Patrick03

So I'm pulling my engine over labor day and I was planning to replace all gaskets as there are oil leaks everywhere. Was also thinking about swapping out my cam. My long term plan is to rebuild the bottom end as it feels a little tired. Plan would be to stroke it to 383. I believe it is the original engine. '64 365hp. I did a compression check and most cylinders are around 150 psi. I don't have the time now to rebuild it and thought "hey, I should keep my original block and drop in a 383 short block!" My plan would be to keep the top end and exhaust as-is for now. When I have more time I'll pocket port the heads. Everything should bolt right up to a 383 short block, right? I want to keep my non vented valve covers and I know I have to do some modifications to get the pcv system to work. I'll want a driver's side dip stick. Anything else I should consider? Is a forged bottom end necessary if I'm not planning on outrageous power?

Thanks, Patrick

Crunch527

For starters, head work is expensive...a new aluminum-headed, forged 383 will be better in the long run...you can dress it up to look the same as the original engine.

65air_coupe

I think it's a good plan, I was going to do the same thing but leave the heads alone just to save the time and money. I got a little carried away in the end with an aluminum head 406 but still used all my other SBC parts.

GearheadJoe

Hi Patrick:

Buying an assembled 383 short block is the easiest and possibly least expensive option for creating a "stock appearing" 383, but you will probably have to settle for a passenger side dip stick and a missing rear crankcase vent. The missing rear crankcase vent means you either have to give up the un-vented valve covers or use one of several possible schemes to create an alternate crankcase vent.

You *can* build a 383 that has the driver side dip stick and the rear crankcase vent, but there are only two block castings that are well suited to this conversion. One is the 1967 3892657 block, and the other is the GM replacement block 3959512 used in the 1970s. These two blocks have the driver side dip stick and the rear crankcase vent.

Both blocks are cast to accept boring for large-journal main bearings, and both blocks have added clearance notches for the longer stroke of a 350. These features make them better suited for a 383 than the earlier 327 blocks.

I built a 383 using a 3892657 block and it came out fine. The key issue is selecting the right "stroker rod" to minimize the amount of grinding you need to do at the base of the cylinder bores to clear the rods.

In theory you could build a 383 using your original '64 '870 block, but you would probably have to stick with small-journal crank mains, and clearancing the block for the rods would be more challenging (and risky, since grinding too far can hit the water jacket and ruin the block).

I'm still doing some research to find the "best" stroker rod, but until I find something better, the most stroke that I would recommend for your original 1964 '870 block is 3.625," which I think comes out to 362 CID. The additional stroke to 3.75" (383 CID) is just too risky when dealing with an original '870 block.

I have lots of additional info on stroking vintage 327s if you are interested, including a couple articles I wrote in the NCRS Restorer.

I want to reiterate that the easiest path is to just buy an assembled 383 short block and bolt on the top end from your original engine. The only problems you will have to deal with are the dipstick location and the rear crankcase vent. This assumes that the block used for the 383 has provisions for a mechanical fuel pump and clutch Z-bar mount (most do, but check first).

Regarding your question about whether a forged bottom end is necessary, most builders would say that a modern aftermarket cast crank is good for at least 500 HP. My view is that the rods should definitely be modern aftermarket forged "stroker profile" rods.

Since the cost of a cast crank is about $200 and the cost of a forged crank is about $600, I decided to pay the extra $400 for the extra "insurance" of a forged crank. But, I don't think this was really necessary.

Patrick03

How are you liking your 406? I'm worried it would be too much engine for the car and I'd have to go down the path of beefing up everything else.

Patrick03

Thanks Joe! Lots of good info you provided! I'm on the hunt to find the right short block or machined block I can assemble myself. I'm up against a time crunch though. Got to have everything ready to go by Labor day. I'll start a new build thread once I pick a direction to go.

Patrick03

[QUOTE=Crunch527;1595199703]For starters, head work is expensive...a new aluminum-headed, forged 383 will be better in the long run...you can dress it up to look the same as the original engine.[/QUOTE​​​​​​]

Thanks for the suggestions. I'll probably do most of the head work myself. Aluminum head's would be great, but not sure budget will allow it. I've had this car for a year now and it's amazing how much I've spent on what I thought was a pretty well sorted out car! Oh well, my dad and I have had a lot of fun working on it, so it's all good.

Randy G.

Best bang for the buck. Many on here have this, including me. Later block with one piece rear man seal means very little if any leaks. Warranty included. Aluminum heads, comp Cams roller rockers, hydraulic roller lifters means no special oil required. Gobs of torque. Free delivery and in stock. $3,999.


https://www.summitracing.com/parts/m...3ct1/overview/





Mine on the engine stand fresh out of the crate:

DucatiDon

Just spent Sunday enjoying the 383 in my 63.... In 100 degree Cali heat, and it ran 180* or less all day. Tire roasting power anytime, anywhere.

I built mine on a 512 block, so looks nearly completely stock. AFR aluminum heads and the Holley dual feed are the only obvious signs (besides the roar) that its not a factory 327.

