1970 Corvette LT1/ZR1 Radiator hoses

[Ronald R.]

Can't find these in correct style? Does anyone repro or re stamp these? thanks Ronnie

[Joe L.]

Re: 1970 Corvette LT1/ZR1 Radiator hoses

Can't find these in correct style? Does anyone repro or re stamp these? thanks Ronnie

Ronald------

GM #3946011, upper, and GM #3946012, lower. Several NOS examples of each on eBay right now.

[Gary B.]

Re: 1970 Corvette LT1/ZR1 Radiator hoses

The ZR1 should have an aluminum radiator. If it does, it should have the following numbers ink stamped on them:
Upper: 3997761 ST AU
Lower: 3947669 KK AU
Both are like trying to find a pair of chicken lips.
The number above are for a ZR2 with a 454 LS6.
Gary B

[Joe L.]

Re: 1970 Corvette LT1/ZR1 Radiator hoses

The ZR1 should have an aluminum radiator. If it does, it should have the following numbers ink stamped on them:
Upper: 3997761 ST AU
Lower: 3947669 KK AU
Both are like trying to find a pair of chicken lips.
The number above are for a ZR2 with a 454 LS6.
Gary B

Gary------


GM #3997761 did not exist in 1970. It was once cataloged for 1971-72 ZR-1. However, I believe this was an error. GM #3997761 was discontinued in February, 1981 and replaced by GM #368765. The latter was catalogued for many Corvette applications with copper/brass radiator. Some sources say the 1970 ZR-1 upper hose was GM #3977671. That could not be, though, since GM #3977671 was a chassis frame for some non-Corvette Chevrolet application.

I can find no record of a part number of GM #3947669. However, GM #3917669 was a lower radiator hose for 1968-72 Corvettes with the GM #3155316 aluminum radiator (base engine small blocks with manual transmission and without A/C). 1970-72 ZR-1 used a different aluminum radiator (GM #3007436) with a 2" wider core. It required different radiator hoses than the 3155316 aluminum radiator.

[Ronald R.]

Re: 1970 Corvette LT1/ZR1 Radiator hoses

So do I need to exsect a fight with the judges???THANKS rONNIE

[Gary B.]

Re: 1970 Corvette LT1/ZR1 Radiator hoses

Fight might be strong word. Wrong hoses will warrant a deduction.

A reproduction hose will draw a 40% deduction. 20% Configuation and 20% date. Some might do do 20% Finish instead of configuration. 3-points are allocated for hoses and clamps. If you assign 2-points to hoses and 1-point for clamps, it might be hard to make a full point deduction for a wrong hose. If both hoses are wrong, you might warrant a point deduct. Out of 4500-points, 1-point is hardly worth a fight, is it?

The 3917669 lower hoses are not real hard to find. I usually find them a Carlisle every year. I keep a couple around, as they also fit base motor cars. The upper hose, 3997761, is impossible to find. I have only found one in the last 15-years, and I had to buy a box of 25-assorted hoses to get it. I have a few friends that have ZR-1's and I keep them maintained for them. So I try to keep those around for them. No, they are not for sale.

Your not using your imagination on how to make a hose. And with that, I'll let sleeping dogs lie....

Gary Bosselman

[Patrick H.]

Re: 1970 Corvette LT1/ZR1 Radiator hoses

I'll consider taking a point if the owner hasn't at least removed the modern dot matrix ink printing letting me know the hose was made last month. Some owners/restorers miss the obvious stuff. Otherwise, as Gary notes, it can be difficult to take points off given the small amount allotted.

PH

[Ronald R.]

Re: 1970 Corvette LT1/ZR1 Radiator hoses

I have a NOS 3917669, it is a good fit and I have considered remarking it, but with what Joe has suggested is the ZR2 hoses are correct and the 3997761 was not made in 1970??? . The upper hose I have found that will fit does not match any of the JM numbers. I will try a NOS 3946011 and see if it is a good fit. If it fits I will consider remarking if I can figure out who is correct. RDR

[Ronald R.]

Re: 1970 Corvette LT1/ZR1 Radiator hoses

I found a NOS 3946854 Bottom hose, so now with no possible chance of finding a 3997761 looking for next best candidate for upper. Just trying to squeeze every point possible!!!

[Gary B.]

Re: 1970 Corvette LT1/ZR1 Radiator hoses

The bottom hose should be 3917761. I corrected the manual this morning, it's the same part number as a base motor. Original cars I have seen uses a 3917761. 399 I think is a typo.

