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1951 Mack A-40 Engine ID


Go to solution Solved by steve s.,

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Hi All. I am brand new to the sight. I am working on a 1951 A-40 Concrete Mixer. It has a Smith mixer on it. I am trying to figure out what the engine is. I am having trouble locating anything on it. The engine is a Maxydyne inline 6 Gasoline engine. The number, I think is on the front right (passenger side) corner on the block. The Number is E 1(or capital I) 377 43 65. I set the points at .020 and it started up. It hasn't ran in several years. It needs a new fuel pump. This truck was  restored in the early 90's. It was used in parades. When I get it up and running. And, cleaned up. So, I can get it outside for some pictures. I will post them for ya. Any help would be appreciated.  Thanks 

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  • 2 weeks later...

Hi all. Just an update here. I was able to read the engine number better after we got it out of the shed it was stored in. The number on the block is actually EN 377 43 65. I still cannot find anything on this. But, While driving it back to our shop. I drove it in direct. 1st and 2nd worked well witth plenty of power. When I put it in 3rd (direct), it ran good for awhile. Then it started running very rough. If I shifted down it would clear up and run fine. Almost like the governor isn't working under power. If I can figure this engine out, I can figure the governor out too. Thanks   Pat

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Oops sorry this one slipped through the cracks. I'd love to see some pictures of the truck and engine! There isn't all that much info out there about Mack gassers. Is it a flathead of overhead valve? 

 

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  • Solution

Your engine is an EN 377. Serial number 4365.  Bore and stroke 4"x5", 377 cubic inches.  Almost all Mack gas engines of that era called for a point gap of .022", you're real close. Are you looking for any specific information?  With any old truck that has been sitting for some time, you have to suspect some crap in the fuel system will cause you trouble. But in the other hand, it could be any number of things making it run rough. Good luck.

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I have a 405A firetruck based on the A40 chassis.  It also has a 377.  I agree with Steve.  It’s probably not getting enough fuel.  I had a new fuel tank made and put an electric fuel pump on mine and it runs great. Both the old tank and the old fuel pump leaked. I don’t have any manuals. Michael. 

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Thanks all for the welcome. Also, for the info. I was thinking a fuel issue as well. It does have a Carter electric fuel pump. I am suspect of it. I had to tap on it to get it to pump after sitting with no fuel in it. The in cab tank was rebuilt when the restoration was done 20 years ago. The truck only gets to go outside when paraded or going to a show. It gets ran out of fuel when stored. I am not a believer in that. I recommend that it be ran and driven at least a few times throughout the year. But, I am not in charge. Here are a few pics while she was inside the shed. I will get more when I have it cleaned up and outside.

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Well? I guess I cannot load pictures. It says server error when I tried to post from my Android phone. I was able to add text. But, not pics . I don't know why. Any Ideas? 

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I'm not sure about Android but with Apple you have to screen shot the picture to get it into the right format. I can DM you my Email and can post them if you'd like. 

Edited by BOBWhite
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Yeah BOBWhite. Lets try that. My email is patricknorbertjay@gmail.com . I don't really know what else to try. The pics are from the other day when I got it running. But, lets try.

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Welcome 6 wheeler

So I don't think you have a Maxidyne as they were diesel

Photos probably have to many pixels, try emailing them to yourself, this reduces their size quite a bit

Yes fuel  blockage is most likely 

Try putting a pressure gauge on the fuel line before the carby and this will tell you if the problem is the fuel pump or the carby is blocked

If the fuel pressure drops of its the pump, if it doesn't it's the carby

 

Paul 

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Pretty sure it will be a side valve motor 

Get a cheap fuel pressure gauge like this

Screenshot_20240423-082503_Chrome.thumb.jpg.081fd497c87ef808d59ed6d0d864f830.jpg

 

 

20 bucks Australian, so $1.95 US

A tee, a foot of rubber fuel line and maybe a few hose clamps

50 bucks and you will find some definite answers with out any guessing 

 

Paul

 

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9 hours ago, 67RModel said:

Interesting to see a hub mounted backup bell still installed on something.....

now YOU have distinguished Yourself as a detective / mechanic. It's  the small items noticed which make a difference. to have only a $1.oo for everyone of those bells I installed.!!! major construction fleet in CT having bought (#356-376)first batch of DM686 SX dumps I had to weld a 1/2 (5/8?) fine thread nut onto center of axle cap allowing install of the backup bells. couldn't use the brackets due to deep axle cap. also welded nut center cap for hubometers.

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21 hours ago, BOBWhite said:

IMG_B979D485801E-1.thumb.jpeg.a3db28b4eb5c3675988d3ae33cf28f67.jpegIMG_2674E94A85F7-1.thumb.jpeg.bece40fcc7f4b8c0faeb100d829b342b.jpeg

What a cool truck! Most people chucked the flatheads but I'm glad this one was able to be preserved. Magnadyne is such a cool name for an engine 

beyond sharp looking piece of history. best of positive to it restoration. 

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