Anyone recall the stock jet size that was in the Holley carbs installed on the L78's/LS6's? Thanks in advance

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1970 Chevelle SS396/M20/4.10 My 70 SS396 (http://www.chevelles.com/showroom/mr4speed70SS1)
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My Black Cherry 70 SS454 (http://www.chevelles.com/showroom/Photo0031.jpg) 13.74 @ 97.45 with exhaust manifolds and 2.73's
1968 Oldsmobile Cutlass convertible
1985 Cadillac Eldorado
Chris Corwel,TC Member # 785
Member # 141 AMCA

The '70 Chevy Chassis Service Manual lists the L78 and LS-6 Holley as #70 primary and #76 secondary jets. FWIW, the '69 manual lists the L78 and L72 as #71 primary and #76 secondary.

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von '69 300 Dlx SS TC #15 ACES #1575
My '69 SS (http://mywebpage.netscape.com/jerryacheson/vons69.html)

This link lists the jet sizes with the jet numbers. I don't know if you can use this to cross reference the LS6 carb or not but I thought it might help:
http://www.prestage.com/db/default.asp?Content=Carb_Holley_Standard_Main_Jet_ Sizes

MR4Seed,

Also note that the 427CID/435HP motors used a stager jetting set-up. This tuned for a better fuel to air ratio for long and short runner divided plenium Hi-riser intakes. The factory reccomended set-up is as follows...

Left Front Jet #78
Right Front Jet #74
Left Rear Jet #80
Right Rear Jet #82

Now keep in mind that with headers or cam you will need to richen these jets up a size or two or three. Change all jets up or down by the same numerical size...(All up 1 size or all up 2 sizes or all back down 1 size ect). Keep the stager sizing the same.

The engineers spent a little more $Bucks tunning these big guys and the L78's and LS6's can benifit from these fine tunning tricks.

Reading spark plugs will be a big help in getting it right.

My L78 runs much better and I get a much more consistant read on my plugs with the staggered jet set-up.

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FastSS396Man
Brian

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69' SS396 Chevelle
L78 396/375hp
M-21 Close Ratio
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It's brand new again!
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ACES# 3466

Thanks guys http://www.chevelles.com/forum/smile.gif

"Also note that the 427CID/435HP motors used a stager jetting set-up. "

What kinda book is that coming from? Every 427/435 ever built by Chevy was a tri power.

I think Brian's talking about the 430 hp L-88/ZL-1. They used an 850 cfm carb and milled out center divider in the manifold. That's the reason for stagger jetting and the 850 cfm carb required larger jets than the 780 cfm carb on the LS-6/L-78.

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von '69 300 Dlx SS TC #15 ACES #1575
My '69 SS (http://mywebpage.netscape.com/jerryacheson/vons69.html)

Von, Thanks for covering for me. Sometimes my fingers get in the way while using my keyboard. http://www.chevelles.com/forum/rolleyes.gif

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FastSS396Man
Brian

Fastss396 (http://chevelles.com/showroom/fastss396manflqtr3.jpg), Fastss396 (http://chevelles.com/showroom/fastss396manflqtr2.jpg),Fastss396 (http://chevelles.com/showroom/fastss396manrrqtr3.jpg),
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69' SS396 Chevelle
L78 396/375hp
M-21 Close Ratio
Cortez Silver
10 year Resto
It's brand new again!
02' Harley FatBoy, Diamond Ice Pearl and lots of chrome!
ACES# 3466