 / 35.5.  165 airs.  Cheers

[gizago]

No worries, cheers.