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Cylinder head alignment for Chevy V-8


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This is the engine from the AMT 1966 Chevy Nova Pro Street kit. As you can see in the photos, one head sits significantly forward from the other, is this the way it is 1:1? Or, do I need to bring them more in alignment with each other, which is what I've always done in the past, just wanted to clarify this for myself once and for all. Any info is much appreciated! Thanks!

Without the heads attached:

blockalignment1_zps2apf2sdo.jpg

With heads attached:

blockalignmrent3_zpsuaxcmfvn.jpg

View showing rear deck:

blockalignment2_zpswwesxlhj.jpg

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Wrong! Even the example you posted shows the misalignment, just look at the Z in the front of the intake manifold, it's there to align the ports properly with the offset cylinder head. This is a result of the crankshaft and the inability to have to rods and pistons exactly across from each other, and the larger the cylinder bore is the larger the offset required, each crankshaft throw has two connecting rods on it, one going to each side of the cylinder block, the fact that they are one in front of the other on the crankshaft means one cylinder (and its head) are offset from the one on the other side.

Usually the side that the number one piston is on is the forward head.

I hope this explains it better to you.

I googled the engine that this is supposed to represent, and in all the photos I found, it is the drivers side head that should be the forward one on the block.

Edited by horsepower
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Wrong! Even the example picture you posted shows that the block on the passenger side is sticking out. This is a result of the crankshaft and the inability to have to rods and pistons exactly across from each other, and the larger the cylinder bore is the larger the offset required, each crankshaft throw has two connecting rods on it, one going to each side of the cylinder block, the fact that they are one in front of the other on the crankshaft means one cylinder (and its head) are offset from the one on the other side.

I hope this explains it better to you.

Correct.

One side of a vee- or otherwise-opposed engine with any number of cylinders will ALWAYS be offset or staggered somewhat to allow for connection of connecting rods to the crankshaft.

This is a flat-4 opposed engine, but you should get the idea...

subaru-boxer-diesel-pistons-crankshaft_1

And a V8, with shared rod-journals...

stock-photo-pistons-and-crankshaft-isola

Edited by Ace-Garageguy
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Thanks everyone, the heads in the photo you show Skylar sure don't have that much difference. It looks like the passenger side might sit back an 1" or so. I need to google a 327 L-79. I just did, and I don't see any set back like the model block shows for the heads, at least not that drastic. Sooooooooooooo, I guess I can move the passenger side forward a little to lessen the stagger, and then it's just a matter of getting the exhaust to line up properly?

Edited by Speedfreak
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Thanks Skylar, the heads in the photo you show sure don't have that much difference, if any. It looks like the passenger side might sit back an 1" or so. I need to google a 327 L-79. I just did, and I don't see any set back like the model block shows for the heads. Sooooooooooooo.

Just FYI...ALL smallblock Chebby engines from 265 through 400 have the same bore-spacing (same as LS engines too), so ALL smallblock Chebby engines will have the same amount of offset between cylinder banks, and so, heads as well. Most kit engines take this into account, and represent it reasonably correctly.

mmMAx_gDuq0vZESdMYItr0w.jpgm2MgrghVAOtTG2shjDACQxw.jpg

Edited by Ace-Garageguy
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Just FYI...ALL smallblock Chebby engines from 265 through 400 have the same bore-spacing (same as LS engines too), so ALL smallblock Chebby engines will have the same amount of offset between cylinder banks, and so, heads as well.

mmMAx_gDuq0vZESdMYItr0w.jpg

Yes but the 396 isn't a small block, it's a big block, and they don't all have the same bore spacing.
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Thanks Del, if the picture that Bill show's (Thanks Bill!) is a Chevy small block, that's the offset I'll go for I think. It's not that far off now. My only question now is do I align the heads so the exhaust lines up? You don't want an offset in that right? I've never seen one anyway.

Edited by Speedfreak
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Yes but the 396 isn't a small block, it's a big block, and they don't all have the same bore spacing.

There's a 400 smallblock. I said "smallblocks", and I'm fully aware the 396 is a big-block, but thanks for the clarification for everyone who didn't already know that. :) The 348 (also being a number less than 400) is a W-block. We have 'em all now? :)

Edited by Ace-Garageguy
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You have to remember that the larger the bore the bigger the offset...

ALL Chevy smallblocks, no matter WHAT bore, have exactly the same bore-spacing. Bore-spacing is the distance between BORE CENTERS, and it's 4.4".

