Thread: Please Help Fuel Issue i cant seem to shake!

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Hello there, this is my first post and boy is it long past due.
I have a sbc 355 in my datsun that me and my father began building about 3 years ago. He is a mechanic and has been building sbc's all his life but unfortunately he is no longer around and I've continued our mission to get this thing up and running.
But all I know about this is what I've been through with this car, and am still very new to it.
Well my issue is fuel related I'm sure of.
I can't tell if she's starved or flooding.
Idles great but as soon as I get it on the road she starts running like crap. Getting some black smoke but nothing crazy.
I've fouled out the brand new plugs I put in 2 days ago and the engine doesn't even have 10 miles on it yet. This leads me to believe I'm flooding it. My electric fuel pump reg is set at 6.5 psi.
I've tried 7 and I've tried 5.5 but still the same.
Runs great until spark plugs go out.
Sorry if some of this seems incorrect and please correct me if I'm wrong but this is what I can remember as far as engine parts go.
4 bolt main with steel crank
2.02 heads (not aluminum or w/e)
282 cam (I was told comp cam?)
Edelbrock 750 cfm
Holley performer intake
It's bored .30
Forged speed pro pistons
Holley electric fuel pump and regulator running from the cell
If I missed any important parts please let me know and I'll answer any questions I can.
Any help would be greatly appreciated
Thanks.

to me it sounds like your carb is too big. i personally would go with a 600 cfm. i am sure that some one here will answer soon and correct me.

unhook the power from the electric fuel pump and start the engine and see if it smooths out before it runs out of gas .. that will give you a pretty good indication of a flooding problem ...and then when you hook the fuel pump back up see if it bogs down as it primes/fills the carb ... and look down the throat of the carb and see if fuel is running thru the carb when it shouldn't be ... but don't look down the throat with the motor running ...

Thanks, yea i've been reading up some more on the 750 and it seems that many people are saying the same thing. Someone mentioned to down jet the carb but i'm not sure if that could fix the problem at all. I feel maybe a new carb is necessary. Which blows because this one is brand new and i bought it right after i bought the block 3 years ago haha sat in the box too long and i'm sure the warranty is no bueno.

You might be able to jet it down to where it would idle smoother, but it will be pig after that. You might get by with a 650 though I think a 600 would work better unless you can find someone that can rebuild a Quadrajet, and get it right, as that's probably the best street carb made.

I do have a buddy willing to sell me a quadrajet that has a fresh rebuild and ready to go for $200.
issue being is that it is also a 750 cfm. Wouldn't i still be having the same issue? I also believe id need to get new fuel line hook up and maybe extend my line some. I learned the hard way that those fittings and the line can cost a pretty penny also.

Originally Posted by Fairlady350

I do have a buddy willing to sell me a quadrajet that has a fresh rebuild and ready to go for $200.
issue being is that it is also a 750 cfm. Wouldn't i still be having the same issue? I also believe id need to get new fuel line hook up and maybe extend my line some. I learned the hard way that those fittings and the line can cost a pretty penny also.

No you will not. The primaries on the Quadrajet are similar in size to quarters while the secondaries are like old style silver dollars and you run mostly on the primaries.

You should be able to re-plumb your fuel line at little cost. If you have the tools.

That Quadrajet would be my choice and get the fuel pressure down to about 4lbs.

Let me start with adding my welcome to CHR.

Your efforts to get the Fairlady on the street are commendable and your father would be proud. I too think that the 750 is a bit big. Short of buying a new carburetor, there are several things you can do.

1. Set your fuel pressure to 5psi – no more.

2. Replace your stock jets (.113) with a .107 (Edelbrock part 1431 – $5.99 at Summit http://www.summitracing.com/search?S...elbrock%201431)

3. Replace your stock metering rods (071 x 047) with 068 x 047 (Edelbrock part 1447 - $11.99 at Summit http://www.summitracing.com/search?S...elbrock%201447

4. Get the gasket set as well – Edelbrock 1472 - $10.97 at Summit http://www.summitracing.com/search?S...brock%20gasket

5. If you don’t already have the Owner’s Manual, download it at, http://www.summitracing.com/search?S...brock%20gasket

This is really a pretty easy fix, but you need to take your time and be very careful as there are several small parts involved here. I have done a lot of these and it takes me about 30 minutes but if you have not worked on a carb before, I’d recommend you take it off the car and accomplish this on a thick stack of newspaper covered by a white absorbent cloth in an area with a lot of light. The above will certainly help in the fuel delivery area and you may find it takes care of all the issues.

In the event it still bogs down, a different carburetor would be recommended – I like Quadrajets as well but there will in all likelihood be a manifold conflict between spread-bore (Q-Jet) and square-bore (Edelbrock). The 1406 Edelbrock would be a good choice for ease of installation and not having to change your intake manifold.

Also check your timing – 8 degrees initial and 30-34 degrees all in should work fine on most SBC combinations.

Let us know what you come up with.

Regards,
Glenn

I had problems with fuel pressure above 5.5lbs, try setting your regulator lower as suggested above and reset your floats (mine were out of adjustment from too high pressure). Also, have you checked for a vacuum leak?, a vacuum leak can make the metering circuit too rich.

Some helpful info;
http://www.edelbrock.com/automotive/...ers-manual.pdf

And here (read at the bottom of the page, TECH TIP: Is my carb too big or small?);
Quick Fuel Carburetor Size and Series Chart

Thanks guys for all the replies, sorry about not getting back sooner to thank everyone. I just relocated to Conroe tx, I'm all settled in and ready to start working on the car again.
Again thanks for all the help and I will let you guys know what I decide to do.
It may be the cheapest to start out by trying out Glenn's method.(thanks for laying it out so clear for me)
If I'm still having issues I'll try out the quadrajet

Keep us in the loop as you progress.

Fairlady,
Hoping that the steps Glenn gave you work, but if you start thinking about a Quadrajet, you mentioned that you have "...a buddy willing to sell me a quadrajet that has a fresh rebuild and ready to go for $200." Unless you're 110% sure that your buddy knows all of the ins & outs of the Quadrajet you'd likely be a whole lot better off spending a bit more and getting one that's refreshed by someone who guarantees their work. There are simply too many places that an inexperienced guy can screw up a Quadrajet for you to take that chance, IMO.

Welcome to CHR! I as well am betting your father will be honored for you to get your project up and going! If the edelbrock mods don't cure it completely, or if you're thinking a different carb is in order, check out summit's new carbs. I have a few friends running them on small blocks and big blocks and they are really happy with them. Price isn't horrible either.

http://www.summitracing.com/parts/su...00vs/overview/