Intake manifold bolt length?


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By Melly - 5 Years Ago
Getting ready to install intake on my y block. Can anyone help me with the length of the bolts. I have read of issuse with starting the bolts after install new intake gasket. To long on bolts would hit the push rods.
Don’t want to make big problems so please any and all info is needed.
If I was to take valve cove off would I be able to see the bolts and clearance?
By Florida_Phil - 5 Years Ago
Intake manifold bolts are different lengths depending upon the location.  If you pull the valve covers and look down the push rods holes, you should be able to see any interference with the push rods.  I have tubular push rods in my motor which are much thicker than stock.  My stock manifold bolts do not interfere.  If your intake bolts came from Ace Hardware, this may be the case.
By darrell - 5 Years Ago
when you drop the bolts in the hole you should have about 5/8 sticking out before you start them.if you take the covers of you can see.
By Florida_Phil - 5 Years Ago
My end intake manifold bolts are 1 1/4" long from the bottom of the head to the end of the bolt.  They do not touch the push rods.
By charliemccraney - 5 Years Ago
Use thread sealer on the bolts that go into the pushrod holes and water jacket.
By Ted - 5 Years Ago
A little bit of a repeat here.
 
As mentioned, bolt lengths will vary somewhat depending upon which manifold you are using.  From the parts manual, most oem 1957 and newer Y intakes use:
(2) 3/8-16 X 1 1/8” at the fronts
(2) 3/8-16 X 3” at the second from the fronts
(2) 3/8-16 X 1 ¾” at the rear.
 
The front bolts are much the same on all manifolds and those are the ones that usually get you in trouble if being too long.  The front bolts being 1¼” long is not expected to be a problem but looking at the front pushrod holes with the valve covers off to verify that the bolts are not extended into those pushrod holes would be a good idea.  On the aftermarket intakes, bolt lengths for the other bolts must be double checked before installing the manifold to ascertain the correct lengths.
By Florida_Phil - 5 Years Ago
Good info.  I will be swapping manifolds soon and will be sure to check push rod clearance. Thank you!
By Melly - 5 Years Ago
As always you all come through for us that are not so in formed..This is what makes this such a great site, and great people.  Willingness to reach out on timely manner with great help.  This is what keep the Dream Alive everyone here.

Figure that I might as well remove the valve cover and check it out.  Better safe then a major issue 

Thanks again