1969 - 1972 LT1 and Big Block Hood

[David S.]

Hi All,

What's the difference between a first design 69 - 72 LT1 and Big Block hood and a second design? Any reference pictures?

Thanks,
Dave

[Joe L.]

Re: 1969 - 1972 LT1 and Big Block Hood

Hi All,

What's the difference between a first design 69 - 72 LT1 and Big Block hood and a second design? Any reference pictures?

Thanks,
Dave

Dave------

The differences apply to both BB/LT-1 and small block hoods.

Externally (i.e. as viewed with the hood closed), I don't know of any difference.

Viewed from the underside, there are two notable differences. First, the 1st design hood has two anchor points (embedded nuts) for the cross cable. The 2nd design has one anchor point. Second, the mounting bolt pattern for the right (passenger) side lock plate is different than 1st design.

There MAY also have been a difference in location for the hood support attachment point for 1972 hoods. I'm not sure about this as my recollection is somewhat "hazy" on this point.

[Terry M.]

Re: 1969 - 1972 LT1 and Big Block Hood

Dave------

The differences apply to both BB/LT-1 and small block hoods.

Externally (i.e. as viewed with the hood closed), I don't know of any difference.

Viewed from the underside, there are two notable differences. First, the 1st design hood has two anchor points (embedded nuts) for the cross cable. The 2nd design has one anchor point. Second, the mounting bolt pattern for the right (passenger) side lock plate is different than 1st design.

There MAY also have been a difference in location for the hood support attachment point for 1972 hoods. I'm not sure about this as my recollection is somewhat "hazy" on this point.

Joe
You are correct in the mounting point for the 1972 hood support. It is farther forward for 1972 than for 1969 to 1971 to accommodate the different 1972 hood support. There were some SERVICE hoods made with provisions for both mounting points.

[David S.]

Re: 1969 - 1972 LT1 and Big Block Hood

Hi Guys,

Thanks for the info. Trying to determine if this LT1 hood is original. Pictures aren't the greatest but it gets the point across. This is from a March 70 built car. My June 70 LT1 has a slightly different under hood design. Both have the part number and both have the circles.

I'm not sure of the small pop rivets that the pictured hood has.

Thanks,
Dave

IMG_8558.jpgIMG_8559 2.jpgIMG_8560.jpgIMG_8561.jpg

[Joe L.]

Re: 1969 - 1972 LT1 and Big Block Hood

Hi Guys,

Thanks for the info. Trying to determine if this LT1 hood is original. Pictures aren't the greatest but it gets the point across. This is from a March 70 built car. My June 70 LT1 has a slightly different under hood design. Both have the part number and both have the circles.

I'm not sure of the small pop rivets that the pictured hood has.

Thanks,
Dave

[ATTACH=CONFIG]67430[/ATTACH][ATTACH=CONFIG]67431[/ATTACH][ATTACH=CONFIG]67432[/ATTACH][ATTACH=CONFIG]67433[/ATTACH]

Dave------

I believe this is a SERVICE hood from 1972+. Note that it has the dual mounting points for the hood support. This is what Terry M. was referring to in his post. I would not rule out the possibility that this type of hood was used in PRODUCTION for some cars but, IF so, that would be applicable only to 1972 models. The alternate hood support requirement would not have existed prior to that time.

The pop rivets that you mention retain the nut plates for the hood support. There are two sets of rivets because there are two hood support mounting points on this hood.

What about the cross cable anchor points and right side latch plate bolt pattern I described? I can't see those in any of your photos.

[David S.]

Re: 1969 - 1972 LT1 and Big Block Hood

Hi Joe,

Those are the only pictures I have right now. Let me see if I can get more.

Is a 70 and 71 BB hood the same as a 70 and 71 LT1 hood? For a March car I assume the hood should have one anchor of the release cable and the hood prop should be on the driver side with no pattern to bolt on the passenger side?

My June built LT1 has its original hood and the hood prop is on the driver side. I believe it has one anchor but I would have to double check.

