Midyear BB & SB Differences + Reference

[Jack H.]

In looking to purchase a 1965-1967 SB or BB Roadster, I have encountered many supposed BB cars that seemingly started their lives as SB's, i.e. wrong gauges, wrong rear, etc. Others are harder for me to tell, plus the fact that things like gauge clusters, rears, sway bars, etc. are easily swapped. My questions:

1) What are some of the more subtle differences which truly differentiate the SB/BB that may be more definitive, often overlooked, or otherwise not done with an engine swap? If it varies by year I am mostly interested in 1967.

2) What is a good reference book which would include this type of info? I already have the more basic Black Book and Buyer's Guide type books, so I am looking for the next level of detail. Recommendations?

Thanks,

Jack H. (#33879)

[Iron Duke NCRS #22045]

Re: Midyear BB & SB Differences + Reference

SBs and BBs might have the same rear gears and tach redline depending on the horspower rating, so this is not a good indicator, unless the car has a claimed 425/435 horsepower BB with a redline lower than 6500. The big clue might be the rear anti-roll bar. To the best of my knowledge, all mid year BBs, regardless of horsepower or suspension option (if any), had a rear anti-roll bar. Some SBs may have had the frame holes and weld nuts and the holes in the trailing arms, but no mid year SBs, even with the HD suspension, had rear bars from the plant.

Another good clue might be the differential side yokes. SBs have a "strap" retaining the U-joint cups, and I believe all BBs had the "cap" type retainers. For this reason all mid-year BBs have a unique two letter code for the diff, so you can check the actual diff code with the NCRS Spec Guide and determine if the diff was originally for a SB or BB. The rear diff code may be the smoking gun, but you should look at all the indicaters and draw your own conclusion.

Duke

[WayneC]

Re: Midyear BB & SB Differences + Reference

I am not an expert in this area, but I've saved some past posts that gave these possible clues:

1. spindle yokes differ on the big blocks (including 65 396's): the big block U-joints have caps with bolts thru them instead of regular U-bolts to hold the bearings.

2. a rear sway/stabilizer bar

3. 1" diameter front sway bar (7/8" on small block)

4. 3/8" frame fuel line with 45 degree bend to fuel pump (versus 5/16" and 90 degree); the fuel line is difficult to change without lifting the body.

5. 0 to 80 psi oil gage

6. 6500 rpm redline on tach (but hi-perf small block engines also had this)

7. hood support is on the drivers side (also true for some small block cars with air conditioning)

[Iron Duke NCRS #22045]

Re: Midyear BB & SB Differences + Reference

The 80 psi oil pressure gage is on SHP and Fuel Injection SBs beginning in late '63, but I'm not sure if it continued with the SHP with hydraulic lifters (327/350) engine from '65 to '67. Didn't know about the fuel line. That could be the real smoking gun. The front anti-roll bar on the mid year SBs should be 3/4 " except the HD suspension, which is 15/16". Base suspension BBs have a 7/8" front bar and 9/16" rear bar. Not sure about the bar on F-41 BBs in '66 and '67, but I believe F-41 just added the HD springs and specific shocks with the same bars.

Duke

[Don O'Connell #33101]

Don't over look the VIN number...

Jack,

Assuming it has not been restamped (lots of stuff in the archives on restamps), this is a "simple" check (i.e. the last part of the VIN number is stamped into the engine block on the pad in front of the passenger side head).

Don

[Wayne M.]

[grr]

Re: Iron Duke has it right.

My 67 B/B L-71 coupe has just been described by all the treads but this last one by Iron Duke is really good info. Write it down and make out a check list. Even ask questions we gave you some info to use.

Check the hoods on these cars also. If you have a small block you shouldn't be running a B/B striped hood w/427 numbers on it. The small block hood had no scoop or stinger. Except...........????????????????????

I read somewhere in 1967 for a very short period of time. I mean like days they had no small block hoods availble so they put big block hoods on all the corvettes to be shipped out. So if some guy tells you about his stock SB with a original big block hood (w/out) numbers, he may be right. I think I read it in Nolan Adams mid-year book. I can't remember if he mention the build date period.grr#33570

[Jeff]

I think you read it in the National Enquirer...

...right next to "Aliens Buried in the White House Lawn".

JP

[grr]

Re: No I read it where i said it, Jeff.

Jeff, REf: Big block hoods.

I'm sure you have a copy of Noland Adams-Vol.2 1963-67,updated edition. I ask you to read it.

I bought my book about 4 months ago from NCRS Store. If you have a mid-year and don't have the book get it. It has stuff I never knew existed such as the "67 Hood". A must for resto research.

Turn to page no.384, Section "BODYWORK" read paragraphs 4-5 and 6. Read and then you can think whatever you want. I hope you learned something if you read it. I sure did, I would have thought like you,impossible. There may not be to many who have ever read this before or know it.

It was part my research for the 67 resto I'm doing now so I would have a better handle on the cars production releases and weird stuff. How about a little help with my post on the exhaust pipes. I blame myself for not checking when I bought them right away. I'll find out tomorrow.grr#33570

[Jim T.]

Re: (some) Midyear BB & SB Differences

A lot of information is given here on what to look for especially the fuel line difference. If I was going to buy a BB I would put the car on a lift and examine the fuel line front to rear to make sure it wasn't spliced. Would't it be nice to be able to contact the NCRS or Corvette Museum and for a fee by just supplying your VIN find out how a Corvette left the factory?

[Gene M.]

Re: Midyear BB & SB Differences + Reference

Jack.......If you are looking at a 67 big block it MUST have a St. Louis body and NOT an AO Smith.

[Gene M.]

Re: Midyear BB & SB Differences + Reference

I must add to my last post that a BB 67 with a very low VIN number is possible with an AO Smith body just prior to elimination of BB build at the AO Smith plant. The VIN would have to be below 1,000.

[Jeff]

Has anyone ever seen one of those cars?

I am pretty sure that someone (I know) put together the car Noland uses as an example in his book and I think that, at least at one point in its life, it had 65 dated glass and the wrong color fiberglass (which it likely still has).

JP

[Robert C.]

Re: ) Yes Jim, that would be the Holy Grail! nt

Texas Chapter NCRS

[Robert C.]

Re: other differences

There are some other things; All small blocks w/o power stearing have a bracket on the left side front frame(just behind the tire at 3 o'clock) to hold the end of the stearing dampner. NO big block has this bracket. You look close for evidence of the bracket being installed. All frames have the holes but if the bracket was there before, you can tell. Also the hood support, where it bolts to the right side inner fender on small blocks would have to be filled etc. to be moved to the left side for big blocks. I have been told that there are places on the firewall that appear different, although I don't know what the difference is. The best place to look and the quickist is the trailing arm holes for the end pivit support for the rear stabilizer bar. NO original small block trailing arms have these holes. They would have to be drilled to install the bar. A 400hp 67 BB i just looked at yesterday had no stabilizer bar and the left side trailing arm had NO holes. You could see where the front stearing dampner bracket had left an impression on the frame. The tach is the same for the 400 BB and the 350 sb so I couldn't get any thing there. The hood support was skrewed into the wrong place on the inner fender. The car was offered as a WRONG ENGINE car.NO DOC'S. You have to watch these NON MATCHING #s car also!


Texas Chapter NCRS