Octane additives

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kell
Posts: 404
Joined: Sat Jun 19, 2004 2:58 am

Octane additives

#1

Post by kell » Thu Jan 08, 2004 3:33 am

Thinking about how to relieve the overheating problem my pan has in the summer. Sometimes it gets so hot that it will ping just revving in neutral. What's the deal, will higher octane gas make it run cooler, should I use an additive> and is there something cheaper but just as good as the off-the-shelf "octane booster" additives?
Don't know what compression the old bird has. It is a '52 with STD heads and a Super E. Have never done the sudsy "EML" test as per Cotten... but at least the heads are new/ fresh O-rings and tight clamps. Installed the heads myself about a year ago, but couldn't fit the torque wrench in there so just tightened them by feel, mea culpa.
Also would it help much to go to external oil feed, as the STD heads were machined to allow for that.
Hoping I can ride in hot weather this year without worrying any more... any advice appreciated.



panhandler
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Re: Octane additives

#2

Post by panhandler » Thu Jan 08, 2004 6:44 am

Kell, I run a 63 with outside oiler and an S&S pump, S&S super E and wiseco 9:1 pistons. I have an Andrews J grind and run a primary belt. I have no problem with heat or ping unless I get bad gas. Don't know if your in North America or not but I run Shell premium fuel in Canada and try to run Chevron in the states, always premium. do you know what temp your oil is running. On the side, Snap-on makes a dandy little dog bone box end just made for tightening pan heads bolts. One end fits on the head bolt and the other onto your torque wrench. they run around 40 bucks US but are worth the cash. I assume you have done all the other prelim's regarding your timing etc. so can't offer you much help other than this. good luck!

Cotten
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Re: Octane additives

#3

Post by Cotten » Thu Jan 08, 2004 1:10 pm

Kell!
Have your strobed your ignition timing?
You may want to set it with the line forward in the hole a bit, for poor gas.
I'm not a promoter of the snakeoil theory of octane improvement.
And you should still bubbletest the manifold as even a tiny leak can raise your combustion temperatures dramatically.

dirtpandan58
Posts: 64
Joined: Sat Jul 14, 2007 9:38 am

Re: Octane additives

#4

Post by dirtpandan58 » Sun Jan 11, 2004 4:24 am

Kell,
I put an S&S super E on my pan last year. It ran good until summer time. I live in Vegas so it gets pretty F'n hot.
Mine would ping or sometimes even clater when pulling away from a light. I took it down to the shop and they put a thunder jet on it. That helped a lot but would still ping just a little. I took it back and he rejetted it. No problems since then. The thunder jet is a little harder to tune, but once you're dialed in, they're tits.

Dirt

P.S I run 100 octane gas. That seems to help too.

kell
Posts: 404
Joined: Sat Jun 19, 2004 2:58 am

Re: Octane additives

#5

Post by kell » Mon Jan 12, 2004 3:07 am

The oil temperature never rises high. Even in summer I don't think the thermometer on the oil tank goes over about 180. Usually reads around 150.
Will strobe the timing. Haven't done that. Went back to my DIY electronic ignition with seperate firing on the cylinders. I should check the relative timing, see that they fire 315 deg crank rotation apart so they're not fighting each other, can use the forward belt pulley as a degree wheel and a strobe. Or maybe go back to the Mallory just as an experiment.
Dirtpandan58: I like the idea of fixing it just with carb mods and tweaking. I'm definitely leaning toward the thunderjet now. What size jets do you run? Do you have stock 74 displacement, overbore, what kind of exhaust/ for comparison purposes.

dirtpandan58
Posts: 64
Joined: Sat Jul 14, 2007 9:38 am

Re: Octane additives

#6

Post by dirtpandan58 » Tue Jan 13, 2004 4:34 am

Kell,
My jets are 68 and 31.
Motor is 70 over,412 cam, solid lifters, mallory unilight breaker,S&S oil pump,1 1/2" primary belt and 2 cycle shack mufflered exhaust pipes. Nothin' real fancy, but it pulls pretty good.
Dirt

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