Spark Plugs for basic tune up? / Waking up a 307

SRD art

G-Body Guru
Thread starter
Jun 16, 2011
519
63
St. George, UT
A plug is a plug for a slug :) Put in the factory recommendation. Not rocket science here.
Lol, that's a great way to put it. It's been near 10 years since I got rid if the factory stock 305 that was in Pumkinator, which ran 17.50s at the track, so I've long forgotten what it's like to drive something with no power. You guys have done a decent job of reminding me about the lack of excitement, lol. I've been racing cars since 1986, and now that I'm "old-ish" I for once feel a little torn between hp and smooth comfy ride with decent gas mileage. I suspect after a few months of driving Grandpa with the stock 307 I'll start to get the itch again to blaze tires and I'll have the motivation to dust off the 350 and get it ready to go in. ;)
 
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Max Headroom

Master Mechanic
Sep 8, 2011
369
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I really appreciate you writing all that. That really puts it into perspective, right? It's got just barely over 75,000 original miles so I think I'm going to do just the basic tune up stuff (assuming it hasn't already been done recently) and call it good. My son works in a local hot rod shop, which shop is also a good rendering client of mine so I may entertain the better exhaust idea. My son and I are allowed to use the shop on the weekends and they have an exhaust tube bender, so the cost of just some tubing wouldn't be a big deal. Converting just the head pipes to fit the SBC later should be fairly easy.
If you do swap to an SBC in way you describe, then a dual exhaust is a must have. IMO, it is probably the single best thing you could do before the engine swap. Also IMO, if you do go duals, spend the extra to go with at least 2 1/2" mandrel bent pipe with a crossover. This will keep you from either buyers remorse on the exhaust and/or deciding to spend more money upgrading the exhaust to what you should have done in the first place. One of the keys to getting the most out of Vortec engines is optimizing the exhaust. They do not breath as well as newer LS engines.

Good luck.
 
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SRD art

G-Body Guru
Thread starter
Jun 16, 2011
519
63
St. George, UT
If you do swap to an SBC in way you describe, then a dual exhaust is a must have. IMO, it is probably the single best thing you could do before the engine swap. Also IMO, if you do go duals, spend the extra to go with at least 2 1/2" mandrel bent pipe with a crossover. This will keep you from either buyers remorse on the exhaust and/or deciding to spend more money upgrading the exhaust to what you should have done in the first place. One of the keys to getting the most out of Vortec engines is optimizing the exhaust. They do not breath as well as newer LS engines.

Good luck.
Thanks for the insight. On other cars I've had good success with single 3". More than likely I'll look into that when I get to the SBC swap. I like single because it's easier to deal with on a G-body, it's lighter than duals and you only need one muffler. Last time I did Pumkinator's exhaust I was living in a different area and for a single 3" I paid an exhaust shop $400 for tubing and labor, I had the muffler and dual tips already. Because my son now works for a friend's local hot rod shop we get to use the shop on the weekends so the only cost would be tubing, which is plenty cheap. I already have a couple old sets of mufflers to choose from. His tubing bender only goes up to 2.5" in dies though, hopefully I can talk him into buying a 3" die set. If not I may do 2.5" duals instead.
 
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Max Headroom

Master Mechanic
Sep 8, 2011
369
63
Thanks for the insight. On other cars I've had good success with single 3". More than likely I'll look into that when I get to the SBC swap. I like single because it's easier to deal with on a G-body, it's lighter than duals and you only need one muffler. Last time I did Pumkinator's exhaust I was living in a different area and for a single 3" I paid an exhaust shop $400 for tubing and labor, I had the muffler and dual tips already. Because my son now works for a friend's local hot rod shop we get to use the shop on the weekends so the only cost would be tubing, which is plenty cheap. I already have a couple old sets of mufflers to choose from. His tubing bender only goes up to 2.5" in dies though, hopefully I can talk him into buying a 3" die set. If not I may do 2.5" duals instead.
You might want to look into prefab exhaust sets. With many brands you can buy just the sections you need and supply the rest yourself. One benefit of buying the whole system aftermarket is that you can usually hang the whole system in your garage with, occasionally, some minor fitment issues.

I am running mandrel bent 2 1/2" exhaust with 1 5/8" primary, long tube headers on my factory roller 1996 355 ci sbc.
I find that the duals are a big improvement, especially off the line and on big downshifts.

With respect to single vs duals, even your present 307 would almost certainly run a little quicker (not faster) with duals.
 
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69hurstolds

Geezer
Supporting Member
Jan 2, 2006
5,675
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One day people will realize trying to wake up a stock 307 is like trying to wake up that super-drunk chick that followed you home from the bar and expecting to have a little fun but passes out on your couch... either something's going to puke, it's more sluggish than you hoped, and likely will take longer to get to the finish line than normal even if you give it everything you got. A lot of work for very little in return. ;)
 
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