I have a 79 with the Performer RPM intake and I'm getting ready to install true dual exhaust. I was wondering if I need to leave the heat riser installed or can I just eliminate it completely? Occasionally I'll drive in the winter but not much, only if it's a nice 40+ degree day. If I remove the heat riser, will it cause other problems if the manifold has the heat crossover on it?
Thanks,

 

You will need the heat riser to work as a spacer for the manifold. I guetted mine so that it is only a spacer. My car has no problem starting, but then again, I don't live in Canada.

 

I gutted mine before the headers but I have seen that somewhere somebody sells a spacer where the heat riser is. It is there just to heat the intake up quicker and make the car run smoother when it is cold. You might have to let the car warm up a little on colder days but it should run fine without it.

 

I do live in Canada and the car does get out on the odd cold (but dry) day just to give it a "run". My heat riser is also "gutted". My car is a little cranky on the cold start (I constantly fiddle with the choke settings!), but basically it smooths out fairly quickly. I would gut it and block off the crossover. Then you (like me) will be all ready for the next step being headers....

 

I know Corvette World sells the extension to replace the heat riser. It costs $24. A little pricey for a short piece of pipe. If you're planning on going to headers someday, you mine as well save your money and gut it. That's what I'll be doing with mine.


[Modified by 79MakoL82, 11:00 AM 11/8/2001]

 

Corvette Central has a heat riser eliminator. It is basically a heat riser without the guts in it. The advantage of this is there are no holes drilled in it. Your heat riser is controlled by vaccum I think so yours might be different from the one that was on my 71. If you are going to put duels on why not go with headders instead of keeping your stock exhaust manifolds?
John

 

I bought the dual exhaust from Mid America and the pipes are the same length but there are instructions that say to remove the donut gasket from passenger side if you are using a heat riser. My heat riser is vacuum controlled, however, I would imagine that I could just plug the vacuum line. However, the intake manifold crossover is not closed off and won't be since that would require removing the intake. If I'm going to remove, I'll replace it and I don't have the money right now. Still a good idea to get rid of the heat riser or not?

theandies-
I'm not installing headers yet for a number of reasons. One is cost but that's not the main factor.
I plan to install headers later but I'm also going to get an X-crossover and mandrel bent pipes. With the X, I'll more than likely need the exhaust welded so I want to wait until I do the suspension to have a welded exhaust. I will more than likely have to take it to a shop to do that and if they see two-into-one cat then back to two, they won't do what I want done. Since it will be at least a year, maybe two before I do the suspension (due to cost), and then another six months to year before the exhaust, I figure the time will give this exhaust a chance to "season" itself and look close to original when I take it to a shop.

 

My 75 never even had a heat riser stock. They were designed to help warmup to reduce (you guessed it) emissions.

I am currently running headers and a blocked exhaust crossover with an electric choke. Little balky on cold mornings but that just gives me time for a cup of coffeee while the car warms up. :jester

 

So if I get rid of mine, it shouldn't really cause any problems other than cold starts?
Thanks

 

I guess I didn't address this question:

As previous stated above the heat riser just "blocks" exhaust a little to aid in engine warm-up. You car may become a little cold natured but if you keep it in a garage you should be OK. I hope all C3 owners keep their babys indoors :lol: :lol: sharklover, sounds like you got a good plan on the undercarriage of your ride.....good job...... stick with it.
John


[Modified by theandies, 8:43 PM 11/8/2001]

 

I use a heat riser elimanater(spacer) from Paragon. I only drive it in the summer about 1000 miles per year. No problems

Dwayne

 

I don't think it will hurt anything to gut it, wire it open or put in a spacer. When I got my '70 the original heat riser valve was wired open with a coat hanger wire - and judging from the looks of it - it had been that way for a LOOOOOONG time. ;) The symptoms of not having one is more of a cold blooded starting beast - and a longer warm up time before the choke comes off and the idle speed comes down. Anyways, there's something kind of neat about it taking a bit more effort to get the beast fired up - assuming it does start eventually. :yesnod: Something about having to work for it I guess. :lol: