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| carb size? https://slantsix.org/forum/viewtopic.php?t=58899 |
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| Author: | bigcasey123 [ Fri Jan 01, 2016 11:47 am ] |
| Post subject: | carb size? |
Hello i am pretty new to slant 6's and i bought a 69 dart 225 a few months ago. i was thinking or totally rebuilding the engine but it only has 54k miles on it, so im just going to leave it relatively stock, but i will probably put a carb intake and a muffer and maybe the full exhaust on it. i was just wondering what size carb i should run. i was thinking a 390 4bbl would be overkill. any ideas? thanks for the feedback |
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| Author: | sandy in BC [ Fri Jan 01, 2016 12:28 pm ] |
| Post subject: | |
If you are not changing else then just stick with a 2 barrel The 390 is overkill and you wll hate it. Best upgrade is 2 1/4" exhaust and a Super 6 |
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| Author: | bigcasey123 [ Fri Jan 01, 2016 12:49 pm ] |
| Post subject: | |
what size 2 bbl do you think will be adequate. |
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| Author: | sandy in BC [ Fri Jan 01, 2016 12:55 pm ] |
| Post subject: | |
The stock super 6 carbs are perfect for stock motors. The Carter BBD is around 255cfm IIRC.... |
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| Author: | bigcasey123 [ Fri Jan 01, 2016 1:02 pm ] |
| Post subject: | |
ok thanks. do you think that 2 1/2 exhaust is overkill? i know that the factory exhaust manifold is what is going to be the exhausts limiting factor. and do you think a cam swap to a very mild cam is a bad idea without entirely rebuilding the motor. |
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| Author: | sandy in BC [ Fri Jan 01, 2016 1:37 pm ] |
| Post subject: | |
On a stock or mild slant 2 1/2 " is overkill and hard to fit. A 2 1/4" exhaust is a tight fit . A cam is a waste unless you increase compression. I would mill the head and use the stock cam first. |
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| Author: | bigcasey123 [ Sun Jan 03, 2016 2:56 pm ] |
| Post subject: | |
ok so a no go on the cam. would a stck 318 carter carb work? |
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| Author: | bigcasey123 [ Sun Jan 03, 2016 3:11 pm ] |
| Post subject: | |
and what type of gain does a super 6 conversion add? is it significant |
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| Author: | Rick Covalt [ Sun Jan 03, 2016 3:24 pm ] |
| Post subject: | |
@ 10 HP, but that 10 is very noticable. When you only have 100 to start with a 10% increase is pretty nice. |
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| Author: | bigcasey123 [ Sun Jan 03, 2016 3:30 pm ] |
| Post subject: | |
i might do a basic rebuild of my motor as well as the super 6 conversion. just a stock rebuild except for zero decking the block for compression and a mild cam along with a little head porting. do you think that will work well with the super 6 conversion. are those upgrades worth it as well |
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| Author: | Reed [ Sun Jan 03, 2016 3:42 pm ] |
| Post subject: | |
Quote: i might do a basic rebuild of my motor as well as the super 6 conversion. just a stock rebuild except for zero decking the block for compression and a mild cam along with a little head porting. do you think that will work well with the super 6 conversion. are those upgrades worth it as well
Do not go decking the block or head willy-nilly. You need to take the measurement and do the math to calculate the dynamic compression ratio of the engine and calculate how much you will ned to mill of the head and/or block to get the compression ratio you are after.A compression increase will work well with a Super Six to "wake up" your engine. If you are doing a full rebuild, then you might want to upgrade at least to the factory 72-81 mechanical lifter camshaft. It is a bit "hotter" than the stock 69 cam. |
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| Author: | bigcasey123 [ Sun Jan 03, 2016 4:09 pm ] |
| Post subject: | |
please correct me if im wrong but ive read that zero decking the block will give you around 9:1 cr with stock unmilled heads. and i was looking at putting a comp cam in it with .440/.440 lift and 264/264 duration. the cam comes with a whole kit that i would install. idk if that cam is similar to the 72-81 cam but in the description it is a low-mid rpm cam with good tq so i assume it is like an rv cam. |
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| Author: | DusterIdiot [ Sun Jan 03, 2016 4:15 pm ] |
| Post subject: | Ummm... yeah... |
Quote: just a stock rebuild except for zero decking the block for compression
Yeah..."zero decking" a late 70's or 80's block is about a cut of .140 to .175 off the deck-depends on year of block... at that point you will need studs as the head bolts will bottom out and not properly clamp the head to the gasket and block...Also... if you aren't overboring....your SCR will be (assuming it's a 70's engine with a 54 cc 1974-ish drool tube head...), makes it 11.09:1.... which will not run so well on a "mild cam", super six exhaust, less than a 4 barrel...etc.... Just something to think about... |
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| Author: | bigcasey123 [ Sun Jan 03, 2016 4:21 pm ] |
| Post subject: | |
my engine is an original 225 in my 69 dart. ill have to definatly do my hw but do you think 9:1-9.5:1 cr would be appropriate for my mild build? |
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| Author: | sandy in BC [ Sun Jan 03, 2016 4:35 pm ] |
| Post subject: | |
Your compression ratio must be matched with an appropriate cam to get a good result. 9.5 CR with a mild cam wont work as well as 9.5 with a moderate cam. Its all about math and vision. What do you want to achieve? What does your car weigh? where do you drive? what trans? rear gear? What fuel? Then hit the on line calculators |
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