Timing and plug gap advice needed.
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From: Alexandria La.
Timing and plug gap advice needed. I'm changing to a pair of 317 heads so I can turn up the boost a llittle (12psi) and I'm not sure if I need to lower my timing or adjust my plug gap. Right now I'm running 15* timing and .028" gap. I plan on to continue running 93 octane but probably end up throwing in some 112 unleaded at the track for extra insurance. The motor is STOCK compression except for what the 317 heads drop it to with a .058" (compressed) thick MLS gasket.
Last edited by WS6HUMMER; Sep 2, 2009 at 07:06 AM.
Depends on how much boost your running. The heads are going to lower the compression so I woud stay at that gap and see what kind of timing she likes. The 317 shoud put you around 9.5 on the stock pistons so you will be ok.
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From: Alexandria La.
Thanks, I cant beleive I posted all that and forgot to put the amount of boost I plan to run. I'll edit the above post but it was 12 psi that I hope to be able to run.
Not really on topic .. but how much boost are you running now and what did the car make (assuming on stock 241's)? I am in the same boat right now and hoping to get 10 12 psi out of mine too .. so im in for the same question.
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From: Alexandria La.
Well, I had these 317's laying around but was kinda forced to use them. My car kept bleeding off boost & to make a long story short I had 7 bent intake valves. It seems that back before the turbo I ran nitrous for a little while and floated the valves from revving it to high. My stock heads were 853 castings and even with the jacked up intake valves it went 11.20's @ 123mph on 8 psi that would bleed off almost 3psi every gear (6 speed). So I imagine with a steady 12 psi my goal of having a 10 sec slip should happen. Sorry, never put it on a dyno.
12 psi on a stock motor? Your playing with fire lol. I would try the 8-10 psi range the bump in timing may help it pick up better. I know there are some people that run 15 psi on a stock block but it wont last long like that. But your time is dead on to a 10.sec pass if boost is stable through the run then you should hit your mark on 8-10 psi with added timing. If you where bleeding that much boost its like loosing 20 hp per psi.
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From: Alexandria La.
12 psi on a stock motor? Your playing with fire lol. I would try the 8-10 psi range the bump in timing may help it pick up better. I know there are some people that run 15 psi on a stock block but it wont last long like that. But your time is dead on to a 10.sec pass if boost is stable through the run then you should hit your mark on 8-10 psi with added timing. If you where bleeding that much boost its like loosing 20 hp per psi.
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I would watch that fuel pressure on 10 psi. On my stock motor I had the same set up but I had 42 # and on 9 psi I was dam near out of pump up top. I think it drop to 51 psi. But you should be ok post results.
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From: Alexandria La.
