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Carby questions for 265 Hemi 

 

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 Post subject: Carby questions for 265 Hemi
Posted: Wed Jul 12, 2006 5:03 pm 
Getting Side Ways
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Ok, the car in question is my VJ Valiant. Now it's has a 245 block that has been bored out and fitted with ACL 265 pistons and Crow camshaft (I can't remember which one it is but it was definately one of the beefy ones). The head is a very worked 245 (found it impossiable to find a 265 head at the time and a 245 cannot be made into a 265 spec one due to some of the water jackets) fitted with Crow double valve springs. Now this is fitted with a Holley 650 4 barrel vacum secondary carberator, and wouldn't you guess but she's running very rich (still extremely economical on the highway - was averaging 11litres per 100km's driving from Brisbane to Hobart).
At the moment the car is undrivable until it is warmed to near operating temperature, it'll just stall and die if try to put load on the engine. The choke is useless as it floads it to stall. Have to sit there with foot on accelerator until she's warm.
Was just talking to a guy at work who has a Holley 350 2 barrel at home and we were thinking of trying that as it seems a more appropriate size. He did some calculation on the calculator to work this out, he reckoned that a 350 or 400 was the correct size for it.
I did a Google, and found this site - http://www.classictruckshop.com/garage/shopmathcfm1.asp, now based on the 265 CI, and 90% volumetric efficency of engine, a 350 should be large enough for the car to happily rev up to 5600, which is beyond the power range for the camshaft and higher than I plan to ever rev it!
So am I right in thinking that the engine will be better off with the 350? And I was thinking of using a 2 barrell to 4 barrel adapter plate instead of having to dig up a 2 barrel inlet manifold, or is it recomended that I get a 2 barrel inlet manifold instead (or should it make little difference either way)?
The 650 is 10,000km's old (original paperwork box, etc. included), and the plan is to trade the 650 for his 350 and cash (any ideas on what sort of cash figure is reasonable?).

 

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Posted: Thu Jul 13, 2006 5:19 pm 
Smokin em up
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The formulas are all WRONG! 350 2 barrel is measured at 3" hg vaccum, 650 is measured at 1.5" hg. This clearly show that the 350 will choke the s**t out of the engine.

I have run a 456, 600 vac sec, and a 650 dp on a 265. The 600 and 650 were equal best depending on driving style. The 465 was a dog, the circuits weren't designed for big cams.

I did not know that you can bore a 245 to 265?

The carby should be in good working order before making any adjustments or decisions. This means rekit or blast the air bleeds out at a minimum.

Check the jets and make sure they are standard to start your tuning. Check the idle vaccum in neutral for manual and D for auto. Half the value and add .5, that is your required power valve.

Screw in the mixture screws gently to the seat and then back out EVENLY to 1.5 turns out. This is your starting position. Warm up the engine then adjust the idle via the mixture screws (evenly) and idle speed screw to get the best idle.

If you have to move more than 4 jet sizes in either direction then the carby is the wrong application. Also if the carby is a 650 vac sec spreadbore then it will not like a big cam, i.e over 220@050". Spreadbores are designed for near stock motors.
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Posted: Thu Jul 13, 2006 5:22 pm 
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Also sounds like the carby is actually LEAN not rich. Lean will get better as engine warms up, rich will get worse and start fairly good.
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Posted: Thu Jul 13, 2006 10:21 pm 
Getting Side Ways
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For a Hemi 6, the Holley carbs are crap -I mean really.

If you're serious, go for a Carter and look for the long runner Redline manifold while you're at it. They are probably getting rare but well worth the effort. I assume it's cammed E48/E49 spec?

Also mate, regardless of who you listen to, the 245 head is a top performer. They work just fine.

 

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Posted: Mon Jul 17, 2006 3:31 pm 
Getting Side Ways
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Check that your problem is not just a faulty coil failing under load.
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