Compression numbers??? cam help? Carb size?
02-21-2006, 04:33 AM
#1
Guest
Posts: n/a
Compression numbers??? cam help? Carb size?
ok guys i'm trying to pick out what cam i want but first off i'm not sure what my compression will be with my setup.... as i was hopeing to get a little help.
here is my setup so fair
old school 010 4 bolt main block bored .030 over
GM "X" rods
speed pro 10.5:1 flat top pistons
fuelie heads 462 casting 64CC
i'm goign to deck the block and the heads for more compression the cheap way. but after deckign the heads i'm not sure what my true compression will be.... i'm going to be useing stock head gaskets i was told with this setup i would be looking at the 14:1 area for compression but i'm not really sure. i would like to get as much compression as i can with out haveing the vavle hit the piston but i'm still not sure what cam to use.
this motor is gogin to be in a all out drag car so i don't have to worry about engine vac. (i have manual brakes) i don't have to worry about the sniffer test i just want to go as fast as i can with the money and parts i have. this transmission that is goign to be behide the motor is a TH350 WITH a Trans brake. with a 5000 stall right now i have two holley 650DP carbs with a holley trick-kit ready to be installed into them but is this carb goign to be to small or should i go up to a 750?
i'm also thinkign about running a 250 shot 2 stage NOS system (100 shout out the hole and 150 shot at 1/8 mile)
so in a summary
compression is it 14:1 ?
what size cam to use?
carb to small?
here is my setup so fair
old school 010 4 bolt main block bored .030 over
GM "X" rods
speed pro 10.5:1 flat top pistons
fuelie heads 462 casting 64CC
i'm goign to deck the block and the heads for more compression the cheap way. but after deckign the heads i'm not sure what my true compression will be.... i'm going to be useing stock head gaskets i was told with this setup i would be looking at the 14:1 area for compression but i'm not really sure. i would like to get as much compression as i can with out haveing the vavle hit the piston but i'm still not sure what cam to use.
this motor is gogin to be in a all out drag car so i don't have to worry about engine vac. (i have manual brakes) i don't have to worry about the sniffer test i just want to go as fast as i can with the money and parts i have. this transmission that is goign to be behide the motor is a TH350 WITH a Trans brake. with a 5000 stall right now i have two holley 650DP carbs with a holley trick-kit ready to be installed into them but is this carb goign to be to small or should i go up to a 750?
i'm also thinkign about running a 250 shot 2 stage NOS system (100 shout out the hole and 150 shot at 1/8 mile)
so in a summary
compression is it 14:1 ?
what size cam to use?
carb to small?
02-21-2006, 09:57 AM
#2
Moderator
iTrader: (14)
Join Date: Mar 2000
Location: Littleton, CO USA
Posts: 43,169
Likes: 0
Received 36 Likes
on
34 Posts
Car: 82 Berlinetta/57 Bel Air
Engine: LS1/LQ4
Transmission: 4L60E/4L80E
Axle/Gears: 12B-3.73/9"-3.89
From your other threads, I understand the 462's are being used because that's what you've got. I forget if they're already ported or if you're going to do some porting on them. Either way, that needs to be established first, and then have the chambers cc'd so you know what size they are. After that, you can decide how much to shave them to get whatever final chamber size you want. Have you decided yet whether to bite the bullet and have hardened valves & seats installed?
You are really going about this rather hap-hazzard, and you're either going to waste money in the process, or end up disappointed with the results. First, you don't "think" about running a 250 shot 2 stage NOS system, you either will or you won't - because whether you do or don't makes a big difference in how you should build the engine. For instance, you might be able to run 14:1 compression on race gas, but probably not if you're spraying the engine. Same story with the cam.
Decide now what you're going to do and build accordingly.
You are really going about this rather hap-hazzard, and you're either going to waste money in the process, or end up disappointed with the results. First, you don't "think" about running a 250 shot 2 stage NOS system, you either will or you won't - because whether you do or don't makes a big difference in how you should build the engine. For instance, you might be able to run 14:1 compression on race gas, but probably not if you're spraying the engine. Same story with the cam.
