Engine Options
Melting Slicks
Joined: Dec 2009
Posts: 3,235
Likes: 658
From: Thunder Bay
thats where i was at, 2k ish to freshen up this one or get something like this
427 short block
at that price it would almost be silly to not go that route, throw a set of smaller heads on the 383 and sell it off for what that cost me.
i dont know yet, thats why im here, you guys always have some good ideas
427 short block
at that price it would almost be silly to not go that route, throw a set of smaller heads on the 383 and sell it off for what that cost me.
i dont know yet, thats why im here, you guys always have some good ideas
Drifting
Joined: Aug 2015
Posts: 1,939
Likes: 477
From: NSW, Australia
C3 of Year Finalist (track prepared) 2019
And it does depend what you want out of the engine too. That's a big cam, if you're not someone who loves a bunch of revs then a milder cam and compression choice may be more to your liking.
Team Owner
Joined: Apr 1999
Posts: 21,953
Likes: 1,445
From: Reno Nevada
2024 C3 of the Year Finalist- Modified
I'm not understanding the plus and minus piston cc posted
dished pistons and valve reliefs are minus cc. Decreasing compression
+ plus cc or domed pistons increase compression ratio.
as to head sizes for a 383. My first one I built using 227 cc because I thought my canton 18 degree 265 cc would have required custom headers and been lazy below 3500 rpm. I figured it out to be 11.2 with a. 021 head gasket and 64cc heads
as to roller cam 383 motors. The biggest I tried in my vette was a 242 248. It ran very well from 4500 to my rev limiters 7500 not a good around town motor
I down graded to a custom lobe billet steel solid roller of 236 242 112 ground 4 degrees retarded with. 640/.670 lift
I'm not in front of your motor to make a decision on what compression it might really be. But the heads might be 76cc and the big cam bleeds off the cranking compression. I built a 12.5 c/r 396 sbc with +10 cc domed pistons for a clients drag car. So it is doubtful that you have plus 7cc
dished pistons and valve reliefs are minus cc. Decreasing compression
+ plus cc or domed pistons increase compression ratio.
as to head sizes for a 383. My first one I built using 227 cc because I thought my canton 18 degree 265 cc would have required custom headers and been lazy below 3500 rpm. I figured it out to be 11.2 with a. 021 head gasket and 64cc heads
as to roller cam 383 motors. The biggest I tried in my vette was a 242 248. It ran very well from 4500 to my rev limiters 7500 not a good around town motor
I down graded to a custom lobe billet steel solid roller of 236 242 112 ground 4 degrees retarded with. 640/.670 lift
I'm not in front of your motor to make a decision on what compression it might really be. But the heads might be 76cc and the big cam bleeds off the cranking compression. I built a 12.5 c/r 396 sbc with +10 cc domed pistons for a clients drag car. So it is doubtful that you have plus 7cc
Race Director
Joined: Jul 2015
Posts: 13,082
Likes: 3,400
From: SW Florida.
The short block is assembled and paid for. Pull the heads. Measure the chambers. Double check piston dome-dish. Degree the cam. You can CC chambers and pistons with a 4 buck flavor shooter from Walmart and a piece of plexi. Then decide if you are selling heads and buying more suitable, or redoing rotating assy.
Last edited by derekderek; Apr 21, 2018 at 12:11 PM.
Le Mans Master
Joined: Aug 2017
Posts: 8,336
Likes: 2,810
From: Cool Northern Michigan
gkull, When using a compression calulator to find static compression ratio and dynamic compression ratio, a dish piston is figured into the formula as a plus + because it adds volume to the cylinder. A domed piston is figured as a negative because it subtracts vol.
My pistons are domed, 0.125 tall, but are a neg (-2.4) to find my C.R.
My pistons are domed, 0.125 tall, but are a neg (-2.4) to find my C.R.
Thread Starter
Instructor
Joined: Feb 2016
Posts: 215
Likes: 26
From: Bismarck North Dakota
Yeah its $4100 for the short block...(with ching ching no name parts in it)
Plus $400 or so to go through the heads, springs, setup for hyd roller etc.
