checking head to block alignment ?

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mbaird

mbaird

mbaird
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Is there a standard procedure for checking the head to block alignment during rebuild?
I mocked up my heads / block /intake and noticed the intake bolt holes are off a bit pass to drivers side. One head seems further forward than the other or the intake was machined wrong. That got me thinking about the head to block positioning.... Could the dowels and or dowel holes in the head be off?
My cumbustion chambers are a bit bigger than the bore so I will need to notch the bores. But I want to make sure everything is aligned properly first. Not to mention port matching the intake.
 
Checking head to block alignment is easiest to do if the block is bare, no crank, roads, or pistons in the way. With a heads in place and secured with a couple bolts (no need to torque now), just turn it over and reach through the bores with a magic marker and trace the bore diameter onto the head. Remove heads and inspect all outlines on the heads.
 
Good idea on the tracing. The block is bare and I have mounted and flipped the block.
Are offset dowels available if its off?
 
mbaird said:
Good idea on the tracing. The block is bare and I have mounted and flipped the block.
Are offset dowels available if its off?
Click to expand...
Combustion chambers bigger than the bore is a no no. All v 8`s cyl`s are offset. I`d try setting another intake on it for comparison first.
 
most cylinders have a chamfer at the top-measure it, do not go by bore size. try and check intake manifold port to head port alignment-do not go by bolt hole alignment
 
They make offset dowels,yes.

Bare block, bolt heads on, flip and check.
There is nothing wrong with scribing the chambers to the bores, hard to end up bigger doing that when you end up following the bore Id, not od.

More likely the intake is cut too much, thicker gasket or maybe even more likely....what you are seeing is the intake needs cutting...its not sitting level so one side shows off on the threads but really it's both sides.
 
The holes are off front to back. When I line up the drivers side the passenger side holes are too far back by 1/4" ish....
It just got me thinking about all the other motors I had assembled and taken head/block alignment for granted.
Since I am port matching I want to make sure everything is spot on.
 
Pass side head is offset rearwards about the thickness of a connecting rod when compared to the drivers side head. Bores in the block are offset the same amount. It has to be that way.
 
On left hand drive vehicles here in the USA, the passenger side refers to right side of engine as viewed from inside the car. He didn't mean the head itself is different. He meant the block has built in offset toward the rear on the right side. That's built into the block and outside of machining for blueprinting purposes, will not be a factor here. For your intake alignment question, mark your heads and see where they sit compared to the bores. If it's pretty good visibly, just have the intake itself, or the intake manifold and intake face of the heads, machined to correct any difference in mounting face angles, then any one or two bolt holes that still don't line up just get elongated to match.
 
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I want to make sure the intake runners line up to the intake ports.
I will mount the heads to the block and outline the bore with a sharpe .... mount the intake with gaskets and mark exact placement relative to head and intake. Then use the gaskets as templates to verify port/runner alignment.
I have already verified that my cumbustion chambers overlap the bore by about. 060 on the intake side so I could have the machine shop notch the bore accordingly so as not to impede flow.
 
mbaird said:
Yeah.... I was baiting... Lol
Sorry couldnt help myself there.
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You did say "too far back by 1/4". I was just trying to explain to you why it was made like that. They sure as hell didn't machine the bolt holes or the pin locations off by a 1/4". So not knowing WTF you are really asking about, I just did my best to answer your question.
 
I have nevervhad an intake that was this far off. Must be a machining error.... It a never used W2 Victor.
 
U will still need head gaskets to get the intake into proper alignment with ur .015, .030 or .060 thick intake gaskets. Kim
 
Yes... I have considered that. Once the block is decked I will know which one to get desired compression.
 
69_340_GTS said:
Pass side head is offset rearwards about the thickness of a connecting rod when compared to the drivers side head. Bores in the block are offset the same amount. It has to be that way.
Click to expand...
I believe He is saying that the amount of offset appears incorrect on either the intake holes when drilled, or possibly one of the heads had the dowels too far fore/aft.
Yes offset dowels are available in that dia., but do this first........drop a headgasket(the same headgasket) on the block on both sides and examine if the bores are equally
concentric on each deck. If yes, then either pin each head and do the same, or perform the mount & scribe procedure described already. I mark all the heads I do P & D &
score a centerline on each w/a corresponding V notch on the intake and make sure they are "ON" the money before working on them so I know where everything will be
when I assemble it, and that they stay there when it's all torqued down. I still shove My boroscope down there to look around just to be sure..............:)
 
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