Motor compatability
Thread Starter
Intermediate
Joined: Mar 2016
Posts: 31
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From: West TN
Motor compatability
So I started looking for a 350 core to begin a motor project and I'm coming up with lots of option of varying year models. The car is an '85. Do I need to stick with specific year models or will any 350 block work? I've come across everything from mid 70's to late 90's LT1 motors.
I know at some point the blocks changed to accept OE roller lifters, but not sure of any other changes.
Thanks
I know at some point the blocks changed to accept OE roller lifters, but not sure of any other changes.
Thanks
Melting Slicks
Joined: Sep 2010
Posts: 2,422
Likes: 202
the 85 Motor. can be a pot luck surprise having "duel" roller & or flat tappet cam provisions.
the 85 Block is a 2 piece rear main crank. Allowing you to use any standard 85 & older SBC block / crank combo. upgrading to a 86 - 90 block is a 1 piece rear main. this would force you to upgrade you flywheel OR flexplate matching a 1 piece design. LT1/4 based engines you would be better off selling the car.
the 85 Block is a 2 piece rear main crank. Allowing you to use any standard 85 & older SBC block / crank combo. upgrading to a 86 - 90 block is a 1 piece rear main. this would force you to upgrade you flywheel OR flexplate matching a 1 piece design. LT1/4 based engines you would be better off selling the car.
Last edited by THE 383 admiral; Mar 23, 2016 at 12:03 PM.
Racer
Joined: Jan 2014
Posts: 324
Likes: 7
From: Littleton Colorado
Factory roller lifters started in the 1987 model year, but were only used in passenger cars (rare and unverified reports of trucks getting them from time to time, but generally truck engines had flat tappet cams). The block castings were the same, but sometimes the truck blocks didn't have the roller lifter provisions machined. I've seen them both ways (machined and unmachined).
One piece rear main seal was the year before, 1986.
As stated, the one piece rear main seal crank uses a different flexplate/flywheel. And I believe the front cover and oil pan also changed, but I'm not as sure about that.
Roller lifters are much better than flat tappets, so if you can get a later block that's been machined for the rollers, that would be an upgrade.
70's blocks often had machining issues (bores not square to the crank, lifter bores not properly located to the cam lobes, starter bolt holes not properly aligned to the flexplate/flywheel, etc.), porous castings, or thin castings. They also may not have the proper starter mount bolts holes. I'd try for the newer blocks late-80's and up for those reasons.
One piece rear main seal was the year before, 1986.
As stated, the one piece rear main seal crank uses a different flexplate/flywheel. And I believe the front cover and oil pan also changed, but I'm not as sure about that.
Roller lifters are much better than flat tappets, so if you can get a later block that's been machined for the rollers, that would be an upgrade.
70's blocks often had machining issues (bores not square to the crank, lifter bores not properly located to the cam lobes, starter bolt holes not properly aligned to the flexplate/flywheel, etc.), porous castings, or thin castings. They also may not have the proper starter mount bolts holes. I'd try for the newer blocks late-80's and up for those reasons.
Thread Starter
Intermediate
Joined: Mar 2016
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From: West TN
I can get a running '96 LT-1 with the TPI intact for $500. I think it has the flex plate also. Sounds like the way to go. How can you tell an LT-1 from an earlier motor without tearing it down?
Last edited by rrc1962; Mar 23, 2016 at 02:28 PM.
Thread Starter
Intermediate
Joined: Mar 2016
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From: West TN
What concerns me is ending up with a motor that none of my current accessories work on. I've only messed with the older small and big blocks. The plan is to find a rebuildable core, rebuild the short block with flat top pistons, add dart aluminum heads, headers, healthy hydraulic roller cam and MiniRam intake with TPIS throttle body. Probably back it up with a TCI StreetFighter transmission.
So as far as heads go, will the LT-1 block take different heads than the L98? If I decide to reuse the stock TPI, will it bolt up to Dart heads on an LT-1 block?
So as far as heads go, will the LT-1 block take different heads than the L98? If I decide to reuse the stock TPI, will it bolt up to Dart heads on an LT-1 block?
