340 Timing/Carb Size
#705806
05/23/10 05:24 PM
05/23/10 05:24 PM
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Joined: Feb 2003
Posts: 608
NY
old340dog
OP
mopar
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OP
mopar
Joined: Feb 2003
Posts: 608
NY
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I had my 1973 340 motor rebuilt with 2.02 eddy heads, 9:8 pistons and a com cams XE268H (.477 lift, 268 duration) cam. I've been having trouble finding the right setting for timing. Does anyone have this setup with what seems to a good timing setting? I've got a auto transmission, car seems to be sluggish on intial acceleration.And also seems to backfire on harder acceleration.Other than that it runs fine.
I also have a LD340 intake with a 650 Eddy carb.I don't know know if this the best carb/intake for my setup. I've been told my motor will run allot be with a bigger cfm carb. Somehwere in the 700-750cfm range. Any suggestions here?
old340dog
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Re: 340 Timing/Carb Size
[Re: ademon]
#705808
05/23/10 05:49 PM
05/23/10 05:49 PM
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Joined: Jan 2003
Posts: 5,270
Missouri
MY340
master
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master
Joined: Jan 2003
Posts: 5,270
Missouri
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 15-18 degrees with a total of 34 at 2400rpm would be a good setup. If tuned right the 650 Edelbrock should work OK but I think you can benefit from the 750cfm and gain some mid/top end performance. I run 20 intial/34 total at 2500rpm on my motor specs below. I also use the vacuum advance as it works good with my motor combo. Depending on what the specs are on your distributor you might have to have it recurved.
1970 FE5 Duster 360/904/3.91's SOLD
1973 TB3 SpaceDuster 340/4spd/4.10's SOLD
Moparless for now but when the opportunity is right I'll have another one.
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Re: 340 Timing/Carb Size
[Re: old340dog]
#705810
05/23/10 08:10 PM
05/23/10 08:10 PM
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Joined: Feb 2005
Posts: 5,221
Branson, Mo.
joedust451
super gas
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super gas
Joined: Feb 2005
Posts: 5,221
Branson, Mo.
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Quote:
I had my 1973 340 motor rebuilt with 2.02 eddy heads, 9:8 pistons and a com cams XE268H (.477 lift, 268 duration) cam. I've been having trouble finding the right setting for timing. Does anyone have this setup with what seems to a good timing setting? I've got a auto transmission, car seems to be sluggish on intial acceleration.And also seems to backfire on harder acceleration.Other than that it runs fine.
I also have a LD340 intake with a 650 Eddy carb.I don't know know if this the best carb/intake for my setup. I've been told my motor will run allot be with a bigger cfm carb. Somehwere in the 700-750cfm range. Any suggestions here?
What are all the specs, like car/gears/stall, my advice would be to go with a 650dp & mill the tower off, jet it 70/76 as a baseline, even though you have decent heads, that cam is conservative, it'll run much better with the smaller carb, ask me how i know 
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Re: 340 Timing/Carb Size
[Re: joedust451]
#705811
05/23/10 08:47 PM
05/23/10 08:47 PM
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Joined: Feb 2003
Posts: 608
NY
old340dog
OP
mopar
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OP
mopar
Joined: Feb 2003
Posts: 608
NY
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My car is a Duster with 3:23 gears with stock convertor. I'll have to check to see but I thought the new distributor I got from Mancini had a curve kit already in it.If not how to go aobut advancing the curve? I'm not dragging the car it just is used for the street.
I've heard Eddy has been having problems with their 750, Barry Grant has had trouble in past with their carbs. And Holley has had their share also.
So who do you go with?Carbs aren't cheap.
old340dog
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Re: 340 Timing/Carb Size
[Re: old340dog]
#705813
05/23/10 09:36 PM
05/23/10 09:36 PM
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Joined: Jan 2003
Posts: 5,444
Indiana
YO7_A66
master
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master
Joined: Jan 2003
Posts: 5,444
Indiana
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""15-18 degrees with a total of 34 at 2400rpm would be a good setup.""
This would be an excellent starting point. Always get your timing down first. Once you get the timing where you want it, then tune your existing carb.
The 3:23 and the stock converter is where I would go before a new carb. I have made several changes to my once stock 340 and I still think that the best bang for the buck was my converter change from the stock unit. The 340's do not make a bunch of torque so you have to get them up in the rpms to get the performance from them. The 202 heads dont help with toque either, so changing the converter will help get the car off of the line.
Note: I am a huge Quick Fuel fan. The have a few street carbs that work well. Give them a call for their suggestions. But I think you would gain performance else where before a new carb. Timing first, then tune your existing carb, then decide where the next upgrade should be.
1970 YO7 A66 [Canadian Export] F8 Challenger
340 (Currently in shop for stroker assy.)
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Re: 340 Timing/Carb Size
[Re: YO7_A66]
#705814
05/23/10 10:04 PM
05/23/10 10:04 PM
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Joined: Feb 2005
Posts: 5,221
Branson, Mo.
joedust451
super gas
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super gas
Joined: Feb 2005
Posts: 5,221
Branson, Mo.
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Quote:
""15-18 degrees with a total of 34 at 2400rpm would be a good setup.""
This would be an excellent starting point. Always get your timing down first. Once you get the timing where you want it, then tune your existing carb.
The 3:23 and the stock converter is where I would go before a new carb. I have made several changes to my once stock 340 and I still think that the best bang for the buck was my converter change from the stock unit. The 340's do not make a bunch of torque so you have to get them up in the rpms to get the performance from them. The 202 heads dont help with toque either, so changing the converter will help get the car off of the line.
Note: I am a huge Quick Fuel fan. The have a few street carbs that work well. Give them a call for their suggestions. But I think you would gain performance else where before a new carb. Timing first, then tune your existing carb, then decide where the next upgrade should be.
Forget a carb for now, invest in a converter & dial in the timing curve.
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