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Building "Nightmare" (78 GMC Jimmy)

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ashman said:
Maybe try relocating the sensor to the head too. Like @ZooMad75 said, maybe your catching fluctuations from the thermostat that don't really reflect the real engine temp
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Hmmmm ok,
Not even sure where to stick it in the heads lol. Can someone point me in the right direction?

I will say for sure 210 doesnt worry me. But when in the course of 2 mins at a light the temps climb from 206 to 212 or 227 like i was seeing that concerns me a bit.

I can say the flex fan does seem to help.
I also just plugged the gaps on the sides of my shroud to see if that helps at all. It will force any incoming air through the radiator.

I think ill pull the shroud and add some weather stripping foam and mount it again. Zero air gaps. And since my fan only has 1/4" to 1/2" gap around the fan it should really form a solid vacuum.

Btw i noticed zero sound or power changes eith the flex fan... go figure...
 
Also reading that pulling advance off the manifold vs the throttle body might help also.
Not sure what adapter i need to tie into the port on my intake manifold...
 
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Should be a large pipe plug on either head. The standard sending unit for your truck should screw right into it. Stock is usually on the drivers side.
 
the_blaze said:
Also reading that pulling advance off the manifold vs the throttle body might help also.
Not sure what adapter i need to tie into the port on my intake manifold...
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Yes, more advance will help at idle.

The big radiator is going to be about 40" wide with headers.

I don't think @the_blaze's concern is the 210F temps, it's that it keeps climbing. Not sure if the location of the sender is going to change that.
 
mrk5 said:
Yes, more advance will help at idle.

The big radiator is going to be about 40" wide with headers.

I don't think @the_blaze's concern is the 210F temps, it's that it keeps climbing. Not sure if the location of the sender is going to change that.
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BINGO!!

And since both guages creep up that tells me overall temps are creeping up.

So i know @kgblazerfive and @blazinzuk both said to get an aluminum radiator.
If i got one thats the same size and still a 4 core i wonder if that would help at all?

Im also going to try pulling my vac advance out of the manifold because thats really the right way to do it anyways.
 
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Move the windshield squirters to the grill and run them occasionally :D

no seriously, I don't have any, thinking about adding a ebay cheapo setup for those times when I'm really working the truck
 
K85 Octane said:
Move the windshield squirters to the grill and run them occasionally :D

no seriously, I don't have any, thinking about adding a ebay cheapo setup for those times when I'm really working the truck
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This may sound crazy but i have considered something like that lol. I don't think im really to that point yet but its an option lol
 
I'm afraid you won't see much difference just changing materials, but I could be wrong. I feel like the industry has gone aluminum because of cost and weight; primarily cost. My understanding was that copper is still a better heat conductor, but again maybe I'm thinking of electron flow and wire.

So you already have 4 row, correct? If it were me, I would find a way to make the 34x19 core radiator work or just suck it up and call a company like Ron Francis and see what they would recommend for you.
 
And get your vacuum advance hooked up to manifold vacuum so that you are idling with over 20 degrees of timing advance.
 
So @the_blaze why don't you adjust your timing since it is a free test you can run. Once you have it set see if there's any difference. Then step up to the aluminum or larger copper radiator.
 
Ive been reading and watching videos and side by side tests for days now and it looks like aluminum is actually better and the new cross flow designs are a ton better than these old copper/brass radiators. Im seeing side by side a 2 core aluminum will cool better than a 4 core brass copper. I wouldn't believe it until i saw videos hotrod magazines are putting out.

I'll definitely play with timing before i pull the trigger on a different radiator.

I learned that even fitech suggests running your vac advance off your manifold vs throttle body and they said not doing that can make your vehicle run hot. Fitech suggests- run vac advance off manifold, bump idle afr to 13 or even 12.5 if needed and up idle rpm a little. That will make it behave more like a carb and keep temps down a little at idle. Doing this will only cost me time and $10 for the vacuum port.

You learn new things every day....
 
I wouldn't be afraid of 28 with it hooked up then. I think standard vacuum advance is 10 degrees.
 
Does you other truck have factory TBI? If so I would throw a timing light on it and see what it's running for advance at idle. Then set up this truck to be the same.
 
Any of you fitech guys know if the plug on the head is the same size as the temp sensor fitech uses? I dont really want to pull the plug to find out i need an adapter. I just added a t to the intake manifold so im getting vacuum for my timing off the manifold vs throttle body. Fitech seems to think that will help my situation
 
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