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| JT |
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Hey, just looking for some opinions on what carb I should run on my 302.
Edelbk rpm heads, Comp dble valve springs, cam, air gap mani, lightened rods, duratec pistons 9.5-1 comp, 1.7 RR's, extractors, etc hoping for around 350hp rev happily to 6,000 - 6500rpm. I was going to buy a brand new Holley DP, but now I just want something to use to run in before I swap to my Holley 900 TBi. I was thinking if a re-kitted Holley 650 vac sec? Someone told me to make sure to get the model with metering plates on each sides? opinions welcome. |
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| tickford_6 |
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Posts: 6449 Joined: 11th Nov 2004 |
a brand new 1850 600vac is only about $450 if you know where to shop.
or forget the TBI and fit a 650DP STREET HP i think the last one we sold for about $670 what was his reason for getting metering blocks on both sides? |
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| JT |
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I think it's because the metering plates can be tuned on both sides or something like that. Otherwise you just get a block on one side thats sits inside the housing and can't be jetted or anything..
apparently carbs with two metering plates are good for performance where as ones with only one were designed for economy.. anyway.. I just need something do get the engine run in before I swap to a aftermarket computer and my TBi setup. |
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| cjh |
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A 650 Vac sec spread bore Holley will work fine. Use an 85 power valve, 64 jets up to 66 jets. Also have twin fuel lines to the fuel bowls, instead of the p!ssy little tube they normally have. Have you got a recurved dizzy.??? This makes a huge difference. You didn't mention cam specs, to see whether the comp ratio is suited.
Also, you didn't mention if it was auto or manual. If auto, what stallie have you got??? What diff gears are you running??? If the dizzy is recurved, what is the timing on at idle???
_________________ http://youtu.be/jJTh9F3Vgg0 |
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| JT |
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The dizzy is electronic and is controlled by an aftermarket ECU
(yes I know - I'll be the only guy running a LINK and a carb) 9.5-1 comp, mild regrind roller cam with 462 lift using 1.7 RR's, Edelbrock heads and air gap intake, lightened rods, duratec pistons and fresh rebuild. Shiftkit C4 auto with 2200 stall. I'd heard that square bore would be better than spread? I don't know much about carbs really. I just need something that will get it running for a while and run in the engine. As I don't want to be tuning EFi on a fresh motor. |
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| cjh |
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{USERNAME} wrote: The dizzy is electronic and is controlled by an aftermarket ECU
(yes I know - I'll be the only guy running a LINK and a carb) 9.5-1 comp, mild regrind roller cam with 462 lift using 1.7 RR's, Edelbrock heads and air gap intake, lightened rods, duratec pistons and fresh rebuild. Shiftkit C4 auto with 2200 stall. I'd heard that square bore would be better than spread? I don't know much about carbs really. I just need something that will get it running for a while and run in the engine. As I don't want to be tuning EFi on a fresh motor. Hhhmmmmm...............makes it hard mixing old school carby with ECU trained ignition. Can you change the curve, or the base idle timing and the top end timing??? I am one of the very few who use spreadbore carbs on a performance engine, and they work good, when set up right. I am assuming this is a Windsor engine???
_________________ http://youtu.be/jJTh9F3Vgg0 |
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| JT |
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yeah its a windsor 5.0 late model. How can it be hard to use a computer controlled dizzy with a carb lol? the aftermarket computer makes the dizzy infinately adjustible.
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| XR9UTE |
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{USERNAME} wrote: yeah its a windsor 5.0 late model. How can it be hard to use a computer controlled dizzy with a carb lol? the aftermarket computer makes the dizzy infinately adjustible.
Zigactly! What's so hard about it? Something I ask carb guys all the time! Which brings the next question....whats so hard about using the EFI straight up?.....buying a carb and not using the EFI from the get go is a strange thing to do. But then using a 4 hole t-body/carb intake is backward step especially when your engine won't see more than 6500rpm. The EFI Edelbrock intake would have been much better for area under the curve. I realise you were going for a "look" but at what cost to performance? |
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| JT |
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would you want to run in a $10,000 engine without a wide-band O2 sensor and a completely un-tuned computer??? Road-tuning the computer would be a very stupid thing to do on a fresh engine. Otherwise it would have to get started up on a dyno and run in there at a huge cost.
