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Old 02-08-2011, 12:50 PM
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RicardoJM RicardoJM is offline
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Join Date: Jul 2007
Location: Centennial, CO
Posts: 2,396

Originally Posted by subzali View Post
Cool. Thanks for the info. I'm wondering if anybody has an F engine carb, if they could look to see if there are numbers stamped on the venturis, as shown in this thread:

I am expecting to see 28 primary, 31 secondary. If that's true, then those numbers would "flange up" to the research/reading I've done.

Ricardo, are you still jetted to these settings? IIRC, you went from a F block to the F1.5 block when you did the latest rebuild right? And you say the F1.5 uses the same 2bbl carb the F block does?

EDIT AGAIN: I think I found my answer about 38/38 being on F engines:

I'll have to check on the stamping. It may take a few days as I spending my evening giving Sascha a hand with his rig. I do recall seeing numbers stamped into the barrels and they were the same so on that recollection - they don't "flange up".

Yes, I am still running the jet sizes in that post. I did try smaller jets (matching what was in the FSM for altitude) and found that I had a stumble coming of the idle circuit to the primary circuit. Very significant and not good with jet size 112, almost bearable at jet size 114 and gone at 116.

I've actually had 3 engines and 2 rebuilt carbs in my truck over the past year. You need a scorecard to keep track.

My understanding and experience is that the F.5 engine came with the DD38 carb that was also used on the late F engine. Albeit, in 1974 the throttle mechanism was linkage and not cable.

The Blue Mule is running a DD38 on a 2F and many others have success running the combination - I think that Martin has this set up in his rig. Regarding jetting, we put in a slightly larger jet (118 IIRC) in the Blue Mule and noticed a performance improvement. I don't think that Randy tracks MPG so we don't know what the economy impact is. That said, I don't think the Mule will be going back to the smaller jet size.
Ricardo Maestas - Bio Page
1999 LX 470
SOLD - 1971 FJ-40
TLCA #18941
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