If you HAVE to have the 327 PCV and driver side dip stick, you will have to source a block and build your own....Id guess it adds about 50% to the cost to do so.

DucatiDon

Patrick03

Ugh, that's not good news. I'm planning on calling Blueprint and other short block vendors to see if they have blocks that have the dip stick on the driver's side and rear crankcase ventilation. Sounds like I might be out of luck though.

Patrick03

I called BluePrint motors and it sounds like their BP3830 has drivers side dip stick and rear crankcase ventilation. Though when I talked with the sales guy (and with other short block vendors) about the rear crankcase ventilation I didn't get a real warm and fuzzy that they had any clue what I was talking about. With the other short block vendors I left casting number info and they said they'd check and call me back. Didn't think to do that with BluePrint, but I may call them back.

GearheadJoe

I have never seen an aftermarket block that has the vent provision. GM stopped using this vent after 1967. All previous small block castings have this vent, but the only block made after 1967 that has the vent is the 3959512 block that was used as a service replacement for the pre-1968 blocks. Most of the 3959512 blocks were used for warranty replacements, and there are a lot out there.

To help you show potential suppliers what you are asking about, you can use the attached photo that shows the vent hole located near the distributor hole.

There are plenty of the 1967 3892657 blocks and the replacement 3959512 available as used blocks. Just search ebay using the casting number, or call any of the big suppliers such as Engines Limited in Wisconsin.

As I noted in a previous post, these two castings have some other features that make it easier to stroke them to 383 than the earlier blocks such as the '870 block in your '64. Until I find a rod that requires less clearancing on the block, I think the highest you can safely go with stroking a pre-67 block is about 362 CID. But, I'm still looking at candidate rods, so something may turn up.

If you want to save time and cost, an assembled 383 short block is probably the way to go, but you will have to solve the PCV venting problem if you want to use unvented valve covers. There are various ways to accomplish that, but some compromises are involved.

tbarb

Your article in the NCRS restorer magazine is excellent. That's quite a bit of work to use a period correct block and your hp #'s are fantastic.

Patrick03

Thanks for the pic Joe, that helps a lot. I'm an NCRS member, how do I go about getting your article? I've not spent much time on the NCRS website.

Thanks,
Patrick

GearheadJoe

Hi Patrick:

The article about the short block build (which is probably the one that best addresses what you want to do) came out in the Fall 2015 issue of the NCRS restorer. If you can't locate your copy of the Fall 2015 Restorer, PM me and I will send you a copy of the article.

My "Part 2" article describes the rest of the build and the dyno tests. That article is in the Summer 2017 Restorer issue that should be arriving in your mail box any day now.

Westlotorn

If I was building a new 383 short block I would consider using an internally balanced crankshaft. This allows using the stock flywheel ( unless you choose a one piece rear main seal ). Might save a few bucks on misc parts.

GearheadJoe

I think that an internally balanced rotating assembly is highly desirable. The external balancing that GM did on the 400 was a compromise that works okay at low rpm, but it results in more stress on the crank at high rpm, compared to internal balancing.

As I understand it, its a bit easier to do internal balancing with a forged crank than with a cast crank. I have been told this is because the material that a forged crank is made from is a bit heavier, so that a forged counterweight weighs a bit more than a cast counterweight of the same size. However, I've never confirmed that this is really true.

In any event, several years ago when I was looking at buying a complete, balanced 383 rotating assembly, the ones with a forged crank were internally balanced and the ones with a cast crank were externally balanced.

Recently, I think I have seen internally balanced assemblies offered by Scat and Eagle that use cast cranks. This might be due to using lighter pistons or possibly a change in the cast crank design.

jimh_1962

Start off with this... I would think you can make a 383 out of it.

http://www.ebay.com/itm/1968-69-Larg...JYKfYO&vxp=mtr

GearheadJoe

That's a 3970010 block. While that casting number is very popular for building a 383, it does not have the rear crankcase vent.

To my knowledge, only the 1967 3892657 block and the GM service replacement 3959512 block have both the rear crankcase vent *and* the additional clearance notches at the bottom of the cylinder bores that GM added for rod clearance in the 350.

GM used the same raw castings of these two blocks to make both small journal and large journal versions of the finished blocks, so there is no problem line boring a small journal version for large journals.

Just searching ebay using the two casting numbers will usually turn up several listings. Here's an example of a 3959512 service replacement block that was machined by GM for small journal mains:

[url http://www.ebay.ca/itm/327-cu-in-chevy-block-3959512-dtd-K-30-3-std-bore-/122568348076?hash=item1c89a491ac:g:1v0AA OSwr7ZW5cnf&vxp=mtr][/url][/QUOTE]

Line boring a small journal version of either the 3892657 or 3959512 for large journals is easy. In fact, the small journal versions already have the large journal bearing tang notches machined in the main bearing saddles. Apparently, the bearing notches were machined before the block was line bored for either small journals or large journals.