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Old 03-21-2010, 08:50 PM
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gen 2 heads on a gen 1 block??

i have a gen. 2 small block chevy block 4 bolt main w/ a one piece rear main seal and im having some pretty bad over heating problem for heads i have a gen 1 style aftermarket world castings heads could the cooling passeges not be lined up?? i,ve tried a bunch of stuff timing water pump cooling restictors electric fan 3 diff types of fans new head gaskets. open to any suggestions

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Last edited by knappster; 03-21-2010 at 09:30 PM.
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Old 03-22-2010, 08:02 AM
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Generation 2 small blocks are reverse flow cooled. Generation 1 is standard flow cooling. While the heads will bolt on, the coolant passages don`t line up and as you`ve found overheating results. The only fix is to remove the heads weld up the passages and redrill them for reverse flow cooling then remill them flat, if they are cast iron heads cast iron is very difficult to weld and you would come out money ahead by going back to LT1 heads and getting a aftermarket intake. I`m not sure if you knew about the cooling differences before doing this, but if you didn`t, always do your home work before you dive in any project or it can get expensive fast.
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Old 03-22-2010, 08:24 AM
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you're best off selling the heads and sing the money to buy ones that fit the application, or even stock LT1 heads.
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Old 03-22-2010, 09:35 AM
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well it,s a dirt car and i bought the car this way it may be cheaper to buy a new block. With the amount of money that is already in the heads he didnt know anything about the car when i bought it
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Old 03-22-2010, 01:46 PM
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Quote:
Originally Posted by knappster

First note. have a gen. 2 small block chevy block 4 bolt main w/ a one piece rear main seal and im having some pretty bad over heating problem for heads i have a gen 1 style aftermarket world castings heads could the cooling passeges not be lined up?? i,ve tried a bunch of stuff timing water pump cooling restictors electric fan 3 diff types of fans new head gaskets.

Second note. open to any suggestionswell it,s a dirt car and i bought the car this way it may be cheaper to buy a new block. With the amount of money that is already in the heads he didnt know anything about the car when i bought it
Looking at your notes and building on what DoubleVision had to say, let me say this about that.

The GEN II engine is reversed cooled (not to be confused with the reverse rotation water pump of GEN I serpentine belted engines). The GEN II block is a modified GEN I that drives a unique to it water pump from the timing gears rather than from external belts. The pump has the outlets and intakes in the same casting connected with a dual function thermostat that mixes radiator and return coolant to hold a very tight range of coolant temperature within the engine.

If you look on the water pump face of the block you'll see two openings on each side of the engine. The upper is pump output and the lower return from the block. The upper goes into the block and makes an immediate upward turn to enter the head. When the head is flooded the coolant goes down into the block and flows forward to the lower return hole on the pump.

Given the size and location of the coolant transfer holes between the block and head, I'm quite surprised there isn't a big coolant leak into the crankcase from the missmatch.

Since you have a set of race prepped GEN I heads, I think the solution to your problem is to get a GEN I one piece rear seal block, select whether you want to run serpentine or V belts and get the coolant pump appropriate to the direction the belts would turn it. I'm presuming that since this is a race car the engine is already carburated and has a "standard" design GM distributor installed. You will also need a conventional GEN I crank damper for this change, and a standard timing case cover.

The internals of your GEN II engine will bolt into the GEN I block. That's crank, rods, pistons, cam, lifters, oil pump, etc. If your using the OEM roller lifters then you want a GEN I block with the provisions for the factory roller cam so you can transfer the spider, thrust plate, guide bars, and lifters. The roller cam with thrust plate requires a single row roller timing gear and chain set, it's a clearance issue with the block that prevents a two row chain.



