help me pick a carb...

BelueLX

Founding Member

Jul 10, 1999

1,195

1

0

Aug 13, 2004

#1

• Aug 13, 2004

• #1

Ok here are my mods:
stock 91 H.O longblock
weiand dual plane intake manifold
longtubes and full 2.5" exhaust
MSD pro billet distributor

what size carb do i need 600 or 650? can anyone with a similar setup help me with jet sizing and timing settings? im going to put an o2 sensor in tomorrow and try to adjust my current carb until i buy a new one to replace old school marine one.

i did trap 103mph (1/4-mile) in efi trim and now im down to 93mph and im pretty sure its in the fuel/timing...

 

D

D.Hearne

New Member

Sep 29, 2000

11,730

6

0

south louisiana

Aug 13, 2004

#2

• Aug 13, 2004

• #2

If you're running an auto, then a 600, if a manual then a 650

 

V

VictorII

New Member

Jun 19, 2004

148

1

0

Cotati, CA

Aug 13, 2004

#3

• Aug 13, 2004

• #3

AXIStang said:

Ok here are my mods:
stock 91 H.O longblock
weiand dual plane intake manifold
longtubes and full 2.5" exhaust
MSD pro billet distributor

what size carb do i need 600 or 650? can anyone with a similar setup help me with jet sizing and timing settings? im going to put an o2 sensor in tomorrow and try to adjust my current carb until i buy a new one to replace old school marine one.

i did trap 103mph (1/4-mile) in efi trim and now im down to 93mph and im pretty sure its in the fuel/timing...

Click to expand...

You can get by with a 500 but a 600 is better if you're going to do something else in the future. I think the 650 is overkill. I use Edelbrock since they run well out of the box and are pretty tuneable. Some like Holleys.

 

65fastback2+2

New Member

Aug 4, 2003

1,229

0

0

Louisville, KY

Aug 13, 2004

#4

• Aug 13, 2004

• #4

Id go a 600 edelbrock. My last car had a holley and it just went to pot too quick. Just quit on me at a light twice, dumb thing, and would sometimes* bog down if you jumped on the gas, other times, its just melt the tires. finiky thing.

 

T

tjm73

Founding Member

Aug 3, 2000

2,418

2

48

Rush, NY

Aug 13, 2004

#5

• Aug 13, 2004

• #5

I'd go Road Demon (or even Road Demon Jr) 625, maybe even 525cfm. Stock 91 5.0 woun't need 650cfm. If you change the cam or plan to change the cam go 625. B303 is a drop in cam fo rthat motor and makes good power nd nice sound. I have a B303 in my 90 GT.

 

BlueMonster65

Founding Member

Feb 24, 2001

385

0

16

Connecticut

Aug 13, 2004

#6

• Aug 13, 2004

• #6

definately the road demon. the 625 is good for a stock to mildly built 302. and it will be enough if you decide to do a little more engine work. you will probably need to change the acelerator pump cam and possibly the VS spring. and maybe jet it down a bit but it is worth it. if you don't plan on doing any mods the road demon jr 525 might be a better choice. in my opinion you simply cannot buy a better carb than a demon. and i have experience with quite a few brands even the predator which was a popular POS back in the late 80's

 

D

D.Hearne

New Member

Sep 29, 2000

11,730

6

0

south louisiana

Aug 13, 2004

#7

• Aug 13, 2004

• #7

65fastback2+2 said:

Id go a 600 edelbrock. My last car had a holley and it just went to pot too quick. Just quit on me at a light twice, dumb thing, and would sometimes* bog down if you jumped on the gas, other times, its just melt the tires. finiky thing.

Click to expand...

I just don't get why Y'all think Holley's are at fault for your carb problems. Damn, I bought one of them 6 months ago ( Holley list 1850 600cfm vac. sec.) from the local speed shop that took it in on trade from another dis-satisfied customer. All I did to it was to install a lighter "purple" sec spring, swap the bowls for a dual feed set from a 750 ( I like their look) and bolt it onto my 89 Ranger's warmed up stock 5.0 . It's run flawlessly for the last 6 months, WITHOUT TUNING ! I even went to change the over a year old spark plugs last week, but after pulling two, and seeing their light tan look, stuck them back where they came from. THE only time I've EVER had problems with a Holley in the last 30 something years, it was due to dirt or water in the fuel, something that either a water separator and /or a couple of fuel filters in line would have prevented.

 

BlueMonster65

Founding Member

Feb 24, 2001

385

0

16

Connecticut

Aug 13, 2004

#8

• Aug 13, 2004

• #8

i agree holley's were the best carb...until barry grant started making the demons. similar to a holley but a remarkable improvement....and it looks cool.

 

PoliceInterceptor

Keeper Of Automotive Oddities

Founding Member

Aug 5, 1999

2,161

0

46

Live in GA, But could be any where really.

Aug 13, 2004

#9

• Aug 13, 2004

• #9

I think its a bit of an unrealistic expectation to buy a carb, stick it on and have it run 100% correctly out of the box with no tuning. I think a lot of people expect that and get disapointed.

I think Holley's are great carbs and the SA series is very nice if you can get past the finish or you like it to start with.

If I could get a decent manifold for one I'd probably run a Q-Jet, but since there is no brand X stuff around, Holley is my choice. (demons are nice as well, but they look like somebody melted a Holley)

 

Jonstantine

Founding Member

Jul 20, 2002

487

0

0

Oklahoma

Aug 14, 2004

#10

• Aug 14, 2004

• #10

call the company you plan to buy the carb from... they will tell you what to get... and i bet its closer to teh 500 cfm range

if you dont like that option, ill sell you my 625 road demon for 250 so i can go buy a 525

 

Hack

15 Year Member

Mar 23, 2004

1,945

13

69

Minneapolis

Aug 14, 2004

#11

• Aug 14, 2004

• #11

From the Haynes Holley manual, for a 300 cubic inch engine (high performance)...

It depends on how high you want to rev the engine.

rpm cfm
5000 385
5500 420
6000 460
6500 500

 

PoliceInterceptor

Keeper Of Automotive Oddities

Founding Member

Aug 5, 1999

2,161

0

46

Live in GA, But could be any where really.

Aug 14, 2004

#12

• Aug 14, 2004

• #12

Dyno Sim says your max airflow with the stock cam is 422.9 CFM.

Jumping the cam to an E303 raises it to 499.5 CFM.

Changing the heads to ED heads and the E303 goes to 538.8 cfm.

If it was me I'd buy a a 525 at a minimum.

If you have any further modification plans take them into consideration, a 570-670 Street Avenger would probably work fine. VS carbs are reasonably forgiving.

If you don't plan to get to radical in the future, stay at 600 or under.

FWIW

 

BelueLX

Founding Member

Jul 10, 1999

1,195

1

0

Aug 14, 2004

#13

• Aug 14, 2004

• #13

Thanks for the info. Right now I have a Holley 4011 (650 w/ vac secondaries). It has 60 main jets and 64 secondary jets. I might try tuning it a little but Im not really sure what jets to go with. Can anyone running a similar combo offer me a jet setup?