68 427 Straub Cam
Thread Starter
Racer
Joined: Feb 2010
Posts: 362
Likes: 10
From: nashville tn
68 427 Straub Cam
Any one running this cam from Straub:
Retro Hyd Roller
Adv. 288/300
.050" 229/241
Lift 600/570
109 Lobe Sep
Heads on this car are stock closed chamber oval ports ,with small stem stainless valves 2.06/1.72 w/correct springs ect.
intake:factory aluminum dual plan spread bore
rochester 800 cfm from Shaun Murphy Induction. Great carb by the way
Headman headers
Richmond 5 speed
I have heard a great things about this cam but thinking it is may or may not be a little too much.
Thanks in advance
Mike
Retro Hyd Roller
Adv. 288/300
.050" 229/241
Lift 600/570
109 Lobe Sep
Heads on this car are stock closed chamber oval ports ,with small stem stainless valves 2.06/1.72 w/correct springs ect.
intake:factory aluminum dual plan spread bore
rochester 800 cfm from Shaun Murphy Induction. Great carb by the way
Headman headers
Richmond 5 speed
I have heard a great things about this cam but thinking it is may or may not be a little too much.
Thanks in advance
Mike
Le Mans Master
Joined: May 2006
Posts: 9,993
Likes: 1,136
From: League City Tx
Any one running this cam from Straub:
Retro Hyd Roller
Adv. 288/300
.050" 229/241
Lift 600/570
109 Lobe Sep
Heads on this car are stock closed chamber oval ports ,with small stem stainless valves 2.06/1.72 w/correct springs ect.
intake:factory aluminum dual plan spread bore
rochester 800 cfm from Shaun Murphy Induction. Great carb by the way
Headman headers
Richmond 5 speed
I have heard a great things about this cam but thinking it is may or may not be a little too much.
Thanks in advance
Mike
Retro Hyd Roller
Adv. 288/300
.050" 229/241
Lift 600/570
109 Lobe Sep
Heads on this car are stock closed chamber oval ports ,with small stem stainless valves 2.06/1.72 w/correct springs ect.
intake:factory aluminum dual plan spread bore
rochester 800 cfm from Shaun Murphy Induction. Great carb by the way
Headman headers
Richmond 5 speed
I have heard a great things about this cam but thinking it is may or may not be a little too much.
Thanks in advance
Mike
That cam will drive great in your combo! Definitely not too big.
Thread Starter
Racer
Joined: Feb 2010
Posts: 362
Likes: 10
From: nashville tn
Burning Brakes
Joined: Aug 2008
Posts: 878
Likes: 55
From: Deep South Denmark
Depends on what you like.
I have it in my 489 with 10:1 and Brodix RR-O heads.
I'm disappointed with it.
When I ordered it I told them that I don't care if the engine makes 400 or 500 HP as long as it idles nicely and makes enough vacuum to operate the brakes.
As I couldn't get it to idle properly and get decent vacuum I contacted them and I was told that I would probably have to lock my mechanical timing advance out and run full 36 degrees at idle and even then not expect more than 11-12 in-Hg vacuum.
Other than that I think it will run great (have only done 30 miles in it) if I can find a race engine specialist to help tune it.
One good thing is that it starts very quickly.
It is however far from what I ordered.
I have it in my 489 with 10:1 and Brodix RR-O heads.
I'm disappointed with it.
When I ordered it I told them that I don't care if the engine makes 400 or 500 HP as long as it idles nicely and makes enough vacuum to operate the brakes.
As I couldn't get it to idle properly and get decent vacuum I contacted them and I was told that I would probably have to lock my mechanical timing advance out and run full 36 degrees at idle and even then not expect more than 11-12 in-Hg vacuum.
Other than that I think it will run great (have only done 30 miles in it) if I can find a race engine specialist to help tune it.
One good thing is that it starts very quickly.
It is however far from what I ordered.
Last edited by Danish Shark; Mar 26, 2016 at 10:04 AM.
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Team Owner
Joined: Oct 2004
Posts: 81,241
Likes: 3,063
From: altered state
St. Jude Donor '05
link?
Sounds like he still needs to do some tuning to get his right
Thats a baby cam shouldnt take much to make it run right
edit: vaccum cans are cheap
Sounds like he still needs to do some tuning to get his right
Thats a baby cam shouldnt take much to make it run right
edit: vaccum cans are cheap
Last edited by cv67; Mar 26, 2016 at 03:29 PM.
