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Old 09-02-2013, 12:35 PM   #1
jimboh247
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1985 305 vs. 1986 305

Besides the 1 piece real seal, the center bolt valve covers, and the different bolt angle on the intake, is there any other differences between the '85 305, and the '86 305?
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Old 09-02-2013, 12:53 PM   #2
Jake Wade
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Re: 1985 305 vs. 1986 305

86 should have the 1 pc rear main seal but the same perimeter valve cover as the 85. Intake bolt pattern the same also.

87 is when the change to centerbolt covers.
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Old 09-02-2013, 01:07 PM   #3
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Re: 1985 305 vs. 1986 305



The guy says it's an 86, out of a Camaro. But it has the center bolt heads, and what appears to be the old style intake bolt angle.

Whether it's an 86 or 87, is the cam the same between 85, 86 and 87? That is, if the 87 is not a roller cam.

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Old 09-02-2013, 01:18 PM   #4
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Re: 1985 305 vs. 1986 305

Depends on what 305 we are talking about. The truck 305 or passenger car 305
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Old 09-04-2013, 07:36 PM   #5
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Re: 1985 305 vs. 1986 305

Well, I pulled the intake, and it is at least an 87, due to the roller cam.
What I want to know:
Will 85 or earlier heads bolt on to the 87 block if I use the earlier intake?
Can I ditch the roller cam and go with a cam from an earlier (non-roller) motor?
All I really need is the short block.
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Old 09-04-2013, 08:45 PM   #6
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Re: 1985 305 vs. 1986 305

Yes to all your questions. I would take advantage of that roller ready block,myself
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Old 09-04-2013, 09:18 PM   #7
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Re: 1985 305 vs. 1986 305

You'll have to use the 86-up one piece rear main flywheel/flexplate. I agree with Jake, I would use the roller setup. Free upgrade.
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Old 09-04-2013, 10:24 PM   #8
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Re: 1985 305 vs. 1986 305

Quote:
Originally Posted by 07XCSBZ71 View Post
You'll have to use the 86-up one piece rear main flywheel/flexplate. I agree with Jake, I would use the roller setup. Free upgrade.
Thanks for the heads up on the flexplate. I was fixin' to toss it on the scrap pile.

I have a new flat tappet cam, but I guess I could sell it and get a roller cam. I'm going to pull the heads and oil pan to check everything inside out.
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Old 09-06-2013, 09:59 AM   #9
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Re: 1985 305 vs. 1986 305

Another question:
Does the factory cam use a different cam gear on the distributor?
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Old 09-06-2013, 03:07 PM   #10
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Re: 1985 305 vs. 1986 305

Quote:
Originally Posted by jimboh247 View Post
Another question:
Does the factory cam use a different cam gear on the distributor?
A flat tappet cam can take a normal iron distributor gear. Roller cams are steel and will eat through those quickly so you will have to get a melonized distributor gear to run
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