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Discussion Starter #1
I have found a 350 motor out of an early 80's Chevy van and I plan to swap out my 305 to the 350. I have few questions from discussions I have read on here.
1. If I don't go crazy on mods or compression do I need a 4 bolt main motor?
2. Will the 305 and 350 have the same harmonic balancer to swap over?
3. What is the advantage of a roller cam?
4. Car has 80,000 miles. Do I need new motor mounts?
5. Can I use my 305 intake manifold, exhaust manifold and quadrajet carb?
Thanks,RTT:smileyb:
 

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I have found a 350 motor out of an early 80's Chevy van and I plan to swap out my 305 to the 350. I have few questions from discussions I have read on here.
1. If I don't go crazy on mods or compression do I need a 4 bolt main motor?
2. Will the 305 and 350 have the same harmonic balancer to swap over?
3. What is the advantage of a roller cam?
4. Car has 80,000 miles. Do I need new motor mounts?
5. Can I use my 305 intake manifold, exhaust manifold and quadrajet carb?
Thanks,RTT:smileyb:
1. No
2. ?
3. A roller cam doesn't need to have zinc additives added to your oil to protect your lifters.
4. I doubt it but it wouldn't hurt.
5. They will probably fit physically but most likely to restrictive for proper performance.

~JM~
 

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4-bolt main engines are over-rated, you don't need one, and most other people don't either. Good selling point hype on crate engines though :smileyb:
Failed engines from 2-bolt mains is something I haven't heard of....

Roller cams, though expensive, are the way to avoid issues with "modern" motor oil that no longer has the wear additives that help flat tappet cams live.
If it were me, I would spend the 60 bucks or so, for a new balancer.
 

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Are you going to keep the ECM system ?
 

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if you are not makeing over 500 hp a 4 bolt is a waste, half of the 454 production was 2 bolt. small blocks use 2 different sizes of balancers with 2 different timing mark locations.its better off to buy a new one for the 350 they are cheap.roller cams give you better performance and fuel efficiency with the same lift and duration because of better lobe dinamics allowed by the roller design. an 84 with 80,000 miles i would definatly change the mounts,they may look fine but 30 years of a small block sitting on them will at least have colapsed them some what and will be prone to vibrations being alowed into the cab and chassis. they are inexpensive and that far into the car makes no sense not to change them .they are so much more work with the engine in it.as long as the new engine isnt the 87 and newer center bolt valve cover motor your intake will bolt right on,exhaust manifolds are the same .all of your stuff will bolt right on. except if the engine is 86 and newer as mentioned above the flywheel is different,and 87 and newer the intakes are different,if it has a roller cam the dist gear is different. the carb will bolt on and function but will need some work to make it correct for the 350. when you adjust the idle to compensate for the 350 you will throw the tps out of adjustment and the mc solenoid will need readjustment.you will need to change the rear meterinng rods to richen up the secondaries or you will run the engine lean and constantly cook the exhaust manifolds.all in all a worth while swap and worth the work to do it.if running the ecm you want to change the computer chip for a 84 chevy impala or caprice with a 350 to get the most from your 350
 

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If you use a 350 with a left [drivers ] side dipstick the exhaust manifolds from early to mid 90's trucks/surburbans work good for clearence at passenger firewall and clear all on drivers side too.
 

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Discussion Starter #9
Thanks for all the good tech advice. I read the post from CCC and have been looking for a 5.7 L ECM chip online. It appears that 1984 Caprice and Impala's were only available with the 305. I did find a complete ECM on Ebay (220871643308)that supposedly applicable for 1887 model 305 and 350's. My car is an 1984. Where can I find the correct ECM chip for the 350 motor?
rtt
 
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the balancer will fit however you will never be able to time it as the pointer and line on old balancer wont line up, why not use the balancer that comes with used motor, yes if you pull the motor change the mounts as tjey will be shot after yrs of abuse as for the carb i would go with mountain man
no on the 4 bolt main wasted $$$$
no on roler cam unless you plan on 450+hp again a waste of $$$
my research indicates 300 hp is plenty for these trucks
 

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unless you 84 has a knock sensor the 87 computer chip may not work as it will be looking for the knock sensor ,84 impala and caprice police and export cars had the 350, and am pretty sure the us civilian cars were available as well
 
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