Melting Slicks
Joined: Sep 2010
Posts: 2,422
Likes: 202
you cannot use traditional SBC gen1 heads on the 92 - 96 LT1 block without welding 2 coolant passages. then Drill Oil returns. then tap the back of the heads for coolant lines. Like I did to my SBC heads. on my 94 LT1
as you should know the 70 - 72 SBC ~ LT1 is a traditional 2 piece rear main.
if you are looking for a HD SBC block. look for a M block from a 1 ton truck / van. the casting / webbing is much stronger. and actually weighs more.
as you should know the 70 - 72 SBC ~ LT1 is a traditional 2 piece rear main.
if you are looking for a HD SBC block. look for a M block from a 1 ton truck / van. the casting / webbing is much stronger. and actually weighs more.
Last edited by THE 383 admiral; Mar 23, 2016 at 03:28 PM.
Thread Starter
Intermediate
Joined: Mar 2016
Posts: 31
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From: West TN
I'm buying new heads, so I can buy them for either block, but if I end up with an LT-1, I might just use the factory heads. Just need to make sure the original TPI and front end accessories will bolt up to an LT-1 engine.
Last edited by rrc1962; Mar 23, 2016 at 04:11 PM.
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Team Owner
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That will not happen - your original accessory drive will do L98 only
Thread Starter
Intermediate
Joined: Mar 2016
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From: West TN
Looks like I'm back to a pre '86. All I want to do is take my time building up a nice long block, then take a weekend when it's done and do the swap. Don't want to get into replacing the brackets for PS, AC, alternator, etc.
Le Mans Master
Joined: May 2006
Posts: 7,708
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From: indy indiana
while your buying parts, remember that there are two different water pumps for the SBC. Short and long. Around 72 or so, the started drilling the holes in the heads for accys and went to a long water pump. However, correct me if I am wrong guys, our vettes use the short pump. Best way to tell is if your hand can fit between the block and the pump.
Racer
Joined: Jan 2014
Posts: 324
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From: Littleton Colorado
I should have mentioned that the '96-'99 light truck engines have roller lifters, one-piece rear main seal, and earlier heads will fit on the block. As ex-x-fire is saying, though, the heads on those engines are also better, too. Only issue with the heads is your TPI base won't fit on them, but there is a "Vortec" base that will fit on them and the rest of your TPI stuff, and your current accessories, will all fit on that engine. You will probably need to swap over the front cover and oil pan, but that isn't too big a deal. If you go that route, just make sure you're getting a 350 and not a 305.
Team Owner
Joined: Oct 2004
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From: altered state
St. Jude Donor '05
If you can get a truck 1 pc rear seal roller block then add the Dart heads...Id go there. Vortecs are better than stock but a little overrated and most used ones out there are cracked. Blocks are good though many are 4 bolt mains, too
Edit: oops forgot to ask are you using the long tube runner intake or something like a minram?
Edit: oops forgot to ask are you using the long tube runner intake or something like a minram?
Last edited by cv67; Mar 23, 2016 at 09:49 PM.
Racer
Joined: Jan 2014
Posts: 324
Likes: 7
From: Littleton Colorado
Le Mans Master
Joined: May 2006
Posts: 7,708
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From: indy indiana
If you can get a truck 1 pc rear seal roller block then add the Dart heads...Id go there. Vortecs are better than stock but a little overrated and most used ones out there are cracked. Blocks are good though many are 4 bolt mains, too
Edit: oops forgot to ask are you using the long tube runner intake or something like a minram?
Edit: oops forgot to ask are you using the long tube runner intake or something like a minram?
Thread Starter
Intermediate
Joined: Mar 2016
Posts: 31
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From: West TN
The plan is to use a Miniram. I found a 80-85 4 bolt main block. That'll probably be my starting point. Probably end up with just south of $10K between the motor and transmission. I'll spread it out over a few months so it won't seem so bad.
Last edited by rrc1962; Mar 24, 2016 at 06:46 PM.
Racer
Joined: Jan 2014
Posts: 324
Likes: 7
From: Littleton Colorado
I've heard many such reports. Doesn't matter which casting #. I haven't seen it personally, but I haven't done much with Vortec heads (the set I had wasn't cracked).