Decide now what you're going to do and build accordingly.
02-21-2006, 11:09 AM
#3
Guest
Posts: n/a
Originally posted by five7kid
From your other threads, I understand the 462's are being used because that's what you've got. I forget if they're already ported or if you're going to do some porting on them. Either way, that needs to be established first, and then have the chambers cc'd so you know what size they are. After that, you can decide how much to shave them to get whatever final chamber size you want. Have you decided yet whether to bite the bullet and have hardened valves & seats installed?
You are really going about this rather hap-hazzard, and you're either going to waste money in the process, or end up disappointed with the results. First, you don't "think" about running a 250 shot 2 stage NOS system, you either will or you won't - because whether you do or don't makes a big difference in how you should build the engine. For instance, you might be able to run 14:1 compression on race gas, but probably not if you're spraying the engine. Same story with the cam.
Decide now what you're going to do and build accordingly.
From your other threads, I understand the 462's are being used because that's what you've got. I forget if they're already ported or if you're going to do some porting on them. Either way, that needs to be established first, and then have the chambers cc'd so you know what size they are. After that, you can decide how much to shave them to get whatever final chamber size you want. Have you decided yet whether to bite the bullet and have hardened valves & seats installed?
You are really going about this rather hap-hazzard, and you're either going to waste money in the process, or end up disappointed with the results. First, you don't "think" about running a 250 shot 2 stage NOS system, you either will or you won't - because whether you do or don't makes a big difference in how you should build the engine. For instance, you might be able to run 14:1 compression on race gas, but probably not if you're spraying the engine. Same story with the cam.
Decide now what you're going to do and build accordingly.
i knwo for a fact that they are 64CC heads that already have the screw in studs and have the bowl blended i'm just goign to port out the runners i'm also running a high raise intake with a 2" carb spacer....
02-21-2006, 06:08 PM
#4
Supreme Member
To get a 350 based motor to 14:1 with flat tops requires a
42.5cc head. You can't flat mill a 64cc head that much.
.006" flat mill removes 1cc from the combustion chamber.
.060" is about the useable flat mill limit on a stock head.
that will put you at 52-54cc for 64. Not all "64cc heads" actually measure out ot 64cc. Don't assume yours are without measuring them.
You can "angle mill" a cylinder head. Angle milling allows a smaller finished chamber size. Wether you can get them down to 42cc is another story. You have to angle mill the intake port face to correct alignment and angle spot face the cylinder head bolt holes.
Angle milling is $not cheap.$ Might be better off using a domed piston or buying new small chamber race heads.
You need to maintain a minumin piston to head clearance of about .040" or the piston will smack the head at high rpm.
no less than .035". A true "0 deck" and .038" gaskets works well.
For nitrous you'd be better off building to 12:1 or 12.5:1 compression. You can do this with flat tops and head deck milling. let the nitrous make the power. More nitrous=more power.
4.03" bore
3.48" stroke
0 deck height
.038" 8.8cc head gasket
64cc heads milled to 52cc
-5cc flat tops
will give you a 12.10:1 compression ratio.
Use a +3.5cc net volume dome piston and you'll get 13.70:1
thats about a .200" dome height.
Isky cam#201549
will work well. use 1.5:1 roller rockers and iskys recomended valve springs.
This cam works well on or off the juice.
Crane cam #111431
is another good one
Crane cam #114701
is a good nitrous cam for your purposes too.
With any of these the valve to piston clearance will be very close to minimun and must be checked. .100" minimum
You should buy valves with .100" longer stems to work with race valve springs. 1.90" installed height is typical.
Your 650 will work ok ( with larger needle and seats and correct jetting) A 750 or 850 would be better.
For Nitrous make the piston ring end gaps big. Bigger is better. The extra heat of the n2o will expand the top ring , closeing up the ring end gap. ring butting from running too small a ring end gap with nitous is a common hazard. make 'em big.
