[bonneville Joe]

I've been all over the interwebs and I can't find an exact answer... What jet size was stock on a '78 W72 Q-jet?

[oville]

I ran into you at Oreily's there in Anderson in that 78 of yours (had a 79 at the time) probably 1 year ago, I have a 17058276 carb on my bench I can open up if you like, although its not a W72 car, I don't think.

[bonneville Joe]

Oh yeah! It was that day it absolutely poured the rain for like 5 minutes and flooded Clemson Blvd lol. If you wouldn't mind I'd really appreciate it. I'm trying to run smaller jets on a quick fuel I have on the car now. I'm curious as to what the stock size was so I can get in the ballpark. I know what's in there now are way too big.

[tltw72]

Auto or 4 speed?

[pippintook]

For a 78 W72 manual (carb # 17058263), mine had 70 primary jets. With a 39 primary metering rod, I think.
From what I have read , the late 70s qjets are pretty lean at idle and can use some help.

I am using my 17058263 qjet on my stroker 400 (78 400 WC block, 4.25 crank, 6x ported heads 9.2:1, 78 cast intake, SD stump puller cam, 1 3/4" headers). I setup my 17058263 very close to Cliff's #2 receipe...

- 73 jets, 44 rods
- .070 upper (air horn) and .070 lower (carb body) main air bleeds
- idle tubes .037-.038, DCR .055 (stock idle air bleed),; idle discharge hole .100,

[Rick Jones]

My '78 W72 auto carb (17058268, I think) had 72 jets and 45 rods originally.