Godti

I am looking at buying a set of heads (GM 350 LT1/LT4 '96 Hi-Perf. Heads). I was told that "The #'s came up as police package-Impala 9C1 reverse flow cooling engine." So my questions are: 1- What is a reverse cooling engine?? 2- Do I need a special cooling system?? 3- Are these good heads?? 4- Would you recommend using them to build a strong 350?? (350-400 HP)

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Godti
'89 Trans Am (Red)
305 TBI 5spd

Jim85IROC

iTrader: (2)

Those heads are totally non compatible with a traditional small block chevy. The reverse cooling system requires totally different heads.

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Brett

What Jim said. Those heads will not work with Gen 1 or Gen 3 engines. If you're looking for an inexpensive head to work on try the Vortec truck heads. GMPP just came out this month with a manifold that will bolt to those heads for 3rd gen TPI intakes. Or if you were going to spend the $1000 for LT1/LT4 heads, why not get some AWESOME aluminum heads right out of the box. AFR 190s are great heads as evidenced by my buddy's 85 SC (383 swapped in). TFS are supposed to be good now, and I've always been a fan of Edelbrock. There's a lot out there, especially for your price range.



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1991 RS LT1
every imaginable bolt-on, and an all-forged 355 on the way with an ATI following in '01

2000 C5 Coupe
black/black 6-spd, optional polished rims, 'mostly' stock....

"So what DOES the back of a Mustang look like?"

Godti

So what you are saying, is that I will need a 4th gen engine block?? What are AFR190's??

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Godti
'89 Trans Am (Red)
305 TBI 5spd

Vader

Godti,

If they are iron, have large ports and flow better than either the L98 heads or the early aluminum LT1 heads, they are the 10125320s.

If those are aluminum heads you're asking about, they must be 12555690s. They are a further improved aluminum version of the iron heads used on 'B' cars . They have even larger port volumes, higher port openings, and come with 2.00/1.60 lightweight valves.

The reverse flow cooling you're asking about is just that. The coolant takes a path that is essentially the opposite of earlier SBC engines. The coolant from the water pump is routed to the heads first, keeping them cooler to allow higher compression without detonation. It's a neat trick that is more effective than EGR.

Because of the opposite flow, there is no coolant crossover in the intake manifold. Instead, there is a steel tube connecting the water passages on the back of each head. The heads have no provision for coolant ports on the intake manifold side. There is also no EGR provision on the heads.

The system requires a reverse water pump, special bypass thermostat, some clever plumbing, and a separate expansion tank in place of the overflow reservoir. The factory version of the reverse-flow pump is driven from a gear drive connected to the camshaft timing sprocket. The timing cover is cast aluminum and has an additional hole/bearing/seal for the water pump drive above the cam sprocket:



Converting a Gen I SBC to reverse cooling would be a major undertaking.

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Later,
Vader
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vortecfcar

Vortec=cheap=LT1 port design=excellent

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91 RS W/carbed 350, Vortec heads, performer rpm, Comp cams Xtreme energy 280 grind. BFG Drag radials. 3.42 posi,Corvette servoed 700r4, ****ty stock converter
13.24@104

Tas

Vader, you would convert the heads to tradtional cooling, not the old block to reverse cooling. I have a link on the conversion on my site. LT1 heads go for $300 used but there is a lot of work involved. Vortecs make this conversion nearly pointles. http://members.tripod.com/GRK_Taz

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