I am new to the carb world. I have recently had trouble cranking my 92 vert (cold start andwarmed up start) Had a 351W swap about 1 year ago and it has run well for about 2 months of that. A "friend's husband" did the swap and is very good with his car but can't seem to find time to get mine just right so I took it to a shop to pay someone to check it out. The mechanic at a local shop said that my carb was too big... that I didn't need all that power. He said that I should have/run 600 instead of 700 or 800. WTF does that mean???[:@] My husband and I really don't want to change the thing again.. it is finally running good. Any suggestions?

 

More info on the engine combo would help with what size carb would be needed!

 

Here goes...
300 HP Bullit Engine
BBK Chrome Headers
Holley Avenger 670 Dual Line Carb
High Torque mini starter and solinoid
X pipe
Flowmasters

I am not sure if that is all you needed. Like I said, new to carbs. All help is appreciated

 

For a mild 351 build like yours, i would think the 670 would perform well with that engine. I'm assuming it's not a high compression engine. That is a good carb for a 351 on the street. I would not run any smaller. It's a dual feed but not mech. secondaries, your running vac. Is the carb in stock form?

 

Yeah that should be pretty good. does it have a choke?

Nik

 

That carb is perfect. A vac carb is more forgiving on being over sized, so you are double OK. If the engine does not pull enough vac to open the secondaries. they will not open. If it was a mech carb, then a 600-650 would be a better choice.

Your starting problems MAY be carb related, but not size, since it only uses the idle, choke and accelerator pump circuits to start and idle.

 

yup, your definately using the right carb..... its just not set right. this is where a air/fuel gauge and an O2 sensor really comes in handy, i believe i will be buying one myself to aid in tuning my carb.

you have a combination of jetting, power valve, air fuel screw settings, accel pump discharge nozzle sizing, accel pump cam profile, accel pump size, and vacuum secondaries spring to *really* dial you in for the perfectly tuned carb.

the mechanics you spoke to are correct, a 700-800 (most people use the 750) is too big for a 351w unless your packing a wild setup, but why they would tell you this when you have a 670 is kinda strange [&:]

 

Thanks for the input...
92civy it does have an electric choke. Other folks have said that my choke is the problem. But, so far so good.... I have not had any trouble cranking the thing now. I was just curious as to why the mechanic said that.