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Help. Anyone have any issues swapping to a big block. I have a gen 5 454. I tried using the sb mounts but in the position they are at the headers hit on the gear box. If i move the engine forward to clear it the pan hits and the cross member mount doesnt line up
 

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You will need BB engine stands and a BB transmission crossmember. Headers hitting the (steering) gear box is, I think, unavoidable. So you will either have to dent a tube, or get some original equipment BB exhaust manifolds.
The engine stands are designed to hang over the back side of the crossmember. Do not "center" them on the crossmember. Small Blocks Fit a lot easier.
 

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I'm in the middle of putting a 396 in my 73 right now. I used OER-K701 frame mounts & ANI-2283 engine mounts. Put the engine right where it needed to be. Doug Thorley THY-313-C headers fit perfectly around the steering box with no modifications. On the passenger side I think they might be just a little too close to the idler arm. I might give it just a tiny tap right there for my own sanity. But the overall fit with these parts has been drop in.

Jake
 

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The frame, motor and trans mounts are critical, if you want everything to fit nicely. We just went thru this process but our car was originally a big block/4 speed car that someone had converted to a small block/TH400 combo many years ago and had used the correct SB parts. I know there are lots of post saying that small block mounts will work (so long as you don't mix BB and SB frame and motor mounts), but if you want everything to fit correctly, especially headers, I don't recommend doing it until the mounts are all correct. The BB mounts move the motor a bit to the pass side and rearward, IIRC. We used Performance World 2" headers (part #420110) and they fit easily without needing a hammer, but our car does not have power steering so that likely helps. Also, Performance World is a Canadian Company so I don't know if they are available in the US. I'm sure other brands will fit too, once the motor is in the right place.

There are lots of other considerations also. Heater core, fan, shroud, water pump, core support, to name a few. There is a really good article in the January 2019 edition of Musclecar Review that explains everything that is needed. I have scanned and attached a copy.

Also, the OP mentions a Gen V block but doesn't mention whether it is a manual or auto. trans. I don't believe the Gen V has a provision for a clutch bell crank. Not an issue with an auto.

Hope this is helpful.
Oliver
 

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1969 Nova . . 2dr . . Chino Valley,Az USA
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"ls6owner" . . . . . I just 'clicked on your ' Attachment ' .

would not work , for me ................ I was just looking , thanks .

later , jim
 

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It works for me but it is a large file (6.6 MB) and it actually downloads onto my computer in the lower LH corner. If that won't work for you, I will try to downsize it.

Just let me know.
Thx
 

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Absolutely right about the heater core. It must be moved, but kits are available and it doesn't involve working under the dashboard. Summit has a very nice original style BB fan shroud for under $90. The radiator support was easy for my Sawsall, as my factory original radiator support had a "pattern" showing where to cut it. I put a very small dent in one of the tubes of my Hooker headers and did file/grind a bit off the corner of my new power steering box to gain a small bit of clearance.
 

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1970 Nova ZZ502/TH400
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BB mount stands, Doug's Headers (D320, has 2" primary), Pypes 3" exhaust system. If you relocate battery to the trunk, you can fit a Chevelle radiator with minor mods to radiator support (cut opening to width of radiator core and fold down tabs on lower support. I also lined bottom with high temp foam). If not, you're stuck with Nova size radiator. Buy a good quality radiator (made in USA with American aluminum like Ron Davis or Be Cool) if you can afford it. I went through several cheapos with running hot drama and gave up and spent $1700 on Ron Davis Chevelle radiator with dual 16" fans. I'm on my second 70 Big Block car.
 
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