ddecart

I'm stumped. I'm trying to figure out what the radiator/shroud in my car is SUPPOSED to be so I can get it cooling properly. I'm not so worried about returning anything to factory correct necessarily, I just need to figure out what kind of mess Bubba has left me with.

My car is a '69 L46 (350). It has a copper 27" radiator in it. A "shallow" plastic shroud and an expansion tank. Is any of this correct? The only references to a 27" radiator I can find mention big blocks. Looking through catalogs I see that there are multiple choices for radiator/shroud combos offered for my car. copper vs alum. rad, plastic vs metal shroud, etc...

Can anyone help me out with what SHOULD be in my car?
I have a [URL=http://www.corvetteforum.cc:88/zerothread?id=128610]thread[URL] going in the C3 section as well.

Thanks!
Dave

67's

Dave,

Do you have an A/C car? Is so I can check my numbers and get back to you.

Tom McCabe

ddecart

Sorry Tom.
I forgot to mention that. I do not have A/C. Who needs A/C when you have ASTRO VENTILATION!!! :D

Easy Mike

Does your car have an automatic transmission? Big block radiators were used with auto tranny cars to assist with the additional cooling needed.
;)

sb69coupe

EasyMike, the L46 only came with 4 speed.

ddecart

Yup. It's a 4 speed. I can't make heads or tails of this yet. Except that Bubba installed the wrong radiator and shroud.

JmpnJckFlsh

ddecart, If you have the Assembly Instruction Manual (AIM), go the options section under L46; the correct radiator part number and shroud part numbers should be there. That assumes that it requires a different radiator than the base engine; If it's the same as the base engine, that information will be located in UPC 11/13.

However, I am not sure what you can do with those part numbers except to maybe shop at Carlisle or trol ebay. If you're lucky, maybe the correct part was one of those high-dollar aluminum radiators being reproduced by DeWitt.

ddecart

Thanks Chuck. I haven't looked in the AIM recently. There seems to be so much confusion in general surrounding the cooling system. Some have expansion tanks, others dont. there are a half dozen different seal kits listed for 350s in the Zip catalog. Plastic and metal shrouds listed with the same useage with some fiberglass ones thrown in for good measure.

Without a smattering of 69s to compare to, it looks nearly impossible to find out which combo was original. I'm pretty darn sure the 27" rad wasn't though.

Dave

Joe Lucia

"ddcart"-------

1969 L-46s were originally produced with 2 different radiator systems. There's really no way to tell, for sure, which way your car was produced but either system would generally be considered "correct". However, a "mix-and-match" system is NOT correct. Here's the details of the two systems which I'll call "A" and "B":

System A:

1) aluminum GM #3155316 radiator; GM-discontinued but available in reproduction

2) radiator mounts to support with two rubber cushions on the bottom which fit into "cup" brackets welded to the radiator support. Top support is provided by single, central bracket and rubber cushion; bracket is attached to center of support with 5/16" bolts. Support, last available under GM #3966591 is GM-discontinued but available in reproduction;

3) external, aluminum supply tank, GM #3016340, is mounted on right side inner fender well

4) Steel, "cylindrical" fan shroud is used with steel lower baffle plate. This shroud, GM #3938943, is long-since GM discontinued and is not reproduced, as far as I know;

System B:

1) copper brass radiator of GM #3018803; core is 26" wide; GM discontinued

2) radiator mounts to support with upper and lower u-shaped brackets on both sides with attached rubber cushions; this method of attachment is similar to big block radiator mounting but the right side u-shaped brackets are different; radiator support, last available under GM #3966594, is discontinued but available in reproduction

3) radiator shroud is plastic shroud of linear polypropylene construction with graphite and fiber reinforcements. This shroud is GM #3956109 and is still available from GM;

4) NO external supply tank was used with this radiator; radiator has an integral filler cap and tanks.

That's the story.

ddecart

Thanks Joe!

WHEEEE!!!! This is getting fun. I actually find a mystery like this rather interesting and educational.

OK. I checked the AIM, and what a useless POS that is. It lists ONE rad and 3 shrouds, none of which matech what i have.

I have a 27" rad as I mentioned before. I made a statement, I think in the thread in C3, that the shroud was narrower than the radiator. That was incorrect. The shroud is part #3956119 which doesn't show up at all in my AIM. No part numbers or anything for the rad btw. The shroud is interesting. It's plastic and is "missing" the bottom half. It looks as if there's supposed to be an extension bolted to the lower half of it or something.

That was pretty interesting Joe since I can't see anyone installing an expansion tank on a car that didn't have one, so i can assume my car SHOULD have one. Now...could the 27" rad actually be correct for my car (i.e. could it ave been a Big Block car originally)? This doesn't seem likely since I have a 6000 rpm tach and an L46 hp/torque plate inside. Not that these couldn't have been changed, but I don't believe that any big blocks had 6000 rpm redlines.

