305 to 350 swap, how much interchange-ability?

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86Jackie

n00b
Oct 25, 2018
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Looking at swapping out my 305 as I may have some serious issues that can only be fixed by rebuilding it. I really don't want to rebuild a 305 as my opinion they're pretty doggy motors as far as power.
I'd like to know how much exterior parts of the 350 will interchange with the old 305. I plan to get a mostly complete crate 350. How much parts will interchange as far as brackets, motor mounts, and transmission mounts. The car currently has a th700r4 overdrive transmission.

Thanks.
 

565bbchevy

Geezer
Aug 8, 2011
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Michigan
It is a direct swap so everything from the 305 will fit on the 350.
 
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TURNA

Rocket Powered Basset Hound
Jul 24, 2009
10,941
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IF you are using the 305 exhaust manifolds depending on year the only thing you might see different is the pass side exhaust manifold.

You might not be able to fit one bolt in it, but that will not effect it the gasket should hold without it.
 
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Tomeal

G-Body Guru
Apr 17, 2016
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Asking because I'm following this for info!

Don't alot of crate motors not have provisions for mechanical fuel pumps. Wouldn't some type of electric pump be needed?
 

airboatgreg

Comic Book Super Hero
Oct 2, 2016
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Piece of cake. Good time to swap over to a serpentine belt. I got my stoff off a 84 S Blazer with a throttle body. Lots of other options though. Don't forget to also change the water pump as it turns opposite.
 

paul.m

Master Mechanic
Oct 20, 2018
404
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Stay with a pre 86,87 sbc chevy and you will be fine fuel pump rod is there or one can be installed. Engines between 88- 95 are iff depending on make and model engine came out of , some do not even have the lobe on the camshaft to work a mechanical fuel pump. Al-tho i have heard of people getting replacement camshaft,s for certain engines that does allow for the mechanical pump to be used. As far as the 305 swap, the 350/290 is the best bang for your buck as far as GM crate engines go, The revised numbers are 308 HP 347 ft/tq . If your budget is really tight get the base GM 350 it has advertised 195 HP , But is easly upgraded to 260. Plenty enuf for daily driver . If you shop around you can find them for under 1500 buck,s And there NEW not rebuilt !
 
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Larryneil

Not-quite-so-new-guy
Sep 22, 2018
8
3
3
Looking at swapping out my 305 as I may have some serious issues that can only be fixed by rebuilding it. I really don't want to rebuild a 305 as my opinion they're pretty doggy motors as far as power.
I'd like to know how much exterior parts of the 350 will interchange with the old 305. I plan to get a mostly complete crate 350. How much parts will interchange as far as brackets, motor mounts, and transmission mounts. The car currently has a th700r4 overdrive transmission.

Thanks.
I just swapped a 305 in my 87 El Camino and it was a pretty clean bolt up. I have the 200r4 transmission, but you should be able to hook up the 700r4. I love the 350 I purchased from Scoggins and Dickey. It purrs like a beast. Good Luck!!!
LN
 

paul.m

Master Mechanic
Oct 20, 2018
404
201
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Absolutely don,t waste your time on a 305 ! All your bracket,s will bolt right up to a 350 , bellhousing of course the same as all 1 st gen sbc . The only exception is one of the exhaust manifolds , cant remember which side , has extra hole . It will still work just has provision for some kinda smog garbage from the 70,s . I wouldn't think you would be useing those during a swap though
 

pagrunt

Geezer
Sep 14, 2014
9,128
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Elderton, Pa
The only exception is one of the exhaust manifolds , cant remember which side , has extra hole . It will still work just has provision for some kinda smog garbage from the 70,s .
From '78 up most Chevy heads had seven bolt holes (on the passenger side it would be to the rear, drivers side to the front.) This was for the manifolds first used in our cars starting in '78 (passenger side had the rear hole pushed back for the outlet covered the sixth bolt hole.) I have used a set on a '68 307 in my old '72 Monte cause those were the only set I had at the time. The passenger side only had five bolts holding it on & didn't leak at all. Used the gaskets & all was good.
 
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Clone TIE Pilot

Comic Book Super Hero
Aug 14, 2011
3,831
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Galaxy far far away
The really good SBC crates are the ones with Vortec heads, which are also the ones that lack provisions for mechanical fuel pumps. However, a intank electic fuel pump solves that. Those base 260 and 290 HP engines have lousy CR, only 8.5 which makes them weak and thristy for gas. Better to get at least a mid grade engine with a CR of 9 or better. What year is your 305? That will determine how much you can swap over to a replacement 350.
 
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