My dealings with a cold natured motor

[junkyardjeff]

Ever since I converted the 302 thats in my 65 custom 500 to a 4 bbl it has been cold natured and would not run right untill everything under the hood is warmed up,I never really cared at first since the heater did not work and it got parked in october but after I got it to put out heat I have been tinkering with it as I am driving it untill the snow flies.    First thing to go was the open element air cleaner and in its place went a 84 mustang dual snorkel air cleaner and I made heat tubes to go from the headers and it was a little better,a few weeks ago I bumped the jets up 2 sizes and it was much better but it still could use some help.    The air temp sensor on the air cleaner did not work so I hooked it up to a ported vacumn switch but I picked up a second air cleaner and it worked so it went on and I hooked up the vacumn switch to the distributor.  I got the distributor full vacumn when cold and when warm it gets vacumn when given throttle like how my 78 F150 was setup and I noticed another improvement,I had to do what they did to the 70s and early 80s vehicles to get it to run right on this one and todays gas might be part of the problem.  I think I installed those restrictors on the heat passage under the carb when I installed the aluminum intake which I think is mostly to blame in causing the cold natured issues,I will probably have to do this all over again as the motor needs to come apart to repair a valve guide and ever since I converted to a 4 bbl it started using oil so I am thinking on installing a factory cast iron 4 bbl intake when I repair the motor and then the tuning will start over again.

[kb426]

What kind of choke does it have and how is it set?

[Carnut]

I put the heat crossover restrictors on a motor in my 83 Blazer when I put a aluminum manifold on it.

It started and ran pretty good but in cold raining or wet snowing weather it almost wouldn't run, had carb icing like crazy even when all warmed up.

Really wanted a carb heat knob on the dash when that happened.

Kinda hard on a Blazer that I liked to get out and run in the snow with.

[enjenjo]

Ford used a water headed carb spacer on some models. It splices into the heater hose.

[junkyardjeff]

What I have done to this motor probably is the cause of its cold nature but the new crappy gas has to have a effect too,shorty headers and 2 1/4 inch dual exhaust on a little 302 so no wonder it ran so lean,the two size richer jets made the most improvement but the other things I done helped a little.  Its got a manual choke which I have on all my vehicles with aftermarket carbs and I probably push it in too early,it seemed to run much better when it had the Holley 500 2 bbl carb and I might just put it back on when I pull the head but since I got a factory 4 bbl intake I will use it.  I remember the water heated carb spacer as the original 352 had it and could find one but I really dont want to go with one and get the carb too hot as this crappy gas likes to perculate too much,I think I got it as good as I can for now.

[Crosley.In.AZ]

i had a ZZ4 motor with no heat cross overs... I would warm up here at home.. after a mile or two the manifold would kool off enough to cause stumble problems.

I remoived the fresh air intakes,  for an open air filter setup.. that helped with radiator heat in the compartment.  It does not get that cold here , but it would be in the low  40's in the AM

[junkyardjeff]

If I have the restrictors in it they will be removed and I think I have one of those water heated carb spacers in the shed and could use it if I can find a way to shut off the coolant flow during the warmer months.

[wayne petty]

holley 108-51






felpro  60677

[junkyardjeff]

I will look into those when I work on the one head and change to a cast iron intake,I got about 90 percent of the cold issure handled but the way it acts I am almost certain I put the restrictors in the heat passage. I can start out with the motor completely cold and even after the motor warms up there is still a slight issue but is bearable but after I shut the motor off like going into a store and come back out it runs great,the intake absorbs the heat and finally gets the same temp as the rest of the motor or that can be the way a aluminum intake acts as its the first one I had in about 30 years.

[junkyardjeff]

Since I have the mid 80s mustang dual snorkel air cleaner on the car I decided to install the correct year valve covers to the air cleaner so I can complete the PCV system to a closed system like on the mustang,I had to move the PCV from the pass valve cover to the drivers side so I had to use about 1 1/2 feet of hose to do it and it now acts like it has leaned out the carb some.  It looks like I will have to find a carb spacer with a vacumn port so I can shorten the hose to the PCV,on the mustang the vacumn came from the front of the carb spacer and I have a Holley that the vacumn port for the PCV is on the rear on the pass side and I dont think there is a place on the front of the intake to screw in another vacumn port.  I am not going to use the carb spacer from the mustang since it includes a EGR valve,I read  that adding a EGR to a higher compression motor will reduce the octane requirment and my 70 motor is on the edge of not likeing regular grade gas but that would require me to buy a different intake and cant afford that right now.

[58Apache]

If it's a manual choke and you admit you may push it in too soon, what happens if you adjust the timing on that?

If it is much better after it gets warm I wonder if there might be an ever so slight vacuum leak that gets sealed when things warm up?

Try re-tightening the carb and intake bolts?

Any chance the carb needs to be rebuilt?

Are the jets adjusted for the correct fuel/air mixture?

[junkyardjeff]

I cant believe just adding a longer hose to the PCV and changing the valve covers would change anything but it set me back a little but is still tollerable and I can live with it untill I pull the head and go back to a cast iron intake,in the mean time I am going to install a carb spacer with a PCV port and run it out the front so I can have a much shorter hose to the PCV like before and see if its the cause for this setback.  It does not have a vacumn leak as it idles too good even when cold,its been severly cold natured since the parts were taken out of the boxes and got better but it looks like even a simple change can effect tuning so I need to quit changing things in the middle of trying to get it right.

[junkyardjeff]

It looks like I shut off the vacumn to the flaps in the air cleaner,I put a valve inline so I can just leave the flaps open in the summer and forgot to turn it back on after installing the aircleaner.  Its been sitting most of the day and will be running some errands after I get off the computer and will see if that was the problem,I am still going to see if there is a way to move the vacumn port so there is not 2 foot of vacumn line going to the PCV and its probably going to be a carb spacer with a vacumn port as the easiest fix unless there is another port on the intake I overlooked.

[junkyardjeff]

I kept a AFB off a truck I sold and since it has a front port for a pcv I installed it tonight and its back to the way it was and running great,now its time to get the electronic ignition back on. If I only knew it had a adjustable vacumn advance when I took it back out I could of had it set right,I robbed it for the distributor in my sunliner so I ordered another tonight and will have to make another harness since I used it when I put the 460 in the 66 F250.

[junkyardjeff]

I also found the bearings in the water pump were almost frozen up and must have been robbing some power as its running better.