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have 85 T/A....bought 98 350 Vortec.

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Old 09-06-2013, 05:19 PM
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Car: 85 Trans Am
Engine: 416 headed LG4 (i think)
Transmission: auto
Axle/Gears: 9 bolt, unknown ratio
have 85 T/A....bought 98 350 Vortec.

couple questions, Most importantly, will the stock cam have the fuel pump lobe on it? or will I have to go aftermarket in order to run a mech fuel pump?

second, will the 305's starter work?

pretty certain my car has a 200c, and where the new engine will be 1 pc rear main seal will there be any fit up issues?
(eventually plan to run 700r as funds allow)

will the 305's Q-jet be enough to feed the 350? im thinking no, but ive been wrong before..

Anything ive missed?

Old 09-06-2013, 07:06 PM
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Car: 82 Z28
Engine: 383 SP EFI/ 4150 TB
Transmission: T400
Axle/Gears: QP 9" 3.73
Re: have 85 T/A....bought 98 350 Vortec.

Originally Posted by MachinistMark
will the 305's starter work?
the new engine will be 1 pc rear main seal will there be any fit up issues? :
Everything bolts up
Must use a 1 pcs RMS flexplate that fits the new engine so the starter has to match that.
Usually Vortecs have the larger 168 tooth flexplate with it's matching starter and the block only has the holes drilled to suit that 168 tooth starter.

2 choices
Buy 1 pce version of 153 tooth flexplate , drill the extra hole in the block and use your starter
or
Buy a large starter and use the stock 168 tooth Vortec flexplate

Originally Posted by MachinistMark
will the 305's Q-jet be enough to feed the 350?
Q-Jet will be fine but may need re-jetting to 350 specs.
You know you need a special Vortec intake manifold?
Your intake won't fit the Vortec heads

Last edited by vetteoz; 09-06-2013 at 07:10 PM.
Old 09-06-2013, 07:09 PM
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Car: 82 Z28
Engine: 383 SP EFI/ 4150 TB
Transmission: T400
Axle/Gears: QP 9" 3.73
Re: have 85 T/A....bought 98 350 Vortec.

Originally Posted by MachinistMark
will the stock cam have the fuel pump lobe on it?
if you look at the engine , you will see Vortec blocks don't have the hole drilled for the pushrod that operates a mech pump so you would need a elec pump
Old 09-06-2013, 08:05 PM
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Car: 85 Trans Am
Engine: 416 headed LG4 (i think)
Transmission: auto
Axle/Gears: 9 bolt, unknown ratio
Re: have 85 T/A....bought 98 350 Vortec.

Typically if it has no pump block off plate it hasn't been drilled, if it has a block off plate they usually have been drilled.

I know my engine has the block off plate. so, heres hoping.

will the flexplate off the 305 fit the 350?


I know the intake will not fit, already have that covered. just need to know if im buying an intake or an intake AND a carb
Old 09-07-2013, 08:24 AM
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Car: 82 Z28
Engine: 383 SP EFI/ 4150 TB
Transmission: T400
Axle/Gears: QP 9" 3.73
Re: have 85 T/A....bought 98 350 Vortec.

Originally Posted by MachinistMark
will the flexplate off the 305 fit the 350?
What I said above , must use a flexplate to suit the engine
The Vortec has a 1 pce RMS crank , your 85 305 has the older style 2 pce RMS crank.
Flywheel / flexplates don't interchange between the two different types of engine.
The factory even changed the crank bolt pattern to prevent the wrong flexplate style accidentally being used

Originally Posted by MachinistMark
Typically if it has no pump block off plate it hasn't been drilled, if it has a block off plate they usually have been drilled.
FWIW
All my Vortecs have the holes for the plate drilled / threaded as is normal for SBC's but have no pushrod hole.
All factory Vortecs were EFI so they had no need for a mech pump
Old 09-07-2013, 09:10 AM
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Car: 85 Trans Am
Engine: 416 headed LG4 (i think)
Transmission: auto
Axle/Gears: 9 bolt, unknown ratio
Re: have 85 T/A....bought 98 350 Vortec.

I'm aware. My engine builder/speed shop owner buddy said that if the block off plate is present its likely drilled. If it wasn't there would be no need for a block off plate. Either way I won't know till its out of the truck and on my stand.
Old 09-21-2013, 11:07 PM
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Car: 91 Firebird,00 c2500,75 Vette
Engine: 3.1 but 350 soon, 350, 350
Transmission: T56 soon
Axle/Gears: stock 3.42 Posi to come
Re: have 85 T/A....bought 98 350 Vortec.

I would not expect a fuel pump lobe on the cam. Both the 2000 in my truck and the 97 vortec block I found for the 350 swap in my bird do not have the fuel pump push rod hole drilled. GM started not drilling some of the earlier blocks with 1 pc rear main seal because it wasn't needed with everything being fuel injected. My 89 TBI suburban wasn't drilled.
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