Plug gap question

Indy1K

Seaman Apprentice
Joined
Jul 3, 2015
Messages
39
I have twin Volvo Penta AQ260A/290 units in my 1986 Sun Runner 310SB. These are 5.7L chevy small block engines. one block is dated 1987 and the other block is dated 1991. Obviously not original. The engines do have the solid state pickups and not breaker points. I bought the original VP shop manual and it instructs to gap the Bosch plugs to .028" I could not get the Bosch plugs but they cross to an AC Delco R43T. I have build alot of chevy small blocks over the years and .028" bothered me. Here is the question. Should I be gapping to .035" and not .028" ? Any advice here
 

79_banshee

Petty Officer 2nd Class
Joined
Sep 2, 2016
Messages
176
I could be way off here but it could have something to do with the marine distributor and detonation point. There is some differences between a 350 in a truck vs the marine 350. Just my 2 cents
 

Fun Times

Moderator
Staff member
Joined
May 16, 2009
Messages
9,120
What is the gap currently set to?
Is there any engine specification stickers on the engine with the spark plug gap mentioned?
I didn't look but does the service manual show/talk about both Points and Electronic Ignition Systems? If so, is there by chance any specifications written next to each system with gap size?

If you happen to have the upgraded Volvo Penta Hot Spark system then the Spark Plug Gap: With the Hot-Spark ignition kit, the stock spark plug gap specification is fine. Volvo- Penta - Hot Spark - Electronic Ignition...Electronic Ignition Conversion Kits for Volvo-Penta Marine ...

http://www.answers.com/Q/What_is_the_spark_plug_gap_for_a_1985_Volvo_penta_260a?#slide=2
 

Indy1K

Seaman Apprentice
Joined
Jul 3, 2015
Messages
39
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So, here is where it is confusing and clear. I am referring to the original VP shop manual for the AQ260a, or b for that matter. It says to gap to .028" but that is for a breaker ignition. My manual does not talk about Pertronix solid state ignition. must be aftermarket. I have the Pertronix 1581-82 plate in my distributor. And the old plugs appear to be close to .035". I guess I will go with that on the new ones. Any help on a replacement cap and rotor part number? Sierra?
Thanks,

Kevin and Tatyana aboard the "Russian Princess" docked on the Ohio River.
 

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