Bogie
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Old 03-22-2010, 09:23 PM
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ok its strange the water pump is a convetional pump already no coolant leak have a fluidamper balencer all iron eagle rotating crank not the problem switching over the casting number is 010 every 1 told me that this is a gen2 block im thinking it is a gen1 one piece rear seal block with the old water pump on it turning the wrong way?? possible?? bexause it would have been a serpentine belt b4 and is now a v belt
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Old 03-23-2010, 10:24 AM
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Quote:
Originally Posted by knappster
ok its strange the water pump is a convetional pump already no coolant leak have a fluidamper balencer all iron eagle rotating crank not the problem switching over the casting number is 010 every 1 told me that this is a gen2 block im thinking it is a gen1 one piece rear seal block with the old water pump on it turning the wrong way?? possible?? bexause it would have been a serpentine belt b4 and is now a v belt
A 010 (3970010) is a GEN I block.

Gen I engines start with the 1955 model year and proceed to the end of production. They are conventionally cooled with coolant into the block, returning thru the head and intake manifold. The GEN I includes the L31 Vortec, they may be carbed or injected and include a host of engineering differences and refinements since 1955.

GEN II engines are a variation on the GEN I; They span the years 1992 thru 1997 and are identified by Regular Option Code LT1 for 1992/94,at 350 inches with aluminum heads; LT4 for 1994/98, at 350 inches with improved aluminum heads; and L99 94/97, 263 inches with cast iron heads. They all cool backwards, that is heads first then block which provides the return. They have a water pump driven off the cam not by belts of any sort be they Vee or serpentine. The front timing cover houses the distributor and is not interchangeable with GEN I blocks at all. But the GEN II ignition can be retrofitted to GEN I with a plug kit, different intake, and a distributor. The heads and blocks between GEN I and GEN 2 do not simply interchange though GEN IIs aluminum heads can be converted to fit GEN I blocks with some hole welding and fabrication of a coolant return system. The internals of the GEN I and II will interchange with minor mods to the damper and cam.

GEN III small block from 1997 to present is the new LS series and its derivatives. It doesn't share anything in common with GEN I or GEN II engines, it is a fresh design.

Your 010 block is a heavy duty 4 inch bore GEN I block found in things from the original 302, Z-28 Camaro to heavy duty trucks and industrial uses. It is among the best of Chevy SBC production blocks whether in 2 or 4 bolt main form.

Yes the OEM serpentine pump turns backwards to the OEM V belt pump. The pump, and if used, pump driven fan must be correct for the belt drive system used. Some aftermarket serpentine systems use the v-belt pump and some don't, you've got to pay attention to whether the belt goes over or under the pump pulley. The OEM belt drive systems are interchangeable across those years using V or serpentine belts as long as a the long style pump is used with the heads having end style accessory bolt holes. The belt drive system of Vee or serpentine does not differentiate GEN I from GEN II engines, coolant routing does and the attentive design changes that drives the pump, belt for GEN I, or gear and shaft for GEN II does that.

Bogie

Last edited by oldbogie; 03-23-2010 at 03:27 PM.
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Old 03-23-2010, 03:13 PM
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Quote:
Originally Posted by knappster
the casting number is 010 every 1 told me that this is a gen2 block im thinking it is a gen1 one piece rear seal block with the old water pump on it turning the wrong way?? possible??
IF it has a 2-piece rear main seal, it is a Gen I.

IF it has a 1-piece RMS, it can be a Gen I or II (or III, but that's not for here).

A Gen II (aka LT-series) can ONLY have a 1-piece RMS. There are NO Gen II blocks w/a casting number ending in 010 (AFAIK they all end in "327"), that I'm aware of. IF it has an "010" casting number, it is a 2-piece RMS, Gen I block.

If you are mistakenly thinking that just having a 1-piece RMS makes a SBC a "Gen II", you need to know the Gen II was only used for a few years, and has reverse cooling. And a 1-piece RMS. Coolant passages are different from a traditional Gen I block.

Gen I SBC's can have a 1- OR 2-piece RMS. The TBI and Vortec engines w/1-piece RMS are Gen I engines.
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Old 03-23-2010, 04:59 PM
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thanks for your help guys really i;ll figure it out and let you know what i find out and what fixes it
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Old 03-23-2010, 05:11 PM
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As you`ve already found, if a serpentine was on it before then chances are it rotated in reverse. Simply change it over to a V belt pump and the problems solved. Ask for a pump that`s for a 1980 Chevy truck with a small block, simple as that.
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