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Discussion Starter · #1 ·
Recently picked up a 010 block that just cane back from the machine shop bored and clearanced. Ive got a 400 crank and it came with I beam rods, and domed pistons. Ive got a cam with the whole valvetrain. Ill post a link to the cam specs below. 4 speed manual, gears are 4.11 but looking to change to 3.73.Looking for advise on what if i should be using domed pistons with this cam setup or if i should change it up. Its going in a 79 camaro just looking for a decent amount of reliable power on a budget. Thanks in advance.

 

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Are you trying to do this using pump gas??

Street car (cruiser), street/strip car, or drag car??

I hope that those engine block pics are a "before" shot, because that isn't fresh and ready to go....its hack honed and should be bored oversize more than it is.
You can still see ring top travel divots in the bore wall....not going to seal at TDC worth a crap!!!.
Please say those are "before shop" pics?!!!!

Is that an actual 400 crank with the main journals ground down to fit a 350 block....or an aftermarket 350 mains crank with the 3.75" stroke from the 400?? ("383 stroker crank")

What is the connecting rod length??
Reason I ask is the piston picture shows a pretty tall distance from center of the piston pin to the flat deck section....like sombody using the short stock 400 rods and 350 replacement pistons to make an old school short rod 383.

The domed piston is just part of the total compression ratio picture, you also need head chamber volume and head gasket volume in order to get a reasonable estimate of final compression ratio.
 

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Judging by what looks like new cam bearings thats the after.

I think your first step is getting an estimate from a respected machine shop and going to small claims court to get your money back for that mess you have sitting on your floor.

I seen better hatching done with a hand drill and a flex hone.
 

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That kinda looks like the lifters bores are bushed although it's hard to tell from over here.
I'll agree that not brand new, might be used but not used up, but it aint new.
Regardless of that, on the longer stroke of 3.750 it's easier to make compression with so if you go dome, an .0125 is about all you can get in there unless on you go E85 than you got a margin of error to about 15:1cr.
 

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A 383 takes custom compression height and skirt length pistons that are matched to the 3.75 inch stroke within the confines of the 9.025 inch deck height from the centerline of the main bearing diameter. This and the need to move the crankshaft counterweights under the piston when it’s at Bottom Dead Center (BDC) determines the rod length and piston combination. GM solved this with a story rod and unique piston for the 400 but at least the piston from this cannot be used on a 400 builds as its diameter is bigger than a 350 block can be bored.

The 400 crank needs to have its main journals reground to that of the 350 diameter to fit this block, this will be as expensive or more than just buying a new cast 383 crank sold for this purpose. As with above the rod and piston makes a unique height combination there are combination choices here for 5.56, 5.7, 5.9, 6.0, 6.1 inch rods. The 383 cam be internally balanced like a 383 but that takes a high level of engineering in parts selection to get the rod and piston weights in a range the counterweights of the crank can work with. More typically it is much less complicated to go with internals that net out inside the range of the 400‘s external balance then use the offset weight 400 damper and flywheel or flex plate as appropriate to the transmission type.

Domed pistons are meant for extraordinarily high racing level compression ratios, they are poor burners in that they present a lot of surface area that removes heat from the burn simply as a heat sink and they slow the burn by physical obstruction. They do make power to a point but it’s a race of more power through ultra high compression against power either not achieved through the slower burn speed or actually lost to heat sinking. So this gets you into 100+ octane fuel which these days and for the previous 45 years has not been available at corner gas stations. So at best you need to design around 91-93 octane unless your going to go to the nearby race track for high octane fuel for every fill up. The additional stroke of a 383 alone drives very high compression ratios, in the end what that is depends on combustion chamber volumes. But typically a flat top piston is plenty sufficient to drive 100+ octane fuel, more common on these builds is a dished piston to get the compression down to something that 91-93 octane can burn without blowing the head’s off the engine.

So in summary I don’t think your going to get there on the parts in hand and probably not inside a budget your thinking about. 383’s are tricky builds when you step outside the commercially available parts. Back in the day before kits using 400 parts you had to be a very knowledgeable builder and machinist to pull this off.

Bogie
 

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Discussion Starter · #6 ·
Are you trying to do this using pump gas??

Street car (cruiser), street/strip car, or drag car??

I hope that those engine block pics are a "before" shot, because that isn't fresh and ready to go....its hack honed and should be bored oversize more than it is.
You can still see ring top travel divots in the bore wall....not going to seal at TDC worth a crap!!!.
Please say those are "before shop" pics?!!!!

Is that an actual 400 crank with the main journals ground down to fit a 350 block....or an aftermarket 350 mains crank with the 3.75" stroke from the 400?? ("383 stroker crank")

What is the connecting rod length??
Reason I ask is the piston picture shows a pretty tall distance from center of the piston pin to the flat deck section....like sombody using the short stock 400 rods and 350 replacement pistons to make an old school short rod 383.

The domed piston is just part of the total compression ratio picture, you also need head chamber volume and head gasket volume in order to get a reasonable estimate of final compression ratio.
The crank is out of this car...


This is my Dads wagon his top end got all f***** up and just got a new fresh done 383. Crank was inspected by a machine shop, told us it was fine so i will use that and the rods out of that engine also. I paid $500 for the block,rods and pistons, with a set of POS smog heads that im not going to use. I will have a local machine shop look at the block before i assemble it
 

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Can you be specific? What brand crank??
What brand, or at least what type of rods?? How long are they?

Article about that car says forged crank, internal balance, 6.0" long rods, Diamond pistons, 10:1 compression.

That piston you posted a picture of doesn't look like a Diamond, it's not even forged....liiks like a hypereutectic.
It clearly isn't a 6" rod 383 piston, I can see that. It's also not a 10:1 piston
 

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Like everyone so far has said, it doesnt look right. Dont buy that cam until you have everything else in order, especially the heads. Profiler makes a nice 200/205 cc head for a medium size street engine. If you research here a 379 Chad Speier build you will have a very good ides how to make over 500 hp using a similar mild roller. Make sure you get the pressurized lube rollers
 

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As far as budget engine goes I found out letting someone else build a engine then change direction has always paid off for me.

You can find a good running engine broken in with "low" miles and a few goodies from $1000 to $2000 after a bit of searching over a few weeks.

Generally your buying the parts and getting the labor for free.
Now built sbc do get snatched up fast because they are just not as many being built with LS being a option. Your best bet is actually finding someone doing a LS swap with a built sbc still under the hood.

I am sure if I spent some time I could find a 383 or 400 for cheap. But daylight is currently burning.

Here is a 355 for $1500 thats local to me.


I would offer $1250 to $1300 after checking a few things then drop it under that camaro's hood within 2 weeks and beat the snot out of it for the next 4 years.
 
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