Thanks,
Dave

[Joe L.]

Re: 1969 - 1972 LT1 and Big Block Hood

Hi Joe,

Those are the only pictures I have right now. Let me see if I can get more.

Is a 70 and 71 BB hood the same as a 70 and 71 LT1 hood? For a March car I assume the hood should have one anchor of the release cable and the hood prop should be on the driver side with no pattern to bolt on the passenger side?

My June built LT1 has its original hood and the hood prop is on the driver side. I believe it has one anchor but I would have to double check.

Thanks,
Dave

Dave------

The 1970 and 1971 big block hoods and 1970 and 1971 LT-1 hoods were not the same. The early 1970 big block hood was GM #3964150 and late 1970-all 1971 big block hood was GM #3966669. The LT-1 hood for both 1970 and 1971 was the same GM #3962690. Just what the difference is, I do not know. There certainly was no difference as far as the functionality aspects I mentioned previously. I do not think that these hoods had the dual mounting locations for the hood support.

I did a little more research and found that for 1972, the big block and LT-1 hoods were the same----GM #3996864. The 1972 big block SERVICE hood was also the same part number. The 1972 small block PRODUCTION hood, GM #3996855, was also the same part number as the SERVICE hood. Both the 1972 BB/LT-1 hood and 1972 SB hood became SERVICE for 1968-71 Corvettes and remained so until both were finally discontinued without supersession. All C3 hoods used left (driver) side hood supports.

This makes me wonder if PRODUCTION 1972 hoods had the dual hood support mounting locations. Of course, it's possible that the specifications for the 1972 hoods were changed sometime after the 1972 model year to include both mounting locations. That seems rather unusual to me, though, for a change such as this. What can folks with 1972's with original hoods tell us about the support mounting provisions on their hoods?

[Kevin G.]

Re: 1969 - 1972 LT1 and Big Block Hood

Dave------

The 1970 and 1971 big block hoods and 1970 and 1971 LT-1 hoods were not the same. The early 1970 big block hood was GM #3964150 and late 1970-all 1971 big block hood was GM #3966669. The LT-1 hood for both 1970 and 1971 was the same GM #3962690. Just what the difference is, I do not know. There certainly was no difference as far as the functionality aspects I mentioned previously. I do not think that these hoods had the dual mounting locations for the hood support.

I did a little more research and found that for 1972, the big block and LT-1 hoods were the same----GM #3996864. The 1972 big block SERVICE hood was also the same part number. The 1972 small block PRODUCTION hood, GM #3996855, was also the same part number as the SERVICE hood. Both the 1972 BB/LT-1 hood and 1972 SB hood became SERVICE for 1968-71 Corvettes and remained so until both were finally discontinued without supersession. All C3 hoods used left (driver) side hood supports.

This makes me wonder if PRODUCTION 1972 hoods had the dual hood support mounting locations. Of course, it's possible that the specifications for the 1972 hoods were changed sometime after the 1972 model year to include both mounting locations. That seems rather unusual to me, though, for a change such as this. What can folks with 1972's with original hoods tell us about the support mounting provisions on their hoods?

Not the best shot but here is a photo of my 71 454 5 Star Bowtie car #8555

[Terry M.]

Re: 1969 - 1972 LT1 and Big Block Hood

Dave------

The 1970 and 1971 big block hoods and 1970 and 1971 LT-1 hoods were not the same. The early 1970 big block hood was GM #3964150 and late 1970-all 1971 big block hood was GM #3966669. The LT-1 hood for both 1970 and 1971 was the same GM #3962690. Just what the difference is, I do not know. There certainly was no difference as far as the functionality aspects I mentioned previously. I do not think that these hoods had the dual mounting locations for the hood support.

