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Excellenceautosoluti 06-12-2019 10:31 AM

638 Block
Hello Guys.
I figure we might as well make this official, as I'm probably picking up a 1 piece RMS block this Monday. I will be sending to machine shop and getting proper work done to put a 383 Rotating Assembly into.
It is a 638 casting with provisions already for the Dog Bone and front cam holder in there. It has 4 bolt caps, but a little surface rust. I'm going to throw down $150 for it if it looks decent when I get there.
I have been scouting around here for awhile and there's not much to choose from for building a factory roller motor. Been seeing a few 400 blocks which would be ideal, but one has been punched .06 already, and the other needs machine work still and they want $500 for it. Not to mention the added cost of Retro Cam and Lifters. Also there's another that needs a sleeve, so I have decided just to go for a 383.
I am already putting together the 200cc intake runner heads right now, and am hoping to get this thing together rather quickly.

Excellenceautosoluti 06-12-2019 10:37 AM

2 Attachment(s)
Pics for block I'm thinking of getting.

ericnova72 06-12-2019 10:59 AM

Nothing wrong with a 538 block.

Are you also getting the 1-piece rear man seal adapter with it, it's missing in the photos??
If you have to buy a new one that almost doubles your buy-in price on the block.

Make sure the shop is going to cleanup hone those lifter bores if you can see any rust in them.

Excellenceautosoluti 06-12-2019 12:13 PM


Originally Posted by ericnova72 (Post 4677755)

Are you also getting the 1-piece rear man seal adapter with it, it's missing in the photos??

It's been about 2 years since I built my 880 Block which is also a 1 piece RMS. I don't remember anything special back there, although I have slept quite a bit since then and also had a few beers!

I will be ordering the one piece RMS rotating assembly from Skip White after we see how the block turns out. Will be something similar to this

Please try to get me a PN, because I'm only seeing the seal, and nothing else back there on my commercial Advance, NAPA, and Vato Zone accounts. I'm finding BS 40626 for Fel-Pro and JV554 for Molly. Does it have that big cover back there that holds the seal on the late model LS? I see a bunch of them every time I pull out an old burned up 4l60E I try to put a new rear main seal in it too...

ericnova72 06-12-2019 12:35 PM

This piece, bolts into that cavity behind the rear main cap on the block and holds that 1-piece rear main seal. Can't put the engine together without it. It is missing in your block pics.

Price has come down a bit, was over $100. 1-piece rear main seal retainer.

They also make these as adapters, to put a 2-piece seal crank in a 1-piece seal block.

Excellenceautosoluti 06-20-2019 10:25 AM

Talked with Chris Straub this morning, and told him everything he wanted to know. This is the camshaft he recommended to me and I'm going to go for it. It is a LOT BIGGER than I was planning on, but I am glad I spoke with him. Again from Excellent recommendations from You Guys on here.

He also recommended 1.6 rockers with this combo.

Excellenceautosoluti 06-20-2019 10:28 AM

1 Attachment(s)
Here is a pic of the heads I'm building.

Excellenceautosoluti 06-20-2019 02:58 PM


Head Improvement Kit

4 Bolt 1 piece rear main seal, going to have forged and balanced rotating assembly similar to this, will be somewhere around 10.5 to 1.

He didn't seem too concerned about the 3800 lb. weight of the truck with me in it.

Really seems like a lot of cam, but I hear the 383s soak up alot of duration...

Excellenceautosoluti 06-20-2019 08:54 PM

Any thoughts? This truck is not my daily driver. I don't mind putting a little effort into the tune, I know it's going to be a handful to get it right on the street. I was after a 288ish advertised generic grind at first, then talked to Straub... His grind is specific to the cubes, heads, compression, gear, and stall converter I am using.
His is really not that much more radical, is it?
There is a wealth of knowledge here, and I always look forward to input from members. But you guys are making me think twice from a lack of response.

ericnova72 06-20-2019 09:56 PM

The cam doesn't strike me as being overly radical. It'll be a good stout street/strip type cam, If you've got 3000+ rpm stall converter and at least 3.42 gears w/28" tire or 3.73 w/30" tire diameter it should be fine. 3.90 or 4.11 gear would be even better.

I don't recall what you had in your truck's driveline.

It is true the larger 3.75" stroke really soaks up duration, related to the fact piston speed at mid-stroke is a good bit higher than a 3.48" stroke 350.
Airflow demand by the engine is higher with the longer stroke compared to the 350.

You might not have gotten any response because there really isn't a specific tech question or a request from you for advice or comments ;)

Excellenceautosoluti 06-21-2019 05:41 AM

Thanks Eric, I do have 3.9s in the rear, with a 28ish tire. 10 inch converter that foot brakes at 2600 and hoovers at 3000 when I lean on it in going down the road.
I should have been more specific with my thoughts. I guess I was looking for an AttaBoy!
Maybe someone could run a simulation for me? 3.75 stroke, 4.030 Pistons will be at zero. Flat top -7, heads should be 68cc. With the 200cc runners. Straub is telling me 850 carb with the dual plane RPM intake.
Heads are clones of Dart? Pro Platinum?
Exhaust is currently,
Full length headers 1 5/8 into 2.5in. Xpipe.
Will I need 1 3/4 and 3 inch exhaust with this motor?
Thanks again, if I need to post more info, I can later today.

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