Another couple hundred for a good intake, gaskets etc...
Another hundred for good pushrods in the correct length
Another couple hundred for a GOOD oil pan to help with windage from that 4" crank.
So on, so forth....it'll add up quick. $5k+ for a long block full of no name Chinese stuff in it...No telling if it will actually make power...(since they already have a cam in it, without knowing what heads/induction you'll be running
)....
At this point, you may as well start over and build a GOOD 427 from scratch.... spend the $10k-12k, make 600hp and call it good. At least then you know what you are getting...
Or spend $3k on the 383, make 500hp+ and reuse 90% of what you already have sitting there...
Its your money......
Plus $400 or so to go through the heads, springs, setup for hyd roller etc.
Another couple hundred for a good intake, gaskets etc...
Another hundred for good pushrods in the correct length
Another couple hundred for a GOOD oil pan to help with windage from that 4" crank.
So on, so forth....it'll add up quick. $5k+ for a long block full of no name Chinese stuff in it...No telling if it will actually make power...(since they already have a cam in it, without knowing what heads/induction you'll be running
)....At this point, you may as well start over and build a GOOD 427 from scratch.... spend the $10k-12k, make 600hp and call it good. At least then you know what you are getting...
Or spend $3k on the 383, make 500hp+ and reuse 90% of what you already have sitting there...
Its your money......
and yeah, the rest of the parts needed will add up in the end as you have stated, so would be looking at around 3x the cost of just changing pistons.
i actually just went and got the car out of storage today so am going to start with just a few small things, im pretty sure i have a 750 holley laying around somewhere i may stick on there see how that does.
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Thread Starter
Instructor
Joined: Feb 2016
Posts: 215
Likes: 26
From: Bismarck North Dakota
I'm not understanding the plus and minus piston cc posted
dished pistons and valve reliefs are minus cc. Decreasing compression
+ plus cc or domed pistons increase compression ratio.
as to head sizes for a 383. My first one I built using 227 cc because I thought my canton 18 degree 265 cc would have required custom headers and been lazy below 3500 rpm. I figured it out to be 11.2 with a. 021 head gasket and 64cc heads
as to roller cam 383 motors. The biggest I tried in my vette was a 242 248. It ran very well from 4500 to my rev limiters 7500 not a good around town motor
I down graded to a custom lobe billet steel solid roller of 236 242 112 ground 4 degrees retarded with. 640/.670 lift
I'm not in front of your motor to make a decision on what compression it might really be. But the heads might be 76cc and the big cam bleeds off the cranking compression. I built a 12.5 c/r 396 sbc with +10 cc domed pistons for a clients drag car. So it is doubtful that you have plus 7cc
dished pistons and valve reliefs are minus cc. Decreasing compression
+ plus cc or domed pistons increase compression ratio.
as to head sizes for a 383. My first one I built using 227 cc because I thought my canton 18 degree 265 cc would have required custom headers and been lazy below 3500 rpm. I figured it out to be 11.2 with a. 021 head gasket and 64cc heads
as to roller cam 383 motors. The biggest I tried in my vette was a 242 248. It ran very well from 4500 to my rev limiters 7500 not a good around town motor
I down graded to a custom lobe billet steel solid roller of 236 242 112 ground 4 degrees retarded with. 640/.670 lift
I'm not in front of your motor to make a decision on what compression it might really be. But the heads might be 76cc and the big cam bleeds off the cranking compression. I built a 12.5 c/r 396 sbc with +10 cc domed pistons for a clients drag car. So it is doubtful that you have plus 7cc
Team Owner
Joined: Apr 1999
Posts: 21,953
Likes: 1,445
From: Reno Nevada
2024 C3 of the Year Finalist- Modified
My 383 has two valve relief flat tops pistons -7 cc. decked block .015 compressed gasket, 64 cc heads......... and it comes to 11.18 C/R or so
Le Mans Master
Joined: Mar 2004
Posts: 7,510
Likes: 1,519
From: Little Rock AR
Several aftermarket piston manufacturers provide a CR calculator that uses those crazy negative number net dome volumes. JE does it if I remember right. Some others do too. Counter intuitive if you ask me. If you calculate it yourself you probably would use a positive number for the dome volume. I know I do.