Drifting
Joined: Oct 2005
Posts: 1,527
Likes: 148
From: East London/SW Essex UK
Depends on what you like.
I have it in my 489 with 10:1 and Brodix RR-O heads.
I'm disappointed with it.
When I ordered it I told them that I don't care if the engine makes 400 or 500 HP as long as it idles nicely and makes enough vacuum to operate the brakes.
As I couldn't get it to idle properly and get decent vacuum I contacted them and I was told that I would probably have to lock my mechanical timing advance out and run full 36 degrees at idle and even then not expect more than 11-12 in-Hg vacuum.
Other than that I think it will run great (have only done 30 miles in it) if I can find a race engine specialist to help tune it.
One good thing is that it starts very quickly.
It is however far from what I ordered.
I have it in my 489 with 10:1 and Brodix RR-O heads.
I'm disappointed with it.
When I ordered it I told them that I don't care if the engine makes 400 or 500 HP as long as it idles nicely and makes enough vacuum to operate the brakes.
As I couldn't get it to idle properly and get decent vacuum I contacted them and I was told that I would probably have to lock my mechanical timing advance out and run full 36 degrees at idle and even then not expect more than 11-12 in-Hg vacuum.
Other than that I think it will run great (have only done 30 miles in it) if I can find a race engine specialist to help tune it.
One good thing is that it starts very quickly.
It is however far from what I ordered.
Burning Brakes
Joined: Aug 2008
Posts: 878
Likes: 55
From: Deep South Denmark
Is that 28 degrees plus vacuum advance? If so how much vacuum advance?
I don't know anything about this, which is why I called someone with a good reputation. From what I now understand the low LSA his cams have shifts the power band upwards (again the opposite of what I wanted). Maybe it is also the lower LSA that makes it idle so poorly?
My AFR indicator said it was running rich (about 11, but that value surges up and down), but the exhaust is eye watering and smells bad like it's lean?
It doesn't change the idle characteristics much when I adjust the mixture screws in or out, until I get to the points where it won't idle anymore.
I tried this with different ignition settings with no change.
That's why I called the man himself and since he told I would have to run weird ignition timing and still wouldn't be able to get enough vacuum to operate the brakes with that cam I thought I would probably have to replace it with a cam for grown ups.
I even bought a set of poly engine mounts in a attempt to tame the shaking engine a bit, haven't installed those yet.
Last edited by Danish Shark; Mar 27, 2016 at 10:03 AM.
Race Director
Joined: Sep 1999
Posts: 11,361
Likes: 383
From: Plano TX
28 dgrs is what the timing light shows. I have EFI, so so vacuum advance, I can set the advance to whatever I want individually for idle, cruise, WOT, etc. I've tried lowering it to 22 dgrs at idle. It still idles OK, but not as smooth, so I went back to 28.
I've tried different idle AFRs. 14:1 was definitely rough. I could feel random misfires and there was engine shake. Currently running 13.3:1 and it's smooth.
Eye-watering and smelly exhaust makes me think you have a lot of misfires going on. It's unburnt fuel that makes eyes water.
See if you can get the idle AFR to 12.5:1 and set idle timing in the high-20s and then see what you've got for vacuum. The vacuum should be stable at that point. If it wanders up and down something else is wrong. Since you're carbed you might not get as much vacuum as my EFI, but you should see more than enough for power brakes.
I've tried different idle AFRs. 14:1 was definitely rough. I could feel random misfires and there was engine shake. Currently running 13.3:1 and it's smooth.
Eye-watering and smelly exhaust makes me think you have a lot of misfires going on. It's unburnt fuel that makes eyes water.
See if you can get the idle AFR to 12.5:1 and set idle timing in the high-20s and then see what you've got for vacuum. The vacuum should be stable at that point. If it wanders up and down something else is wrong. Since you're carbed you might not get as much vacuum as my EFI, but you should see more than enough for power brakes.
Last edited by zwede; Mar 27, 2016 at 10:00 AM.
Le Mans Master
Joined: Mar 2001
Posts: 5,738
Likes: 644
From: Lincoln, CA
Sounds like you need to reduce your Idle restrictors.
I had very little adjustment on mine. I went two sizes smaller and can now get a full 1.5 turns from closed. This will also clean up the smell and get your target AFR closer.