42.5cc head. You can't flat mill a 64cc head that much.
.006" flat mill removes 1cc from the combustion chamber.
.060" is about the useable flat mill limit on a stock head.
that will put you at 52-54cc for 64. Not all "64cc heads" actually measure out ot 64cc. Don't assume yours are without measuring them.
You can "angle mill" a cylinder head. Angle milling allows a smaller finished chamber size. Wether you can get them down to 42cc is another story. You have to angle mill the intake port face to correct alignment and angle spot face the cylinder head bolt holes.
Angle milling is $not cheap.$ Might be better off using a domed piston or buying new small chamber race heads.
You need to maintain a minumin piston to head clearance of about .040" or the piston will smack the head at high rpm.
no less than .035". A true "0 deck" and .038" gaskets works well.
For nitrous you'd be better off building to 12:1 or 12.5:1 compression. You can do this with flat tops and head deck milling. let the nitrous make the power. More nitrous=more power.
4.03" bore
3.48" stroke
0 deck height
.038" 8.8cc head gasket
64cc heads milled to 52cc
-5cc flat tops
will give you a 12.10:1 compression ratio.
Use a +3.5cc net volume dome piston and you'll get 13.70:1
thats about a .200" dome height.
Isky cam#201549
will work well. use 1.5:1 roller rockers and iskys recomended valve springs.
This cam works well on or off the juice.
Crane cam #111431
is another good one
Crane cam #114701
is a good nitrous cam for your purposes too.
With any of these the valve to piston clearance will be very close to minimun and must be checked. .100" minimum
You should buy valves with .100" longer stems to work with race valve springs. 1.90" installed height is typical.
Your 650 will work ok ( with larger needle and seats and correct jetting) A 750 or 850 would be better.
For Nitrous make the piston ring end gaps big. Bigger is better. The extra heat of the n2o will expand the top ring , closeing up the ring end gap. ring butting from running too small a ring end gap with nitous is a common hazard. make 'em big.
Last edited by F-BIRD'88; 02-21-2006 at 07:00 PM.
02-21-2006, 11:16 PM
#5
Guest
Posts: n/a
thanks for the info! but i'm goign to be workign with a 4.030 bore is that goign to change anything? also i'd liek to keep the pistons i have now since i don't really have the money for domed pistons. so what kinda of compresion will that be? mor alone the lines of 12.5:1 ? also if i do would i still be able to get around with pump gas (93 with 10% ethe.) i have been told that 10.5:1 is the most you can go and if i angel mill the heads will that trow off the spaceing for the intake? i was told that i would have to deck the block and the heads so the intake would fit with out useing some type of spacers.
i'm still not use to moding out blocks other then boreing line honing and all that normal stuff. do you know of any web site i can read up on this type of info?
again thanks for the info!
i'm still not use to moding out blocks other then boreing line honing and all that normal stuff. do you know of any web site i can read up on this type of info?
again thanks for the info!
02-22-2006, 10:18 PM
#7
Supreme Member
Yes those are all solid flat tappet cams. No this motor will not run on pump gas. The cr will be 12.10:1. If you want a pump gas motor, build a pump gas motor. 10.5:1 max.
If you want to run a roller pick one with simular .050" durations as I listed. But any and all rollers of this size will require piston fly cutting to gain VTP clearance with severly decked head and block. There is no free lunch. These specs are for a 4.030" bore. check my post again.
If you're on a budget use a good flat tappet solid cam and let the nitrous make the power. If you really want to run it on 93 octane build it with no more than 10.5:1. Again just use a little more N20. Haveing to use race gas on a street driven car gets old in a hurry. You really cannot have both. Decisions decisions decisions...
If you want to run a roller pick one with simular .050" durations as I listed. But any and all rollers of this size will require piston fly cutting to gain VTP clearance with severly decked head and block. There is no free lunch. These specs are for a 4.030" bore. check my post again.