Upper hose, buy a NOS 368765 off Ebay. I think Sal has a couple. Cut the end at the radiator to fit. Who is going to know if it's the right configuration? Clean the part number off, either make a stencil or have have a stamp made with the correct part number. With about 25 cars made, how many judges even know what the stamp looked like?
Blow this picture up, you'll see an original 3997761 on a restored 70 ZR1. I'll look some more through my pictures and see if I can find a 3917761. Also post is a 71 ZR2 upper hose. You could probably copy that, just cahne the number. Who would know?

.

[Joe L.]

Re: 1970 Corvette LT1/ZR1 Radiator hoses

The bottom hose should be 3917761. I corrected the manual this morning, it's the same part number as a base motor. Original cars I have seen uses a 3917761. 399 I think is a typo.

Upper hose, buy a NOS 368765 off Ebay. I think Sal has a couple. Cut the end at the radiator to fit. Who is going to know if it's the right configuration? Clean the part number off, either make a stencil or have have a stamp made with the correct part number. With about 25 cars made, how many judges even know what the stamp looked like?
Blow this picture up, you'll see an original 3997761 on a restored 70 ZR1. I'll look some more through my pictures and see if I can find a 3917761. Also post is a 71 ZR2 upper hose. You could probably copy that, just cahne the number. Who would know?

.

Gary------


I'm very curious about this. Are the radiator hoses on these ZR-1 cars known to be the original hoses?

The April, 1970 edition of the Corvette P&A Catalog does not show the GM #3997761 hose at all. It catalogs the GM #3946011 as the hose for 1970 applications with HD 4 speed (the ZR-1 was the only 1970 application which used the HD 4 speed). The 3946011 was also used for 1969 L-88 and 1971 LS-6. Both of these applications used the same GM #3007436 radiator as the ZR-1.

As I mentioned previously, I doubt that the GM #3997761 even existed for the 1970 model year. I don't know of any part numbers as high as 3997xxx that were released for the 1970 model year. As a matter of fact, GM #3997761 had a predecessor part number. It was GM #3995627. That part number appears in the February, 1971 edition of the P&A Catalog and is cataloged for "1971 w/HD 4 spd/ Spec HiPerf 350". The GM #3995627 was discontinued from SERVICE in June, 1971 and replaced by the GM #3997761. I doubt that even the 3995627 would have been released for the 1970 model year but, if it was, it would have been the hose used for 1970. I also expect that, assuming that either hose was used for 1971 ZR-1, the 3995627 would have been used at least for earlier built cars.

The 3997761 is pretty much the same as the GM #3946852 used for 1969-72 with small blocks and copper/brass radiators. In fact, both of these were discontinued in favor of the GM #368685. The later was thereafter cataloged for many 1969-77 Corvettes with small block and copper brass radiators.

As far as the lower hoses goes, I can't find any hose of GM #3917761 that you mention above. Base engine cars with manual transmission and without C-60 use hose GM #3917669.

[Gary B.]

Re: 1970 Corvette LT1/ZR1 Radiator hoses

Gary------


I'm very curious about this. Are the radiator hoses on these ZR-1 cars known to be the original hoses?

I prefer to look at original, unrestored cars and gather my information from them. I prefer to see how they built, not what a service parts catalog calls for. Was that hose original to the car? Only the hose and car can answer that, and I have yet figured out to get a car to talk. It was very old, orginal clamps still on it, and swelled up with age. I would assume yes. I don't remember the VIN, or if it was an early or late car.


The April, 1970 edition of the Corvette P&A Catalog does not show the GM #3997761 hose at all. It catalogs the GM #3946011 as the hose for 1970 applications with HD 4 speed (the ZR-1 was the only 1970 application which used the HD 4 speed). The 3946011 was also used for 1969 L-88 and 1971 LS-6. Both of these applications used the same GM #3007436 radiator as the ZR-1.

As I saidin an earlier post, those hoses listed above are for 427 and 454 cars. the 3946011 is physically to short to reach the radiator on a ZR1. Samll blocks are farther away from the radiator and require longer hoses.

As I mentioned previously, I doubt that the GM #3997761 even existed for the 1970 model year. I don't know of any part numbers as high as 3997xxx that were released for the 1970 model year. As a matter of fact, GM #3997761 had a predecessor part number. It was GM #3995627. That part number appears in the February, 1971 edition of the P&A Catalog and is cataloged for "1971 w/HD 4 spd/ Spec HiPerf 350". The GM #3995627 was discontinued from SERVICE in June, 1971 and replaced by the GM #3997761. I doubt that even the 3995627 would have been released for the 1970 model year but, if it was, it would have been the hose used for 1970. I also expect that, assuming that either hose was used for 1971 ZR-1, the 3995627 would have been used at least for earlier built cars.

