I would like to use a set of Vortec heads for a 400 SB build-up I planning for my daily driver 84 C20 Suburban but I'm concerned with cold weather driveability. The Vortecs have NO heat cross-over for a carb. I plan on using a Q-jet with a Vortec Performer intake.

Here in Indianapolis, the temperature during the winter months can get to -20 to -25 deg F. Anybody have any ideas? I will use a stock type snorkel air cleaner with the exhaust heat tube to the air cleaner. Will this be enough to warm-up the carb to run properly? Do I have any other options when using the Vortec heads?

Thanks in advance.

Maybe a hot air choke with a tube running down to the headers/or manifolds?

My old 73 F250 had a clip on the choke that held the heater hose against the carb. Probably wouldn't do too much until it warmed up though. I had a lot of carbed combos without a heat crossover, and other than adjusting the choke for summer/winter, it always worked out OK. I would use the heat stove on the exhaust to air cleaner in the winter, and an open element during the summer.

Just went through a winter with the same setup. It really isn't what you would call a real great setup. I hooked up a manual choke to the Q-jet but the fact that the manifold stayed cold for an awfull long time didn't make things work real well. It rarely gets into the low 30s where I live so you may have a real problem. I would make some sort of a hot air aircleaner setup. I am going to round up all the parts to do mine this summer.

My son drove his 355 w/vortec heads all winter here in Missouri,,,no choke on the Holley carb. It took a while to get it warmed up,but it worked.

I think as long as you run hot air into the air cleaner you'll be fine. My '78 Caprice has exhaust heat crossover in the manifold. I disconnected the hot air once in the winter and it ran terribly. Idled rough and bogged on acceleration as if the accelerator pump in the Qjet had gone bad. With it hooked up, the throttle response is great; a night and day difference.

A buddy of mine put a 383 vortec in his '91 Suburban with the stock TBI. The shop that installed the motor recommended he disconnect the hot air. It ran terribly, lousy throttle response, even when the coolant warmed up. He connected that hot air hose and all the cold-running drivability problems went away.

You can run without the hot air. You just have to retune accordingly. Idle mixture and accelerator pump. I ran my 86 Cutlass all winter here, it was -40C for a week, and didn't have any problems. That's with an open 3" filter and blocked cross over passage.

Steve

On mine in the winter it just takes a lot longer to get it warmed up enough to drive normally...but our winters don't get as bad as yours. Interestingly enough, the vortec performer rpm (but not the vortec performer) has provisions to run water under the carb. I believe the factory uses something similar to this on stock vortec truck motors? I know one thing, winter driveability with the performer is much, much better than the vortec rpm.

2 things you can do- get a stock single snorkel air cleaner with a hot air tube to the header or manifold and put it on during the cold months, and get either a performer RPM or the GM vortec carb intake that have a passage under the carb that you can run coolant thru to warm up the intake as the engine warms up. i can't for the life of me figure out why that passage isn't on the performer intake, as that is supposed to be the "everyday driver" intake.
my Nova has the vortecs and a performer intake with an Edelbrock RPM 850 q-jet- and when it gets down to about 40 degrees or so, it takes a long time for the temps to stabilize enough for it to idle at all after the crappy electric choke opens up. i really, really wish for a way to hook up a hot air choke on that thing for the early spring/late fall driving seasons.

Thanks for all your input guys. I would really like to use the Vortec heads on this setup. I think it would produce the best low / mid speed torque that I need to move this 6000 lb tub.
:D
I had forgot the fact that my choke runs off the hot air from the cross over. graemlins/clonk.gif I could switch to an electric choke on my Q-jet, but I have heard that they don't work nearly as well as a hot air choke.

Does anybody have a part number or link to the GM intake that was the coolant passage under the carb? This setup may have possibilities. Is this intake more like a Performer or RPM? I don't think I need the RPM style intake because I figured everything would be all over and done with by 4500 rpms graemlins/boring.gif

I want a setup that is pretty simple and idiot proof. Pump the gas a couple of times, turn the key and go. My wife will be the main driver of this vehicle most of the time, so I don't want anything too complicated to drive. ;)

I may just go back to my original plan and rebuild the oem heads (casting 993) with a little bowl and port work or a set of S/R Torquers with a little port work. :confused:

You can't compare a blocked crossover to the vortec with no provision for any exhaust heat into the head. It has started to warm up here 80s low 90s the engine really runs a lot better. You can put an elec. conversion on the Q-jet choke I did it isn't perfect but with some playing you can make it work. you will just have to adjust it for winter but that is a simple process.

I would use the Vortecs. My 355 would be a super engine for a heavy vehicle with an automatic. You really can't believe how much torque those heads make.

Originally posted by 71454Chevelle:

Does anybody have a part number or link to the GM intake that was the coolant passage under the carb?
I believe this is what you are looking for
http://www.gmpartsdirect.com/results.cfm

http://www.paceparts.com/product.asp?0=243&1=248&3=600

http://store.summitracing.com/default.asp?target=search%2Easp&type=bymanufacturerspart&searchtype=both

What a shame. That GM intake with the coolant passage under the carb looks like it only comes in a square bore design. I need a spread bore for a Q-jet. :(

I run Dart IE180 heads with no heat risers, and a Holley carb with electric choke. Electric choke is the way to go with no heat risers. This works fine with what passes for winter down here in Georgia, hopefully it would do OK up there too. On really cold days, the choke pulls off a little quicker than the engine truly heats up, but it's not really a problem.

another die-hard q-jet guy, eh? why can't they just put a water crossover in the performer vortec for us? don't make no sense at all..
if you can't use an intake with a hot water crossover, then at least get a stock single snorkel air cleaner and hook up the hot air deal on that. you could even make up a dual snorkel air cleaner and have both hot air flaps hooked up, and hoses picking up air fro mthe front of the car.
i know at anything under 40 degrees with the open element air cleaner, my Nova is a pain to drive for the fist 10 miles or so. the electric choke opens up in about 30 seconds, and then it doesn't want to idle.it takes a while to get heat into the carb, and the hot air would definitely help.

I could just use the heat from the manifold to the snorkel, but I'm not convinced that would be enough for it to run properly in the winter months.

I love the q-jet that is on the truck now. If I didn't know any better, I would swear that it was fuel injected. The carb just runs great, so I don't want to be changing / modifing much from the stock type setup because of that reason.

I was wanting to use a Performer intake when I do a rebuild but after doing a little research, I found that the hot air tubes for the choke will not work with that intake. Not sure what I'm going to do, still very early in the planning stages, just bouncing some ideas off you guys.