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| Head differences? https://slantsix.org/forum/viewtopic.php?t=37417 |
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| Author: | 82Stepside [ Wed Oct 07, 2009 6:29 am ] |
| Post subject: | Head differences? |
Are there any differences between the 70's head and an 80's head? My 82 truck has the hydraulic cam in it and I'm wondering if any 225 head will work, or if it would need to be from an 80's motor. |
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| Author: | 66aCUDA [ Wed Oct 07, 2009 6:37 am ] |
| Post subject: | |
80's head is different. Different valve cover and Hydrolic valve train. If you are going to have the engine out (cam change from Hydro to Flat Tappet) then you can move to any head. If your not going to change the cam I would stay with the 80's head. Frank |
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| Author: | coconuteater64 [ Wed Oct 07, 2009 7:04 am ] |
| Post subject: | |
Later heads had the spark plug holes cast in; earlier heads had a spark plug tube like the hemi. You can swap the older head onto a hydro motor from what I have read, if you also swap the hydro valvetrain AND the bolts. Seems one of the bolts is "beehive" shaped for oil passage. I could be wrong, and of so I am confident someone will set the record straight in short order. |
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| Author: | 82Stepside [ Wed Oct 07, 2009 7:19 am ] |
| Post subject: | |
I figured I'd have to stick with the 'newer' ones with the spark plug tubes cast into the head. Just wasn't sure about the hydraulic vs. non-hydraulic set up in the head. |
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| Author: | Doc [ Wed Oct 07, 2009 9:00 am ] |
| Post subject: | |
The reason why 81 and newer "hydraulic" heads have a different (wider) valve cover is that they are slightly wider, this allows room to make larger pushrod thru holes in the head. The larger thru holes will allow you to remove a lifter, without pulling-off the head. As many mechanics know, hydraulic lifters can get plugged, worn or be "problematic" so easy removal for replacement is a good thing. DD |
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| Author: | SlantSixDan [ Wed Oct 07, 2009 9:08 am ] |
| Post subject: | |
But cant the '74-down heads (w/spark plug tubes) also be used with hydraulic lifters, keeping the advantage of lifters removable from the top? |
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| Author: | Doc [ Wed Oct 07, 2009 9:25 am ] |
| Post subject: | |
Yes, the 60-74 S.P. tube heads can also be used to allow lifter access. The hydro rocker arm assembly and pushrods have to be used but this hardware will transfer to the earlier head. You do have to enlarge the lower half of the rear hydro rocker shaft hold down bolt hole and use the early (3/8 - 16 unc thread) bolt. DD |
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| Author: | Reed [ Wed Oct 07, 2009 9:31 am ] |
| Post subject: | |
Quote: But cant the '74-down heads (w/spark plug tubes) also be used with hydraulic lifters, keeping the advantage of lifters removable from the top?
I have this very question. From what I have been able to determine, the hydraulic head didn't add any oil passages to what were already there in the late 70s peanut plug heads. The rocker arms changed to non-adjustable ones, but the rest of the valvetrain and oil passages in the head were the same as the pre-hydraulic late 70s motors. The only real difference I can find between the 74 down heads and the hydraulic heads, besides the spark plug tubes and holes around the pushrods, is the rearmost rocker arm bolt and the slightly enlarged oil passage at the back of the head. However, if the stepped bolt and the oil passage were used for mechanical lifters in the late 70s and were carried over without modification into the hydraulic motors, then the hydraulic motors don't really need any more oil pressure or passages than the mechanical cam motors do. If this is true, then I don't see why a pre-74 head can't be run on a hydraulic motor.In fact, I believe Eric W actually ran a 67 head on an 83 motor for a while with no problems. Chime in here Eric- I think the "red head" we put on your hydro motor in your Satellite is a 67- it has the unrevised combustion chamber with the "dots." I am interested in the answer to this question since I plan on putting a 72 head on a hydraulic motor eventually for my brother's Duster. EDIT: Looks like Doc answered the question while I was typing. Thanks Doc! |
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| Author: | oldblue [ Wed Oct 07, 2009 2:47 pm ] |
| Post subject: | |
What are the port size differences between the peanut head solid lifter vs.Hydraulic?Dadtruck had both types .There seemed to be more width in the hydraulic.I am talking about where the manifolds mount. |
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