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Discussion Starter · #1 ·
I'm going to do a manifold swap on my sb and at the same time I'm trying to neaten up the engine compartment. It's in an 87 but the motor is a 400 that came out of a 78 pu truck. I'd like to use the rear drivers side water outlet on the new manifold to supply the heater core instead of the one on the front. Do any of you guys see that as a problem? From what I've read GM used to do it that way but switched to the front for heat/emission related reasons.
Thanks again for the wealth of knowledge on the site, Ang.
 

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do you have a pic or a link to the manifold??
:dontknow:i dont remember a heater outlet on the driver/rear being common,,

its kinda tight back there with the cruise/throttle/dist..

i guess it'll work the 88 and up tbi truck had a outlet on the pass. side rear..:texas:
 

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Discussion Starter · #3 ·
It's a Professional Products brand similar to the Eddy RPM air gap.

CROSSWIND® for 23° Heads
1957-’95 Small Block Chevy V8
Polished Satin5202552026The new CrossWind Manifold is a special version of the 52020/52021. While it is the exact same height, it features an open area under the plenum chamber. This provides for a flow of cooling air which keeps the temperature of the air/fuel charge lower thus producing more power and torque. The interior plenum and port design are identical to the 52020/52021 and will provide somewhat better overall power than the 52020/52021 due to the special air gap style design.



 

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you can use the rear port the late 80s and early 90s caprices used the same rear port to feed the heater
 

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Discussion Starter · #5 ·
Thanks guys
 

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You can use the rear port but keep in mind that there is no crossover at the back of the intake so you will be drawing you source from only one side of the engine so there will be uneven heating in the block. Plus the water is hottest after it has flowed all the way through the head to the front....So will it work--yes, is it ideal--no......Dan

P.S. If you have installed a late model reverse flow engine, then everything I said---just nevermind :secret:
 

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Discussion Starter · #7 ·
Very good point about the crossover, I didn't think about that.
Thanks, Ang.
 

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I just re-read the post and see it's a 400 which has heating issues anyway because of the siamesed cylinders so thatmight make it even worse to unbalance the heating...Hope that helps some.....Dan
 

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no it wont.400 are no more prone to overheating than any other small block, i ran a 11.7 to 1 dart headed 400 in my 86 for over 10 years with the original 305 hd cooling system and never ran hot.i have a tbi 350 with the heater hooked up to the rear port as it came from the donor car a 93 caprice with absolutely no heat issues.it doesnt unbalance the cooling at all.the front port picks up water directly from the intake just past the pass head any way,no differance. gm made millions of these cars plumbed this way without problems. hey dont change a screw without extensive testing and would venture to say they are smarter than all of us.dont bore a 400 over 30 and they never overheat if all esle is as it should be.
 

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if you look at what you are doing is cooling more water with the heater never a bad thing ,after the heater core is a small radiator.
 

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Discussion Starter · #11 ·
I have read about the 400s overheating issues. Mine is .30 over and I'll say that with the 165 degree thermostat in the car on the hottest summer day in traffic I've never seen the temp over 200. As soon as the car's moving again it settles down to around 165. This is with a stock radiator(for now) and a belt driven clutch style fan.
I've seen and read about guys tying the two rear ports on the manifold together creating a crossover to help with cooling.
I know"if it ain't broke don't fix it" but I don't like the current set up with the supply hose coming off the front of the manifold, and it's real close to the fuel line into the carb heating that too I just want it out of there. I wanted to ask about it because I didn't want to do anything that would be detrimental to the cooling system of the engine.
So if its not a problem I'm guessing I could use ether of the rear ports to supply the heater core or tie them together and tee off of both of them for the supply to the core. I'd end up with a crossover in the back as well.
Thanks again for the input guys, Ang.
 

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I've had several SB400s over the years and haven't had any overheating issues but then again I treat them as big blocks in small packages so I make sure I get good water pumps and put good flowing radiators on them....Like i said before will it work yes---is it ideal--my opinion is no---your mileage may vary.....Dan
 

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as above with 400s use good cooling system components,never take the cheap way.my car was registered in ca. untill last year and i had to run the 180 thermostat to pass smog.and it litteraly never ran hot.i have 3 400s and plan on usring them again in other projects,i love these small blocks,big block power in a small block size.what more could you want? if its still out put a good hv oil pump.i use the melling m99hvs, it comes with the screen and steel sleeved drive shaft.it keeps the oil pressure where you wan it.and use the felpro one piece pan gasket.i have them on my 400 and the pan is dry as a popcorn fart after 10 years
 

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Discussion Starter · #15 ·
You guys and this forum are great. Since the motor's been built, or at least since I've had it (knock on wood) its been the balls. Plenty of power,and it's still got manners. It runs in a good temp. range and has got real good oil pressure. After the manifold and carb swap, I'm hoping for another 20 horses. Yeh I like the fact that it's a small block and you can wind it up allot quicker than a big block. With the spring will come a new aluminum radiator and a trany cooler. As I said before I'm running a 165 degree therm and Vinnie(thats it's name) likes it. The car puts a smile on my face every time I fire it up.
 

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any of you 400 guys ,do you know about the dart shp block.you can make a late model roller cam,one piece rear main seal motor.they come 4.in and 4.125 bore as well
 

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I was doing a search on rear water crossover and came on this older discussion. I have an '87 that I am rebuilding the engine (350 now, but originally 305) and the intake manifold has a rear water cross-over port in the manifold. Not just the taps on each side, but a passage all the way across. It has a small 3/8" heater hose tapped into it that connects to one of the heater hoses. What is strange is that upon disassembly the ports are blocked at each head entrance, so the hose connection in the middle is non-functioning. Upon my rebuild, I am going to leave the blocking fittings out and let coolant flow across the back of the manifold. The engine had been previously rebuilt, so I am certain the blocking plates are not stock.

I know this rear crossover is uncommon, and wonder why it was included in my manifold. It is the stock GM manifold with EGR and computer quadrajet, but just curious what is going on.

I will post a separate thread asking the same question.

Ralph
 
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