MikeM

Yep! All '67 SB's had draft tubes. BB's too afaik.

All '68 Production line engines were void of the draft tube provision except an early, small sized, block build of left over 283 engines that exhausted leftover '67 engines.

GearheadJoe

Attached is a photo that shows the two distinct provisions that make a 3892657 block different from earlier 327 blocks. These are easy to recognize in a decent photo of the crankcase.

I believe that the replacement 3959512 block has the same features.

Note that if either block has been machined for large journals, the shallower small journal notches will be either missing entirely or only faintly visible.

GearheadJoe

I checked several web sites that claim to have information on Chevy block casting numbers. A couple of them show the 3959512 as a 1962-1967 327 block, but I'm wondering whether this might be a mistake.

I can't find the 3959512 casting listed as having been used in Corvettes. I checked an Impala web site and the 3959512 was not shown as having been used in Impalas. Same for a Chevelle web site and a Chevy truck web site. It seems to me that if Chevy was making the 3959512 from 1962-1967, it would have appeared in at least one of these vehicles.

I suppose that one way to prove that GM made this block in 1962-1967 would be to find a block that has the 3959512 casting number but does *not* have the large journal bearing notches or the rod clearance notches that I showed in a previous posting. Those features first appeared in 1967 when the 350 engine was introduced.

It's worth noting that Flint used only a single-digit for the year in their casting dates. So, a date of A173 could be January 17, 1963, or January 17, 1973. Perhaps some people mistook some 3859512 blocks that were cast in the 1970s as having been cast in the 1960s.

Patrick03

The site below shows the '512 as 62 to 67 and then in the notes it says it was also a CE service replacement part. I've asked the guy on CL to send me a pic of the journals.

http://www.mortec.com/castnum.htm

Patrick03

Here is a closer up picture of the journals. Looks to have provisions for both small and large journals.

GearheadJoe

Yes, that block clearly has both sets of bearing notches.

The notches at the base of the cylinders also appear to be present, which would be expected. It even looks like someone may have enlarged them just a little bit for some previous stroker application.

So, I think think this block is a candidate for your project.

snoopybob

I can't believe all this! We build 383s, and there are thousands of 350 blocks out there with driver side dipsticks (67-80) that will make 383s. The crankshaft is (or can be) simply a 400 crank with the mains turned down to 350 size.

Patrick03

I'm also looking for a block with crankcase ventilation on the rear of the block. Not as many block choices out there with that provision.

68hemi

You already have this with your original engine. Did you read my post about using your original engine for this stroker?

Or do you simply want to uild a new one from scratch and pickle your original?

GearheadJoe

The OP said he thinks his engine is original to his '64 Vette. That would make it an '870 block.

The '870 does not have the rod clearance notches that the 3892657 and 3959512 blocks have, so getting a 3.75" stroke without grinding into the water jacket is a bigger challenge compared to the newer blocks.

A related problem is that the '870 is probably not a good candidate for line boring to large-journal mains. Unlike the other two blocks, the '870 casting was not designed to support this option. There is less meat around the front main journal in the casting of an '870 block.

This being said, I think it is possible to stroke an '870 block to 383, but doing so requires a lot of attention to the rods that are used, and you are still left with small-journal mains. The small-journal mains probably aren't a problem if the crank is a high quality forging.

Personally, I am optimistic that with careful planing, an '870 block can be successfully stroked to 383. I continue to look at options for how this could be safely done to an '870 block. However, if the block in question happens to be the car's original block, great caution must be exercised to avoid turning the original block into a watering can.

Patrick03

I want to build from scratch and save my original block. Don't want to chance ruining it. Thanks for the suggestion though.

