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Username Post: Cold blooded 307        (Topic#359180)
doubleE 
Valued Contributor
Posts: 3874

Loc: Eagan MN
Reg: 06-02-03
12-20-19 01:43 PM - Post#2782560    

Hey -
Newly retired and down to one car and my 72 C10. In the past the C10 went into hibernation come November here in Minnesota. But now down one vehicle, the C10 has been pressed into winter duty when both the wife and I need to go our separate destinations, not too often, maybe once a week.

This led me to discover that the 307 is very cold blooded and unless I let her warm up a good 5 to 10 minutes, she stalls every time I pull away from a stop.

The 307 is stock with a Rochester 2GV (divorced choke)and no heat riser exhaust valve. So question one is "should there be one?" My guess this truck originally had single exhaust that a PO changed to dual exhaust and may have removed the heat riser if there was one?

My 2nd concern is when I rebuilt the 307 I think I placed the optional exhaust restrictors (came with the intake gasket set) on the intake manifold in the effort to prevent paint discoloration on the intake. Not a problem until now.

So when I start her up when cold the fast idle sets and after a few minutes I'll tap the accelerator to lower the idle - all good, but if I try to drive it before waiting 8-10 mins, after stopping,she stalls when I try to move again. Not fun when there's a line of cars behind me at a green light

So any thoughts...

Eric

Proud owner of My Blue 62 Impala SS


 


Mel Foye 
*VIP* Original Founding Member Group
Posts: 4959
Mel Foye
Reg: 09-29-00
12-20-19 11:07 PM - Post#2782587    
    In response to doubleE

Former Shakopee boy checking in Eric. Remember that Smokey said that the air/fuel just after the base of the carb was just above freezing. That is not helping the a/f to stay in many fine droplets.
Now in Los Angeles and fixed the heat riser on a buddy's car. He could not believe how much better the carb performed very soon after starting. Also said it ran better on the freeway.
So I would go with a 180 thermostat. Then a heat riser and pull those restrictors. What is your setup for getting heat to the choke?
I was luckly enough to have a one on one face to face with Jim Mcfarland and he never waivered from the smaller the droplets the better for everything.



 
2plus2 
Member
Posts: 1236

Loc: Mission,BC
Reg: 02-03-05
12-21-19 12:00 PM - Post#2782617    
    In response to doubleE

It only does this when its not fully warmed up?

69 Canadian Pontiac 2+2
factory L48 350 Chev,TH350,PW,PT
99 Silverado RCLB 4.8 NV4500 14BSF 4.10's locker 6" Procomp 35 bfg m/t's 9k winch cutout flares
07 Town Car Loaded,Tinted,Getting Bagged


 
doubleE 
Valued Contributor
Posts: 3874

Loc: Eagan MN
Reg: 06-02-03
12-23-19 01:47 PM - Post#2782757    
    In response to 2plus2

Thanks for the replies. No problem with the thermostat as she warms up and the temp gauge is right where it should be. Good heat from the heater too.
Yes, this is only a problem on a "cold Start". Once the engine has run for 8 to 10 mins the problem goes away and drivability is fine.

My one big question is was there originally a heat riser on the passenger side exhaust manifold that forced exhaust to go through the intake manifold to both heat up the carb and the divorced choke spring. I do plan to remove the restrictors soon and to heck with blistered paint on the intake runners.

Shakopee is not too far, maybe 10 - 15 miles from Eagan MN.

Eric

Proud owner of My Blue 62 Impala SS


 
JimKshortstep4x4 
Chevytalk Moderator & "16th Year" Silver Supporting Member
Posts: 5113
JimKshortstep4x4
Loc: Muskegon, MI, USA
Reg: 03-28-02
12-24-19 08:58 AM - Post#2782817    
    In response to doubleE

My snow plow with a 307 has similar problems but since I only use it when the snow is on the ground I always let it warm up. My 307 had a heat risor but it was removed when I put duals on it. Since I always let it warm up to clear the windows it is not much of an issue for me. I have had issues with accelerator pumps at times.

My 307 had a heat risor on the passenger side.

Jim

65 Impala SS, 400sbc, Muncie M-22
66 Impala SS, 396, TH 400
69 El Camino, 350, TH 350
71 Short bed stepside 4x4, 350/TH 350
71 Snow plow, 4x4, 350, TH 350
72 GMC Shortbed, stepside, 427/TH 400


 
doubleE 
Valued Contributor
Posts: 3874

Loc: Eagan MN
Reg: 06-02-03
12-24-19 09:34 AM - Post#2782819    
    In response to JimKshortstep4x4

Thanks Jim, that's the conformation I was looking for. Looks like my new project for after the holidays will be to pull the intake to remove the restrictors (had some anti-freeze leaks to deal with on the intake too)and add a heat riser to the passenger side. Good thing I have a heated garage
Eric

Proud owner of My Blue 62 Impala SS


 
JimKshortstep4x4 
Chevytalk Moderator & "16th Year" Silver Supporting Member
Posts: 5113
JimKshortstep4x4
Loc: Muskegon, MI, USA
Reg: 03-28-02
01-01-20 09:52 AM - Post#2783397    
    In response to doubleE

A heated garage is a necessity!

Jim

65 Impala SS, 400sbc, Muncie M-22
66 Impala SS, 396, TH 400
69 El Camino, 350, TH 350
71 Short bed stepside 4x4, 350/TH 350
71 Snow plow, 4x4, 350, TH 350
72 GMC Shortbed, stepside, 427/TH 400


 


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