Weber IDA-3C jetting for 3.2ss & big valve SC heads

[lupin..the..3rd]

Hello everyone, lets say one were planning to use a pair of Weber 40's on a 3.2 SS. Yes, I know, they are a bit small for this application, but to avoid breaking the bank, they will be used, at least initially. The heads are single plug large valve SC heads.

What is the recommended venturi and jet sizes for the 40 IDA-3c's for this application?

I know I'm not the first to do this, but I'm having trouble finding this information with the forum search.

Thank you

Edit: I should also add that my intentions are for mostly track use, only very occasional street use, and emissions testing is not required.

[Steve@Rennsport]

Mister Lupin III,

Excellent question that begs a LOT more details to get a constructive & useful reply.

Jetting is affected by:

Displacement
Cam profile
Compression ratio
Exhaust system
Muffler
Location (altitude)

Sooooooo,......to answer your question, I'd kindly suggest you post all of the details so you receive the assistance that you need.

[lupin..the..3rd]

Thank you for the reply Steve, some details are below in red.

Originally Posted by Steve@Rennsport

Mister Lupin III,

Excellent question that begs a LOT more details to get a constructive & useful reply.

Jetting is affected by:

Displacement: 3.2 liters (3.0 sc crank w/ 98 mm p&c)
Cam profile: Not yet selected. Any recommendation for this?
Compression ratio: 10.5:1 JE pistons. No actual measured CR yet as engine is only partially assembled.
Exhaust system: None yet, planning to go with SSI's (I want working cabin heat).
Muffler: None yet, planning to go with some free flowing sport muffler(noise level not a concern)
Location (altitude): near sea level (less than 1000 feet)

Sooooooo,......to answer your question, I'd kindly suggest you post all of the details so you receive the assistance that you need.

[Steve@Rennsport]

Originally Posted by lupin..the..3rd

Thank you for the reply Steve, some details are below in red.

Hopefully, you are planning on installing twin-ignition so you can safely use pump gas at 10.5:1,...

Cam choices depend on what the car is used for and what you like. After you measure your piston-to-valve clearances, you'll know what cam profiles you can accommodate. If this is a street car, I use Mod S cams in such things.

[lupin..the..3rd]

Originally Posted by Steve@Rennsport

Hopefully, you are planning on installing twin-ignition so you can safely use pump gas at 10.5:1,...

Aye, that's the plan.

Originally Posted by Steve@Rennsport

Cam choices depend on what the car is used for and what you like. After you measure your piston-to-valve clearances, you'll know what cam profiles you can accommodate. If this is a street car, I use Mod S cams in such things.

This is a mostly track car with occasional street use. I'm looking for big power from 4500 - 8k, and don't care much about what happens below 4500, so long as it's usable for occasional street use.

If I understand you correctly, I need to have heads built and ready for use, so I can measure piston-to-valve clearance *before* selecting an appropriate cam?

I have a set of used heads, but they need to be rebuilt, and also modified for twin-plug. Is this a service that you perform in-house Steve? If so, I'd like to call and make arrangements to have it done.

[Harriet03]

I'd kindly suggest you post all of the details so you receive the assistance

[Steve@Rennsport]

Originally Posted by lupin..the..3rd

This is a mostly track car with occasional street use. I'm looking for big power from 4500 - 8k, and don't care much about what happens below 4500, so long as it's usable for occasional street use.

Assuming that you have done (or will do) all of the mandatory oiling modifications for reliability above 7K, one would choose an appropriate race cam profile that works with the exhaust. SSI's will kill power above 7200 RPM on a 3.2 due to their 1.5" primary size so some reconsideration may be necessary.

It bears mentioning that engines are a collection of matched components specifically chosen for the RPM range and desired performance. Any deviation or compromise can seriously degrade both peak HP as well as overall drivability. If you need heat AND power, I would not use SSI's unless you are willing to scale back your desired RPM range.

If I understand you correctly, I need to have heads built and ready for use, so I can measure piston-to-valve clearance *before* selecting an appropriate cam?

I have a set of used heads, but they need to be rebuilt, and also modified for twin-plug. Is this a service that you perform in-house Steve? If so, I'd like to call and make arrangements to have it done.

You need to be able to accurately measure and calculate compression ratio while juggling piston-to-valve clearances and deck height,....

I think we need to discuss this in detail,....

We do all of our own machine work here in-house so I'd be pleased to help you in any way I can.