Author Topic: 69 302 on pump gas?  (Read 4252 times)

deadmetalprez1952

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69 302 on pump gas?
« on: December 11, 2016, 10:02:49 PM »
Anybody here running their 302 on pump gas? I heard with the stock cam they can run on Super, I have a zip 510 cam and I think I may have to run a mix of 110ll and super...

camaroboy68ss

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Re: 69 302 on pump gas?
« Reply #1 on: December 12, 2016, 05:47:16 AM »
what compression are you currently running? that's a big factor if you plan on running pump gas. My built 350 with 11 to 1 barely runs on super. I usually have to add octane booster to the tank.
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deadmetalprez1952

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Re: 69 302 on pump gas?
« Reply #2 on: December 12, 2016, 01:16:39 PM »
Stock DZ302, just has a bigger cam, so 11.5 to 1?

camaroboy68ss

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Re: 69 302 on pump gas?
« Reply #3 on: December 12, 2016, 08:08:49 PM »
you can try super and if you get detonation, you can mess with the timing then to run on the pump. Although I would still run at least an octane booster in the tank. 
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deadmetalprez1952

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Re: 69 302 on pump gas?
« Reply #4 on: December 12, 2016, 08:39:55 PM »
Ok thanks, I plan on winding it out too like it was meant to be run, I guess I'll try it with super and see how tolerant it is. I have a set of aluminum heads that I was gonna run but they have 210cc runners which are way too big for this little 302...

X33RS

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Re: 69 302 on pump gas?
« Reply #5 on: December 12, 2016, 09:02:12 PM »
Fresh 302 build, everything cc'd, true 11:1 compression using original heads with a slight surface clean up cut and JE original type dome replacement pistons.   Stock solid cam, stock intake and carb, running 36 degrees of total timing all in at 2400 rpms, vacuum advance at manifold vacuum to add an additional ~10 degrees if idle timing.   Runs perfect on 91 octane, driven daily and occasionally romped on.   Plugs show no signs of any detonation.  Even getting 14.2 to 14.7 mpg around town.

deadmetalprez1952

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Re: 69 302 on pump gas?
« Reply #6 on: December 12, 2016, 09:55:27 PM »
Nice, that's what I like to hear! What rear gear are you running? I have an m20 and 4.56 gears. I don't expect to get gas mileage in the teens, haha. The original cam in these cars was the duntov 30 30 right?

X33RS

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Re: 69 302 on pump gas?
« Reply #7 on: December 12, 2016, 10:40:05 PM »
I've been switching rear gears around lately with complete rears I have stashed away.  4.88's were in for a bit, 3.73's, and right now running 3.55's with an M20.   Wife seems to like that the best at the moment.  She drives it daily.

Yes the stock cam is referred to as a 30-30.  I'm running a tight lash version of it (14-14) to keep the valve train beating minimal.

x66 714

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Re: 69 302 on pump gas?
« Reply #8 on: December 12, 2016, 11:18:02 PM »
Mine is set up like X33RS & I have no problems with pump gas. It runs better with racing gas of course. My car is M21 with factory 4.56. Fun in town. Never checked fuel mileage...didn't care....Joe
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deadmetalprez1952

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Re: 69 302 on pump gas?
« Reply #9 on: December 13, 2016, 12:59:58 AM »
Thanks for all the input guys, I won't be daily driving it but don't want it to cost a small fortune every time I take it out.

Kelley W King

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Re: 69 302 on pump gas?
« Reply #10 on: December 13, 2016, 12:34:27 PM »
My 302 and L78 both run OK on pump high test. I try to find non ethanol. But mixing a few gallons of race gas really shows a difference. But with the race gas get out of the shop quick. Stuff really burns your eyes and stinks up anything inside.
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deadmetalprez1952

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Re: 69 302 on pump gas?
« Reply #11 on: December 13, 2016, 01:29:06 PM »
I have easier access to 110ll aviation fuel, and right now it's roughly 4.80 a gallon so that's what I would use if I did use a mixture.

z28z11

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Re: 69 302 on pump gas?
« Reply #12 on: December 13, 2016, 02:24:33 PM »
My 302 and L78 both run OK on pump high test. I try to find non ethanol. But mixing a few gallons of race gas really shows a difference. But with the race gas get out of the shop quick. Stuff really burns your eyes and stinks up anything inside.

At least you know when you're around a Holley burning high octane gas. Not a stink to me, just a mark of GM high performance - lol. Plus an unforgettable odor -

Regards,
Steve
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cook_dw

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Re: 69 302 on pump gas?
« Reply #13 on: December 13, 2016, 03:08:33 PM »
My 302 and L78 both run OK on pump high test. I try to find non ethanol. But mixing a few gallons of race gas really shows a difference. But with the race gas get out of the shop quick. Stuff really burns your eyes and stinks up anything inside.

At least you know when you're around a Holley burning high octane gas. Not a stink to me, just a mark of GM high performance - lol. Plus an unforgettable odor -

Regards,
Steve


   


These are what I run in the blue and green cars...  Along with 90 octane from the local COOP and 5-7 gal of Renegade Racing Fuels Pro110+.  They will both run on the lower octane just have to knock the timing down to around 28 degrees total.. 
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X33RS

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Re: 69 302 on pump gas?
« Reply #14 on: December 13, 2016, 04:12:19 PM »
Wow, that's knocking a lot of timing out of it.

I have had a fair amount of success running high compression engines with cast iron heads on the street with pump gas.   But I'll admit, with pump gas getting worse, I felt the need to cheat a bit with mild modification on this build knowing it was going to see a lot of street miles.   
    So when I built the 302, knowing a steady diet of 91 pump would be used, but not wanting to detune, I took extra precautions.  Making sure piston wasn't in the hole (near zero deck height promotes better mixture motion and fights detonation)  I also removed all sharp edging from the piston crowns, as well as the combustion chambers.  I run a cooler plug, and I also keep engine temps in check with cooler stat.  We were also careful with camshaft position, making sure we had enough off seat timing with later intake closing so as not to build cylinder pressure too early in the rpm range.
  Really have to stay on top of the tune as well.  On the dyno we found 36 degrees to be a happy spot for the engine on 91 octane, where it made best power and no sign of detonation.  Carb jetting was 74-72 front side left to right, and 82-80 rear left to right with the rear power valve blocked.  Stagger jetting helps the lean cylinders and makes a smidge more power.
   Driving the car during the hot desert summer time is where I was most worried.  Hot ingested air and warmer engine temps under load is where I thought I might have a problem.  Engine never ran over 185 shooting with a temp gun, and plugs are showing no signs of detonation.
   I'm willing to bet if I wanted to run some high octane race gas and crank some more timing in it,  38-40 degrees maybe, It might make a few more ponies, but I'm extremely happy with the performance and how the car drives on crap pump gas.   When the car hits the track I may play with timing and fuel just to see if I can find anything.