355, carb too small?

bitchin'71SS

Veteran Member
Sep 10, 2009
397
Poughkeepsie, NY
I'm almost done putting together a mild street 355 for my buddy's chevelle and trying to decide on what size carb would be best. Right now I have the eddy performer that was on it before which is a 600cfm and worked well on the bone stock 350 but seems like not enough for the new motor. Basic specs:

10.4:1
eddy e-street 2.02 aluminum heads
comp 280h
RPM airgap
roller rockers, etc
max rpm will be around 6600
converter is mild, slightly higher stall than stock.
gears will most likely be 3.55 or 3.73's

I am thinking mechanical choke, vacuum secondaries, maybe 700ish cfm?

Looking at new holleys right now, thinking about a 770 street avenger.

http://www.summitracing.com/parts/HLY-0-81770/

Does that sound too big, and are those decent carbs? I'm open to any suggestions for different brands and sizes.

Also, I've been thinking about whether or not the stock mechanical fuel pump will be able to keep up. what do you think?

IMG_2047.jpg


Thanks,

-Andrew
 

hutchenc

Veteran Member
Aug 21, 2007
345
Wyoming/Colorado
650 vacuum secondary should be fine on that motor. You'll get lots of opinions about which brand...pick your poison.

As far as the fuel pump goes, I have a stock replacement pump on a warmed over ZZ4 (more or less the equivalent of a ZZ430) and the replacement pump is just fine. I'm also running a 650 vacuum secondary Speed Demon on it. I'm gonna swap it out for a 650 Holley double-pumper to see if it's any faster, but the 650 Speed Demon is pretty decent to be honest.

EDIT: Just noticed what you said about max RPM being about 6600...that seems really high to me with that cam. I'd think a 230 at .050 cam would be done by about 6000 RPM in a 355. If you are gonna wind it that high though, maybe a 700 CFM carb is in order.
 
Last edited:

SupplySgt

Veteran Member
Lifetime Gold Member
Jun 20, 2009
1,393
Central OK
I'd run a 650 or 670 personally. I'm by no means an expert on carbs (I've only been messing with carbs for 3 years now) but that's where I'd start if I were you. Might run a 700 but I wouldn't go any bigger than that.
 

[email protected]

Veteran Member
Feb 16, 2009
1,244
London Ontario
With a 3.55 or 3.7 ish rear gear/ 2500 and up stall....> Double Pumper.
That motor seems like great candidate to have a 4777 650 slapped on.
I ran one on my 357 roller with larger patriot heads/ valves and runners.
I also tried 3 different combos and here is how they performed....
Cruising and not much more the 600 Edelbrock was ok but ran out of juice in the 4800 and up area.
A 750 Holley vs carb was fine and I liked it until I tried a dp..put on a new 650 Holley dp and loved it. That performance outta the hole was and on up was very good.

I liked the Holley 4777 650 dp the best.
 

hhott71

R.I.P 11/19/18
Lifetime Gold Member
Mar 30, 2001
14,377
Joplin Mo. 64801
bitchin'71SS said:
I'm almost done putting together a mild street 355 for my buddy's chevelle and trying to decide on what size carb would be best. Right now I have the eddy performer that was on it before which is a 600cfm and worked well on the bone stock 350 but seems like not enough for the new motor. Basic specs:

10.4:1
eddy e-street 2.02 aluminum heads
comp 280h
RPM airgap
roller rockers, etc
max rpm will be around 6600
converter is mild, slightly higher stall than stock.
gears will most likely be 3.55 or 3.73's

I am thinking mechanical choke, vacuum secondaries, maybe 700ish cfm?

Looking at new holleys right now, thinking about a 770 street avenger.

http://www.summitracing.com/parts/HLY-0-81770/

Does that sound too big, and are those decent carbs? I'm open to any suggestions for different brands and sizes.

Also, I've been thinking about whether or not the stock mechanical fuel pump will be able to keep up. what do you think?

IMG_2047.jpg


Thanks,

-Andrew

650 is more than enough carb.
 

bitchin'71SS

Veteran Member
Sep 10, 2009
397
Poughkeepsie, NY
hutchenc said:
650 vacuum secondary should be fine on that motor. You'll get lots of opinions about which brand...pick your poison.

As far as the fuel pump goes, I have a stock replacement pump on a warmed over ZZ4 (more or less the equivalent of a ZZ430) and the replacement pump is just fine. I'm also running a 650 vacuum secondary Speed Demon on it. I'm gonna swap it out for a 650 Holley double-pumper to see if it's any faster, but the 650 Speed Demon is pretty decent to be honest.

EDIT: Just noticed what you said about max RPM being about 6600...that seems really high to me with that cam. I'd think a 230 at .050 cam would be done by about 6000 RPM in a 355. If you are gonna wind it that high though, maybe a 700 CFM carb is in order.

You're right, it looks like the power curve for this cam is about 2k-6k. I will set the msd box rev limiter to 6500 but it won't see that very often.

I'm glad to hear the stock replacement pump kept up with your ZZ4. Also I'm interested to see if a DP outperforms your speed demon. Thanks for the help
 




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