Carb adjust- starting point
Thread Starter
Instructor
Joined: May 2005
Posts: 222
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Carb adjust- starting point
I'm looking for a recommended primary jet size for the initial start up after top end upgrade. I'm using my original Qjet on L48. The lars paper says 2 sizes larger than stock for a starting point when adding headers or intake manifold upgrade. I have upgraded cam (XE262-10), heads (Dart SS 165 w/1.6 rockers), and intake (performer). Does the "2 sizes larger" still hold true for a good starting point? I want to be sure the car starts imediately for proper cam break-in. Any comments are appreciated.
Race Director
Joined: Mar 2006
Posts: 14,112
Likes: 28
From: Florida
I assume you are going to run it for around 1/2 hr initially to brake cam in.
It wouldn't hurt to go a little more to be richer and safer. IMO I would go a little more to keep the internals a little cooler at first.
I don't think you can get higher than #79's so you will have to start drilling jets. Your oem should be #77's
I would change oil and filter after that run in too.
It wouldn't hurt to go a little more to be richer and safer. IMO I would go a little more to keep the internals a little cooler at first.
I don't think you can get higher than #79's so you will have to start drilling jets. Your oem should be #77's
I would change oil and filter after that run in too.
Tech Contributor
Joined: Aug 1999
Posts: 14,373
Likes: 6,371
From: At my Bar drinking and wrenching in Lafayette Colorado
For cam break-in at no-load 2500 rpm, you're running on the transition circuit of the carb, so jetting is nearly irrelevant. Run the stock jetting with correct float setting (.420") and back the idle mixture screws out a turn.
