Holley carb problems

[IH8DSM]

Holley 650, 13b, msd blaster coil, premixing.
Ok so now onto the problem here lately it's been getting harder to start when warm and today it wouldn't idle when warm and now is all around hard to start. I think it's floodin at start up but why would it gradually start any ideas to tweak it or check would be helpful. This car used to run very well and has gradually developed the hard start problem and it's driving me crazy

[djmtsu]

Compression check.

[IH8DSM]

New motor and runs to good to be low compression

[IH8DSM]

Good compression just checked it

[fire85gslse]

what fuel pressure? Back it down a half or whole number to see if that helps.
You could always toss in a 12a! he he

[IH8DSM]

It's at 4 1/2 -5 lbs and a 12a is never the answer

[fire85gslse]

Originally Posted by IH8DSM

It's at 4 1/2 -5 lbs and a 12a is never the answer

wow, lower that down to 3 - 3.5 and start there. Drive it easy to see if the starting issues go away. If you find out then you dont have enough volume then you can go up slowly but might have to look at the fuel pump.

Pressure is one thing but high volume at a lower pressure might be the FP you need. The stock SE one might not be cutting the volume once knocked down to carb pressure. Did you swap that out yet or running a different one?


Cant believe what RB says here:
Fuel Pump - You will need to purchase and install a fuel pump that provides a 6 PSI delivery with a minimum 20 GPH rating - selection will depend largely on installation location. The stock fuel pump unit is designed to provide high pressure (40+ PSI) for a fuel injected intake and is not compatible with this carburetor application. It is NOT recommended that a fuel regulator be used to reduce the stock fuel pump pressure to 6 PSI- the stock pump will fail.

6 psi seems way too high! Are you still running the return? If so then maybe the 6psi is fine. On all the carbs I have used with out the return it seems like 3.5 was the max.

[fire85gslse]

ok reading the rb site a bit more. Their recommended FP is internally bypassed at 6psi and allows you to set you regulator at your setting.

looking at holley's site:

Fuel Pressure Regulators – Carbureted
Two Port 1-4 PSI, Chrome
PART #: 12-804
Fuel pressure Regulators are used to adjust for fuel pressure requirements of various carburetors. Too much fuel pressure for a given needle and seat assembly may cause flooding or driveability problems.
3/8" NPT Ports; Allows Adjustment of Fuel Pressure to Compensate For High Flow Fuel Pumps

Features
* 3/8" NPT ports
* .220" (7/32") restriction
* Low Pressure (1-4 PSI)






Again I would drop down to 3psi and try a few days at that to see if the starting issue goes away.
Seems you might be flooding it with too much pressure. It might be blowing past the needle and seat but not real sure on holley's

[IH8DSM]

See charles said the same thing two years ago we started off at 4 lbs but it would cut out at higher rpms. I'm running a mr gasket pump good for up to 7 lbs. I'm not running a return, but I do agree it is flooding somehow I'll try lowering the pressure again see what it'll do on the 4 port

[fire85gslse]

Originally Posted by IH8DSM

See charles said the same thing two years ago we started off at 4 lbs but it would cut out at higher rpms. I'm running a mr gasket pump good for up to 7 lbs. I'm not running a return, but I do agree it is flooding somehow I'll try lowering the pressure again see what it'll do on the 4 port

I would drop down to 3psi and try that. Stay out of high rpm's right now.
The reason you were getting cut out at high rpm's was not your pressure but your volume. You need a high volume pump at low 3-4psi pressure.
The Mr. Gasket one wont do the higher volume if I remember right.