What plugs on an unknown 350? - Team Camaro Tech
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post #1 of 4 (permalink) Old Jun 1st, 10, 11:16 AM Thread Starter
Ed
 
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Location: PAC NW
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What plugs on an unknown 350?

My son's 76 LT has been worked on by the previous owner. He says he does not know if a cam was installed or if the block was overbored?!?!

The car runs well, lots of torque and compression. It has a B&M auto matic shifte; but I don't know what the tranny is yet.

My Main question is this: Since I don't know what, if any thing, has been done to the engine what is the best way to tune it up? Should I continue to follow factory specs? It has a standard looking HEI distributor; but the plugs installed are the BoscH Platinum HR9BPX. Also there is an edelbrock 1406 and performer intake and headers.

Any ideas on where to start with the tune-up. I want to write down the specs and get started.

Ed
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post #2 of 4 (permalink) Old Jun 1st, 10, 06:26 PM
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Lonnie
 
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Re: What plugs on an unknown 350?

Typically an AC R45TS will work fine. If it is built with more compression & 350+hp drop down to a 44 or even 43. This is a good start.

Cross referencing can be off up to 2 heat ranges. Tried this before & got wierd results.
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post #3 of 4 (permalink) Old Jun 1st, 10, 11:00 PM Thread Starter
Ed
 
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Re: What plugs on an unknown 350?

The above Bosch plugs crossed back to a champion 406 OR AC R43TS. So it looks like you are on the right trail. The platinum Bosch plugs ran fine; but I want to try the copper plug to see if there is a difference.

Question now is: Should an unknown built engine be timed to factory specs with regard to timing? How do I know where to set the timing- there may or may not be a cam or overbore?
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post #4 of 4 (permalink) Old Jun 2nd, 10, 01:23 PM Thread Starter
Ed
 
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Re: What plugs on an unknown 350?

YES! Awesome. I was fretting having to deal with the snobs at the Chassis Dyno. Ok so the plugs look like they'll be ok. The factory spec for the timing should be a good jump off as the cam does not seem to have a noticable lope. No fooling on the overbore not affecting ignition timing- thats a relief. The HEI Distributor looks like a factory number- No obvious AXCell OR MSD signage. Anyone have a cheat sheet on the tune-up for a post 75 350. My truck, a 73 C20 and the wife's 73 Cougar- sporting a 351C both have regular distributors (non-HEI) but I have not had the pleasure of tuning a HEI setup yet/

What... plugs, rotor, timing light on factory spec. Anything else? No dwell or points. Fuel filter just changed, will do oil/filter, air filters... Anything else to do ?

Ed
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