Hi All.
I have a 93 Caprice. I had a 305 TBI engine that I swapped with a 350 5.7 (LO5) bought it brand new from a dealer.
The engine shakes when I sit inside the car I feel it, if I lean on the car I feel it, if I look under hood I see it shaking.
Can someone help me please.

I'm seem to remember some discussions here about 305's (some at least) being externally balanced similar to 400 small blocks while 350's are internally balanced. Did you by chance swap flexplates and/or dampners between the motors?

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Scott
'69 400SB, Richmond 5-speed; '99 HD Road King Classic
www.geocities.com/sdenning1 (http://www.geocities.com/sdenning1)

Steve,
Does the LO5 motor have a 1 piece rear main seal on the crankshaft ? If so, your 305 flywheel should be fine. Does the "shake" get worse as you rev the motor ? If it does it might be an out of balance condition. If the shake does not get any worse as you rev the motor up, or even gets better, then it is probably a missfire, or other rough running condition that is causing the problem. Double check the plug wires to make sure the firing order is correct. I have seen a couple of times where #5 and #7 plug wires are crossed and will cause a similar problem but the motor really does not run all that bad at all.
Hope this helps,

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Bill Koustenis
Advanced Automotive Machine
Waldorf Md

[This message has been edited by BillK (edited 06-26-2000).]

305's are internally balanced and the flywheel is smaller diameter/less teeth than a 350 flywheel.
I have a similar problem with a motor right now and it turns out that #6 is dead ... almost no compression. It shakes soo bad at idle that my steering wheel vibrates. The motor just spun a bearing so it was time to go anyway. I hope you don't have a bad cylinder in a new engine!!!

The 350 will also need larger injectors.

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68SS ZZ4, 4sp T-10, 12 bolt, getting painted

78Z28, 330hp vortec, TH350, 10 bolt (just finished)

the 4.3-V-6 and the 305 and 350 have the same injectors.

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Leo Paugh
MCC #017
www.clark.net/pub/chevelle/mcc.htm (http://www.clark.net/pub/chevelle/mcc.htm)
the bitterness of poor quality remains, long after the sweetness of the low price is forgotten

Educate someone from the old school chev64. If that is the case. What is the determining facter on the mixture? Will the computer need replaced or recalibrated for the increased CI?

71 Camairo

<BLOCKQUOTE>quote:</font><HR>Originally posted by RockyMtnRacer:
I'm seem to remember some discussions here about 305's (some at least) being externally balanced similar to 400 small blocks while 350's are internally balanced. Did you by chance swap flexplates and/or dampners between the motors?

<HR></BLOCKQUOTE>

yeah in fact I did swap the flexplate and the engine mounts from the 305.

Yeah guys i did swap the flexplate from my old 305 as well as the dampners and engine mounts.

[This message has been edited by stevecap (edited 06-28-2000).]

It is one pc rear main seal.
How can I balance it? Do I need new engine mounts cuz mine are pretty old?
Thanks.

As far as the shakeing goes when I rev up the engine, it does happen to a certain extent. I had a dealer put it on dyno and cylinders look pretty good.
As far as injectors 305 and 350 have different injectors , they allow more gas. I also changed the chip in the computer and there are no misfires.