blocking

[gene]

Mondello used blocking plates on my manifold. they were stainless plates.

There were reports last year about the metal filling melting out ??? does
any one remember that ??

gene

>In a message dated 10/9/99 6:03:49 PM Central Daylight Time, GMC77PB
>writes:
>
>> I used the Mondello block when I had my valve job this summer. I like
it. I
>> may be nuts but I believe it also slightly changes the sound of the
>engine.
>> Not objectionable, just something I notice. Particularly like the
electric
>> choke.
>
>Justin
>
>Talk to me. Could you notice any difference in performance? I guess
>a valve job would hide a lot of that. What about hot start? I have heard
>that it helps that. Do you know how the guys melted the block stuff? Why do
>you like the electric choke? I was thinking of putting in a manual choke.
>Are you running the stock manifold? Thanks for anything you can tell
>me. At least I dont feel so all alone now.
>
>Take Care
>Arch 76 GB IL
>
Genef -- 77PB/ore/ca
GMC MOTORHOME INFORMATION
http://www.california.com/~eagle/

 

[gene]

Nope the plates just fit into the existing ports on the manifold. The
motor was new to me so I did not notice any difference. However I was sick
when I found my manifold was broken,,, the new motor came with a manifold
so was not too bad. They said they could have welded it and ground it back
, but I wanted one that was not cracked. Have you looked at yours?? was a
crack right under the carb.

I saw the metal filled ports also, they just used a melting pot like a lead
melting pot .... He told me what it was but now I do not remember.

gene

>In a message dated 10/9/99 9:49:15 PM Central Daylight Time,

>
>>
>> There were reports last year about the metal filling melting out ??? does
>> any one remember that ??
>>
>Gene
>
>I remember that. I also saw a post on the Toro site that said the
>plates had eroded away. Just trying to get as much info as I can.
>Why cant any of this be easy. How long have you had your plates?
>I ordered the plates. The local speed shop has some stuff they use
>to block the ports. It is an epoxy concrete type mix. May use plates
>and mix. Saw a head there that had 50,000 on it and it was still
>holding. This is not a recommendation----I just saw it.
>
>Gene did they have to mill something to put the plates in? A friend
>is checking on something the big speed shop in St. Louis uses. I
>honestly dont know what to do. Did you notice a difference after
>you had the crossovers blocked? If so what? I know I am all
>questions tonight but I know nothing about this. Hate doing something
>that I know nothing about. Thanks in advance Gene.
>
>Take Care
>Arch
>
Genef -- 77PB/ore/ca
GMC MOTORHOME INFORMATION
http://www.california.com/~eagle/

 

[thomas g. warner]

I have just about decided to go with the new Edelbrock aluminum heads,
Performer manifold and fuel injection. See this"
http://www.tcsn.net/mondello/edelhds.html

>Arch,
> I see others have givven good advice on this topic, just thought I'd recap
>a little.
>
> The "heat riser" system as we all know directs hot exhaust through a
>passage in the bottom of the intake manifold to create a "hot spot" beneath
>the carburetor. This helps more fully vaporize the incoming fuel, especially
>in cold weather. To control this system, a "heat riser valve", consisting of
>a bimetallic spring and a weight connected to a damper valve actually (in the
>case of a V8) blocks off one exhaust manifold outlet, forcing the exhaust
>from that side of the engine to flow across the heat rise passage to the
>other manifold. As you can imagine, this heats up things quick. When the
>engine warms up, the valve is supposed to relax and open, allowing free
>exhaust flow out the headpipe. In the real world these heat riser valves
>often rust solid (soaking with penetrating oil and graphite, and beaing on
>them with a hammer, was a regular part of a "real" tune-up.). When they
>stuck shut (as they usually did) the result was pinging, low power,
>overheating.
> BTW, in-line 6s and 8s and 4s also used a heat riser, which is why their
>intake and exhaust manifolds usually bolt together to form the hot spot. As
>emissions and fuel economy became more critical, GM (at least) jazzed up the
>old "heat riser valve" by replacing the bimetallic coil and weight with a
>vacuum diaphragm controlled by a thermal vacuum valve for more precise,
>positive on/off action. This they relabelled an Early Fuel Evaporation valve
>(because it made the fuel evaporate sooner than it otherwise would during
>warm-up). Whatever the fancy name, the effect is the same.
> A competing system was introduced to the automotive world with the 1958
>Edsel/Mercury/Lincoln 410+ cu. in. V8. The thermostatically controlled air
>cleaner draws air from a shroud or "stove" around the exhaust manifold,
>attempting to deliver intake air at a constant (and warm) temperature to the
>carburetor. This has the added benefit of eliminating carburetor iciing in
>cool damp weather, and is, I believe, similar to the "carb heat" system that
>every pilot must remember to manually turn on when landing or flying in wet
>weather. (BTW, the Edsel/Mercury/Lincoln system completely did away with the
>heat riser passage, which I consider relevant to our situation.)
> As we all know, our GMCs have both air cleaner preheat and heat riser
>systems. As we also know, they work a lot harder and run a lot hotter than
>the Toronado ever did, and that heat causes problems, even damage, to
>carburetors, plumbing, even manifolds.
> For my part, I intend to block off the heat riser and rely upon my
>(functioning) thermostatic air cleaner system to warm things up as necessary.
> This will necessitate an electric choke, as I will no longer have the
>roastingly hot manifold to supply superheated air to the choke thermostat as
>it did originally.
> That's what I plan to do.
>
>Rick Staples
>'75 Eleganza
>Louisville, CO
>
>