Heat Riser - Free or Keep Frozen?

[WissaMan]

Regarding the exhaust cross-over through the intake. Years ago I experimented with blocking off mine and I recall it actually seemed to decrease WOT power a little bit with it blocked off -- but that was with dual exhaust and no crossover pipe. So presumably the intake crossover was reducing back pressure.

However, once I had a crossover pipe installed on the exhaust, I noticed an additional increase in WOT power. Then when I blocked off the intake crossover I didn't notice any power loss. And the whole engine bay tends to stay cooler with it blocked off

I will say, however, that there was always a difference in exhaust note between having the intake crossover blocked or unblocked. There tended to be a mid-rpm drone with it blocked.

 

[Snotty]

There are some valley pan gaskets available that have the intake crossover closed off. But, if your heat riser is functional you will NOT want to sue one of these.

 

[MattfromMaine]

Not trying to get to a page 4 but I have a legitimate question. After having enough of a rattle that I thought was due to something up against my exhaust pipe and/ or manifold, I discovered the manifold heat control valve or heat riser was the source. Reading up on the threads on here confirmed what I found.

My question, I'm reading that many people have an issue with it being stuck and hitting it w/ solvents, tapping on it, etc. are good routes to take. I just want the damn thing to stop making noise. I'm going home to fool with it to see if it moves in about 30 mins but I really just want it to stop rattling. The car is running well but does sputter for the first 15- 20 seconds when I start it for the first time in a day so I'm pretty sure it's open. Suggestions?

 

[MattfromMaine]

Not trying to get to a page 4 but I have a legitimate question. After having enough of a rattle that I thought was due to something up against my exhaust pipe and/ or manifold, I discovered the manifold heat control valve or heat riser was the source. Reading up on the threads on here confirmed what I found.

My question, I'm reading that many people have an issue with it being stuck and hitting it w/ solvents, tapping on it, etc. are good routes to take. I just want the damn thing to stop making noise. I'm going home to fool with it to see if it moves in about 30 mins but I really just want it to stop rattling. The car is running well but does sputter for the first 15- 20 seconds when I start it for the first time in a day so I'm pretty sure it's open. Suggestions?

Welp, valve moves freely. BUT, it's missing the spring. The only replacement spring that I've been able to find are NOS small block springs for $55 a piece! I just want the God-awful rattle to stop. Suggestions? Thanks in advance for any info you can provide.

 

[Samplingman]

I left mine in place, frozen and all, but have been told that once the motor goes through a few heat cycles it might loosen up and rattle around. I can't imagine paying $55 for a small spring, I honestly don't know if that would stop the rattling. Someone here must have an extra spring lying around, I'll take a look too. I'm afraid you might end up removing the manifold, punching out the assembly then tapping a bolt bolt with thread sealer to seal it up or you will end up with leaks. Hope someone chimes in with better advice for you!

 

[HWYCRZR]

Some hardware stores have a small selection of springs but are getting harder and harder to find ones that do.
It just needs a little tension to keep it from rattling.
They are awfully close in size to some distributor advance springs.

 

[HWYCRZR]

Distributor advance spring, exhaust crossover spring. A little different but likely close enough to do the trick and nobody the wiser.

 

[Tireguy]

if it is stuck open leave it or cut it out they are more trouble than they are worth