Big blocks and W-blocks have bore-center-spacing of 4.84". That's all. :)

Edited by Ace-Garageguy
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Just FYI...ALL smallblock Chebby engines from 265 through 400 have the same bore-spacing (same as LS engines too), so ALL smallblock Chebby engines will have the same amount of offset between cylinder banks, and so, heads as well. Most kit engines take this into account, and represent it reasonably correctly.

mmMAx_gDuq0vZESdMYItr0w.jpgm2MgrghVAOtTG2shjDACQxw.jpg

Actually all the early small block motors have the same 4.400 spacing but the LS engines vary from 3.898 to 4.100. So none of the LS series engines have the same bore spacing as the early small blocks not even the new 427 inch one.

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Excuse me for not being exactly clear, what I meant TO say was that the bore spacing was almost a half inch difference, actually it's almost .400 difference but a tenth of an inch the way I measure is not even noticed, you know what they say about racers, measure with a micrometer, mark with a crayon, and cut with a torch.

I'm sure that if you're a rivet counter repositioning the cylinder heads on the block is a necessity, but to me and other average builders it's not worth the work of redoing the intake manifold and the exhaust system to do something that for most of us wouldn't even be noticed IF we show the car with the hood open.

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Actually all the early small block motors have the same 4.400 spacing but the LS engines vary from 3.898 to 4.100. So none of the LS series engines have the same bore spacing as the early small blocks not even the new 427 inch one.

Ummm...wrong. The BORE varies by the numbers you quote, but the BORE SPACING is the same as smallblocks at 4.4".

BORE is not the same as BORE SPACING.

Crankshafts interchange between many members of the LS family, and this simply WOULD NOT BE POSSIBLE if the bore spacing was different between engines. Quoting from Motor Magazine http://www.motor.com/article.asp?article_ID=1681

"The Gen III engine (LS1/LS6) started with a clean sheet of paper in terms of design. Aside from cylinder bore spacing, rod journal diameter and lifter diameter, Gen III/IV engines have nothing in common with previous Chevy small-blocks."

And a further FYI...there is an aftermarket smallblock-Chevy-like block casting that accomodates LS heads. I've posted an article about it here much earlier. This is possible because both the LS and the smallblock have identical 4.4" bore-spacing, but the aftermarket block provides different head bolt locations to fit the LS heads.

Edited by Ace-Garageguy
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Thanks Del, if the picture that Bill show's (Thanks Bill!) is a Chevy small block, that's the offset I'll go for I think. It's not that far off now. My only question now is do I align the heads so the exhaust lines up? You don't want an offset in that right? I've never seen one anyway.

It doesn't really matter WHAT conventional V8 engine you're building...they will ALL have about the same head offset, including old flatheads...which is why I wasn't all that careful about the pix of bare blocks. They're just to illustrate the point.

Here is a blueprint of the SBC basic engine, clearly showing the 4.4" bore spacing, and the offset between cylinder banks, as discussed, to accommodate connecting rod fitment on shared rod-journals of the crankshaft.

SBCbottCustom.jpg

Edited by Ace-Garageguy
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Correct.

One side of a vee- or otherwise-opposed engine with any number of cylinders will ALWAYS be offset or staggered somewhat to allow for connection of connecting rods to the crankshaft...

Unless it has knife & fork con rods...

:rolleyes:

Sorry Bill. Couldn't resist.

Fred

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Correct.

One side of a vee- or otherwise-opposed engine with any number of cylinders will ALWAYS be offset or staggered somewhat to allow for connection of connecting rods to the crankshaft.

I'm guessing you've never worked on a Harley Davidson have you :rolleyes: Zero Offset.

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Unless it has knife & fork con rods...

:rolleyes:

Sorry Bill. Couldn't resist.

Fred

Ok, I should have said "any vee or opposed engine you're likely to encounter in a car"... :D

I'm guessing you've never worked on a Harley Davidson have you :rolleyes: Zero Offset.

You are correct sir...I have never once laid a wrench on a Harley engine of any kind...and I should have been more careful about making a sweeping generalization. :D

I have, however, worked on a few of these...which also have zero-offset. wasp-3--Wasp-Jt.jpg

radial10.gif

Edited by Ace-Garageguy
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One of the Best Birthday Presents I ever got my Wife was Stick time in a Stearman. Good ol' Radials, the best sounding Internal Combustion Engines EVER!!

I have to agree with that. Every time I hear one fly over, I run outside to listen as long as possible. I worked for a few months on the Kingman, Az. airport next to the hangar where several CL-215s lived in the off season. The engines were Pratt /Whitney R-2800s, and they'd push 'em out and run 'em up several times a week. Wonderful.

Edited by Ace-Garageguy
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