Boy that Bubba is a slick fella. Always keeps you guessing... We're getting closer to the bottom of this though.

Thanks!
Dave

Joe Lucia

"ddecart"-------


The 27" wide copper brass radiator is trhe big block radiator. If it's original (or an original replacement) you should find the part number 3019190 somewhere on the right side tank.

The GM #3956119 is the big block fan shroud. It was originally used ONLY for big block applications during the 69-72 period. Some big block applications used an extension in conjunction with this shroud.

If your4 speed car car was originally fitted with an external coolant supply tank then it had to have originally been one of the following:

1) a big block; ALL 1969 big blocks used an external supply tank;

2) an L-46 with the aluminum GM #3155316 radiator;

3) a base engine car; ALL with manual trans used the aluminum 3155316 radiator with external supply tank.

Those are the only possibilities

Corvettes White

Rick Bizzozo confirms what Joe says in his book"1969 Stingray Guidebook." Further he lists a dozen L-46 cars by SN. Looking at the list the early non-AC car got the aluminum radiator and the later the copper without the remote tank. The aluminum radiator is listed also as 3155316. He goes on to discuss hood blanks and etc. If you are interested I could fax the pages. It is all very confusing. Although I can't prove it I do not think that a 27" was used.

George

ddecart

Joe: Thanks again. I've been here for 3 years and you still amaze me! I'll take a look at the radiator to see if I can find a part number on it. Is the rad support itself specific to the bigger radiator, or could one conceivably put a bigger rad in a "smaller" support? My rad fits perfectly into the rubber cushions/cup brackets.

Any other obvious and relatively unchangable things that would identify a car as a big block or not?


George: Thanks! I'll have to get out my VIN and see where it falls within the VIN numbers that Rick mentions. That would be a pretty good clue if it fell in the range without the expansion tank.

Thanks again guys!
Dave

Rowdy Rat

Joe,

Dave (ddecart) had posted photos of his engine compartment over in the C3 Forum and it certainly appeared to be a big block radiator/shroud combination. The part numbers that he posted last night confirm this: radiator #3019190 and shroud #3956119 are definitely big block pieces (and the same ones that are installed on my '69 L-89).

Dave didn't mention it in this post Joe, but he did write on the other board that he picked up a fan for his car at a salvage yard and has been using that. I gather that the correct fan for this application is a five blade unit, probably 18" in diameter, but I'm not certain of this. It might help Dave to know what fan he should actually have for his 1969 L-46 (I'd be interested to know the part# and description myself).

I also agree with your statement regarding radiator application. Considering the external coolant supply tank, the car almost certainly had an aluminum radiator. The aluminum radiators tend to be a bit expensive to replace which might explain why a copper radiator is in the car now.


George,

I also noted that trend in the 1969 Stingray Guidebook. Dave, posting a partial VIN might also give us some clues as to what the correct radiator for YOUR car is supposed to be. If your car DID have an aluminum radiator (#3155316) originally, I believe Tom DeWitt recently started reproducing these units. You'll also need the steel fan shroud that was used with the aluminum radiator as well as the correct core support. If you are looking for something functional rather than historically accurate, a more simple (and less expensive) solution might be to locate the correct copper radiator and use the appropriate plastic shroud (#3956109) and core support. In any case, I'd still be interested in learning where your car falls in the production sequence.

Regards,

Stan Falenski



[Modified by Rowdy Rat, 8:03 AM 8/9/2001]

ddecart

Thanks Stan.

I did start this topic over in C3 and posted some pics there. I'll dupe them here:








I've been trying to un-bubba this thing from the day I bought it, but Bubba is one heck of an opponent.

That fan is just something that I picked up from a junkyard to replace the cheap mostly-non-functional fan that the car had. It's actually too big to fit inside my shroud.

From what I've been able to find, a 5 blade, 17 1/2" fan is correct for a non a/c car.

At this point I'm definitely looking for the functional solution as opposed to the factory correct solution. That will have to wait a few years until my son and I get the car ready to hand off to him when he's old enough (he's all of 6 now).

This whole mess started when I went for a drive a week or so ago and my car started overheating. That led me to replace the lower rad hose (the hose they gave me now makes sense knowing that I have a bb radiator. I had to trim the hose to fit). Then I started looking into the radiator sealing and shroud, and the whole thing has ballooned into this discussion.

