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Carburetor/Intake recommendations for my rebuilt engine
https://slantsix.org/forum/viewtopic.php?t=67188		 Page 1 of 2
Author:  cmann [ Mon Apr 10, 2023 5:38 am ]
Post subject:  Carburetor/Intake recommendations for my rebuilt engine
I have a 1965 Dart with the 225 engine. I had the engine rebuilt and it is .030 over. I have a Oregon Cam grind #819 (.436 Int./.436 Exh) I have a Super Six 2 barrel intake. I am looking for some input/recommendations on a carburetor. I have already run my Lokar cable linkage and my Kick Down. Per a quick CFM calculation it looks like my engine needs 271cfm for a street engine and 351cfm for a race engine. I was originally thinking of running the Super Six intake and stock exhaust manifold, but if a different intake and headers are a good gain I am not against it. Thank you for your time and input.

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Author:  hyper_pak [ Mon Apr 10, 2023 7:01 am ]
Post subject:  Re: Carburetor/Intake recommendations for my rebuilt engine
Nice Dart!
I am sure folks will give you some good suggestions.
Author:  drgonzo [ Mon Apr 10, 2023 7:24 am ]
Post subject:  Re: Carburetor/Intake recommendations for my rebuilt engine
I ran a Holley 4412 500CFM 2 barrel on a stock engine with headers, Offy intake and a the head cut .100", can't recall now but somewhere close around 8.8-8.9:! compression ratio.. It performed beautifully with only a small main jet change. I really like the 4412.
That's a good lookin' Dart!
Author:  cmann [ Mon Apr 10, 2023 7:55 am ]
Post subject:  Re: Carburetor/Intake recommendations for my rebuilt engine
Was that an Offy 4 barrel manifold with a 2 barrel adapter plate?
Author:  drgonzo [ Mon Apr 10, 2023 8:07 am ]
Post subject:  Re: Carburetor/Intake recommendations for my rebuilt engine
Yes, Offy 4v with 2v adapter. If you haven't re-curved your distributor advance curve then please look into that as well. There is a lot of info on that here on the forum.
Author:  Dart270 [ Tue Apr 11, 2023 7:26 am ]
Post subject:  Re: Carburetor/Intake recommendations for my rebuilt engine
If you have a stromberg 2bbl and supersix intake, that is a great setup for such a mild motor. How do you know it's the carb that is making it not run right? How did you adjust the valve lash? What is your ignition timing at idle (vac adv unplugged)?

Maybe we should try to diagnose your current setup rather than change it...

Best wishes,
Lou
Author:  cmann [ Tue Apr 11, 2023 7:40 am ]
Post subject:  Re: Carburetor/Intake recommendations for my rebuilt engine
Sounds like a plan. I called Mikes Carburetors yesterday in regards to a rough idle and it not wanting to run. He suggested that there might be debris in the throttle body. I am going to remove the carb today and see if I cant spray out the throttle body. Again, it was new in the box when I installed it. Valves are set at .012 Int. and .012 exh. per the cam card from Oregon cam. I will check my timing today as well and get back to you on where it is at.
Author:  Dart270 [ Tue Apr 11, 2023 7:54 am ]
Post subject:  Re: Carburetor/Intake recommendations for my rebuilt engine
Good to know. I think your valves are too tight and that will make it idle rough and stall, especially in gear. Try opening up your intake valve lash to 0.014" and your exhaust lash to 0.022" and see if the idle improves. 0.012" is definitely too tight on the exhaust - no doubt. Your poblem likely has nothing to do with the carburetor, but we can find that out after you have readjusted the valve lash. I'll be interested to know the ignition timing. Make sure to record the RPM where you are reading the timing.

Did you get the carb from SlantSixDan? Just curious. He is a reliable source.

Thanks,
Lou
Author:  cmann [ Tue Apr 11, 2023 8:06 am ]
Post subject:  Re: Carburetor/Intake recommendations for my rebuilt engine
Got it. I will loosen them up. Even with the 819 cam grind I should open up the lash? That is exactly it is doing- wanting to die in gear.
Author:  Dart270 [ Tue Apr 11, 2023 8:21 am ]
Post subject:  Re: Carburetor/Intake recommendations for my rebuilt engine
Thanks. 90% likely it is tight valve lash then. The stock cam settings are 0.010" and 0.020" and I have NEVER found a cam that liked tighter settings than that. I also almost always settle on a different (looser) valve lash than what is stated on any cam card. I have run 10-15 performance cams over the years, from mild to wild...

Let's see what you find next!
Lou
Author:  cmann [ Tue Apr 11, 2023 8:39 am ]
Post subject:  Re: Carburetor/Intake recommendations for my rebuilt engine
Thank you again for your time and information. I am going to work on the valves now. I will post my findings after done. Standby.
Author:  cmann [ Tue Apr 11, 2023 11:52 am ]
Post subject:  Re: Carburetor/Intake recommendations for my rebuilt engine
That did it! Intake at .014 and Exhaust at .022. Idles smooth and does not want to die in gear now. I did try to adjust the idle mixture screws on the Stromberg and it does not want to idle with less then about 5 turns out. Timing is a approx. 12 degrees right now with the vacuum line unconnected and idling at about 900rpms. Thank you to all for your help, and thank you Lou for your great input and experience with the cams and lash settings. Love this forum and love learning about the Slant. Any additional input is appreciated.

Corey
Author:  drgonzo [ Tue Apr 11, 2023 1:30 pm ]
Post subject:  Re: Carburetor/Intake recommendations for my rebuilt engine
Fantastic! Lou knows.
Author:  Dart270 [ Tue Apr 11, 2023 1:48 pm ]
Post subject:  Re: Carburetor/Intake recommendations for my rebuilt engine
Super! You should be able to drop the idle to 700-800 RPM in neutral and it should be smooth. Recheck the timing at idle at 700 RPM and see if it is different (lower) than 12 deg. What fuel are you running, 87? It would help to know the piston-deck volume with piston at TDC, and your head chamber volume, and your head gasket thickness. Then we can calculate the state compression ratio. You might try the ign timing at 7-10 deg BTDC and see if that allows you to turn the idle mix screws in a little. More ignition advance will require a richer mixture at idle. Just some additional thoughts...

Happy Slanted motoring,

Lou
Author:  SlantSixDan [ Tue Apr 11, 2023 6:01 pm ]
Post subject:  Re: Carburetor/Intake recommendations for my rebuilt engine
Quote:
I did try to adjust the idle mixture screws on the Stromberg and it does not want to idle with less then about 5 turns out. Timing is a approx. 12 degrees right now with the vacuum line unconnected and idling at about 900rpms.
Still a little high. Remember, ignition timing and idle speed affect each other, and both of them together affect the idle mixture setting. Try for a timing setting of about 5 degrees BTDC and an idle speed of about 650 to 700 rpm.
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