C3 69 exh and intake bolts?

[dick foehringer]

what is correct? the 427/400 with aluminum intake manifold is supposed to have the "A" flanged bolts?? what about exhaust? Flanged or standard head with cast iron washers? from what i have figured out, the exhaust bolts are the same for with/without a/c and PS except for one bolt on each side that has a stud instead of a regular head. i really enjoy this stuff. if anyone has a 2nd gen camaro question i can help. radio questions also welcomed. you guys have been a great help!!
thanks, dick

[Joe L.]

Re: C3 69 exh and intake bolts?

Dick-----

Three lines (SAE grade 5) with an "A" is one of the headmarks used for 1969 big blocks. 3 lines with an "M" is another. There may have been others, too. All big block intake bolts were flanged head. Engines with aluminum manifolds usually had zinc plated bolts.

The exhaust manifold bolts were of 2 types. Some of the bolts were plain hex head; others were flanged head. I've forgtten which positions used the plain hex head and which used the flanged head. The lengths were very slightly different, too.

[dick foehringer]

2 kinds of exh bolts used at the same time?

were the different exhaust bolts used at the same time? i have about 7 each on my engine plus the 2 special studed ones for PS and A/C. i thought someone had replaced one side. does anyone know where/which they are?
thanks, dick

[Chuck S.]

Re: 2 kinds of exh bolts used at the same time?

Dick, it is not unusual for one side of the vehicle (engine in this case) to have one head stamp and the other side to have another headstamp, or even for two (or more) different headstamps in the same application to be mixed on either side.

This resulted from GM having multiple fastener suppliers (e.g. "A" or "M"), and having two people working the vehicle(or engine), one on each side, and drawing fasteners out of different bins that were being constantly resupplied. If the headstamps are period correct headstamps, the bolts almost certainly original unless the car has been restored by an AR restorer...that is to say if the car has been restored, it is possible that the restorer has replaced any incorrect fasteners with correct (but not original) fasteners.

If there are different types of fasteners (lengths, flanged head vs plain hex head, stud head), the AIM will call out different part numbers at that location. Getting the description of the part numbers, however, is usually not so easy.