[goatjunkie]

running the original 400 in my '67 goat with stock 67 intake and stock 67 Rochester carb. When I went back together with the engine I blocked the heat riser crossovers to the intake at the gasket. I currently am not running the choke assemby (coil spring with linkage set up).
The idea was to keep the carb as cool as possible in the summer for fear of vapor lock.

In the fall or spring of course the engine takes a while to warm up with no choke and can be a bit tough to start.

Question is if I leave the heat crossovers blocked at the intake and simply put the choke assembly on will it work well enough and know when to shut the choke down? Will it not heat up enough on time and keep my choke running way too long?

Don't run the car in the winter months but again spring and fall make for hard starts with no choke whatsoever. By adding the choke back on to the carb and going ahead and open the crossover passages as they were designed will this have a huge affect in summer with excessive heat under the carb? I have also heard horror stories about warping the carb base or other issues prone to that year set up.
Any thoughts on this, thanks.

[gtofreek]

If you don't mind it not looking original, you can install an electric choke housing off a later Q-jet. Then you can leave your intake plugged off.
The problem with the 67 intake is that the exhaust crossover comes right up to the carb base. This intake requires a steel shim under the carb base gasket to keep those exhaust holes from over heating the carb. I usually tap and install pipe plugs in these holes.

Most later model electric choke housings will bolt up to earlier carbs. There might be some exceptions. I'm sure Cliff or some other Q-jet experts can say for sure. I know I have done it to a few of them.

[Kenth]

It would be hard to fit an electric choke housing on a Q-jet not aimed for this.
Especially hooking up a functional choke pull-off?
May not be worth the effort with all 1976 and later units available?

Maybe an electric choke conversion kit replacing the original 1967-71 choke is still available at www.carbs.net?

[gtofreek]

I've done it before, but in all honesty, I do not remember what year carb it was. It might have also had that setup that looks electric but has the heat tube into the manifold. Thinking about it the 67 carb does not have this does it?

[68 Firebird]

I had a Q-jet setup by Cliff for my car 2 years ago. I had a 73 GTO carb and that is what
was used so I could use and elec choke and converted to 68 throttle shafts. One thing I tried one day was to block the heat crossover and found even with the choke working correct the intake took a while to heat up and cold driveability was not as good as with crossover opened.(until car really was warmed up) Since I like to take my car out whenever I can, I installed correct gaskets and left crossover wide open. I can give her one pump of gas to set choke and turn the key!!!
Wait 20 seconds and tap throttle and choke kicks down to 2nd notch and GO!!
She will take about another 1.5 and drop down to curb idle while driving down the road.
Heck since the Sandy hit I have used Bird to get around as I need to save fuel in my DD.

Only effect of open crossover is intake has to be touched up every spring due to paint burn off.

[Kenth]

Good point!
Engineers do thing for a reason, blocking heat riser/intake crossover on a street/original vehicle never solves any problems, only add problems.

Carb and intake needs all the heat they can get for superior driveability/economy/performance.

[goatjunkie]

Think I will pull the intake and remove the crossover blocking plates I installed to open the crossover on the intake manifold and reinstall the choke assembly. Not too worried about paint burn off.
I think I will still plug the intake for the passage under the carb as it sounds like that is not as big a deal for retaining heat as the crossover. Besides most of the '67 manifolds I have seen seem to have a lot of carbon built up in that passage and are partially blocked anyway.
Guess I was more worried about vapor lock in the summer and will just have to wait and see what happens.
thanks for the responses.

[Cliff R]

Blocking the holes in the channel under the carb will really help. It keeps the hot exhaust gasses off the carb, but the choke will still function correctly since the main crossover passages are open.

If the carb still gets too hot, it helps to upgrade to a thicker gasket between the carb and intake to insulate the carb from the heat.

When we use 67 intakes here, I weld up the drivers side end of the channel/machine the flange flat, plug the holes in both sides, and use a thicker gasket between the carb and intake.

An easier fix is to make a slightly thicker steel plate, stock gasket under it, then a later style thicker gasket on top of the plate.

The choke arm becomes too short with the carb sitting higher, bend the arm or make a longer one if needed.....Cliff

[Schurkey]

Originally Posted by goatjunkie

Guess I was more worried about vapor lock in the summer

Vapor lock doesn't happen in the intake manifold.

Happens in the fuel pump; or the fuel plumbing rearward of the pump.