1970 Corvette Q-Jet bolts

[Dennis D.]

Re: 1970 Corvette Q-Jet bolts

First from my 70 and second from a rather original car....

[Joe L.]

Re: 1970 Corvette Q-Jet bolts

First from my 70 and second from a rather original car....

Dennis------


Can you do a good close-up of the bolt head on either or both of these?

[Dennis D.]

Re: 1970 Corvette Q-Jet bolts

Took the bolt out. Always thought it was a crappy design, since the milled in washer didn't prevent the bolt head points from digging into the airhorn

[Joe L.]

Re: 1970 Corvette Q-Jet bolts

Took the bolt out. Always thought it was a crappy design, since the milled in washer didn't prevent the bolt head points from digging into the airhorn

Dennis------

Excellent photos. This is not a flanged head type bolt; it's just a conventional hex head bolt. The slight raised area under the head is typical of most standard, hex head bolts. While it provides some bearing surface, it's so small in area that it galls any sort of soft surface it bears on (like a Q-Jet air horn).

This bolt is almost identical to the original bolts from my 1969 with Q-Jet. The only difference is that there is a headmarking. The bolts on mine had no headmarking, at all. I always considered this unusual since GM usually requires a manufacturer's ID on bolts. Plus, the bolts that were supposed to have been used for 1968-69 models equipped with Q-Jets were GM #187147. This bolt is supposed to have been manufactured of GM 280-M material (SAE grade 5; 3 lines). So, the fact that there were no grade identification lines on the bolt head is also curious. While your bolts do have a headmarking, they have no grade identification marks either. I can't find that ANY bolts specified for use for 68-81 Q-Jet application were supposed to be ungraded steel (although I can't see where any significant strength would actually be required and don't know why all the specified bolts were 280-M in the first place).

As far as I can tell, you bolts are essentially identical to the ones used on my 1969 except that yours have a manufacturer's ID headmarking and mine do not.

[Dennis D.]

Re: 1970 Corvette Q-Jet bolts

I enlarged the bolt from the other photo's carb. Has the "A" but also 3 dashes as you indicated

[Alan S.]

Re: 1970 Corvette Q-Jet bolts

Hi Again,
Stirring the pot....
In the bag with the bolts were 2 lock washers with the same plating as the bolts and the same slightly used condition! Thus I've thought that there were lock washers on these bolts. Has anyone else seen them?
I have them in place but....?
Regards,
Alan

[Terry M.]

Re: 1970 Corvette Q-Jet bolts

I don't think the front bolts get lock washers, but what is the configuration of the rear fasteners?

[D S.]

Re: 1970 Corvette Q-Jet bolts

I don't think the front bolts get lock washers, but what is the configuration of the rear fasteners?

Would they both be threaded studs with nuts on them? Would they be nuts with built in washers?

[Terry M.]

Re: 1970 Corvette Q-Jet bolts

They could be studs with nuts (NO built-in washer) and those might have a split lock washer -- OR they could be short bolts with no built-in washer and no lock washer.

I sort of thought you might know what the configuration of yours was. Maybe I should have just suggested the lock washers you have might go on the rear, and quit at that.

[D S.]

Re: 1970 Corvette Q-Jet bolts

They could be studs with nuts (NO built-in washer) and those might have a split lock washer -- OR they could be short bolts with no built-in washer and no lock washer.

I sort of thought you might know what the configuration of yours was. Maybe I should have just suggested the lock washers you have might go on the rear, and quit at that.

Terry, mine are studs with nuts and lock washers. Maybe someone here reading this might be able to provide a photo of original studs and bolts and washers used, if any.

[Clem Z.]

Re: 1970 Corvette Q-Jet bolts

the throttle cable holding bracket was attached to the 2 rear bolts on the Qjet so i would guess they would use lock washers to be safe.

[Joe L.]

Re: 1970 Corvette Q-Jet bolts

Hi Again,
Stirring the pot....
In the bag with the bolts were 2 lock washers with the same plating as the bolts and the same slightly used condition! Thus I've thought that there were lock washers on these bolts. Has anyone else seen them?
I have them in place but....?
Regards,
Alan

Alan------

My 1969 never had any lockwashers on either the front bolts or the rear studs/nuts. Plus, the AIM's do not show that any washers of any kind were used on the front bolts or rear studs/nuts. The use of lockwashers on either the bolts or the nuts would guarantee damage to the soft aluminum or zinc diecast material on which they bear.

[Joe L.]

Re: 1970 Corvette Q-Jet bolts

Would they both be threaded studs with nuts on them? Would they be nuts with built in washers?

Scott------

The nuts used for the rear studs were a standard hex head nut and were NOT of the flanged variety based on my original 1969 and other original 68-71's I've looked at. Plus, the nut specified in the AIM, GM #120368, is a standard, non-flanged, 5/16-18, GM 280-M, zinc plated nut. That's exactly what was apparently used on my car.

For 1972 the method of attachment for the rear Q-Jet fasteners was changed. Instead of studs with nuts, standard, hex head bolts were used. These bolts were supposed to have been used with no washers of any kind.

[Clem Z.]

Re: 1970 Corvette Q-Jet bolts

Alan------

My 1969 never had any lockwashers on either the front bolts or the rear studs/nuts. Plus, the AIM's do not show that any washers of any kind were used on the front bolts or rear studs/nuts. The use of lockwashers on either the bolts or the nuts would guarantee damage to the soft aluminum or zinc diecast material on which they bear.

the steel cable holder bracket fit on top of the Qjet base in the rear so the lock washers would make contact with the steel bracket not the aluminum Qjet base plate if lock washer were used

[Joe L.]

Re: 1970 Corvette Q-Jet bolts

the steel cable holder bracket fit on top of the Qjet base in the rear so the lock washers would make contact with the steel bracket not the aluminum Qjet base plate if lock washer were used

clem------


Yes, that's correct. A lockwasher could have been used at this location without causing any damage to the carb. However, there were no lockwashers on the left rear stud on my carb and the AIM does not specify that any were to be installed at this location.