The 3997761 is pretty much the same as the GM #3946852 used for 1969-72 with small blocks and copper/brass radiators. In fact, both of these were discontinued in favor of the GM #368685. The later was thereafter cataloged for many 1969-77 Corvettes with small block and copper brass radiators.

As far as the lower hoses goes, I can't find any hose of GM #3917761 that you mention above. Base engine cars with manual transmission and without C-60 use hose GM #3917669.

The hoses listed in the 6th Edition TIM&JG are what we have seen on cars presented during judging and cars I have seen in peoples personal collections. I'll stand by those numbers as being correct until somebody can provide pictures of low mileage original cars showing something different.

This picture shows the difference in lengths between a small block lower hose and a big block lower hose.



This picture is from a 290-mile ZR-1.



I'll let you continue to have the last word.
Gary B

[Ronald R.]

Re: 1970 Corvette LT1/ZR1 Radiator hoses

i guess you can see what a problem this is for a person trying to do a car correctly? I'm not a expert on hoses but joe has an excellent point. Even a low mileage car might not have original hoses and some evidence of records should exist. I punt!!!

[Ronald R.]

Re: 1970 Corvette LT1/ZR1 Radiator hoses

Are you saying the

bottom hose should be 3917761? or top hose with 399 being a typo or the top hose? thanks RDR

[Joe L.]

Re: 1970 Corvette LT1/ZR1 Radiator hoses

The hoses listed in the 6th Edition TIM&JG are what we have seen on cars presented during judging and cars I have seen in peoples personal collections. I'll stand by those numbers as being correct until somebody can provide pictures of low mileage original cars showing something different.

This picture shows the difference in lengths between a small block lower hose and a big block lower hose.



This picture is from a 290-mile ZR-1.



I'll let you continue to have the last word.
Gary B

Gary------


I TOTALLY agree with you that the best source of information as to what parts were installed on the cars are original cars, themselves. There's no doubt about that, at all. However, for parts like radiator hoses, belts, tires, etc. it's very unusual to find cars that have not had these components replaced at some point in their lives. Based upon the fact that the waterpump seen in your second photo appears to be a GM #3991399, the application must be a 1971 or early 1972 ZR-1 and, probably a later 1971 or early 1972. If so, it has exactly the hose that the P&A Catalogs specify. As I mentioned previously, I thought that this was an error but, apparently, it is not. However, I doubt that the hose pictured is the actual hose that was originally installed on the car. From what I can see of the waterpump, intake manifold and belt, that does not appear to be a 290 mile car to me. I could well be wrong, but that would be my opinion based on the little that I can see.

The original question involved a 1970 ZR-1 and that's primarily what I was responding to. I just don't see how a GM #3997761 could have been originally installed on a 1970 ZR-1. As to what hose was installed, I don't know for sure. Actually, I do not see why a GM #3946852 as used for small block copper brass applications could not have been used.

With respect to P&A Catalogs some folks somehow consider that these were developed in some sort of "vaccum" and do not necessarily represent the parts actually used in PRODUCTION. That's totally incorrect, though. The basis for the P&A catalogs are PRODUCTION records. These originate from sources like the AIM, GM part specifications, other PRODUCTION documents, PRODUCTION utilized "charts", bills of materials, etc. In the case of the latter three items, the P&A catalogs are the only "window" we have to the parts originally used since most of us don't otherwise have access to those records. In the vast, vast majority of cases the cars were built with the parts that GM intended them to be built with as reflected in all of the aforementioned documents, including the P&A catalogs. . I have cross-checked many parts shown in the AIM with the P&A catalogs (published in the same time period as that in which a particular model year was built). I have found them to be highly accurate, almost amazingly accurate. By extension, I consider the P&A catalogs to be accurate for parts not shown in the AIM. Are there errors in the P&A catalogs? Of course there are, just like there are errors in the AIM's and, likely, the other records which we don't have access to.

I also TOTALLY agree that small block radiator hoses are generally longer than big block hoses for exactly the reason you mention. So, I consider it likely that the 3946011 and 3946012 hoses were not used for the ZR-1 application. In fact, I came to that conclusion years ago but I forgot it when I posted my original response to this question. It's not the first thing I've forgotten and likely won't be the last.

By the way, I have no desire or intention to be the "last word" on this or any other subject I can think of.