250 Cast Exhaust and HEat plate

[notahybrid]

Hey everyone, I have a 68 c10 w/ a 250. I am interested in cast iron headers but am concerned about the heat plate for the bottm of the intake. Anyone had any problems just blockinging it off? I know some manufacturers make a plate that plumbs the exhaust gases back to the intake... is this really necessary or recommended for the 250??? Thanks

[68gmsee]

Not sure what you mean by heat plate. Do you mean the heat riser that opens when the exhaust is hot? Most old vehicles that had it in Texas either don't have it anymore or it has been rusted in either the open or partially open position.

I drove my old truck for about 10 years without it (cut it out because of rust) and never had any problem. I bought a new manifold after I broke the old one that has it on but never noticed any difference.

Maybe it's cause it's a little warmer here in Texas...

[notahybrid]

Yea, since the intake sits on top of the exhaust manifold on this motor, if I remove the stock ex manifold there will be a hole in the bottom of the intake manifold that will need to be covered. I have noticed that some people recommend plumbing the exhaust gases back to this cover using some tubing and fittings attached to an aluminum plate. I also have noticed that some manufacturers use a water system to warm/cool the intake...
I am not sure if I close off the bottom of the intake to install a header if the truck will run as well. I know that this aids in warming the motor on cool days but am not certain if there may be some other reason.

[68gmsee]

Someone correct me if I'm wrong, but my understanding is that the heat riser was strictly to aid in warm up for quicker driveability.

As I mentioned, I never noticed the difference on my trucks. I had a 69 six and a 68 six and both had the heat riser removed at some time or another.

I suppose that if you just bloc it off you should be okay. Maybe a few minutes of warmup in the winter (which most people do anyway).

Clifford Performance sells the water heated intake manifold which I suppose takes the place of the heat riser. Offenhauser sells these parts also. Check them out. May even want to call them to get their opinion. These guys have been in the business for a long time.

http://www.cliffordperformance.net/

http://www.merchantamerica.com/chevy...&product=75243

[nplocoman]

I think what you are talking about is a tin work to pull warm air into the air cleaner. It aided in faster warm up and driving in very cold temps. If the hole is on the snorkle of the air cleaner it's ok without the ductwork. most systems used a flexable metal foil type hose to connect the manifold to the snorkel. Clear as mud?

[68gmsee]

Originally Posted by notahybrid

Yea, since the intake sits on top of the exhaust manifold on this motor, if I remove the stock ex manifold there will be a hole in the bottom of the intake manifold that will need to be covered.

I reread this. I don't recall a hole on the bottom of the intake when I removed it to replace the exhaust.

There is an opening on the top of the exhaust manifold where the intake bolts to in order to allow it to heat the intake, but if there was a hole on the bottom of the intake, all of the gas would go down the exhaust.

Maybe we're talking of two different things..

[PanelDeland]

For the real "skinny" on this pop over to www.inlinersinternational.com and ask.The guru's over there will probably give you a couple of opinions and options.They can also tell you just about anything you need to know about a inline engine.They can also give you a step at a time upgrade plan for the 6 if that's your plan.It's like here only for inlines,and from the times I've been there just about as friendly.

[notahybrid]

Thanks for your comments. I'm gonna to try the cast headers and see how it goes... its only money right.

[68gmsee]

Originally Posted by notahybrid

Thanks for your comments. I'm gonna to try the cast headers and see how it goes... its only money right.

Great, let us know what you get and keep us posted on progress. I've tinkered with the idea of giving my 68 GMC 250 a little boost, also.

The only thing that keeps me from doing it, is I wanted to keep it as stock as possible. Never know what may change in the future....

[notahybrid]

Yea, the only reason I'm not too worried about stock is I got the truck for free and the engine and tranny are from varrious years vehicles. Runs good but it would be more trouble to put it back the way it was then to make it faster. I'll post a few pics soon. I've been working on it about 7 months. The interior is finished and the engine is close. Tranny has been rebuilt. I think most people would have parted it out. I still have some body work to do. I'm just looking for a cool truck... nothing to win a show just a good looking reliable truck that a normal backyard guy can work on.

[2bits]

Yeah the inliners site is great.

Stock 250 intakes have holes on the bottom of them, but it look's like a water jacket, like the Clifford intakes. Here a pic of my spare one. You won't hurt your intake valves with this exposed and you won't be sucking air with a vacuum leak. With the headers, you will be getting rid of the exhaust leak in the stock manifold.

You can bulld a makeshift heat riser that won't be as good as OEM but it will do a little in the winter. It will not plumb gases into the intake like PVC, just around the intake like a warm little blanket

[notahybrid]

Thanks again for the comments/suggestions.

[Brad]

I had the Stovebolt cast iron exhaust and they were really nice. The only reason I went with the Clifford's is that they look a heck-of-alot better. Those Stovebolt manifolds will last waaaay longer than your truck- or you and I!