Gustav455

Hey guys, hope everyones having fun crusing their Oldsmobiles. I have question, i got about 4000 miles on my fresh rebuild 455 thats in my 71 Delta 88. It first had the 2bbl carb and factory cam, when i did the rebuild, i converted the 2bbl to a 4bbl of the same year and its a Q-jet. The machine shop also but a little bigger cam, i believe its a 286. But when i had the 2bbl on there, i could just put the pedal down just a little bit and it would lite the tires up like no other, after i have done this rebuild, it just hasnt had that response like it did before i did the rebuild. The machine shop told me to set the inital timing to 17-18 degrees, i did, they also said set the total to around 37-38 at 2000 rpm. ive read alot and this doesnt seem to be right. i just like some opinions on what about should the timing be on this particular motor and since i used the stock distributor do i need to change the springs and weights? thanks

compedgemarine

hard to tell from the info but if the distributor is stock it probably doesnt see full mechanical advance till over 3000 rpm. if you set it to 38 at 2000 you are possibly 43-44 total advance. the first things you need to know is how much mechanical advance does the dist. have and at what point is it all in. you then would need to set your total advance at the rpm that is using all the mech adv. do you know what compression the engine is? was the cam degreed? what are the actual specs on the cam (lift, duration, centerline, overlap, etc.)? some cams, especially with low compression engines, wont make any power till higher rpm. My 76 trans am with a 13 to 1 400 wouldnt make ANY power till almost 4000. it was a 4 speed and I usually shifted it a 6700-6800.

Gustav455

for the compression, they bored the block .60 over and since my heads were cracked i put some Ka heads on, which havent been milled down or anything. i used not deep dished pistons but there a little dished. a rough estimate i think the compression would be 8:5:1. for the cam, its a Melling cam, its number is SOC-9. heres the specs below



the cam came from the parts place just like the specs they didnt do anything i just put it in when i put the engine together. for the mechanical on the distributor, i bought a adjustable vacuum advance, when the machine shop told me to set it the inital to 17-18 degrees inital the total would be like 50 @ 2000 rpm so i bought a adjustable and turn the screw with the allen wrench and got it down to 37@ 2000 rpm, but im not sure if thats right looking at many post on the internet. i been reading 10-14 inital and total at 3000 rpm. thats why i was thinking maybe i need to adjust the weights and springs in the distributor from the stock settings since its now a little different motor setup

svnt442

That's a mild cam for sure.

Gustav455

yeah, i said i wanted something that had a noticable sound but wasnt going to make the motor stall at every stop light and wasnt going to affect anything wear i would need a new torque converter and i wasnt sure about the rear end gear ratio of 2.93, i said i wanted some performance but i was also worried about gas mileage a bit too. i dont know too much about cams and what that stuff means. and how to time it according to those numbers.

Gustav455

since this is the stock point distributor i found the mechanical advance @ distributor rpm specs in my book. 0-2 degrees at 400 RPM, 6.5-8.5 @ 1200 RPM and 13-15 @ 2000 RPM