Best jets for engine

mr white · Posted: Sun Sep 20, 2020 7:54 pm Post subject: Best jets for engine

Hello everyone,
I have a 1967cc engine with an 8:2:1 compression ratio with 63cc combustion chambers. I just bought a pair of 36 dellortos for it. Any recommendations for jetting? My mains are 80s. Any input is appreciated!

Danwvw · Posted: Sun Sep 20, 2020 8:09 pm Post subject: Re: Best jets for engine

I have always wanted to build one, I have been calling them 1968cc. It's a 74mm Stroke X 92 Bore Right? Yes that is a fair amount of displacement for the Dellorto 36's I take it we are talking dual carbs. What 80 doesn't sound like anything right maybe it's 1.80 for the air correction that would be normal.
They are usually and it will depend on the Venturi Size around 1.22 to 1.40 mm a 1967cc 68 probably needs maybe 32mm venturi's maybe even 34's. The Air correction jets will normally start with 1.80mm air jets. People do all kinds of things though to get the air fuel mix right for a given engine.
Start by identifying all your jets sizes and the sizes you have available and take a look at what size of Venturi's it has. Dellorto 36's came with 30mm venturi's. Is it a Bug or a Bus engine?
For Example this looks like a 1.25mm Main Jet:

Image may have been reduced in size. Click image to view fullscreen.

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1960 Beetle And 1679cc DP W-100 & Dual Zeniths!

mr white · Posted: Sun Sep 20, 2020 8:32 pm Post subject: Re: Best jets for engine

Thank you for the reply Sir. This is a thick wall 92. 74mm crank. Full flowed. The engine is going in my lifted 73 thing and at times my 58 double cab. I will take one carb apart tomorrow night and start writing down all my numbers. Where is a good source for a quality rebuild kit for these? Yes, they are duals.

mr white · Posted: Sun Sep 20, 2020 8:57 pm Post subject: Re: Best jets for engine

120 mains and 58 idles. Couldn’t resist taking it apart partially. Beautiful inside!

mcdragracer · Posted: Sun Sep 20, 2020 9:03 pm Post subject: Re: Best jets for engine

I carry all size rebuild kits in stock (italian) for the Dell's and most every part that you might need for your carbs, your idle Jet size will most likely range between 55/60. Your air sould be 180, 9164.2 emulsion tubes, mains will depend on what size your venturies are, your carbs came factory with 30mm vents and 122 mains.

Danwvw · Posted: Sun Sep 20, 2020 9:55 pm Post subject: Re: Best jets for engine

I have found hard to find Dell parts on e-bay a Italy seller named alfa1750 has them may be the same guy as above. Also EuroCarb has them and here in the US I think ACN and CB Performance still have most of the Jets.
Yeah, in the Thing you could probably go with 34's especially if it's got a fair amount of cam and or Big Valve heads. But Low Rpm Torque will be better with the 32's. I am running 30's in my 74mm X 88mm Bus Type 1 Engine with Dell 36's. I probably would be better off with 28's but it's nice on the highway with the 30's.
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1960 Beetle And 1679cc DP W-100 & Dual Zeniths!

Alstrup · Posted: Mon Sep 21, 2020 7:37 am Post subject: Re: Best jets for engine

32mm venturies are sufficient for 120 hp.
With that low CR I doubt the OP is in the neighbourhood of that.
Also, keeping them 32 will also make the jetting much more predictable.
0,58 idle sounds about right. Now we need to know actual venturi size. float height, cam, valve size and exhaust. Then we can get really close even on bench tuning.
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