http://www.chevelles.com/cgi-bin/forum/ultimatebb.cgi?ubb=get_topic;f=4;t=018908
here is the old post from some time ago.......
i just got done tonight doing some final readings and readjusting of the carb and timming....
since i had low vacuum readings and sluggish bottom end i had to make a few changes.....the car was not performing as i was wanting....
breaking into the motor closer i found the retainers to give a false reading,the cam wasnt as near as retarded as first thought, but it was still retarded, advancing the cam 4 degrees just put the intake lifter barely over the exhaust lifter it was enough to tell me i was better then straight up and way better then the slight retard i had......
but this tasked didnt do much for idle quality or vacuum readings or cranking compression readings or the seat of the pants feel.......i gained about 5 psi more in cranking compression....and a rough .5" of vacuum
i installed new high flowing mufflers "fullboar" and new pipe all the way out the back...the car seemed to have picked up some....but the bottom end still lacked
after i did this task the heads came off for total do over.....i had one guide give way so the heads where totally redone with new stainless steel valves that are necked down.....bronze inserts and 3 angle angle valve job with some extra chamber cleaning to help blend everything in.....
note: the heads was rebuilt when i built this motor in the begining but they was not done properly from the other machinist..he did not put in the 3 angle valve job and the 20 degree back cut on the valves as i asked for, he also didnt buy the necked down performance valves as i asked for and on top of that he shoved the entire replacement valve guide liners thru the intake and exhaust port instead of putting them in like they should be and cutting the extra length off for clearence...and he didnt set my springs up at the recommended spring height ...they was all over the place with no shims under the springs.....i should have checked his work for i took for granted all would be done......
anyways i put together my own heads and set them up as they should have been. i reinstalled them with steel shimmed gaskets to help bring up the compression some....i lost some cc's in the do over and porting of the chambers so i only netted a .3 more in compression ......so my compression went from 10.2 to 10.5 to 1
after the head do over the engine felt like the lower end went away some without changing anything on the carb or timming. but it sure felt like i gained something on the upper rpms for the car was pulling so much harder. the other thing i noticed i lost about 200 rpms on my brake stall.......before the head change i could bring the convertor up to 2800 rpms against brake under full throttle.......now it will only go 2600 rpms under full throttle.......im thinking i lost some low end torque.......
i installed my other posi unit that i went thru and installed 2.73 gears....other then a slight increase in highway rpms it didnt change to much.....from the 2.41 posi set up..
i put in the rhoads lifters and i have gottten alot of the improvements i was looking for..........vacuum is now at 10" at 700 rpms and it is just under 13" at 900 rpms (old was 5.5 at 600 and 10.5 at 1000 rpms) the idle is really smoother and more snapper and the best thing it pulls just as hard or harder as it did with regular lifters on the upper end so i didnt loose nothing up top (at least thats what my butt tells me) it pulls hard all the way to 6400 rpms......and my rpm drop from park to drive was cut in half it was 1000 in park and 600 in drive now it is 900 in park and 700 in drive........
i had to redo my hei some the timming had to be backed off on the initial because it was harder to start.....but the magic number was 18 initial and still 36 total were as it was 22 and 36........my cranking compression is now 180psi best and 170psi worst and the other 6 holes fall right at 175 psi......
what it comes down to is that i found what i was looking for, very good street matters around town ,rpms that i can live with out on the highway, and endless top end speed ( for what ever reason it should be needed) and it has a wide rpm span that just seems to keep pulling........now i can jump in it drive anywhere get ok gas mileage and i have a decent car that will e.t. well.......
now that the car is to my likings it will go to the track next weekend in wichita and see if my goal of 13.80's or better with more then 100 mph trap speed will me met........and i think it will.......all on 87 pump gas and in full street trim......
thanks to all that had help me with my questions and read my long winded posts.....
here is the old post from some time ago.......
i just got done tonight doing some final readings and readjusting of the carb and timming....
since i had low vacuum readings and sluggish bottom end i had to make a few changes.....the car was not performing as i was wanting....
breaking into the motor closer i found the retainers to give a false reading,the cam wasnt as near as retarded as first thought, but it was still retarded, advancing the cam 4 degrees just put the intake lifter barely over the exhaust lifter it was enough to tell me i was better then straight up and way better then the slight retard i had......
but this tasked didnt do much for idle quality or vacuum readings or cranking compression readings or the seat of the pants feel.......i gained about 5 psi more in cranking compression....and a rough .5" of vacuum
i installed new high flowing mufflers "fullboar" and new pipe all the way out the back...the car seemed to have picked up some....but the bottom end still lacked
after i did this task the heads came off for total do over.....i had one guide give way so the heads where totally redone with new stainless steel valves that are necked down.....bronze inserts and 3 angle angle valve job with some extra chamber cleaning to help blend everything in.....
note: the heads was rebuilt when i built this motor in the begining but they was not done properly from the other machinist..he did not put in the 3 angle valve job and the 20 degree back cut on the valves as i asked for, he also didnt buy the necked down performance valves as i asked for and on top of that he shoved the entire replacement valve guide liners thru the intake and exhaust port instead of putting them in like they should be and cutting the extra length off for clearence...and he didnt set my springs up at the recommended spring height ...they was all over the place with no shims under the springs.....i should have checked his work for i took for granted all would be done......
anyways i put together my own heads and set them up as they should have been. i reinstalled them with steel shimmed gaskets to help bring up the compression some....i lost some cc's in the do over and porting of the chambers so i only netted a .3 more in compression ......so my compression went from 10.2 to 10.5 to 1
after the head do over the engine felt like the lower end went away some without changing anything on the carb or timming. but it sure felt like i gained something on the upper rpms for the car was pulling so much harder. the other thing i noticed i lost about 200 rpms on my brake stall.......before the head change i could bring the convertor up to 2800 rpms against brake under full throttle.......now it will only go 2600 rpms under full throttle.......im thinking i lost some low end torque.......
i installed my other posi unit that i went thru and installed 2.73 gears....other then a slight increase in highway rpms it didnt change to much.....from the 2.41 posi set up..
i put in the rhoads lifters and i have gottten alot of the improvements i was looking for..........vacuum is now at 10" at 700 rpms and it is just under 13" at 900 rpms (old was 5.5 at 600 and 10.5 at 1000 rpms) the idle is really smoother and more snapper and the best thing it pulls just as hard or harder as it did with regular lifters on the upper end so i didnt loose nothing up top (at least thats what my butt tells me) it pulls hard all the way to 6400 rpms......and my rpm drop from park to drive was cut in half it was 1000 in park and 600 in drive now it is 900 in park and 700 in drive........
i had to redo my hei some the timming had to be backed off on the initial because it was harder to start.....but the magic number was 18 initial and still 36 total were as it was 22 and 36........my cranking compression is now 180psi best and 170psi worst and the other 6 holes fall right at 175 psi......
what it comes down to is that i found what i was looking for, very good street matters around town ,rpms that i can live with out on the highway, and endless top end speed ( for what ever reason it should be needed) and it has a wide rpm span that just seems to keep pulling........now i can jump in it drive anywhere get ok gas mileage and i have a decent car that will e.t. well.......
now that the car is to my likings it will go to the track next weekend in wichita and see if my goal of 13.80's or better with more then 100 mph trap speed will me met........and i think it will.......all on 87 pump gas and in full street trim......
thanks to all that had help me with my questions and read my long winded posts.....
