new parts and lost performance?

[mooncows]

k im frazzled. i got a 305 sbc wich i dont want to swap cause i want the stock engine. anywho i added some new spark plugs, performance spark plug wires, headers with true dual exhause, performer edelbrock dual plane intake, and a new 500cfm edelbrock carberator as well as some other small goodies and i lost 3 tenths and the strip. im confused. heres my before and after time slips (btw i got 3.73's in the rear and my tires are tiny at 185/60/14) what did i do

Before After
RT=0.065 0.099
60'=2.377 2.472
330=6.797 6.894
1/8=10.508 10.624
MPH=65.93 65.68
1000=13.731 13.858
1/4=16.467 16.611
MPH=82.21 81.44

 

[mooncows]

btw not sure if my spark plug timing is correct because we had to remove the dist whenw e installed the intake manifold. as well after the race when i was slowing down the engine would backfire once or twice

 

[bjohn07]

u need to make sure ur timing is set right. timing can make all the difference.

 

[chevyman454]

well. 305 ? did you change the cam when you didt the intake and carb?
try a 600 instead of a 500 probably not flowin enough air

 

[mooncows]

i thought that 600cfm on a 305 was way to much carb? i dont got a timing light but i can try by ear

 

[jrm81bu]

The weather alone could make you loose that much. The timing is prolly a big issue. You lost a tenth in your 60' which could have been from spinning and then you just never got it back. However if you had spun I think you mph would have been higher. I'm not sure where you are seeing 3 tenths difference, I only see a .144 difference.

 

[mooncows]

sorry i was just comparing my 2 fastest times of the day this year and last year cause i only went once last year. My slowest time this year was a 16.98 in the quarter and that was awefull. all i wana know is why a bunch of new parts arent adding any speed increase what so ever.

 

[G_Body_Enthusiast]

timing most likely.

and you cant tune it by ear. the only way to know what your timing it is with a timing light. i dont have one myself but it's on a list of crap i need before i do an engine swap.

you'll also need to know RPM to set timing.

 

[gpguy]

You probably dont want to hear this. But the parts you installed are only aftermarket parts just as good as the ones that came on the 305. It came with a aluminum dual plane and a 500 or so carb. So except opening up the exhaust you really did nothing. Try different timing. Use a light!

 

[mooncows]

K so i might have found the problem but not sure. My new carb has 2 vacuum ports, and originally the dist vacuum was in the drivers side but ive read its supposed to go on the passanger port. Could this affect my performance?