Which is why I said the carb was just to run in the engine before swapping to the TBi. Yes I realise the TBi isn't as good as port injection. But the Edelbrock intake wouldn't fit under the capri bonnet for starters and wasn't the look I wanted. I don't believe the performance loss going to a 900cfm TBi to be of too much significance. After-all a properly setup carb can equal injection for performance stakes. I don't think I'll notice a small performance loss under the curve in a car that only just tips 1000kgs with 350hp.. 
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| XR9UTE |
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{USERNAME} wrote: would you want to run in a $10,000 engine without a wide-band O2 sensor and a completely un-tuned computer??? Road-tuning the computer would be a very stupid thing to do on a fresh engine. Otherwise it would have to get started up on a dyno and run in there at a huge cost.
Which is why I said the carb was just to run in the engine before swapping to the TBi. Yes I realise the TBi isn't as good as port injection. But the Edelbrock intake wouldn't fit under the capri bonnet for starters and wasn't the look I wanted. I don't believe the performance loss going to a 900cfm TBi to be of too much significance. After-all a properly setup carb can equal injection for performance stakes. I don't think I'll notice a small performance loss under the curve in a car that only just tips 1000kgs with 350hp.. You answered your own question....buy a wide band with the money you would have spent on a carb. I just bought an LM-1 for $360...cheaper than a carb! And you can road tune with a WB enough to get you in the ball park. I'm currently doing a $25K engine on the road. BTW I had to rebuild a cleveland because the 600vac I used on it washed the bores so much they glazed up so, carbs can be just as dangerous too. As for noticing a loss....whether you notice it or not you still lose it. Fair enough if it's not the look you're after but won't that scoop stick through the bonnet? Something else that may help...4 hole throttle bodies never perform as good as single blade jobs. So it may be worth a try to use a 70mm single blade on top of that intake. Pete. |
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| JT |
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and wideband 02 is about $600 here in NZ..you got a good deal!
I used to borrow a friends one and road tuned my 2L pinto turbo. You are right you can get it very close.. unfortunately he has lost it.. 
I thought for ease of getting it up and running I'd stick a carb on it for $150. How much power would you expect port injection to make over a carb or TBi? From the tests that I've seen it's not huge. Usually a smoother curve and economy is the result. If I'm not satisfied with the results I'll just use the throttle and drill injector bosses into the lower intake. Yes the scoop will stick out the bonnet. But that looks great  I wasn't keen to have a EFi plenum sticking sideways out the bonnet..
BTW it's not a all out performance race car. It's a street machine, as long as it looks and sounds awesome and can go in a straight line fast enough to scare me I'll be pretty happy. also.. surely a single throttle wouldn't be ideal to feed a dual plane intake? |
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| green car |
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i think the carby size equation goes like this- cubic inches multiplied by max revs divided by 3456,then just round up to the closest cfm
_________________ 165 Killer Wasps all packaged in a green kmart car, almost an explorer in a way... |
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| JT |
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Thanks! so 302 x 6500 /3456 = 567
so a holley 600 vs would be about right then eh? |
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| cjh |
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{USERNAME} wrote: Thanks! so 302 x 6500 /3456 = 567
so a holley 600 vs would be about right then eh? That equation doesn't always compute. I fitted a 600 vac sec Holley to a 250 Xflow alloy head, and it went damn hard. Would smoke a pair of 265/70R15's with 2.92 diff gears (LSD), in 3rd in a 4sp single-rail box. That was with out NOS or turbo, just N/A.
_________________ http://youtu.be/jJTh9F3Vgg0 |
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| JT |
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lols I like the way you made the filter look like an 8 under the bonnet.
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