Manifold vacuum 15

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tundrarules
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Manifold vacuum 15

Postby tundrarules » Sun May 07, 2017 5:17 pm

1985 318 manifold vacuum reading is 15. Reading that 15 is normal for some high performance engines. Not sure if the old marine 318s are in that category. The engine is harder to start than my other one.

See this site #3 http://www.secondchancegarage.com/public/186.cfm
1985 29 Sedan
Edelbrock 1409 carbs
Mallory distributors
Pertronix Flame-Thrower coil & wires
780 hrs/eng
TN River, MM 213.8

:mrgreen:

honestcharlie56
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Re: Manifold vacuum 15

Postby honestcharlie56 » Sun May 07, 2017 7:01 pm

Verify the timing and carb adjustments, if that checks out start looking intake leaks. My newly rebuilt stock 318's were around 20 with the correct timing and carbs set to initial settings.
1990 Marinette 32 Sedan Flybridge "Hubba"
Twin Chrysler 318's

DougDoty
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Location: Madison In.

Re: Manifold vacuum 15

Postby DougDoty » Wed May 10, 2017 9:56 pm

I would like to see some more actual idle vacuum readings for reference.
1984 39 Marinette Sedan, " LIBERTY ONE " Warsaw KY, 440 chryslers, Westerbeke 9.0 kw , 1 3/8" shafts 93 1/4" long and 19x22 dyna quads or, 19x20 DQX's 38.5 MPH GPS best.

Fastjeff
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Re: Manifold vacuum 15

Postby Fastjeff » Sat May 13, 2017 5:25 am

Lacking a vacuum distributor advance, marine engines tend to have a much lower vacuum at idle.

Jeff
"We live at the bottom of an ocean of air, not at the top." General Marvage Slatington

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tundrarules
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Re: Manifold vacuum 15

Postby tundrarules » Tue May 23, 2017 6:51 am

Amazing what a simple vacuum guage will tell you. Need to compare my sbd engine. Timing is at 5*. Carb idle is set for max vacuum. Don't think it's a vacuum leak because the reading would be lower. She holds steady at 15hg. I hooked a vacuum on it about 5yrs ago and I think it was at 20hg. Need to do rapid throttle chop to check for worn rings. Only have about 800 hrs on eng so hopefully that's not it. Will report findings in a month or so. Stay tuned.



Thanks for the input.

:mrgreen:
1985 29 Sedan
Edelbrock 1409 carbs
Mallory distributors
Pertronix Flame-Thrower coil & wires
780 hrs/eng
TN River, MM 213.8

:mrgreen:


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