Radiator support Bracket Washers 66/67 Big Blocks

[Don M.]

Guys, I have reviewed the archives, and I see at lot of discrepancies about what may be correct. I see what appears to me to be correct, BUT I have an old edition of my Judging Guide, what I am wondering is what have we(NCRS) made a decision in the latest judging manual what we think is correct. I believe the 2 outer bolts on each side should have a thick and a thin washer, the 2 center bolts should have a large thin and a lock washer, what thought to be correct?

Oops, guys, I never said what year I was referring to, I am talking about 66-67 Big Blocks, radiator bracket bolts and washers, there are 6, looking through the archives it seems that various combinations may have been installed at the factory. I am asking if we have a determination as to what we feel is correct from a judging standpoint?

[Leif A.]

Re: Radiator support Bracket Washers 66/67 Big Blocks

Don,
This from the 5th edition TIM&JG for the '67 model year.

[Don M.]

Re: Radiator support Bracket Washers 66/67 Big Blocks

THANK YOU Leif, I appreciate the help. I see they say, occasionally a second thicker washer is also used. So I am going to use , on the right and left outers, a thicker large washer, and thinner large washer and a lock washer. They reach and fit just fine. I think the way it reads , that will be acceptable. Whew! Thanks, Don

[Richard M.]

Re: Radiator support Bracket Washers 66/67 Big Blocks

Don, This was the configuration I installed on a recent BB restoration. Note additional thick washers on the outer ends. No deducts.

Rich

[Anthony P.]

Re: Radiator support Bracket Washers 66/67 Big Blocks

My 66 BB that i bought in 1972, looks Identical to Richard's photos. I knew the previous owner who had it from 70-72. I feel 98% sure that is how mine was built, Dec.16th '65 build date. FYI

[Richard M.]

Re: Radiator support Bracket Washers 66/67 Big Blocks

Got me thinking......Were the 5/16" RSC bolts really Grade 8 originally, as mentioned in the JG? Just seems odd to me that bolts to hold a radiator to a core support had to be Grade 8. I'll have to look up the part# in the AIM and do a little research.

Ref LI Corvette photo.

[Gene M.]

Re: Radiator support Bracket Washers 66/67 Big Blocks

A possible reason for double washer is the bolts originally specified were substituted by the supplier to be standard length bolts vs a non standard specified length. The longer length was an issue in clearing the radiator on the rear side. Stepping out the bolt with an extra washer solved the problem. This may be all wet but just looking at the assembly there is no other sound reason for two washers.

As for the grade 8 bolts IMHO the reason for that high a grade in the assembly could be lesser also. It could be another situation as the Grade 8 was a standard manufactured hardware. GM allows for exceeded specification but not lesser. In this case almost anything exceeds grade 2.

[Don M.]

Re: Radiator support Bracket Washers 66/67 Big Blocks

Gene, I agree, I have been told 2 reasons for the thicker washer, one due to the length of the bolt, and also not to take a chance of crushing the radiator. I'm still asking about the correct or accepted combinations of washers, and there may be no specific answer. Don

[Leif A.]

Re: Radiator support Bracket Washers 66/67 Big Blocks

Gene, I agree, I have been told 2 reasons for the thicker washer, one due to the length of the bolt, and also not to take a chance of crushing the radiator. I'm still asking about the correct or accepted combinations of washers, and there may be no specific answer. Don

Don,
According to the page in the TIM&JG that I posted, either is accepted...with or without the larger washer. I'm with Gene on this one...the supplied bolt was a skosh too long and the extra washer pulled it back just enough to clear the radiator.

[Richard M.]

Re: Radiator support Bracket Washers 66/67 Big Blocks

According to my research, the bolt is 5/16"-18 1 5/8" long, part# 454872 and is 300M(Grade 8). It's the same bolt for the 1967 small block cars center radiator to core support bracket.

[Gene M.]

Re: Radiator support Bracket Washers 66/67 Big Blocks

According to my research, the bolt is 5/16"-18 1 5/8" long, part# 454872 and is 300M(Grade 8). It's the same bolt for the 1967 small block cars center radiator to core support bracket.

Rich,
Your turn to educate me. What is 300M? Not familiar with 300M. I think Grade 8 is part of ANSI spec's.

[Richard M.]

Re: Radiator support Bracket Washers 66/67 Big Blocks

Rich,
Your turn to educate me. What is 300M? Not familiar with 300M. I think Grade 8 is part of ANSI spec's.

Gene, I only learned these classifications from the GM books. It was noted as their GM material numbers, the greater the number the greater the tensile strength.

here's the info from their P&A's....


More info Here online that I just found.

Rich

[Don M.]

Re: Radiator support Bracket Washers 66/67 Big Blocks

Rich, In your picture of your car that had no deducts, just for my curiousity(I just can;t see it) you have no Lock washer on the outer bolts, and no thick washer on the centers, and with or without a lock washer in the center?

[Richard M.]

Re: Radiator support Bracket Washers 66/67 Big Blocks

Rich, In your picture of your car that had no deducts, just for my curiousity(I just can;t see it) you have no Lock washer on the outer bolts, and no thick washer on the centers, and with or without a lock washer in the center?

Don, Hard to see but yes the lock washers are there on the 4 outer bolts. I scoured my 7,000+ photos I took of that restoration but no front views of that area. Shameful of me.

Center also has lock washers and flat washers(368003, same as outer thin washers), but NO thick washers. The same bolts, Part# 454872 were used for the center two bolts. This is depicted in the standard production assembly section in the 1967 AIM, UPC 11-13 Sheet A5. It is not shown in the L36(1967 or 1966) (BB) AIM sections as the same bolts were used for the small block center bracket, therefore the BB AIMs don't show those center bolts, only the outers.

The reason the center didn't have the thick washers, as shown in my photo, is that there was no clearance issue to the radiator core. The outer bolt tips came close to the radiator end tanks which bulged forward. IMO that's the primary reason they were added as others mentioned.

The AIM doesn't show thick washers for the BB cars probably due to a assembly line discovery after a few radiators got poked. There must have been a GM part# for them, but I don't know what it is. I only know of them from working on original cars and the repro part availability.

Rich

[Don M.]

Re: Radiator support Bracket Washers 66/67 Big Blocks

Fabulous, thanks for your help, I am sure I beat this subject to death, but I wanted to be as correct as possible. If you had no deducts, that is great. Again, thank you Rich, and to the rest of the contributors! Don