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 Qjet setup for a 400 performance build 
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Joined: Sat Mar 12, 2016 8:07 am
Posts: 21
TDC verified several times from short block stage with a dial indicator and again with a piston stop with heads on. Cam was originally for a 10:1 383 but degreed it per Mike Jones 106ICL instead of 104ICL since the compression got bumped almost a point on this 400. I'm glad I set it at 106.

Sat May 06, 2017 9:24 pm

Joined: Sat Mar 12, 2016 8:07 am
Posts: 21
I've found the engine wants alot of initial advance and not too much total. 30total is a sweet spot but idle sucks because then I'm only 8-10 initial. Just for kicks I set initial at about 24 and vacuum peaked at 13.5. That initial is not gonna work with the distributor curve I have now where travel is about 22 degrees.

Sat May 20, 2017 7:50 pm
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Joined: Fri Feb 08, 2013 2:37 pm
Posts: 1702
Remove the rotor and take a picture of the advance mechanism from about a foot above or so, so the mechanism of the weights, springs and advance cam fills the image, so exactly what you have to work with is easy to see. Is it a GM HEI or a Chinese copy? Are the pins (and bushings if there are any) the weights pivot on in good shape? Do you have any other HEI distributors you can rob advance parts from? If I can see what you have, I might be able to give you some advice. Perhaps some simple tinkering with springs and such will shorten the curve so you can have the initial and total where they need to be. If the weights are steel, solid steel, not the sintered type, they can be heated and bent to shorten the range of the curve.


Sun May 21, 2017 10:45 pm

Joined: Sat Mar 12, 2016 8:07 am
Posts: 21
It's a Pertronix Flamethrower HEI. I would assume it's proudly made in China.... It works as described with 20 or so advance movement but running the lightest springs it jumps around a little on idle up to about 1000rpm. Was thinking about just putting the heavier springs in and advance the initial but that would just slow the advance down and move it up in the rpm band right? Right now it's all in at 3000. Looking at the old HEI from the 350, the center plate is a bit damaged from having a weight riding on top of it and they are sintered steel. It's doubtful the Pertronix nor the old HEI have the good heavy GM weights in. I'll take a pic when I have time.

What I think could be the next step, IF the Pertronix weights are also the sintered ones, is to hook the vac advance up again and see how that acts. Initial is now about 8deg and with the vac stop limiter in place that would maybe put it at a "total" initial of 16deg. Vacuum is low at 8deg so it might not kick in that much. Well that's what I'm thinkin.

Mon May 22, 2017 11:46 pm

Joined: Sat Mar 12, 2016 8:07 am
Posts: 21
I just hooked up the vac advance and it pulls another 8deg initial advance max now on vaccum and it idles, runs and responds nice. Got to close the throttle plates a quarter turn again. I had the little *puff* in the exhaust when slamming the throttle and secondaries open on a low initial(8deg) and throttle plates open 1/2 turn(because initial was so low I had to) but now with ~16deg vac and mech initial there's no puff and no secondary feel it just goes. Seems like I've cheated a little. Part throttle is super nice.

Sat May 27, 2017 5:18 pm
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