stock engines in cold climates...exhaust question

[68speedalert]

Need some guidance guys. Having numberoneson's 72 shortstep exhuast installed tommorrow.

1. With the stock carb & choke set-up (350 w/4bbl), will the choke operate ok (warm up and open completely) without the heat-riser orexhaust restrictor in it?

We are going with 2 1/2" pipe with turbos.

2. Adding an H pipe worth it for a stock engine?

Steve

[oldsub86]

If I read your address right, you are in Missouri. I wouldn't call that a particularly cold climate. Based upon that I think you could get away without the heatriser setup. I would think the worst case scenario is that it will take your truck longer to warm up. You may find that the engine does not run really smooth during the warm up period and you may find that it runs a bit rich and the exhaust smells a bit gassy. I would think that the major issue is one of emissions during the warm up period.

[JimKshortstep4x4]

We have two trucks that we run a lot in the winter. Neither have heat riser valves on them nor thermactor setups. Both are setup with dual exhaust on the 350 engines. The choke works ok on both of them and opens up in a reasonable time. We do run 195 degree thermostats in the engines, which you need in Michigan in the winter.

You have to make sure the choke pull is set right and the linkage is free. One of the trucks is used for plowing so it gets started a lot in the winter. Drivability is good, not like EFI of course.

We don't do the h-pipe connections on the duals. No particular reason, but feel that is unneeded for the way the trucks are used.

Jim

[68speedalert]

Whatyamean it ain't cold in MO? My goodness it got below zero twice this winter!!!

That's the answers I was needin'. I seem to see more problems with heat risers and intakes clogging on the '73 thru '78 trucks than the '72 & olders for some reason.

If you guys up north can go without I'ma thinkin I can too.

Thanks,

Steve

[StingRay]

Well cold here is -40 and I don't run the heat riser valve. I switched to an electric choke last year but ran the divorced choke for 10 years with no problems. The biggest problems I have had have been when the temp is right around freezing and it is humid outside. If I don't run a stock air cleaner with the stove pipe the carb freezes up. The only way it will idle after that it to shut it off and let the engine heat thaw the carb and it's fine after that.

[68speedalert]

Stingray you've just described a typical Missouri winter......around freezing and humid. I've had my carb do that a few times myself.

Did you switch to a different carb for the electric or did find some kind of conversion?

Steve

[Jeepster376]

Must use stock snorkle type air cleaner in winter with stove pipe from manifold. Otherwise in freezing rain or wet snow conditions you'll be pulling into the breakdown lane every 20 minutes to let your carb thaw out.

[StingRay]

I got a carb that is typically 79-80 truck and had a professional re-build by a local guy that specializes in fuel systems. IF you can find a Camaro q-jet of that vintage it's a bit better for performance applications.

[68speedalert]

That should be a carb with a big black round choke attached to the carb, then you had to run a wire to it. The factory style chokes were pretty well gone on all light duty trucks by '79.

That is an option we can do...I've got a couple of big block q-jets sitting in the garage. So far this engine is bone stock (except for the missing air pump) and was trying to keep it that way untill I have to change something.

Steve

[StingRay]

I just used the wire from the stock idle stop solenoid and crimped a new end on it. The later vintage carb never runs on so the solenoid is not needed. It's an easy swap either way and for the most part it inproves drivability for me. I do have to say though that when the divorced choke carb was set up right it worked perfectly from 110 above to -40..........as long as it stayed set up right. The electric choke carb is good from real hot to around freezing and then I have to adjust the choke coil housing after that. I just adjust it seasonally and it's fine. You probably would'nt have the same issues in your climate. Be careful with the air cleaner spacer stack as some of the choke linkage can get hung up on it with the later carbs and it might need a little tapping out with a small hammer to clearance it.

[68speedalert]

do you mean that it won't open all the way when real cold unless you adjust it?

If so, ask your carb guru if he plugged the vacuum source that goes into the choke housing. I tried to just plug the old heat tube opening on the outside of the housing, yet it wouldn't fully open. I removed the housing and plugged (with a toothpick) the opening in the carb that supplied the vacuum. Now the electric choke worked as advertised! It must still have been sucking enough cold air to keep the choke thermosatat from warming up fully.

Steve

[StingRay]

No it opens and closes fine. It's just too rich or too lean of an opening curv for the ambient temp at the extremes. 150 degees F is a big range to expect an automatic choke to handle well. The best carb I've ever seen at handling our weather were the 80's Toyota carbs........but what a nighmare to work on and wee bit small for the ole 350

[68speedalert]

you could always put 4 of the Toyota carbs on it.

Steve

[68speedalert]

Went without a heatriser or restrictor, thanks to your guys suggestions. Drove this morning with outside temp about 40 degrees, choke was completely open after about 1 mile and 5 minutes! Couldn't happier!

Exhaust sounds SWEET as well.

Thanks again,
Steve