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73-87 Chevy _ GMC Trucks => Performance => Topic started by: LTZ C20 on March 24, 2012, 03:05:49 pm

Title: Modified Firing Order
Post by: LTZ C20 on March 24, 2012, 03:05:49 pm

I have a 79 Chevy Cheyenne, 350sb, Edelbrock intake, Edelbrock carb, HEI ignition, and smog. We all know that the famous Chevy firing order is 1-8-4-3-6-5-7-2. I have been working on my 91 Chevy Camaro, has Gen 3 LS1 Corvette 350sb with tuned dual port fuel injection. The firing order for those engine is 1-8-7-2-6-5-4-3. GM swapped the pairing around to reduce vibration and noise. The pairing stays the same however, being 1-8,4-3,6-5,7-2. Know in learning this little stunt GM pulled with modifying the firing order, I was wondering if changing the original firing order of my 79 truck to match the modified order of the 91 Camaro. Would this cause my 79 engine to have less vibration and noise with a slight increase in power like the Gen 3? Or would changing my order cause my engine to run like garbage and make weird nose, like does it included having to swap cam shaft and things like that because the timing sequence doesn't work and everything would be out of whack. So ultimately, can I safely change my firing order to the LS1 Gen 3 timing or should I leave it as the original version that we all know? Thanks ya'll.  :)

Title: Re: Modified Firing Order
Post by: beastie_3 on March 24, 2012, 04:02:20 pm

I believe it would be an improvement, but you need a crank and cam to match, as well as correct plug wire placement. I believe there are kits out there to convert your 79 block.

Title: Re: Modified Firing Order
Post by: LTZ C20 on March 24, 2012, 04:07:02 pm

OK. I wasn't sure if I would need a kit of some sort or if I could just change the order on the top of the distributor. So that means it's not something I can do without some new parts?

Title: Re: Modified Firing Order
Post by: Engineer on March 24, 2012, 08:13:42 pm

The camshaft is all you have to change.

You can do a google search, it is almost an exclusive mod for race engines.

Not really worth it for a street engine IMHO.

Title: Re: Modified Firing Order
Post by: LTZ C20 on March 24, 2012, 08:37:44 pm

Oh ok, well yea I'm not drag racing a 3/4 ton haha. The truck is quick, but it aint THAT quick. :P Just an idea, thanks anyway ya'll.

Title: Re: Modified Firing Order
Post by: VileZambonie on March 25, 2012, 10:18:22 am

Unless you're planning on putting your engine in a drag boat, don't waste your time and $$$

Title: Re: Modified Firing Order
Post by: LTZ C20 on March 25, 2012, 11:58:53 pm

Haha got it.

Title: Re: Modified Firing Order
Post by: beastie_3 on March 26, 2012, 10:00:24 pm

Here is an article I found written in Hot Rod Magazine.

http://www.hotrod.com/techfaq/113_0701_lunati_cams/viewall.html