I have a home brewed motor here, 1996 Vortec 350 shortblock
with cam, 94 Chevy PU 350 heads (ported) with an 88 TPI setup
sitting on top. The car started fine in this configuration for about
a year.

Last winter I pulled the intake and port matched the runners
to the upper and base and port matched the lower to the heads
and bored the upper intake bores to 52mm and removed the
EGR walls. Then I did the Mass Airfolw Meter, removed screens
and removed the fins from inside, bored the throttle bores and
installed larger plates then put it back together with 1.6
rockers and Ford yellow top injectors and an AFPR.

When the motor is cold it cranks for a long time before it will start.
If it is below 50 or so outside you need to hit it with starting fluid.
After the car runs for a little bit, you can shut it off and fire it
back up fine as long as the motor don't get cold again.

I have replaced the cold start timer and valve with new items and
verified that they work. Reset fuel pressure using a Snapon
scanner for readings, fuel is set at 52psi.

Any ideas on this one?

 

Have you tried starting it with the MAF disconnected? Some people have had success with porting/removing screens, but many I've heard have ruined their sensors.

 

You've added a lot of airflow into the engine you may just have leaned out the mixture too much. Especially as the maf mod is known for leaning out the mixture. Try adjusting your IAC and TPS that may help.

 

rezinn, no I have not tried starting it with the MAF disconnected
but will give it a try, although it does not throw a code I guess
it could have gone bad.

rhuarc30, I checked the TPS with the scanner and it is right on
the money. would I want to increase or decrease the voltage
to richen it up. What adjustments could be made to the IAC?

 

Try resetting the ECM. I do it after I mess with anything in conjunction with the TPI.

 

Before winter set in I put in a new 88 Corvette prom but that
made no change at all.

I will not mess with it for a few more weeks yet until they get
the salt off the streets and we get a nice dry day.
The car is in storage and has never seen snow before and has
never tasted salt and is not about to in my life time.

Before I put it away last fall it clocked a 13.89 @ 96 mph,
the car weighs 4890 so we figure the rear wheel hp at
about 375. One race shop here says I need #30 injectors
and crank the fuel pressure back towards factory specs,
that it is running way too lean at an idle.

Is there any way to increase the cold start valve flow?

 

Damn thing, went to get it out to install a ball joint this weekend
and hit the key for the heck of it and it started after about 4
cranks. Temp in the garage was 38. It acted like nothing was
wrong. I will have the intake off in a few weeks to install a
different base that I am siamesing. And will check everything over
again and bump up the TPS voltage a tenth or two when it goes
back together.