304 engine jet size?

[Doc Stewart]

304 factory rebuild, used. Holly 2300 taken off previous , now blown, 392 engine.
What would be the recommended jet size for use at sea level??

[Brian Huver]

Hey Doc, at sea level that should be a #61 or $62 jet size. If i can remember these are the ones that come factory with the carb.

[Thomas]

Originally Posted by Doc Stewart

304 factory rebuild, used. Holly 2300 taken off previous , now blown, 392 engine.
What would be the recommended jet size for use at sea level??

---It depends on the list # and application really. If it were a 1710 (early 266-304) like mine, I would recommend something in the range of #44 to #47, but Holley said they showed #53 was standard when they built it. Largest I have seen on any 304's 2300, which I knew, with absolution, had never had more than basic rebuilding, is #57. I ran it at 350' in MI with no problem, all through elevations on my way to AL, as well as here in WI (#45 because I couldn't find new #44s at the time), where IIRC I read was 850'. In AL, the humidity gave me hell, but it still showed excellent readings on the plugs as well sniffer/detector. Don't forget a new Holley 108-52 (or the Felpro version 60677). There's also reusable (buna rubber) gaskets you can place on either side to prolong use of the 1/4" thick Base Plate Gasket.

---Call Holley to see what they have in their books. You might get lucky & catch someone in partz that knows how to look up the parts list... and just recently someone posted they had snagged an illustrated pats book off eBay, maybe they'll chime in or you can find that thread & ask there. I would base the search on threads made within the last month. Sorry, no history beyond the page I am looking at now on mobile, or I would try to provide you with a link to the thread.

[Doc Stewart]

Thanks, guys. It had 53s. I had a pair of 59s so that is what is in it now. I'll bump it up and see how she runs.

[Eric VanBuren]

List number makes a big difference in the proper jets I've seen and ran 50-53 in my IH spec carbs on 345s near sea level.

[Kurt_M]

I have the Holley llustrated Parts Guide and can look up stock jet sizes. On the IH 2 bbl Holley there were 2 pretty common venturi sizes used. The small venturi carbs had 53 jets and the larger venturi size used 61. But there are many others mixed in thru that whole bunch. The 1710 carb does show it had 53 jets. Also, keep in mind the jet size is the design of the carb and not so much what engine it is on, the carb doesn't know if the air going thru is is going to a 304 or a 392 the fuel ratio is still the same, with tweaks just for each individual engine.

[Greg R]

Kurt is pretty spot on and sums it best.

If yore burn'in E10, you might find bumping it up 2 sizes from stock will help with ping and drivability.

[Doc Stewart]

thanks guys. Got it running well.

[Dave Peters]

Doc- What did you end up using?

[Thomas]

Originally Posted by Doc Stewart

thanks guys. Got it running well.

---Glad you got it Doc.

Originally Posted by Kurt_M

... Also, keep in mind the jet size is the design of the carb and not so much what engine it is on, the carb doesn't know if the air going thru is is going to a 304 or a 392 the fuel ratio is still the same, with tweaks just for each individual engine...

---Ehhh, sorta. It's true that the carb can't adjust how much air is taken in without human intervention (manually working the choke). The cfm/design determines how much air goes through the carb and the circuitry, power valve & jets determine how much fuel is sucked in. If too large a jet in a carb with too small of venturi (cfm does* matter), it will run lean once the line is crossed for measured air flow and vice-versa. Sure you know that, but I saw somewhat backward, partial information in your informative post that could be misleading. Don't get me wrong, I understood what you meant.

---Glad you had the opportunity to find the HIPG. I purchased if memory serves correctly, a new, mint (not a "remainder"), 5th Edition about 20 years ago & someone 10 years ago or so, apparently needed it more than I. While a vital edition to the library, I haven't gotten round to purchasing another. When that sort of thing happens, Say they cost $60ea new, I would only justify buying another if the total price paid for both was equal or lesser than one new. Yes, when it comes to stolen tools I am often conservative ~shrug~

Originally Posted by Dave Peters

Doc- What did you end up using?

---If you hadn't seen/heard already, I believe Doc said #61 in another recent thread.