digithead
Well-known member
- Joined
- Jan 24, 2016
- Messages
- 264
- Reaction score
- 2
- Location
- UPSTATE NY
- My Car
- 1973 Mustang 351C-4V 4BBL 4 SPEED CONVERTIBLE White
So I admit I have not tinkered on 4BBL since 30+ years ago. Ok, so I have a new Edelbrock 4BBL on 351C, with 2V heads, but a 4V intake made for 2V heads. Car really runs good but was rich smelling. A local motorhead friend told me that with a cam I probably have a lower then normal vacuum. He said I should try a lower strength step up spring. I bought the 1840 Edelbrock carb tuning kit for my 1806 carb. I dropped down to the yellow 4"HG springs. Seemed to run just as well but not the rich fuel smell. So I tried blue 3"HG springs. Still no fuel smell, seems a tad less power. SO I need schooling. If I am only changing spring, no metering rod or jets, wouldnt it make engine produce "same HP" at cruise irregardless of spring? In other words, at idle I have less vacuum and need a lighter spring to keep metering rod down on leaner portion, but once I am running 50-60 mph I am up on same part of metering rod (richer) and so I should be getting same performance (HP) correct? I thought it felt a little less power but I can be imagining it too. Seems like spring would only effect transition from idle to cruise, but to affect overall mixture cruising I would need a different rod or jet, is that right?