I finally got a chance to swap step-up springs in my Edelbrock this week. The car has had a bad stumble when you tried to go WOT from an idle. It would actually die if you held the throttle open. I called Edelbrock and after I told them the specs. on my engine, they told me to switch to a set of pink step-up springs and try that. I ordered a calibration kit from Summit and finally put the springs in....What a difference! It's still a little slow to rev up, but I have WAY more power on the top end at WOT. More power on the bottom end too, but I'm gonna play with the timing some and try to get the hesitation out. I'm kind've thinking about swapping in the next set of springs and seeing what that does....I'll try it this way for awhile first though. It's just nice to finally be able to see SOME of what this engine should be doing. I was amazed at the difference. Anyway, I just wanted to share! Y'all take care! Preston
If I am not mistaken, there is a way to test which spring to use. I think I put a vacuum gauge on one of the ports in the front of the carb, the other one beside the vacuum advance, and divided that number by 2, and used the springs that had that number. For example, I think I had a vacuum of 14, so I used the #7 springs. I did that several years ago, so I don't remember the exact procedure or numbers. But I think I ended up with the natural colored springs... It made a significant difference. I had a really good time with that calibration kit, and solved many problems with it. Just sold it with the carb to Bowstick, in your neck of the woods (South-West Louisiana somewhere)
308ci, heads ported/polished, 204/214@.050 duration and .448/.472 lift hydraulic cam, Holley Street Dominator intake, Flattop pistons, Edelbrock 600 carb, long tube 1 5/8" headers, dual 2 1/4 exhaust, Crane Cams ignition.....I think that's about it. I have no idea what kind of power I'm making, nor do I have any idea of a quarter mile time as it has never run good enough to try it.....Any ideas? Thanks, Preston
What heads are you running? The rest sounds a bit like my old engine, I can plug the numbers into my desktop dyno under my old profile and get you an estimate... Take that number and knock off about 20% and it will be pretty close to accurate. Desktop dyno tends to shoot a little high, or maybe it is accurate at the flywheel only...
DD said I had 300 HP and 275 tq on my old setup--GT40P heads, 600 edelbrock on Torker 289, 8:1 compression, similar cam to what you have, and long tube headers. I think it was more like 250 based on seat of pants and performance at the track.
My heads are 1983 302 heads....I had them ported/polished/shaved. I don't have any numbers on them. My DD says 353hp@5500 and 373tq@4000. I know that the engine really seems to wake up around 2500 and goes from there.... I don't know how accurate the DD is....this seems high to me. I still have the 3.00 gears and I run a 275/60 R15 rear tire.....I at least hook up sometimes now.....I really want to swap to 4.11's just for the seat of the pants feeling. I don't drive the car much anymore, so fuel mileage is not a factor....Thanks for the help! I'll hafta read up on how to change the rods and other things...I don't know how. BUT, I'll learn! I have to, nobody else down here knows how either!
It is really easy, at least the rods are. You will need to find the graph that lists the rod/jet combos and where they fall on the ranges of richness/leanness... Your instruction manual will have several of them, make sure you use the graph for the correct model carb. From there, I first messed with just rod-only swaps. To swap a jet requires taking the top half off of the carb off. Not very hard, but takes about 10 minutes compared to the 2-3 minute rod swaps. Even with just swapping rods, you should be able to screw around and see what seat of the pants changes you pick up.
