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Author Topic: '85 318 2bbl roller tappet stock? '84 heads fit on?  (Read 1992 times)

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david.randall

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'85 318 2bbl roller tappet stock? '84 heads fit on?
« on: March 27, 2008, 13:13:46 »

All et al,

I've read that in '85 Chrysler went to roller tappets in the 318. If this is true, will the top-end from an flat-tappet E46 4bbl 318 fit on the E44 2bbl 31 in my '85 5th Ave?

Thanks,


David
'78 New Yorker Brougham coupe (factory sunroof)
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'85 5th Ave (factory monroof) 
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Reggie

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Re: '85 318 2bbl roller tappet stock? '84 heads fit on?
« Reply #1 on: March 27, 2008, 13:48:20 »

All et al,

I've read that in '85 Chrysler went to roller tappets in the 318. If this is true, will the top-end from an flat-tappet E46 4bbl 318 fit on the E44 2bbl 31 in my '85 5th Ave?

If you mean the heads and intake together, they will all bolt on, but you may have problems.  Here are things to consider if you want to swap the 4-bbl intake and the heads:

  • Pushrod clearance:  Roller cam engines have a slightly different pushrod angle than non-roller engines due to the taller roller lifters, so roller cam heads have larger pushrod holes in order to clear the pushrods.  Using a non-roller head with the smaller pushrod holes on a roller cam engine may cause pushrod interference.
  • Compression: 4-bbl heads are open chambered 360 heads.  Using them on your current engine will lower your compression ratio.

If you just want a 4-bbl setup, you can swap the 4-bbl intake to your current heads.  Because the 4-bbl factory intake is meant for larger port 360 heads, there will be a slight port mismatch, but it will work.   - RR
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undercover1

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Re: '85 318 2bbl roller tappet stock? '84 heads fit on?
« Reply #2 on: March 27, 2008, 14:21:05 »

Reggie is dead on. Stick with the smaller port heads. They may be a 302 casting with a small heart shaped combustion chamber. Good for better compression and efficient combustion. With a good bowl cut,valve job and port match the heads will flow much better.

Be carefull. Your 85 may or may not be a roller cam engine. That year was a cross over where chrysler was still using up older hydraulic cam stock and blocks. I have seen engines that should have been roller but were not. Could be the engines were replaced at one point too, but you really need to comfirm what you have. Take a valve cover off and look for the casting # on top of a runner. Will be hard to see due to rocker shafts etc so have a bright light handy.
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MarkM

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Re: '85 318 2bbl roller tappet stock? '84 heads fit on?
« Reply #3 on: March 27, 2008, 14:35:24 »

Take a valve cover off and look for the casting # on top of a runner. Will be hard to see due to rocker shafts etc so have a bright light handy.

The last three digits will read 302 if it's a roller motor with the swirl port heads.

You might want to consider swapping to Magnum heads at this point.
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petebert

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Re: '85 318 2bbl roller tappet stock? '84 heads fit on?
« Reply #4 on: March 27, 2008, 17:22:20 »

I'm sure it comes up once a week there but moparts has a big thread on 360 heads on a 318 right now http://board.moparts.org/ubbthreads/showflat.php?Cat=0&Number=4302979&an=0&page=4#Post4302979
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patrickgrossman

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Re: '85 318 2bbl roller tappet stock? '84 heads fit on?
« Reply #5 on: March 27, 2008, 18:28:44 »

if you want to use older non-roller heads on a roller cam motor, you'll probably need to break out the die grinder and grind some clearance into the pushrod holes.
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Reggie

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Re: '85 318 2bbl roller tappet stock? '84 heads fit on?
« Reply #6 on: March 27, 2008, 19:58:18 »

if you want to use older non-roller heads on a roller cam motor, you'll probably need to break out the die grinder and grind some clearance into the pushrod holes.
  Yup.  Just don't go crazy with it.    :D
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"There is only one success - to be able to spend your life in your own way." - Christopher Morley 1890-1957, American author and editor

Library format and content © 2007- 2012 Reginald A. Royster, Sr., unless otherwise authored or noted.
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