it doesnt really matter exactly. You arent looking for exact PSI, you just want to check for a rapid drop that will indicate a faulty pump. it should be around 40 psi with the vacuum atached and 43-45 without it.

 

Just FYI i made 398/375 mail order tuned with a stock bottom/cc306 and heads flowing 267, stock TB even..

 

thanks 96ta, i know my numbers dont add up, somethings not right thats what im trying to figure out? on the dyno sheet it shows the car falling on its face at 6k rpms, which doesnt make sense w/ the 847 cam at all and its powerband. one question i have is that my rockers are very noisy could this be causing valve float and equate to my car not making proper power numbers or possibly the cause of not making power past 6k rpms? After putting it on the tech 2 my car seems to be running fine. w/ very minimal knock at all, tps is at .60mv, i did have a code for h02s bank 1 (code 13). also another thing i noticed is that when i start the car, it will hold rpms up around 1800-2000 for about 30 seconds before it drops down to idle (900rpm). what would the cause of this be? IAC? it had 47 or 57 counts i believe.

thanks,
Nick

 

anyone? i'm really at a loss

 

Id think a cam that big would pull up to 7000 rpm so maybe you are floating the valves a little. I dont know the specs on those springs however I do believe you have a solid set of lifters in there. Since you said the rockers are rather loud, have you tried resetting them? Obviously if the rockers arent tight enough then the valves wont open properly.. kinda the opposite of valve float though. Did you notice the car smoking at all where the power was falling off?

 

nope no smoke what so ever. it just looks like it fell on its face at 6100 rpms, i'm wondering if thats the way they tuned it? because i'll post the dyno chart later. it almost looks as if it hit the rev limiter and then they just let off gas and decell numbers.

 

also from around 1800-3100 rpms my cars afr is around 14.5-14 according to the dyno sheet is that normal? i mean i'd think it was almost to lean, i have 42# injectors, walbro 255, so i dont think i'm lacking fuel.

 

What do you have the preload set to on the lifters? With the 'R' series lifters you dont want anymore than 1/8 turn past zero. I had tried more in an effort to quiet my rockers, but all it did was kill top end power.

-Tony

 

i have those same lifters then, could it be possible that some of them are over adjusted and hurting me high up in the rpms? because only a few are noisy or making some noise.

 

Those are my projected numbers for my stock cube motor with GM 847 Stage 2 heads BBK shorties and 3.73's... something is deffinately wrong there, I would have expected more out of your combo.

 

i know the numbers are low, lol i just wanna find out why their low? does anybody have any other ideas on what to check or look for, last nite i check FP it was 40 psi at idle w/ vaccum line on, then at WOT it went to about 46 psi. O2's are fine, no more knock retard. afr on the dyno pull ranged from about 14.5 in the low rpms to around 12.5-13 throughout the powerband.