68hemi

I have puzzled over this in the past but have come to the conclusion that I would rather take the chance building and original engine over the expense of building a new one. The cost is much higher building from scratch. I am building a 383 for my 57 and want a stealth look of a 283/270 h.p. 2x4 car. To date I have:
$8155. in my engine and the machine shop is still finishing up the
porting and has additional parts yet to bill me. Then I have to
pay my mechanic to install it and set it up. subtract
2320. For the dual quads
930. For the new 2 1/2"exhaust
225. For the hipo oil pan
645. Add for my additional parts and porting labor for a round
number of
$6500. This is adjusted because you don't need/already have these things for your car with the original engine.
I am guessing you will have all of this or more in your new build. BTW, I paid $600. for my bare block which I think was a fair deal.
What do you think you are going to spend If you stroke your original engine?
I would take the chance with the original engine being stroked rather than storing the original and building a new one. The original has lasted 50 years and when you stroke and balance/blueprint to better than factory specs and put a rev limiter on it, you stand an even better chance of not hurting it. If I had an original engine 365 h.p. car I might want to have it judged. You have your original engine if you want it judged. If you build one from scratch you likely won't want to have it judged and will suffer the naysayers grumbling about it not having the original engine even though it is at home in a bag.

IF you blow your original engine document that you HAD the original engine while you owned the car so someone does not think you are trying to pass a 250 h.p. car as a 365 h.p. car. Save the original block and pieces even if you think it is not salvageable. You would be amazed at what can be done to save it.

Just MHO but food for thought for you. I would only want to spend the extra money IF I blew my original engine if ever.

Patrick03

Good point about judging. I'm not at that point yet so it's kind of a non-issue for me. I'm going to scavenge everything I can from my current engine. Will pretty much just be saving the block for posterity. Really the only delta in cost should be $300 in the block I'm buying.

Patrick

68hemi

Are you saying you are planning on using your original pistons (if possible,) cam, heads and just going to buy a stroker crank/rods and of course rings and bearings?

karkrafter

I had a big block Chevy Engine in my 69 GTO, Had the Pontiac air cleaner, painted it Pontiac blue and put a 400 cu in Pontiac decal on the valve cover.

5 years and nobody noticed it was a Chevy mill in a Pontiac....and you guys are worried about a crankcase vent?

I think this is being over thought a bit....

cv67

wesmigletz used a # block and did a 383 many yrs ago turned out real well, why is everyone worried about a block exploding?

Id be more worried about some "rebuilds" you see where the block isnt machined, bored & reuse every single thing except maybe rings and bearings, timimg chains obsessing over value

jimh_1962

I can get what the OP is doing. He wants his engine to look a certain way and build a 383.

The cost is really whatever he wants to pay to get it done. I do not think that's in question here. I think we have established that building a 383 from a 327 CE block will cost the OP.

I have a 512 CE block in my corvette. It can accept a large journal crank. I never thought about building a 383 when I built my engine. Looking back, I probably would have done it simply because I could do it. Is it cost effected compare to putting a 383 crate engine? Heck no! Would it have the cool factor! Yes for sure!

Last weekend, at a car show I noticed I enjoyed checking out the rides which have something different to them. The ones I always am impressed rides where someone has put some thought in the engine. I hate seeing hacked up corvette scripted valve covers to make it breath properly for the stock 350/383. Sorry not offend anyone regarding to the valve cover reference. Yes, I know a 350 is very reliable and cheap way to get horsepower.

I even gave a nod to the guy who was running a ford 302 in a 35 chevy truck. He went against the grain! I guess he did not know the "rules". You can put a chevy in a ford but you cannot put a ford in a chevy!

OP, do what you want to do! Build that 383! Put a downdraft tube or a PCV.

Quit criticizing and help the guy out!

MikeM

I think you should consider leaving your original block intact and assembled as is. If you build the engine you want, the only thing you'll save out of your short block is the block. How much is that original (running) short block worth to you or someone else?

If you insist on the 870 block, buy a bare one and start from scratch. The only money you'll be out is the new block vs the value retained from the original.

I don't think it's been mentioned here but 327's have been known to crack the main bearing webs in stock configuration, let alone modified.

jimh_1962

I thought he is going to use a 512 block from this statement:
I want to build from scratch and save my original block. Don't want to chance ruining it. Thanks for the suggestion though.

GTOguy

Karkrafter, it drives me NUTS to see one of those Buick engine call-out stickers on a Pontiac air cleaner. Pontiac never had them in the '60's. On anything. Here's my 383, based off of a 1967 3914678 block......with the road draft vent converted to PCV and the stock WCFB's in place. Looks totally like the original 283 that I wish I had.....