General Big Block Question (396)

[Ashley S.]

I have a 3935440 engine. I was looking through the Chevy By the Numbers book and it says that this engine could be a 2 bolt or 4 bolt main. I am unable to remove the oil pan at this time to look, but I would still like to know which it is.

Does anyone know if there is a way to tell from the outside whether it is a 2 bolt for 4 bolt engine? It is a service replacement engine that is in my 65 corvette. The engine stamping says CE872424 and it has a casting date of F58.


Thanks,

Ashley

[William C.]

Re: General Big Block Question (396)

Look on the driver's side above the oil filter to see if there are two fairly large plugs in the side of the block where the oil lines are drilled. The four bolt main configuration opened those lines for use with an external oil cooler, the 2 bolt versions did not have this feature provided.

[Ashley S.]

Re: General Big Block Question (396)

Thanks Bill,
I will look tonight. I do not recall but (1) hole that was approximately 3/4" in diameter in the block right above the oil filter. The oil pressure line is connected in that location with a reducer of some sort. I also think there is a stud for a clutch cross shaft to the rear of the oil filter (even though the actual cross shaft is in front of the oil filter).
It is sounding like this may be a 2 bolt block. Hopefully not though...

Ashley

[Ashley S.]

Re: General Big Block Question (396)

Bill,

I found a picture on my flash drive that shows part of the oil filter. Can you see enough in this picture to tell? This picture shows the cross shaft stud I was speaking of earlier.

Thanks,

Ashley





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Look on the driver's side above the oil filter to see if there are two fairly large plugs in the side of the block where the oil lines are drilled. The four bolt main configuration opened those lines for use with an external oil cooler, the 2 bolt versions did not have this feature provided.

[Joe L.]

Re: General Big Block Question (396)

Thanks Bill,
I will look tonight. I do not recall but (1) hole that was approximately 3/4" in diameter in the block right above the oil filter. The oil pressure line is connected in that location with a reducer of some sort. I also think there is a stud for a clutch cross shaft to the rear of the oil filter (even though the actual cross shaft is in front of the oil filter).
It is sounding like this may be a 2 bolt block. Hopefully not though...

Ashley

Ashley-------


If you have the 1965-69 "Chevrolet By The Numbers" book, you will find the configuration differences that Bill is referring to pictured side-by-side on page 56.

However, it is possible that a SERVICE block such as yours might have the 2 bolt above-referenced configuration but still be a 4 bolt block.

In any event, if the block is a 2 bolt block and you ever rebuild the engine, it can easily be converted to 4 bolt by a machine shop. In fact, it can be converted to BETTER than a factory 4 bolt because steel billet caps can be used in a conversion. The factory never used steel billet caps.

[Edward B.]

Re: General Big Block Question (396)

4-bolt main. Love the clutch linkage. Looks as if the engine did some duty in a boat before finding its way into your Corvette.

[Ashley S.]

Re: General Big Block Question (396)

Thanks Joe,
I do have the 65-69 "Chevy By the Numbers Book". That picture is exactly what I needed to see. I will be looking when I go home tonight for sure.
I had heard you could convert a block to 4 bolt, but I didn't realize it was that easily done. That is comforting to me since I plan to rebuild the engine either way.

Thanks for your help.

Ashley

Ashley-------


If you have the 1965-69 "Chevrolet By The Numbers" book, you will find the configuration differences that Bill is referring to pictured side-by-side on page 56.

However, it is possible that a SERVICE block such as yours might have the 2 bolt above-referenced configuration but still be a 4 bolt block.

In any event, if the block is a 2 bolt block and you ever rebuild the engine, it can easily be converted to 4 bolt by a machine shop. In fact, it can be converted to BETTER than a factory 4 bolt because steel billet caps can be used in a conversion. The factory never used steel billet caps.

[William C.]

Re: General Big Block Question (396)

Cross shaft stud is about all I can recognize Bubba did a nice job on the clutch pushrod! If you do a search in the archives, I believe a picture was posted sometime back.

[Ashley S.]

Re: General Big Block Question (396)

Joe,
I was able to get a better picture last night and it looks like I have a 2 bolt main engine. I am definitely going to rebuild the engine, so I will go ahead and have it drilled for 4 bolt caps.
Here is the picture I was able to take last night.

Thank you again for your help.

Ashley

Ashley-------


If you have the 1965-69 "Chevrolet By The Numbers" book, you will find the configuration differences that Bill is referring to pictured side-by-side on page 56.

However, it is possible that a SERVICE block such as yours might have the 2 bolt above-referenced configuration but still be a 4 bolt block.

In any event, if the block is a 2 bolt block and you ever rebuild the engine, it can easily be converted to 4 bolt by a machine shop. In fact, it can be converted to BETTER than a factory 4 bolt because steel billet caps can be used in a conversion. The factory never used steel billet caps.

[Joe L.]

Re: General Big Block Question (396)

Joe,
I was able to get a better picture last night and it looks like I have a 2 bolt main engine. I am definitely going to rebuild the engine, so I will go ahead and have it drilled for 4 bolt caps.
Here is the picture I was able to take last night.

Thank you again for your help.

Ashley

Ashley------

Yes, this configuration is indicative of a 2 bolt block. However, as I previously mentioned, since this is a SERVICE engine, it's not beyond the realm of possibility that it's actually a 4 bolt.

Inasmuch as this is a 396 block and it's not inherently valuable since it's a SERVICE block and, given its casting number, could not even be correctly dated for a 1965, you might just want to look for another block, preferably a 427, that already has 4 bolt mains. That might be cheaper than having this one converted and you'd have a 427 besides. Since you don't have a correctly numbered and dated block now, you wouldn't be losing anything in this regard. A non-correctly numbered and dated core block should not be all that expensive, either.

Of course, if you wish to rebuild this engine and as I mentioned previously, it should be no problem to add 4 bolt mains to this block. This is done all the time. The basic block casting is the same for both 2 bolt and 4 bolt engines. You could pick up a set of good, used 4 bolt caps or go with high quality aftermarket, billet steel caps.

By the way, though, the standard 2 bolt big block configuration is good to at least 500 hp and 500 ft/lbs of torque. So, unless you have or intend to modify the engine to very high horsepower, which I don't recommend for a street engine, you won't be gaining much with the 4 bolt caps. In case of staying with the 2 bolt caps, I'd simply change the cap bolts to the best ARP. It's not expensive and it will provide a little extra "insurance".