pre-'85 and '86-later engine blocks....What's the difference?
Thread Starter
Race Director
Joined: Oct 2000
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From: Kansas City, MO ...I'd like to go fishing and catch a fishstick. That'd be convenient. - Mitch Hedberg
pre-'85 and '86-later engine blocks....What's the difference?
What makes the Gen 1 blocks different between the pre-'85 and the '86-later blocks?
The question is brought up because I'm planning on having my engine rebuilt. I like the idea of a roller cam, so I'm doing some research here on the forum. Do the -'85 engines have to be machined to make a roller cam worked? If so, what machine work has to be done?
The question is brought up because I'm planning on having my engine rebuilt. I like the idea of a roller cam, so I'm doing some research here on the forum. Do the -'85 engines have to be machined to make a roller cam worked? If so, what machine work has to be done?
Drifting
Joined: Aug 2004
Posts: 1,883
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From: Lubbock TX
Pre 86 engines used flat tappet cams, 2-piece rear main seal. Some of the later blocks are equipped for hydraulic roller cams, all of 'em have 1-piece rear main seals, dipsticks are all on the passenger side of the block. The earlier blocks generally don't need any machining to run a roller cam but will need a cam button and retrofit roller lifters.
Le Mans Master
Joined: Jan 2004
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St. Jude Donor '14
Pre 86 engines used flat tappet cams, 2-piece rear main seal. Some of the later blocks are equipped for hydraulic roller cams, all of 'em have 1-piece rear main seals, dipsticks are all on the passenger side of the block. The earlier blocks generally don't need any machining to run a roller cam but will need a cam button and retrofit roller lifters.
I thought you had to machine in some screw holes in the valley of the pre 86 motors so you can install keepers to keep the lifters indexed properly. Roller lifters cannot be allowed to spin in the bores. Am I correct? is that what you meant by retrofit a roller cam? I think that is pretty involved.
Last edited by 7t5; Jun 26, 2009 at 06:12 PM.
NCM Grand Opening Veteran
Joined: Sep 2005
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From: South of giving a damn
St. Jude Donor '11, '17
I thought you had to machine in some screw holes in the valley of the pre 86 motors so you can install keepers to keep the lifters indexed properly. Roller lifters cannot be allowed to spin in the bores. Am I correct? is that what you meant by retrofit a roller cam? I think that is pretty involved.
Le Mans Master
Joined: Aug 2003
Posts: 7,720
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From: Chattanooga TN
Pre 86 engines used flat tappet cams, 2-piece rear main seal. Some of the later blocks are equipped for hydraulic roller cams, all of 'em have 1-piece rear main seals, dipsticks are all on the passenger side of the block. The earlier blocks generally don't need any machining to run a roller cam but will need a cam button and retrofit roller lifters.
There are 2-bolt and 4-bolt versions like the earlier ones. There are conversion kits to use a 2-piece-seal crank in a late block, but why? The bearings are the same, mounting holes in the block the same, really no external difference except the flexplate/flywheel. One small thing to note, many "late" blocks have the pad cast for a fuel pump, but the hole for the pushrod to the cam lobe is not drilled out.
Thread Starter
Race Director
Joined: Oct 2000
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From: Kansas City, MO ...I'd like to go fishing and catch a fishstick. That'd be convenient. - Mitch Hedberg
Thanks for the great info guys. Anymore trivia or bits of knowledge about them, please let me know.
If I were having a machine shop rebuild a long block from a '86+ engine, could they easily adapt a mechanical fuel pump?
If I were having a machine shop rebuild a long block from a '86+ engine, could they easily adapt a mechanical fuel pump?
Drifting
Joined: Aug 2004
Posts: 1,883
Likes: 124
From: Lubbock TX
If you want to run a mechanical fuel pump, you need to find a block with the provisions for one. If the pushrod hole is not drilled out, any competent machine shop can handle that. If it doesn't have the fuel pump boss at all, it can't be added. All the late TBI (early 90's) I have do have the boss and it's drilled, so look for those.
Le Mans Master
Joined: Dec 2007
Posts: 6,422
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From: McHenry Illinois
So, do all '86 and later blocks have provision for the roller cam, such as the bolt holes for the spider in the lifter valley. I understand that not all of those blocks had roller cams, but I'm not clear if its as easy as geting the roller cam and OEM hardware or some will need to be modified.
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