I am trying to determine what would be the best carb for my new 454. I have a edelbrock Proformer 2-O intake, Decient flowing large oval port heads (port and polished), Comp cams mechanical lifter cam duration @ .050 248/248 lift .595/.595 110 lobe sep.
Compression ratio 10:1. Headers. I have 2500 stall a/t. 3:42 rear

From what I have read I should be going with at least a 850 cmf carb.

What I am trying to decide between is:

4781S - Holley mechanical secondaries 850 cfm

80870 - Holley street avenger Vac sec. 870 cfm

Those experienced with carbs I would like to hear your thoughts.

I plan on using this for street/strip, not a drag car.

 

Ill go with the double pumper.I have a similar combo and I have a 4780.Good throttle response and easy to tune.I am still getting a lot some vacuum at WOT though so I need a bigger carb..

 

thanks daz, I was thinking 800cmf would be to small so that is why I was thinking 850 (just don't want to go too big).


Any one else with experience for some feedback......

 

ITs not actually too small for the street. For maximum performance IMO you need a bigger carb.For the street 850cfm is fine.You probably want the smaller carb because its mainly for the street.The bigger carb will generally have a slower velocity which means less vaccuum and you need vaccuum for that kind of cam.I wouldnt go with the VS either for the same reason.THat cam is big for a pure street use machine.

 

This is the cam that cam with the motor, basically new, I was going to give it a try this season. Don't drive car much. If it ends up being too radical I'll change it next season.

 

I have been looking more into it and What do you guys think of Barry Grand Speed Deamon Carbs?

The one that seems to intreague me is the 1563020 850 cmf with annular distarge. Suppose to be good for off the line due to the annular distarge and breathe well .

 

I called up barry grant and they recommended a 750 mightydemon. I called up holley and they recommended a 800 cmf double pump.

The mighty has no provisions for choke, what do you guys think about no choke? It is only driven in the good weather 40+ days.

 

I drive my camaro in October in -20 degree weather wih no choke..You just have to feather the gas the first 45 seconds

 

No choke should be fine in good weather, even in cool weather.

 

Thanks guys, It seems like that should not be a factor in my decision....

 

That cam is mild for a BBC, seen sbc running all of that. Once you get into 260+ actual duration and .700+ lift, then you can call it radical. That will make a nice overall cam for you.

Dont worry about the choke, like mentioned, you just have to feather the throttle a few seconds till the car smooths out then it'll run like a champ

 

look at the rest of the combo? EIther way everybody has their own defentiion of mild or wild

 

I looked at his entire combo before stating that remark, and given the guys that run BBC in my area on the road, he'd be better off putting that in his truck I know opinions on streetable vary, but again, for a big inch motor that is about as mild as it gets.

It should be a nice low rpm grunt monster though with the cam/stall/gear combo. Just hope he stays away from sbc running combo with comparible internals.

 

Maybe when you actually tried it..Dont compare SBC's and BBC's cause they feel totally different.I have almost the same camshaft with higher compression and bigger lif in MY car t.Iit has less power down low than my 383 SUperrammed car until you hit 3000RPM. The application is pure street duty so IMO the cam is too wild for the rest of the combination.

I also had the sam engine but with the solid L88 cam(260/270 duration cam@.05) and it was a dog on the street.It had a 454-0 intake though.I took off the 8" 4500 converter and switched to a 10" 3000 converter and it was much better..

I drove it for 3 mos until I got tired of it.I might put it back if get a 5 or 6 speed in it

 

yea Daz, it`s a baby cam it`ll have some thump and run into the 6,000 rpm range well but considering what`ll make that engine run real well and still remain streetable... it`s on the small side.....on the other side of the coin though, it is a good match for oval port heads and would work good in a truck like IHI said.

BTW 850 speed demon DP here and lovin it..has not slowed me down yet and I`m going to see tens this year on 92 pump N/A

 

Well, I'll let you guys know what I would classify the set up as when I get it on the street.

Since all the parts came with the engine and they are new or have less than 5K on them, I am going to use them for the season.

I am still a few months from getting it all together since I tore it all down to make sure it all the bearings were like new, pistons boars were in good shape, etc.

All Looks great so after I take care of casting flash/polish the heads and do a bit of intake/ gasket matching, I'll be ready for headers and a carb!

 

I dunno. but 10:1 compression with that kind of duration makes it a dog down low..But I guess everybody has their own defenition of mild/wild..If it was a roller then I would call it mild but thats just me