Retrofitting TPI heads on older engine + other questions
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Joined: Jul 2001
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From: San Antonio, TX
Car: 1988 IROC-Z
Engine: L98 (350 TPI)
Transmission: MD8 (700 R4) + 3.42 LS1 Rear
Retrofitting TPI heads on older engine + other questions
i have removed the 882's from my 70's era rebuilt 350. i have placed a top of it a set of stock rebuilt iron 89 L98 heads. i have a Comp XE268H (.477 .480) in that motor. since i have a hydralic flat tappet cam, i do not need self aligning rockers right???? i will be using new stamped steel rockers (pre-86) on that motor. any problems with that cam, the and those heads? anything i'm overseeing??? will an 89 MAF tpi setup have too many problems with that cam, since i am retrofitting tpi on this motor as well. please help!!! thanks again.
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Joined: Jan 2002
Posts: 3,852
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From: Valley of the Sun
Car: 82 Z28
Engine: Al LT1 headed LG4 305
Transmission: TH350
Axle/Gears: 3.73 posi with spacer
No the heads require self aligning rockers, not the cam. The MAF TPI computer may not like working with that cam.
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Supreme Member
iTrader: (2)
Joined: Jul 2001
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From: San Antonio, TX
Car: 1988 IROC-Z
Engine: L98 (350 TPI)
Transmission: MD8 (700 R4) + 3.42 LS1 Rear
. so i will have to buy new rocker again. oh well. i thought the MAF computer wouldn't have too much of a problem? oh well i guess i thought wrong?? Supreme Member

Joined: Jan 2002
Posts: 3,852
Likes: 1
From: Valley of the Sun
Car: 82 Z28
Engine: Al LT1 headed LG4 305
Transmission: TH350
Axle/Gears: 3.73 posi with spacer
I think that if you use guide-plates you may bealbe to use the older rockers. I'm not sure if you can use guide-palte on the newer heads though. But i do know you can't run guide-plates and SA rockers at the same time.
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From: Loveland, OH, US
Car: 4
Engine: 6
Transmission: 5
Look at the heads, specifically the holes where the push rods go through. They may be either little narrow slots that fit tight to the push rods, or large holes that let the push rod wander around in there.
If they're slots (they won't be), you MUST use old-style rockers, and you MUST NOT use either self-aligning rocker or guide plates. If they're big holes (which they should be), you MUST use either SA rockers or guide plates BUT NOT BOTH, and you MUST NOT use old style rockers.
The rockers must have ONE AND ONLY ONE of the 3 possible guide methods installed and in effect: either narrow slots and no guide plates and old-style rockers; or big holes and guide plates and old-style rockers; or big holes and no guide plates and SA rockers.
If they're slots (they won't be), you MUST use old-style rockers, and you MUST NOT use either self-aligning rocker or guide plates. If they're big holes (which they should be), you MUST use either SA rockers or guide plates BUT NOT BOTH, and you MUST NOT use old style rockers.
The rockers must have ONE AND ONLY ONE of the 3 possible guide methods installed and in effect: either narrow slots and no guide plates and old-style rockers; or big holes and guide plates and old-style rockers; or big holes and no guide plates and SA rockers.
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iTrader: (2)
Joined: Jul 2001
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From: San Antonio, TX
Car: 1988 IROC-Z
Engine: L98 (350 TPI)
Transmission: MD8 (700 R4) + 3.42 LS1 Rear
the heads are 14096217 castings. the have the "canted"4 center bolts(87+ centerbolt VC). here's a pic. what type are they guys? i'm not even a head novice.
Last edited by mystikkal_69; Apr 3, 2003 at 06:26 PM.
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From: Loveland, OH, US
Car: 4
Engine: 6
Transmission: 5
You are correct. Those are indeed the narrow slots. Your only correct rocker option is old-style rockers, with no guide plates.
Here's a head that's set up for guide plates. (Not a stock one though) It would also be possible to use no guide plates and SA rockers on this.
Here's a head that's set up for guide plates. (Not a stock one though) It would also be possible to use no guide plates and SA rockers on this.
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