I did a little more research and found that for 1972, the big block and LT-1 hoods were the same----GM #3996864. The 1972 big block SERVICE hood was also the same part number. The 1972 small block PRODUCTION hood, GM #3996855, was also the same part number as the SERVICE hood. Both the 1972 BB/LT-1 hood and 1972 SB hood became SERVICE for 1968-71 Corvettes and remained so until both were finally discontinued without supersession. All C3 hoods used left (driver) side hood supports.

This makes me wonder if PRODUCTION 1972 hoods had the dual hood support mounting locations. Of course, it's possible that the specifications for the 1972 hoods were changed sometime after the 1972 model year to include both mounting locations. That seems rather unusual to me, though, for a change such as this. What can folks with 1972's with original hoods tell us about the support mounting provisions on their hoods?

Joe
I have looked at a lot of original 1972 hood undersides. All I have seen had only one mount location for the hood prop.
If the 1972 PRODUCTION and SERVICE hood part numbers are the same then either the SERVICE hood(s) with the dual mounts came after 1972 or the part number remained the same and the added prop mount came to be without a part number change. I know the latter is unlikely, but not unheard of. Maybe the SERVICE hood with dual mounting locations came after the supply of 1970-71 SERVICE hoods dried up.

[Joe L.]

Re: 1969 - 1972 LT1 and Big Block Hood

Not the best shot but here is a photo of my 72 LT-1 5 Star Bowtie car #20942

Kevin-------


Yes, this shows a hood with only the one support attachment point. However, the really strange thing here is that this car has the 1968-71 style hood support, not the 1972 style.

Also, I don't understand why the hood has the studs for the numerals showing-----LT-1's used decals not stud-fastened numerals. The upper radiator hose, fan shroud and radiator appear like the big block parts to me, too.

[Kevin G.]

Re: 1969 - 1972 LT1 and Big Block Hood

Kevin-------


Yes, this shows a hood with only the one support attachment point. However, the really strange thing here is that this car has the 1968-71 style hood support, not the 1972 style.

Also, I don't understand why the hood has the studs for the numerals showing-----LT-1's used decals not stud-fastened numerals. The upper radiator hose, fan shroud and radiator appear like the big block parts to me, too.

Joe, I will check for my information to be sure but I do believe this is the correct 72 style? My 71 is not the same, let me get a picture of them both. The one must be "released by hand" the other simply lift the hood higher for it's release to operate.

I may have confused my picture albums?

[Patrick H.]

Re: 1969 - 1972 LT1 and Big Block Hood

Kevin-------


Yes, this shows a hood with only the one support attachment point. However, the really strange thing here is that this car has the 1968-71 style hood support, not the 1972 style.

Also, I don't understand why the hood has the studs for the numerals showing-----LT-1's used decals not stud-fastened numerals. The upper radiator hose, fan shroud and radiator appear like the big block parts to me, too.

I think that Kevin may have accidentally grabbed a photo of his big block 71.

[Kevin G.]

Re: 1969 - 1972 LT1 and Big Block Hood

I think that Kevin may have accidentally grabbed a photo of his big block 71.

Exactly.......my apologies. Being the same color often makes for picture mix ups.....Perhaps I should delete the earlier photo?

Here is the 72...

[Joe L.]

Re: 1969 - 1972 LT1 and Big Block Hood

Exactly.......my apologies. Being the same color often makes for picture mix ups.....Perhaps I should delete the earlier photo?

Here is the 72...

Kevin------


That's more like it. I note that there are indentions for the rivets for the second support location but no nut plate and rivets were installed.

So, this pretty much confirms that at least some 1972 hoods were manufactured and used without the secondary nut plate location. Apparently, the specifications for the part number were changed sometime during/after 1972 for SERVICE hoods. Still, it would be interesting to find out if any PRODUCTION 1972 hoods had the dual mounting provisions.

[Kevin G.]

Re: 1969 - 1972 LT1 and Big Block Hood

Again, my apologies for the mix up.

Perhaps we should be looking for a very early 72? This is a May 72 built vehicle. Well, at least now my pictures have shown two different styles for future reference....