Author Topic: Vacuum Advance on HEI 350  (Read 1255 times)

Offline kopeck

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Re: Vacuum Advance on HEI 350
« Reply #15 on: May 16, 2022, 07:42:13 PM »
So I did a little digging.  It looks like the distributor I have (Summit SUM-850001R) has about 22 deg of mechanical timing built-in.  So if I had it set before at 34 (or higher) degrees total the initial I found when I started would have been about right at 12+.

Right now I have 8 degrees initial which in theory would give me 30 degrees total.  The 27 I was seeing might be that I wasn't revving it high enough, full in is between 3000 and 3500 RPM.  I have to admit that I'm a bit of a chicken when it comes to revving engines w/o load.  :-\

I took it for a drive today and it didn't ping but it also felt a little lazy throttle response-wise.  I think I'm going to bring it back to 34, see what it does and if it pings just take a degree or two out until it's right.

I suspect there are some underlying engine issues that might make that no-ping/best-performing window rather small.

K


Offline TexasRed

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Re: Vacuum Advance on HEI 350
« Reply #16 on: May 16, 2022, 10:17:04 PM »
Is the vacuum can adjustable?

Offline kopeck

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Re: Vacuum Advance on HEI 350
« Reply #17 on: May 17, 2022, 07:04:28 AM »
Is the vacuum can adjustable?

No.  I've been thinking about that too.

K

Offline kopeck

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Re: Vacuum Advance on HEI 350
« Reply #18 on: May 17, 2022, 10:01:11 AM »
I reset to 34 deg at God knows what RPM but I made sure the indicator stopped moving this time.  Sadly my timing light can't read RPM and advance at the same time.  I did "tune" my ear into 3500 RPM so I would know when I was getting there.  ;)

Much better throttle response and so far no pinging.

I'll probably call it good.

Like I said earlier I suspect that my engine has a very narrow window to hit.

K