![]() ![]() We only pulled heads and intake to see if anything looked like it needed attention because 2 of the cylinders were at 130 and 125 psi while the rest were around 147 psi. What is the vacuum reading at idle?The build happened before I bought the boat it came out of. So yeah, something ain't right with your setup.ĭo you know if the camshaft was degreed during the build? My car with a 350, 3.23 rear gears, and 245-60-15 tires will spin both rear tires completely through 1st gear and into second.īack in the 80s I drove a 71 SX, 455 hitting on 7 cylinders, 2.56 rearend, and it would light up the right rear tire from 25 MPH. Seemed to work pretty well with my 350 which sadly enough would beat the poorly tuned 455. If all else fails, I could set the timing by incrementally increasing till it knocks them back it off a couple degrees. My mechanic did the same thing with my 455. I remember my friend back in high school tried to set the timing of a '72 SBC 400 my dad put into a '78 HEI Impala using '72 timing settings and it ran like ****. Aftermarket HEI distributors may have more mechanical advance and not require as much initial timing to get the mechanical advance where it needs to be. I checked the stock motors that came with gm HEI distributors (307 ) and they are set to 20 degrees. There is a very short advance curve on the stock GM HEI distributor. Or would it just jump to 11 degrees?Īccording to what I've been reading, you want about 31 degrees with combined initial and mechanical. If you set the t light to 31 andit reads 0 onthe engine timing mark you have 11 mechanical advance.so if set to 20 degrees and rev the motor, would the mark advance from 0 to 11 degrees if the advance is working? I thought the idea is to see how it advances as you increase rpms. Once you set it to 20 for a base timing, You can rev to 4k or so to see how much mech advance you have. if you set the dialto 20 and your seeing zero on the timing mark on the engine its actually at 20 degrees. X2 on innova mine stopped working after 3 uses,Ģ0 degrees initial is a lot are you sure your distributor only has 11 degrees mechanical advance?Īnyway like old cutlass said if your dial is at 0 thats your actual timing on the engine timing mark. I was a bit disappointed in the performance of the 455 set at 10 to 12 degrees after all money and energy spent. Not sure at all how this last step is done or what total timing would be. Check vacuum/total timing (setting the timing light to 31 degrees of advance and revving to 3000 rpm?). Once the mechanical advance is sorted out, reconnect the vacuum advance to the distributor and to a manifold port.ħ. If the mechanical advance reaches 11 degrees to soon (what rpm?) It needs heavier springs, too late (what rpm?) it needs lighter springs or the weight bushings need to be reamed out.Ħ. It is my understanding mechanical advance should reach 11 degrees if the timing light advance is set to 20 degrees and it should reach 11 degrees at about 3,000 rpm. ![]() Rev the engine (gradually?) To determine if and how the mechanical advance responds. The timing should read 0 on the indicator plate?Ĥ. ![]() Once initial timing is set to 20 degrees, reset the timing light advance to 20 degrees to check mechanical advance. (Do I set the light so the digital readout says 10 degrees? Never used a timing light before not to mention an adjustable one).ģ. Adjust timing light to 10 degrees advance so at 20 degree initial timing the indicator plate will read 10 degrees. Disconnect vacuum advance from distributor and plug port.Ģ. Please let me know if the following steps are correct:ġ. The block is a 73, E heads, shallow recessed head pistons, unknown cam (not super choppy but more than stock). I wanted to confirm this procedure for a stock points Oldsmobile 455 with a GM HEI distributor. My engine swap is finally done (I hope) except for adjusting the timing and checking the advance. ![]()
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