Power Valve Selection
thank you everyone for your replies. Well I decided to try to dive into this issue but hit a snag... so while I was looking at changing the power valve I noticed that the carb has 72 jets and not 64 like the documentation says it should have. I don't have any record of me changing them when I installed carb... so I am not to sure what happened. Whether they started sending this carb with 72's, or somehow it was a mistake. However everything I saw online says the jets for 750 holleys should be anywhere from 70-78 for a 440. Unfortunately the only jets I have on hand are 60-69 sizes, which not only appear to be too small but everyone says that if you change jets jump 2 sizes... So Ill order a bigger kit that includes jets in the 60-99 range. So Ill drop the power valve to a 6.5 for now until I get more jets. No point in diving too deep into the PV area before I get the jets right.
Now there has been a lot of talk of timing. I am not to sure if I included that but as of now the initial timing is at 14 deg btdc (vac advance connected to ported not manifold vacuum) with a total mechanical advance of 11 (22 at crank) coming in at 2700 rpm (5400 engine rpm) for a total mechanical of 36 with the vacuum canister adding up to 3 degs (6 at crank) at 9-12 inHg with a total of 8 deg (16 deg at crank) at 18 inHg [Now I believe that's how it works - Crank turns twice for one rotation of the dizzy/cam shaft. So 600 rpm at the dizzy would be 1200 at the crank. I also believe that works the same for the degs of timing - 2 degs at the dizzy would be 4 degrees witnessed at the crank]. I just verified the timing curve on my sun distributor machine.
the transfer slot was set to .040 but I had to close the throttle blades a half of turn of the idle speed screw to get it down to 650-700 rpms
all that said, I'll attach a picture of the number 4 spark plug (I am running NGK XR5's, magnecor wires, a Mopar electronic dizzy with the ballast bypassed using a GM 4-pin module powered by a GM E Coil) . to me and from the references I see online it seems a little white and probably could go a little bigger on the jets. am I on the right direction?
thank you everyone for your replies. Well I decided to try to dive into this issue but hit a snag... so while I was looking at changing the power valve I noticed that the carb has 72 jets and not 64 like the documentation says it should have. I don't have any record of me changing them when I installed carb... so I am not to sure what happened. Whether they started sending this carb with 72's, or somehow it was a mistake. However everything I saw online says the jets for 750 holleys should be anywhere from 70-78 for a 440. Unfortunately the only jets I have on hand are 60-69 sizes, which not only appear to be too small but everyone says that if you change jets jump 2 sizes... So Ill order a bigger kit that includes jets in the 60-99 range. So Ill drop the power valve to a 6.5 for now until I get more jets. No point in diving too deep into the PV area before I get the jets right.
Now there has been a lot of talk of timing. I am not to sure if I included that but as of now the initial timing is at 14 deg btdc (vac advance connected to ported not manifold vacuum) with a total mechanical advance of 11 (22 at crank) coming in at 2700 rpm (5400 engine rpm) for a total mechanical of 36 with the vacuum canister adding up to 3 degs (6 at crank) at 9-12 inHg with a total of 8 deg (16 deg at crank) at 18 inHg [Now I believe that's how it works - Crank turns twice for one rotation of the dizzy/cam shaft. So 600 rpm at the dizzy would be 1200 at the crank. I also believe that works the same for the degs of timing - 2 degs at the dizzy would be 4 degrees witnessed at the crank]. I just verified the timing curve on my sun distributor machine.
the transfer slot was set to .040 but I had to close the throttle blades a half of turn of the idle speed screw to get it down to 650-700 rpms
all that said, I'll attach a picture of the number 4 spark plug (I am running NGK XR5's, magnecor wires, a Mopar electronic dizzy with the ballast bypassed using a GM 4-pin module powered by a GM E Coil) . to me and from the references I see online it seems a little white and probably could go a little bigger on the jets. am I on the right direction?