Leanest Cylinder ?
Thread Starter
Burning Brakes
Joined: Jul 2001
Posts: 831
Likes: 0
From: Reston VA
Leanest Cylinder ?
Hey guys been away awhile getting moved into my new location in VA. Was getting ready to mount up my O2 sensor in my Hooker Headers and wanted to mount it in the leanest cylinder. Some guys say #5 some guys say #7. Anyone with any input on this one ? I dont want to mount it in the collector. Thanks
:seeya
:seeya
Team Owner
Joined: Apr 1999
Posts: 21,953
Likes: 1,444
From: Reno Nevada
2024 C3 of the Year Finalist- Modified
Re: Leanest Cylinder ? (ScubaJKD)
The outer four cylinders are the leanest. At least that has been my experience on the last three head swaps. These were all single plane applications. one roller motor had 15 thousand miles and it only had dark tan carbon build up on the center four. the outer four had towards light tan with very little build up. all of them you could still read the KB + .030.
15K miles is a bettter indication of what's going on over reading plugs.
15K miles is a bettter indication of what's going on over reading plugs.
Pro
Joined: Jun 2001
Posts: 683
Likes: 0
From: Calgary
Re: Leanest Cylinder ? (ScubaJKD)
You won't go wrong mounting the o2 sensor in the #7 primary. In most cases, it is the leanest cylinder. If you look at the firing order, 5 fires just before 7 in the order.
Drifting
Joined: Oct 2000
Posts: 1,824
Likes: 55
From: Shawano WI
Re: Leanest Cylinder ? (74vetteman)
On a small block #5 will alway be the leanest. This is because #6 fires just before it, taking fuel away. Also being a center cylinder the exhaust valve is right next to the exhaust valve of #3 and there is no water jacket between them. This causes a hot spot. On the dyno #5 will alway have the highest temps. If you ever burn a piston it is just about always #5.
Team Owner
Joined: Apr 1999
Posts: 21,953
Likes: 1,444
From: Reno Nevada
2024 C3 of the Year Finalist- Modified
Re: Leanest Cylinder ? (Pete79L82)
The last motor I had that smoked was piston #1. I thought it was rod knock, but it was smeared piston. The whole skirt was out of round and the rings were frozen because of smeared aluminum. I had dings in the forged crank throws. KB hiper pistons can't withstand high rpm for 45 minutes at 230 degrees water temp.
Race Director
Joined: Mar 2001
Posts: 11,322
Likes: 1
From: Living in the Hartland
Re: Leanest Cylinder ? (ScubaJKD)
If I am not wrong, the hottest tube is the leanest running. Why not take you vette to a garage that has one of the heat sensing guns (perometer?) and have them tell you which is hottest and mount it on that one. Butthat won't cost butt $10 or maybe even free. Greasers love hi-po engines no matter what there in and yours is a vette to boot! :yesnod:
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Race Director
Joined: Oct 2000
Posts: 14,996
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From: central FL, near the beach.
Re: Leanest Cylinder ? (ScubaJKD)
the very minimum is to weld bungs in 5 and 7 if a dual plane. i checked all 8 in my 61. You can make 8 bungs cheap with a sears tap and a piece of pipe. or, cut off "oil fouler" plug extentions.
my article: http://community.webtv.net/MATTGRU/AFtesting
my article: http://community.webtv.net/MATTGRU/AFtesting
