dowel pins purpose?

[fivemustangs]

I was wondering how inportant the head dowel pins are to assembling an engine and what could happen if you do not install them. I know they help align the heads, but just wondering the effects of the heads not being aligned right i suppose.
Thanks!

 

[Chythar]

The head bolts (or studs if you use them) do not precisely align the heads, so the dowels are needed. You need a precise alignment so your lower intake manifold will seal up properly without warping or leaking. You also may have problems with piston-to-valve clearance. The tolerances on these things are measured in thousandths of an inch, so you want to make absolutely sure that the heads are exactly where they are supposed to be.

 

[srtthis]

The head bolts (or studs if you use them) do not precisely align the heads, so the dowels are needed. You need a precise alignment so your lower intake manifold will seal up properly without warping or leaking. You also may have problems with piston-to-valve clearance. The tolerances on these things are measured in thousandths of an inch, so you want to make absolutely sure that the heads are exactly where they are supposed to be.

what he said...

they have a ground surface which can be held into the +/- .xxx MM range...

 

[fivemustangs]

Ok that all makes sence. Also do you think it could burn up head gaskets quicker? or let coolant/oil into cylinders, or other places they don't belong?
Thanks-

 

[BlownFiveLiter]

You could easily do a lot of damage to an engine without the dowels installed. Coolant passages might not line up correctly, fire rings on the cylinders may not seal, the heads could potentially move around under load. It could definitely let coolant and oil mix, or let coolant into the combustion chamber.

 

[final5-0]

Yeah ... What them Guys said

But more importantly :Word:

If you don't use em

The head is gonna fall on the garage floor
when you let go of it to put in the first bolt

Grady

 

[Chythar]

Yeah ... What them Guys said

But more importantly :Word:

If you don't use em

The head is gonna fall on the garage floor
when you let go of it to put in the first bolt

Grady

So true.

 

[nmcgrawj]

Yeah ... What them Guys said

But more importantly :Word:

If you don't use em

The head is gonna fall on the garage floor
when you let go of it to put in the first bolt

Grady

So true.

Not if he uses studs....

 

[revhead347]

I love Grady's answer. Ain't that the truth.

Kurt

 

[True 5.0]

Also, many after market heads are bored with 1/2" holes so they can be used on 5.8 blocks. The 5.0 only uses 7/16" bolts or studs which allow way too much slop.

 

[nmcgrawj]

Also, many after market heads are bored with 1/2" holes so they can be used on 5.8 blocks. The 5.0 only uses 7/16" bolts or studs which allow way too much slop.

Not that they fix the problem and allow u not to use dowel pins....but they have the washers to fill in that "slop". So its not like you have 1/32" gap around the bolt...

 

[Black Stampede]

This is not a hypothetical situation is it? Just come clean, you did this. :Track:

 

[fivemustangs]

lol, you caught me! but the problem is fixed now.