If you're on a budget use a good flat tappet solid cam and let the nitrous make the power. If you really want to run it on 93 octane build it with no more than 10.5:1. Again just use a little more N20. Haveing to use race gas on a street driven car gets old in a hurry. You really cannot have both. Decisions decisions decisions...
Last edited by F-BIRD'88; 02-22-2006 at 10:28 PM.
Trending Topics
02-22-2006, 11:08 PM
#8
Guest
Posts: n/a
Originally posted by F-BIRD'88
Haveing to use race gas on a street driven car gets old in a hurry. You really cannot have both. Decisions decisions decisions...
Haveing to use race gas on a street driven car gets old in a hurry. You really cannot have both. Decisions decisions decisions...
ohhh no this car is for track only so i'm not to worryed about running race gas i was just asking because my buddy wants me to built him a motor for his monte carlo and wants the most compression he can get with out running race gas so sounds like 10.5:1 it is
02-23-2006, 12:31 AM
#9
Supreme Member
If you don't have money for domed pistons you won't have money for a roller cam or racing gas.
Build a motor you can live with. You can go real fast at the drags using 93octane friendly 10:1 compression and a good bit of nitrous for a lot less and lot less bother and machining work. Spend the money where it will do the most good.
With the money you save from not maximizing the cr from expensive decking and millng, buy some high flow aftermarket cylinder heads, quality headers, exhaust and induction. Much more bang for the $$$'s Sell off your old stuff.
Build your buddies motor with a real world measured 10:1 compression and tell him what ever you want. he'll go a lot faster, a lot longer if you concentrate on airflow improvements tp make street power, than trying to run a max-ed out compression ratio. It doesn't pay off in the long run on a daily driver.
Build a motor you can live with. You can go real fast at the drags using 93octane friendly 10:1 compression and a good bit of nitrous for a lot less and lot less bother and machining work. Spend the money where it will do the most good.
With the money you save from not maximizing the cr from expensive decking and millng, buy some high flow aftermarket cylinder heads, quality headers, exhaust and induction. Much more bang for the $$$'s Sell off your old stuff.
Build your buddies motor with a real world measured 10:1 compression and tell him what ever you want. he'll go a lot faster, a lot longer if you concentrate on airflow improvements tp make street power, than trying to run a max-ed out compression ratio. It doesn't pay off in the long run on a daily driver.
02-23-2006, 04:09 AM
#10
Guest
Posts: n/a
well see i already have the speed pro 10.5:1 flat tops.. its just then when you ned to built a motor build a trans mission install the roll cage installl the fuel cell install the fuel line buy all the AN fittings bult up the rear end so i don't blow the gears out from the cover buy the racing seats.... it just all adds up. fast... so i'm trying to put most of my money into the chassie of the car and then i'm going to use this motor for now just so i can get to the track and go racing then save some up money and built the motor i really want. but i also want to use this motor as a back up in case i blow a motor racing i'm thinkign about selling this flat top pistons i have to my buddy and i don't want to start off right away with the NOS since one i have never used it before and two i want to get a feel for the car first with out the NOS... can't so from craling right into running i'm goign to admit the first time i lunch the car at 5,000 RPM i'm going to scare the crap out of me. so i'm trying to do what i can with what i have and put the motor where it counts you knwo like roll cage, fuel sell SFC lower control arms panrod bar, rear end , cutting out the floor and moving a new one out of alum. putting the motor into the trans so i'm not smokeing the trans on it over and over i'm not about to put a junk yard trans in just so i can smoke the clutches in it and watch my ET's keep going slower and slower.. will i say to everyone i will be happy if i run low 12's
Thread
Thread Starter
Forum
Replies
Last Post
toronto formula
Engine/Drivetrain/Suspension Parts for Sale
15
11-10-2015 06:17 AM
knight72
Engine/Drivetrain/Suspension Wanted
0
08-10-2015 09:32 PM
