454 Q-jet bolts

[Lyndon S.]

What did the typical factory production bolts look like that hold down the Q-jet carburetor on a LS-5. Did they use a large head and built in washer?

[Kenneth T.]

Re: 454 Q-jet bolts

Intersting question Lyndon. I have seen both types, those with just a normal bolt head as shown in the AIM UPC 6 CI item one and then I have seen the type with the washer in the bolt head as per the picture attached. Which one or are both correct? That is a question for the pros here. Ken

[Kenneth T.]

Re: 454 Q-jet bolts

Got it second try. No my engine, but shows the bolts you were asking about.

[Clem Z.]

Re: 454 Q-jet bolts

What did the typical factory production bolts look like that hold down the Q-jet carburetor on a LS-5. Did they use a large head and built in washer?

never saw that type of bolt used on a chevy BUT the were used on oldsmobiles. i always told people who i did Q jets for to get the olds bolts because the hex on the bolts used on chevys cut i to the carb tops or install washers under the chevy bolt heads.

[Lyndon S.]

Re: 454 Q-jet bolts

Yeah, I mean are those typical of Q-jet bolts of that era even on small block cars? Those are the first that I have ever seen that had that head.

[Kenneth T.]

Re: 454 Q-jet bolts

never saw that type of bolt used on a chevy BUT the were used on oldsmobiles. i always told people who i did Q jets for to get the olds bolts because the hex on the bolts used on chevys cut i to the carb tops or install washers under the chevy bolt heads.

My LS5 (original owner car) has the bolt without the washer and I put them under for just that reason. If I have it judged I guess I will have to remove them?

[Patrick H.]

Re: 454 Q-jet bolts

My LS5 (original owner car) has the bolt without the washer and I put them under for just that reason. If I have it judged I guess I will have to remove them?

If the judges seem them.

I used Grade 8 ones which come in the gold iridite finish. They blend in, and the judges never noticed.

Patrick

[Kenneth T.]

Re: 454 Q-jet bolts

If the judges seem them.

I used Grade 8 ones which come in the gold iridite finish. They blend in, and the judges never noticed.

Patrick

Patrick,
Therein lies the fun!

[Clem Z.]

Re: 454 Q-jet bolts

If the judges seem them.

I used Grade 8 ones which come in the gold iridite finish. They blend in, and the judges never noticed.

Patrick

it is not nice to fool the judges.

[Joe L.]

Re: 454 Q-jet bolts

What did the typical factory production bolts look like that hold down the Q-jet carburetor on a LS-5. Did they use a large head and built in washer?

Lyndon-----


Here's the deal: 1970 Corvettes with Q-Jet carbs used unique-to-that-year front retaining bolts for the carb. These were special bolts of GM #3967476. These bolts were 5/16-18 X 3-5/8". They had a flanged (washer) head. I do not know the material grade, finish, whether or not the head was trimmed or untrimmed, and what the across-the-flats (wrench) size was for these bolts.

So, why did they use these bolts for 1970? Well, it had to do with the NA-9 (California emissions) option. For cars equipped with this option, the front carb bolt holes were equipped with insulators. I expect that to improve retention of the insulators, the flanged head bolts were used. However. perhaps to simplify things, the same bolts were specified for all Q-Jet applications and not just those equipped with NA-9.

For early 1971, these bolts were replaced by GM #9432450. These are, from what I can tell, very similar bolts except that they are 3-3/4" long. They have a flanged head, phosphate finish, GM 280M material grade (SAE grade 5--3 lines), and untrimmed ("indented") head. I believe these are also the bolts used on the Oldsmobile applications that clem referred to.

In later 1971, these bolts were replaced in PRODUCTION by GM #9419047. These bolts are the same thread size and length as the 9432450. However, they are a NON-flanged head bolt. They were phosphate-finished and of GM 280-M material grade. I do not know if they had trimmed or untrimmed heads.

Why GM went back to the non-flanged head bolts during 1971 or why they ever used them for 1968-69 Q-Jets, I will never know. I TOTALLY agree with clem; the flanged head bolts should ALWAYS have been used with Q-Jets to avoid damage to the carb air horn. It was a DUMB thing for GM to use non-flanged head bolts for this application----just as dumb as using non flanged head bolts for small block intake manifolds and non-flanged head bolts for head bolts on both small and big blocks. DUMB!

By the way, all of the above-referenced bolts are discontinued and, as far as I know, not reproduced.

[Lyndon S.]

Re: 454 Q-jet bolts


Thanks Joe
Ok then was 9432450 discontinued ?
___________
Kelly

[Joe L.]

Re: 454 Q-jet bolts

Thanks Joe
Ok then was 9432450 discontinued ?
___________
Kelly

Kelly-----


They're all discontinued, including the 9432450. Unfortunately, flanged head bolts of this length are not too common. Generally, 5/16-18 flanged head bolts fall into the under 3" length category and those over that length are "special" bolts. You will rarely find flanged head bolts of any material grade in a hardware store and even industrial suppliers don't usually carry 5/16-18 in over 3" length.

[James W.]

Re: 454 Q-jet bolts

My 1971 #9465 had the flanged style front carb bolts, phosphate finish. This was a Feb 11 build date, I believe.