Carb recommendation 408 stroker

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1974scamp

1974scamp

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Hi,

Im currently putting my 408 stroker together and Im not sure wich carb to use?

Car is a 1974 Plymouth scamp.
My setup is:

1976 360 block 0.30 over
Scat cast steel crank
Scat I-beam rods
+5cc flattop pistons
windage tray
Melling HV oil pump
Rapom alu heads 2.02 intake 1.60 exhaust valves 65cc
Comp hydraulic flattapped xe274 cam
Edelbrock air-gap intake
about 10.6 to 1 compression
Hughes 2500 stall converter
TF-904 reverse full manual valve body
8 3/4 with 3.23 to 1

I have an 650cfm Holley DP but i think it will be too small?
Car is only for street use.

Thanks
Laurin
 
A 750 would probably be a better choice, but IMO for a cruiser the 650 will be fine, just tune it for your combo.
 
For flat out performance, a nice 750 DBL would be the ticket, but for a nice street car, the 650 will be fine. On the dyno, my low deck 426 big block used 638 CFM so i was bang on with my AED 750 DBL. Its very crisp and responsive.
 
Make sure you put a power valve in the primary side of the 650 , will help for street driving, and then around an 8-10 jet size difference in the secondary side with a plug not another power valve.
 
I'm going this route on my 408 build. But that's just me. 650 should be fine.

20160404_195801.jpg
 
as I say to anyone who asks a similar question - look into Quick Fuel - I have a 750 race (chokeless) on a similar engine - love it!!
 
I have been there the same combo and definitely the same bottom end kit. four words- DUAL QUAD TUNNEL RAM ! !!
No actually do it YR says it will be faster. I'm just old school and like cool stuff..
 
Hi! where from austria are you from?

i also think the 650 DP will be fine if street only. But i´d suggest a bigger cam, check the XE275HL out....should work with the supplied springs (it seems you got these procomp heads from the moparshop? They say springs are ok for use up to .520" Lift - should work with the XE275HL and 1.5 Rockers), the XE274 is too small in my opinion. But if you already have it....use it.

Are you sure about the compression ratio with this pistons? i think with 65cc chambers and +5cc pistons compression is between 11 and 12....could be a problem with detonation (more with the smaller xe274 cam) and pump gas. Check it out!

Michael
 
j par said:
I have been there the same combo and definitely the same bottom end kit. four words- DUAL QUAD TUNNEL RAM ! !!
No actually do it YR says it will be faster. I'm just old school and like cool stuff..
Click to expand...


I am never opposed to a tunnel ram. I'd have one if I didn't have the hood I have.
 
Just out of curiousity what would be the effects of under carbing ?
I ask this because I have wondered how I could detune a hot motor in case the Kids or girlfriend want to drive the car. A carb swap is fairly simple....
 
Yeah... I considered adjusting the throttle cable before they drove it.
But was curious about smaller carb effects....
My girlfriend mentioned driving my 4 sp Swinger when its done. Which is good since she was not exactly thrilled about it or the cost...and I havent mentioned that Im building a 408 with ported W2s and a solid roller....lol
 
The 650 DP, properly jetted, is the best option for street use IMO. Throttle response on low end will be better, especially with 3.23s.
 
360duster said:
Hi! where from austria are you from?

i also think the 650 DP will be fine if street only. But i´d suggest a bigger cam, check the XE275HL out....should work with the supplied springs (it seems you got these procomp heads from the moparshop? They say springs are ok for use up to .520" Lift - should work with the XE275HL and 1.5 Rockers), the XE274 is too small in my opinion. But if you already have it....use it.

Are you sure about the compression ratio with this pistons? i think with 65cc chambers and +5cc pistons compression is between 11 and 12....could be a problem with detonation (more with the smaller xe274 cam) and pump gas. Check it out!

Michael
Click to expand...

Im located at Lake of Constanze near Switzerland.

Yes i got the heads from German Moparshop today.

I already have the whole comp xe274 kit with springs and everything so Im not sure if I use the comp springs or the ones coming with the heads.

Is the power gain from 750cfm worth the 400-500$ for a new carb??
 
Have had great luck with AED 750's on 340s, 360s and on 408's ...I would get one with a choke if its a street car.

IMG_0699.jpg
 
Haha... last KTM I had was a 2003 200SX. I have moved over to Beta now...
 
I'm running 65cc W2's and 20cc dished pistons. I'm calculating my Compression at 9.7ish.
you might want to double check your compression ratio.... or do you guys get REAL gas over there?
 
mbaird said:
I'm running 65cc W2's and 20cc dished pistons. I'm calculating my Compression at 9.7ish.
you might want to double check your compression ratio.... or do you guys get REAL gas over there?
Click to expand...

I calculated 10.63 to 1

But yes we have 95 and 98 octane at every gas station :)
 
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