So a little over a year ago I started down the path of building another '68 383 "beater" motor for my '68 Bee and stash her factory original 383.

Unfortunately I got too busy to get on the build despite having parts on hand and machining done. I'm happy to say that the build is now going forward.

The basic recipe was to punch it .030, use 1.320 CH Diamond flat-tops, BBC 6.700 K-1 H-beam rods, and a 3.915 crank from 440 source yielding 451 cubes. Pistons are only 498g so it should still rev like a 383. Rod Piston assembly is about 450g lighter than the stock 383.

I wanted a bone stock look so I enlisted Dwayne Porter to prep me a set of Stealth (straight plug) heads and he spec'ed me up a comp solid cam to work with factory exhaust manifolds.

Short block is almost together, cam is degreed, its finally getting there! More later

That sounds like a really great build. "Only your hair dresser will know for sure". Uh...am I dating myself?

I have an 69 hp 383 been setting for bout 20 years now ,and was wondering what to do with it. I'll be watching this thread.

Hmm? If you are then I can see how that would be way less expensive than if you were dating the hair dresser.

I want to do something similar for my 68 Roar Runner. Only difference is that I will be using Edelbrock Performer heads I have on the shelf.

Aaahh- Tony Defeo and Cars Illustrated Magazine. I have every issue.

What is the target compression ratio on the build??

[/quote]

I want to do something similar for my 68 Roar Runner. Only difference is that I will be using Edelbrock Performer heads I have on the shelf. [/quote]



I was going to go with Edelbrocks but the angle plugs would put the plug boots close to the manifolds. MP aluminum 452's are essentially straight plug Edelbrocks, but cost is ridiculous, like $2K+ for bare heads .

So tonight I started torquing the K-1 rods. K-1 calls for 35lbs plus 60 degrees or .006-.0064 stretch for their 7/16 "ARP-2000 material" bolts. I noted that almost every other manufacturer with 1.6 UHL ARP-2000 bolts called for 75 lbs or .006-.0065 stretch with ARP lube. So I just measured free length with my point micrometer, cycled the bolts to 75 lbs 3 times, then measured the stretched length. Usually only took 1-2 more cinches with a breaker bar to get to .006". Tedious at first, but pretty straight forward once I got the method down.

Target compression is 10.5, When I calculated things before the build, I estimated that pistons would be .000-.005 out of the hole and would require an .051 head gasket for 10.5. As it turns out, pistons were .009 down (in center), but when accounting for piston rock, they are right at .000-.002. Fortunately my machinist said that decks were straight and parallel, so no decking required. I went with .039 gasket and I'm still at 10.46. If I had to deck the block more than .005-.007, things would have gotten interesting.

I want to do something similar for my 68 Roar Runner. Only difference is that I will be using Edelbrock Performer heads I have on the shelf. [/quote]



I was going to go with Edelbrocks but the angle plugs would put the plug boots close to the manifolds. MP aluminum 452's are essentially straight plug Edelbrocks, but cost is ridiculous, like $2K+ for bare heads . [/quote]

I had zero issues running the Edelbrock Heads / Angled Plugs and Factory HP Exhaust Manifolds

What CC are those stealth heads rated at ?

Pictures of angled plugs and HP Exhaust Manifolds

http://www.hughesengines.com/TechArticles/10hpmanifoldshookersupercompheadersonbigblockangle.php

tighter quench would allow more compresison, I would run a thinner head gasket and try to get about .035 and it should need less octane in my experience. I have run more cylinder pressure than that on iron heads so you should be fine.

Part of the reason for quench having an actual clearance distance is to acount for piston rock so you can run it closer for sure. I have never had a problem setting em up with .035 clearance as measured from the center of the piston sitting flat in the bore.

Good to know that the Eddie Heads are do-able with manifolds but for this build my Stealths are already done and ready to go.


On the quench thing, I can spend $175 on a set of .027 Cometic gaskets for .036 quench but will it make a worthwhile difference over the current.048?

Compression climbs from 10.47 to 10.8 at .036, will 10.47/.048 setup be more prone to detonation?

Well the Cometics are reusable...

R.

80cc

I guess another way to look at it is another 5-8 HP worth $175?

I just ran the math on theoretical efficiency of both compression ratios. The higher CR has a 0.8% increase in power.
In the case of a 600hp engine that amounts to 4.8hp.

R.

And........ With ex manifolds, this build will be well shy of 600hp.

First off, thanks for everyone's feedback and help on this build as the ideas behind it came entirely from members on this forum. This is just a spin-off of AndyF's manifold 400/470 build with cam & head help from Dwayne. Since the 383 is the most common BB out there, I hope other "resto-rod" guys might find the info here useful. A "budget" version could easily be built with offset ground 440 crank, pocket ported iron 452's, and MP528 cam.

So .027 head gasket HP increase is negligible, about margin of error of a dyno test.

Is increase in detonation resistance for tighter quench worthwhile or would I be spending money for no change to go to .027 or .030 Cometics? I'd like to save that money for pushrods if possible.

I basically have 3 Compression/quench options: 10.48/.048, 10.71/.039, or 10.8/.035. I know many have shared that .039 is ideal, anybody have experiences on the trade-offs??