Drifting
Joined: Aug 2008
Posts: 1,528
Likes: 24
From: Calgary Alberta
Like I always say- "No substitute for cubic inches". Seriously, if the decision was mine I would've thrown a BB in that car all day long. It's funny though- you have the car with no engine and I have an engine but no car. Real world issues.........
Race Director
Joined: Jul 2015
Posts: 13,082
Likes: 3,400
From: SW Florida.
I looked on afr's website. Looks like 65 or 75 for chamber size.with 75 chambers and 7 cc dome about 10.5 to 1. With 7cc dish it is about 9.0. I think cranking pressure is so low cuz of too much duration. With 65cc head, it would be 11.91 with 7cc domes.
Last edited by derekderek; Apr 21, 2018 at 07:03 PM.
Thread Starter
Instructor
Joined: Feb 2016
Posts: 215
Likes: 26
From: Bismarck North Dakota
so i may have been too liberal with things such as the deck height and head gasket thickness.
Le Mans Master
Joined: Oct 2002
Posts: 7,098
Likes: 378
From: Las Vegas - Just stop perpetuating myths please.
I bet you don't like it because with that huge cam its lugging and lazy at parking lot speeds and stop & go traffic. Then it can make power w/WOT but it kind'a winds up slow. Correct?
Put a cam with less than 270 degrees full duration and advance it until you get the cranking pressure/throttle response you want. You want a tighter LSA angle also of 108 or tighter. Sorry I don't have an estimate how much cranking pressure increase w/reduced cam duration but its the intake valve closing point that controls it.
But man those are huge intake ports on the heads. More like something for a 427ci short block like you mentioned. Not much else is gonn'a fix that mismatch.
But really for the price of cam core and an weekends labor you can give it a try with a different cam and save what $5k?
Good luck.
Put a cam with less than 270 degrees full duration and advance it until you get the cranking pressure/throttle response you want. You want a tighter LSA angle also of 108 or tighter. Sorry I don't have an estimate how much cranking pressure increase w/reduced cam duration but its the intake valve closing point that controls it.
But man those are huge intake ports on the heads. More like something for a 427ci short block like you mentioned. Not much else is gonn'a fix that mismatch.
But really for the price of cam core and an weekends labor you can give it a try with a different cam and save what $5k?
Good luck.
Last edited by cardo0; Apr 21, 2018 at 07:36 PM.
Is my vette stock?? HAHA
Joined: Oct 2015
Posts: 20,277
Likes: 9,418
From: Im not allowed to tell you
2020 C3 of the Year Finalist - Modified
2020 Corvette of the Year Finalist (performance mods)
2019 C3 of Year Winner (performance mods)
2016 C3 of Year Finalist
swap out the pistons and go from there. Dont be shy about it, grab that motor by its mounts and show it who's the boss!!!! If you got it cheap, put your money in it and make it a monster. If you dont want to change pistons throw a blower or turbo charge it, its gonna need BOOOOOST to make it a fire breather.....
Thread Starter
Instructor
Joined: Feb 2016
Posts: 215
Likes: 26
From: Bismarck North Dakota
swap out the pistons and go from there. Dont be shy about it, grab that motor by its mounts and show it who's the boss!!!! If you got it cheap, put your money in it and make it a monster. If you dont want to change pistons throw a blower or turbo charge it, its gonna need BOOOOOST to make it a fire breather.....
Last edited by Knerf; Apr 21, 2018 at 10:30 PM.
Is my vette stock?? HAHA
Joined: Oct 2015
Posts: 20,277
Likes: 9,418
From: Im not allowed to tell you
2020 C3 of the Year Finalist - Modified
2020 Corvette of the Year Finalist (performance mods)
2019 C3 of Year Winner (performance mods)
2016 C3 of Year Finalist
oops, bad link
