I HAVE QUESTIONS....Please see if you can help

Pvtspencer101 · March 23, 2012, 01:25:46 AM

I need someone to help me out I am having a spark knock problem, and I have a question about my rockers... I know from the factory they are 1.5 Ratio and I am going to buy a roller rocker set up for it, but should i stick with the 1.5 ratio or should I go up to a 1.7? So just so everyone know I have a TBI spacer an Open airfilter headmen header true duals back to 2 thrush welded mufflers, I am going to order a cam through jegs thats rated from 1k-5k RPMS to work with my stock stall and stock computer, I port and polished my intake and heads, and I was having a problem with fuel. Well come to find out the Stock CFMs on a 90 5.7 L TBI is only 480Cfm good up to 240hp which as of right now i am a little over 3 So I got a stock TBI from a 454 Big Block bloted right on and its 649 CFM's and the truck does good now, EXCEPT FOR the spark knock, I took out the egr which is when this started.. is there anyway to fix it becides a chip? and I want to say The spark knock started before all the upgrades.. and I will tell you My ol Man ( retired Master ASE mechaninc) told me to retard the timing to get the spark knock to stop, which worked except now the timing is so retarted it does run like its supose to.. and I was told a replacement chip which takes out the EGR is a good option.. But I want to know if its my only option!

xjs3667 · March 23, 2012, 02:01:31 AM

you should be able to run the 1.7 no problem.... as for the spark knock, have you checked the knock sensor? that would be my guess, its common for what you are describing, they run around 30 bucks, replace it and see if thats it

and have you tried running a higher octane gas?

Pvtspencer101 · March 23, 2012, 02:08:41 AM

Ok so if I do the 1.7 Ratio should I run a bigger diamater Push rod? and no On the gas, And I was told I got the spark knock because I have a whole lot of air comming in, and not enough going out,

Mudbuster · March 23, 2012, 10:04:58 AM

it's either timing's off or running lean has nothing to do with exhaust flow out. like he said try your knock sensor and check your fuel pressure should be around 14psi on a throttle body.

old school truck dude · March 23, 2012, 11:21:37 AM

If youre already goin with a bigger cam, Id be very careful about increasin the rocker ratio, could end up hittin a valve on a piston at higher RPM. Please describe how you took out the EGR.

xjs3667 · March 23, 2012, 01:11:21 PM

Quote from: old school truck dude on March 23, 2012, 11:21:37 AM
If youre already goin with a bigger cam, Id be very careful about increasin the rocker ratio, could end up hittin a valve on a piston at higher RPM. Please describe how you took out the EGR.

x2 depending on what size cam you get the 1.7 might be to much, just do the math before buy them, how much lift your cam will be and how much lift the valves can handle, also i dont think there would be a need for a larger diameter pushrod with the 1.7 its not like your guna be raping it over 10k rpm

its not the exhaust by the way, your set up is letting a lot more out than factory

Pvtspencer101 · March 23, 2012, 09:15:28 PM

alright, the timing i checked and i have it retarted a little bit to stop the knocking, so i will put a new sensor in it and see if it helps... And I took off the egr and put a 3/8 Thick peice of steel i made just for it, and blocked the Vac and unplugged it...

Mudbuster · March 23, 2012, 09:23:36 PM

when you check the timing are you unpluging the wire to disable the computer controled advance and what is the timing set at?

xjs3667 · March 24, 2012, 01:32:19 AM

Quote from: Mudbuster on March 23, 2012, 09:23:36 PM
when you check the timing are you unpluging the wire to disable the computer controled advance and what is the timing set at?

x2 you have to unplug it or you will get a wrong timing reading

Pvtspencer101 · March 24, 2012, 01:43:50 AM

right, and I did unplug the wire, But I set it to 0 to start then just turned it counter clock wise untill it stopped knocking, So I am not 110% sure what its auctally at..

xjs3667 · March 24, 2012, 02:00:12 AM

ok best thing I would do is replace knock sensor then set timing back to factory specs. unplug the wire I believe its brown, set timing to 0 degrees and plug wire back in

Pvtspencer101 · March 24, 2012, 02:10:03 AM

alright i am going to try it.

Pvtspencer101 · March 26, 2012, 12:12:42 AM

Alright so for my Spark knock problem, I got a guy on here that sold me a TBI from a 454 7.4L big block, and i threw it on, and timed it 6 degrees advanced and it run AWESOME, I just think I had to much Air and HP and not enough fuel to feed it, and Now I got it all figured out.