64 300 to 63 Riv 401

C

cobopguy

Member
Hey group,

I had an offer that came up for me to purchase a 63 401 w/ trans for $450. My only questions is how hard is the swap into the 64 Skylark engine bay? Can I use the same mounts/pads/manifolds, etc? Also, would the oil pan fit? Or is it too much of a headache? I know the price is good but.....

Any help would be appreciated.

Thanks,

Chris
 
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it's kind of important to know WHAT you're putting it in.

in general though, a Nail is not a very straightforward swap for a 300ci.

the starters are on opposite sides.

the distributors are at opposite ends of the block.

they don't have the same bellhousing, although that doesn't matter since you're getting the Nail + trans as a combo.


if you decide to go the Nailhead route, you want to get all the mounting equipment for a 1965 Skylark Gran Sport 400 ( actually a Nail 401ci ). the first generation of the Skylark ran from 1964-67 and 1965 was the first year that a Nail was available in the car.
 
Bob,

Thanks for your response. I have edited my post. I have a 1964 Skylark with the 300 hp motor. I wasn't sure if there were any crossmember changes from 64 to 65 to accommodate putting the 401 into the GS?
 
Chris,

You will NEED a rear sump oil pan & matching pickup. GS specific exhaust manifolds. Re-wiring of engine compartment. Bigger radiator & cooling fan & shroud. GS specific motor mounts & frame pads. Move the cross member. Shorten, (best to have a new heavy duty one made) the driveshaft & MANY other things I'm forgetting about at this moment. You need the skills & the $$$$ to source the nec. parts & make the installation. IT'S NOT JUST A BOLT-IN.

Tom T.
 
Tom,

Thanks for the additional info. I spoke with TA Performance this morning as well. They informed me of the same things and there is really no aftermarket for it. I have the know-how and $$$$ but wasn't sure if it was worth it. It would be a cool swap but think I may stay with the hp 300 and swap in a TH350. This will probably give me the output I am looking for to cruise with my family. At least until a 455 comes up.
 
I have a 1964 Skylark with the 300 hp motor.
...
I may stay with the hp 300


sorry i didn't notice you were doing this earlier. the engine is 300 cubic inches and 310 lb-ft of torque, not 300 hp. the highest rated 300ci in 1964 was 250 hp and 355 lb-ft, and that was rated in Gross Power not SAE Net Power like we use today.

back in the 60s, Buick was labeling the air cleaner with the engine torque rating, not the HP or displacement.


and swap in a TH350

better would be a 200r4. you not only get a shorter 1st gear, you also get a highway OD gear.

and it's the same bell housing pattern. or includes it, anyways.

if you're looking for swaps, the 455 is definitely the best bang for the buck. it shares the BOP bell pattern and oiling circuit / distributor layout of the 300ci. you need Big Block frame pads, engine mounts and fan shroud.

otoh, a Buick 350 is very close to an exact drop in. it's got a deck that's a bit taller than the 300 and a slightly larger bore and swapped valve / cam lobe order, other than that it's the same.

AND FOR THE CRAZIEST OPTION

you could keep the 300ci block and put a Buick 350 crank in it. that turns your engine into a short deck 340ci.

https://www.hotrod.com/articles/hrdp-1103-how-to-hot-rod-any-engine/
 
Thanks and sorry for not calling out everything properly in the beginning. When I typed hp I meant high performance. I have the Wildcat 355 with aluminum heads and intake.

I think adding a different trans will give me the intended results without spending a bunch of time fabricating. A 455 would be nice but not realistic at this point. The 350 would be a good choice but man, you can't find them anymore the way you used to be able to. At least not out here in CO or in a close radius.

The 349 would be a great build and may be the eventual path for the engine. I read this article before and the numbers that it put down sound like a lot of fun.

What year(s) were the 200r4 used? I see that they can be bought online but would prefer to pull one and have it rebuilt locally in the event I had any issues.
 
pretty much any small block auto mid size GM from the 1980s has it.

https://infogalactic.com/info/Turbo-Hydramatic#THM200-4R

they are dual pattern cases, so they should have both the Chevy and BOP patterns and it won't matter which engine you pull it off of.

if you don't know what i mean, check out my transmission bell thread.

there are a couple of different OEM grades of 200r4, and the Buick Turbo 6s and Pontiac Turbo Trans Ams will have the heaviest built stock units. pretty much any rebuilder can exceed factory specs though.
 
Perfect. After my last post I started digging through classifieds and answered my own question. If I go with the stroker idea a stage 3 200r4 would probably be best to keep everything intact! Thanks for all of the info.
 
speaking of Turbo 6s, i forgot to mention that they are an option as well. and, except for the turbo plumbing, are a better swap candidate than the 350.

the Buick 6 ( 225ci ) was created by lopping the front two cylinders off of a Buick 300ci ( 300 * 6 / 8 == 225 ). then, in the 70s, they punched the bore out to the same as the 350 diameter to simplify the engine production line which is where the 231ci / 3.8L comes from. but it still has the same deck height as your 300.

thus, there shouldn't be any interference issues to speak of.

and some of the Turbo6 guys are over 1000 hp.

you know. like if you needed to merge with traffic or something. wink wink, nudge nudge, say no more.
 
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