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By heat riser, do you mean the exhaust passage through the intake?
Yes. Most all modern aftermarket heads and intakes have this blocked.
It can mess with the function of the Stove type choke...but otherwise it was a stop-gap emissions thing to help carb get to op-temp faster.
The Fel-Pro 1204 intake gasket comes with this already blocked off.
The blocks were not installed. I debated about installing the blocks when I was putting everything together, but decided against it because of the coil spring choke on the manifold. Damn
The blocks were not installed. I debated about installing the blocks when I was putting everything together, but decided against it because of the coil spring choke on the manifold. Damn
It gets it to heat faster, but it brings a lot of exhaust heat to the plate as well.....I NEVER use them.....
It does make a significant difference in overall heat soaking....
Your problem will be the choke stove....but it will eventually open and it is spring loaded.....the incoming air will open it.....but ask yourself if you really need it.
A few will conflict on this idea......because I am in Texas.....but I never used chokes on my Hot-Rods in Michigan either....just get it going and warm it up.....better for the damn motor anyhoo.
Here is a picture of the carb. I do have a 1/4 base gasket on the intake. I notice some orange substance in a depression (circled in red) in the top of the carb. Dried fuel? is this from the "boiling" that has been brought up?
Before you going putting one on.....you need to verify that the vent tube is actually spitting fuel.....run it without the air cleaner and try to duplicate the condition....
The heat shield will not hurt....but you need to pinpoint the problem.
Personally I would block the Heat Riser before adding a shield.
Update...........Last weekend I replaced the intake gaskets. During the process, I noticed some small black pieces of plastic in the fuel filter. I decided to flush out the fuel line to make sure nothing else was in the line. I clamped a tube on the end of the fuel line, ran it into a empty gas can and began to crank the motor. To my surprise nothing came out. I was able to bring gas up the tube by sucking on the other end, but cranking did nothing to push fuel. I am now replacing the fuel pump and wondering if that was the problem all along.
I am assuming the engine was running by drawing gas into the carb with vacuum? Does this make sense?
Last edited by HunterPayne; Nov 11, 2015 at 09:10 AM.
Sounds like it could be the pump. A fuel pump has more than one failure mode.
It can get weak and only pump when the engine is running. Or only pump via the starter when it's cold, then when it get warm it's even weaker but still pumping if you can get to idle RPM but not at starter cranking RPM.
I think you are on the right track.
I bet if you filled the carb bowl and started it now it would pump, just very weak, enough to get the job done minus WOT operation.
I will be changing the pump this weekend. I will give it test with the tube and gas can since I still have the carb off the motor. I am hoping this solves the problems I have been having lately.
Update- New fuel pump works great and pumping fuel on just cranking the motor. I took a peak in the carb before installing, and the accelerator pump was brittle and broke when I removed it, so it was replaced. Everything is back together and she started right up. Set the dwell, set the timing, adjusted idle mixture screws, and seems to be running great!! Now my challenge is setting the choke spring. With changing the intake gaskets, I installed the exhaust restrictors and the choke does not seem to want to open as it should. Has anyone ran across this issue after installing the heat riser restrictors in the intake?
There is bi-metal coil that when it gets hot unwinds a bit and that in turn pushes the rod and opens your choke.
With the crossover blocked there is much less heat to get that coil hot. It will probably eventually get hot enough on a warmer day but until then will be running rich.
I don't have a choke like yours so I'm not sure what a adjustments may be available to affect when it opens. Check you manual to see.
I removed my choke plate/rod entirely. I only drive my vette in the summer so I don't need it.
An electric choke conversion is also an option.
