48 IDA Baseline Jetting Recommendation

[Brian Silva]

Hi Guys,

I need to order some chokes (venturis) and jets for my carbs and wanted to get your opinions on the setup. Here are the motor specs:

Here are some specs on the motor:

2332
42x37.5 Autocraft stage 3 heads ( older midget racing heads) should make plenty of power!
CB 2300 camshaft
5.4 rods plan to try different rod lengths for power range
10.7:1 compression

[Jim Ratto]

42 intake valve is on the small side for your displacement, depending on port design, your peak HP rpm could be limited to down around 5200-5500rpm. Not sure on the duration of your cam listed, but in order to make up for smaller intake valve area, I would go aggressive on cam profile, like 270'-280' @ .050/ 320 @ lash, to get your top end.
A 40mm venturi is what I'd start with, it will peak out around 6500rpm, use 60x110 idle or 65x120, F2 tube, 165 main and 200-210 air.

[Brian Silva]

Jim,

Thanks for the insight! The port design is very comparable to the CB Ultra Wedge Ports so they are quite large in that respect. The cam is cb's "engine builder shoot out grind" . Slightly larger than a webcam 86C. This is a weekend warrior car with additional oil cooling and so forth. The 42mm intake valve is a little on the small side but like anything else, testing the combo to see what works best. We are starting ut with a baseline on this motor and will be swapping heads/cam combo to see what runs best. Having a 5 speed should help with the higher rpm powerband.

Adv. Duration 317°
Dur. @ .050'' 273°
Lift @ cam .430''
Lift w/1.1:1 Rocker Arms .473''
Lift w/1.25:1 .537''
Lift w/1.4:1 .602''
Lift w/1.5:1 .645''

[Jim Ratto]

I'd tune it with 40mm vents.

[Cheesepanzer]

I'd follow Jim's advice above.  I've seen 42mm vents work well with similar specs, and smaller displacement.  I like the start with 165 mains, might need 170's if you decided to run 42's.  You indicate the engine is for a "weekend warrior" so I assume your gearbox is close, so you might try 42's.   

[Brian Silva]

Thanks guys, Should be getting it wired up in the next 2 weeks so should be ready to fire up by the end of the month. I will post the progress in the "In Da Works" section.

Jim,

Have you come back to the Bay Area recently? I think last time we saw each other was a few years ago at your house with Larry Mckenzie and Ray Schubert before one of the vw evens..

[Jim Ratto]

Hi Brian, no still here in Sunny Simi Valley. Saw Ray last week, was up in Bay Area for 3 days, went and saw him one night, shared a pizza. Good to see him. good luck with your motor it should rip the seat rails off the pan.

[bedjo78]

Hi Guys,

I need to order some chokes (venturis) and jets for my carbs and wanted to get your opinions on the setup. Here are the motor specs:

Here are some specs on the motor:

2332
42x37.5 Autocraft stage 3 heads ( older midget racing heads) should make plenty of power!
CB 2300 camshaft
5.4 rods plan to try different rod lengths for power range
10.7:1 compression

How's your engine running. I am  inprogress assembly the similar engine with CB2300 cam also

[draven898]

jim great avatar lol