Dave

Corvettes White

Dave, looked at the photos you posted:

Check that the radiator is not clogged. The fan shroud should have an extension on it to “cover” the fan blades. Check the operation of the fan clutch as they get old they slip too much. Check the rad cap, it needs to hold pressure, the springs in them go bad. There needs to be a seal between the rad and the rad support and also above the rad support to the hood. There are also seals along the sides and at the bottom and a piece of rubber at the bottom. Check the upper hose, if it is soft sometimes they will cave in (it may be the bottom hose that is under suction I don’t remember but anyway, check it.)

Small block, no ac no trans cooler, 27” radiator should be no problem.

George

Joe Lucia

ddecart------


All of the 69 radiator supports are, basically, the same. They differ only with respect to the type and attachment points of the radiator support brackets and the "width reducing plates", if used.

The radiator support used on big blocks (except L-88) did not use "width reducing plates" to restrict the width of the support opening. Originally, the 427 support was GM #3952980 which was replaced by GM #3966596 in July, 1970. In early 1974 the 3966596 was also discontinued and replaced by GM #339176 which remains available.

The L-46 with copper brass radiator (and base engine with THM and/or AC) used a very similar support. I believe that this support may have used a very narrow (like 1", or so), "width reducing plate", but I'm not sure about this. What was different was the location of the u-shaped brackets. The right lower brackets was welded on slightly to the left of the location used for the 427 right lower bracket. However, the mounting location and configuration of the bolted on upper brackets was also different. Both the 427 support and the L-46 support used the GM #3952977 bracket for the upper, left side. However, due to the slightly narrower width of the L-46 radiator core (26" vs. 27" for the 427) the right side brackets were different. The L-46 used GM #3952974 and the 427 used GM #3952976. ALL of these brackets are discontinued as is the L-46 radiator support, originally GM #3952970 and later GM #3966594. However, all are available in reproduction.

If you have the GM #3019190 radiator you likely have the GM #3952980 or 3966596 support. Either of these supports and the 3019190 radiator are "made for each other" so I would expect them to fit perfectly. However, if you wish to switch to the L-46 3018803 copper brass radiator (which is VERY hard to find), then you'll need to modify your right side support brackets mounting location.

As far as other cues to indicate whether the car was an original 427, look for the presence of an OEM-type rear stabilizer bar. Only big blocks received these. Also, check for cap-type stub axle universal joint attachments. ALL small blocks for 69 used u-bolts, not forged caps. All big blocks used forged caps with bolts for inner u-joint retention.

Another cue might be the presence or absence of the fuel return line. ALL 1969 small blocks used a fuel return line. The 390 hp big block did also. However, the 400, 435, and 430 hp did not.

Joe Lucia

Stan and Dave-------


The correct fan used on 1969 Corvettes with 427 and without A/C was GM #3888366. This is a 5 blade fan of 17-1/2" diameter. It was discontinued from SERVICE in April, 1971 and replaced by GM #3955182 which is a 7 blade fan of 17-1/2" diameter. The GM #3955182 fan was originally used on 1969 Corvettes with 427 and A/C. It is still available from GM for a current list price of $111.43. I recommend this fan for all 69-70 applications as superior to any other available fan from the perspective of cooling performance.

Looking at the pictures below of Dave's engine comparment, I can tell that the radiator is the GM #3019190 big block radiator. This is the ONLY copper brass radiator which GM ever manufactured which DID NOT have an integral filler cap and had provisions for a right side fitting for connection to a supply tank.

Except from the perspective of "correctness" and, possibly, obtaining available molded radiator houses which will fit properly, there is NO rewason to switch to the L-46 copper-brass radiator. The big block radiator will perform as well or better. However, I would recommend using the correct small block radiator shroud for improved low speed cooling performance. It may require some slight lower end modification to work with the slightly wider lower mounting brackets, but I don't think that adaptation will be too difficult.

ddecart

Joe, Thanks so much! You truly amaze me.

Well, a quick look underneath confirms the u-bolts holding the u-joints in. That with no rear bar concluded that this thing started life as a small block. Everything else pointes to being an L46, so I'll run with that. So much for selling my rare L88 on ebay for a mint. :( :jester

George, I'll take a look at the fan clutch and the other items. My fan is slightly larger than an original fan so I'll be checking into a more proper functional replacement with a new clutch as well.

Any suggestions on how to check the radiator flow? I don't believe it to be a problem. The rad looks quite new and has always had clean fluid in it. I've managed to change something often enough that the fluid is removed more often than most cars. I usually put most of the old fluid back in with some new as well.

The seals I definitely don't have. They're what got me started on this quest to begin with. Looks like I'll need to order big block seals to be "correct" for my rad & shroud.

Thanks everyone else, too!! You've all been VERY helpful!
Dave

ddecart

George:
My VIN is 194379S713501

Are you able to fit that into the numbers given in the Guidebook?

Thanks!
Dave