VCCA Home Forums Thread Like Summary - 1932 new head bolts

I am looking for new head bolts for my 1932. I checked some of the usual sources and found used. Any sources for new? Thanks!

I would not be concerned with the new bolt being 1/8” shorter. As noted in that older post, chase the threads in the block and clean the holes very well. I spray brake cleaner in the holes, let it dry, and then blow them out with compressed air. You do not want any liquid in the holes.

Make a couple of guide pins from your old bolts. That will make sure the head gasket does not shift when you set the head on the block.

I will let a ‘32 expert jump in if my practice is not appropriate for a ‘32 engine. I do dip the head bolts completely in engine oil. Then I let them lay on a rag for quite a while so most of the oil drains away. I want just a light uniform coating of oil including under the head and along the full body.

For these bolts being oiled and threading into cast iron I would target 60 ft. Lbs as the final value. I always tighten in the sequence shown in the shop manual. I typically go in 3 steps starting at 50%, then 75%, and then 100% of that final value. Some people like to do 4 steps with the 3rd step being 90%.

Adding to Rusty's idea with the oil I put a drop of oil on the end couple of threads and another under the head just before putting them into place. That way there is no binding of the threads or head to give a false torgue reading.
Tony

A technique I learned from an old mechanic 60 years ago was to tightened each bolt using three to four cycles at each step. The cycles are tighten to the specific torque, back off, tighten again noting if the wrench moved further than last time. If it moved a noticeable amount repeat. What is happening is that the high spots on the threads both on the bolt and block are smoothed out. When re-torquing after several heat cycles I find little to no difference.

I agree that this became a great technical discussion. Thanks for moving it!

If wire brushing removed that coating it definitely did not have good adhesion.

There is minimal risk using those bolts. The big variable that we tried to control in bolted joints was the coefficient of friction between the threads and under the bolt head. Different coatings and platings plus the presence or absence of a lubricant change that coefficient. If the coefficient is high it takes more torque to produce the same clamp load. If it is low you can overload the bolt in tension.

Just do the oil thing and tighten the bolts in stages as discussed. I do not know if the head gasket you are using requires that the head bolts be re-torqued after some use. Follow whatever instructions came with the gasket.

Part16john

are you looking for some close to original bolts for the head ?? same length, same head, etc ??
if my memory serves me the original are NOT grade 5 or 8, grading bolts came around in the late 60's

considering we only torque them down to Cylinder Head Bolt OLD: 55 to 65 ft-lb, Cylinder Head Bolt NEW: 65 to 75 ft-lb

Call Alma Bolt Company out in Michigan [https://www.almabolt.com/] they can make you the bolt you want or tell you what they have in stock that is really really close :) and pretty reasonable pricing. we use them for custom bolting, and i talked to them when i was doing my 1929 head, and they had great info and lead times.

original head bolt height was .386 they have a Gr9 that is .375, Gr8 .320

understood...

I would take the plain steel bolts you bought from McM and put them in the head and see how much sticks out hte other side. Measure the protrusion, and minus 1/16 to 1/8 for gasket crush thickness. as long as you are close to 3/4" i would not blink and eye. I would install and use. all you need is to secure the head to the block and crush the gasket to seal it up :) if they are short then get some 4 1/4" long ones (see below)

the original bolts were not graded, and the bolts of today are far superior.

A Grade 5 bolt has a Tensile Strength: 120,000 psi minimum, so you are more likely to strip/ rip the threads out of the cast iron block BEFORE you destroy the bolt. you are only tightening to 70-75 ft lb !!

Make sure you tighten the head bolts per the sequence in the manual, i did mine in 3 steps. 35, 55, 70 !! each one in order then next torque

4 1/4" long plain grade 5 bolts https://www.fastenal.com/product/details/12220
4 1/4" long yellow zinc grade 8 bolts https://www.fastenal.com/product/details/15220 (most grade 8 are yellow zinc, typically makes them easy to id, plus the head marking)