My 496 likes to be on the lean side at idle but I've got it at 14.7@850 RPM and it's pretty steady.
Vacuum is right at 14. Idle timing is 18 no vacuum hooked up.
I've found this wright up to be pretty perfect so for. http://www.burtonmachine.com/tech
I had very little adjustment on mine. I went two sizes smaller and can now get a full 1.5 turns from closed. This will also clean up the smell and get your target AFR closer.
My 496 likes to be on the lean side at idle but I've got it at 14.7@850 RPM and it's pretty steady.
Vacuum is right at 14. Idle timing is 18 no vacuum hooked up.
I've found this wright up to be pretty perfect so for. http://www.burtonmachine.com/tech
Last edited by ddawson; Mar 27, 2016 at 12:06 PM.
Burning Brakes
Joined: Aug 2008
Posts: 878
Likes: 55
From: Deep South Denmark
Thanks guys.
I wrote down the information in your posts and will get started with the tuning as soon as it gets back from the painter (I had to install an L88 hood).
@ddawson: With idle restrictors do you mean the idle air or fuel restrictors? I just bought the air restrictor kit along wit the fuel jet kit.
We have almost the same carb (mine is the SS-850 and I believe yours is the 830, right?
@zwede: Good point. I have actually been chasing the misfire theory already. I bought a new coil (plugs, cables, rotor and cover have already been replaced) but the engine hasn't run since then as I decided to replace the pulleys with a serpentine kit and have been struggling to find the right belt length (on my third one now
)
I wrote down the information in your posts and will get started with the tuning as soon as it gets back from the painter (I had to install an L88 hood).
@ddawson: With idle restrictors do you mean the idle air or fuel restrictors? I just bought the air restrictor kit along wit the fuel jet kit.
We have almost the same carb (mine is the SS-850 and I believe yours is the 830, right?
@zwede: Good point. I have actually been chasing the misfire theory already. I bought a new coil (plugs, cables, rotor and cover have already been replaced) but the engine hasn't run since then as I decided to replace the pulleys with a serpentine kit and have been struggling to find the right belt length (on my third one now
)
Last edited by Danish Shark; Mar 27, 2016 at 01:53 PM.
Safety Car
Joined: Jan 2009
Posts: 3,736
Likes: 56
From: anchorage ak
OK, that gives me hope that it may be set up to run somewhat better.
Is that 28 degrees plus vacuum advance? If so how much vacuum advance?
I don't know anything about this, which is why I called someone with a good reputation. From what I now understand the low LSA his cams have shifts the power band upwards (again the opposite of what I wanted). Maybe it is also the lower LSA that makes it idle so poorly?
My AFR indicator said it was running rich (about 11, but that value surges up and down), but the exhaust is eye watering and smells bad like it's lean?
It doesn't change the idle characteristics much when I adjust the mixture screws in or out, until I get to the points where it won't idle anymore.
I tried this with different ignition settings with no change.
That's why I called the man himself and since he told I would have to run weird ignition timing and still wouldn't be able to get enough vacuum to operate the brakes with that cam I thought I would probably have to replace it with a cam for grown ups.
I even bought a set of poly engine mounts in a attempt to tame the shaking engine a bit, haven't installed those yet.
Is that 28 degrees plus vacuum advance? If so how much vacuum advance?
I don't know anything about this, which is why I called someone with a good reputation. From what I now understand the low LSA his cams have shifts the power band upwards (again the opposite of what I wanted). Maybe it is also the lower LSA that makes it idle so poorly?
My AFR indicator said it was running rich (about 11, but that value surges up and down), but the exhaust is eye watering and smells bad like it's lean?
It doesn't change the idle characteristics much when I adjust the mixture screws in or out, until I get to the points where it won't idle anymore.
I tried this with different ignition settings with no change.
That's why I called the man himself and since he told I would have to run weird ignition timing and still wouldn't be able to get enough vacuum to operate the brakes with that cam I thought I would probably have to replace it with a cam for grown ups.
I even bought a set of poly engine mounts in a attempt to tame the shaking engine a bit, haven't installed those yet.
Last edited by bluedawg; Mar 27, 2016 at 03:44 PM.
Le Mans Master
Joined: Mar 2001
Posts: 5,738
Likes: 644
From: Lincoln, CA
Get the fuel restrictors. This will lean out the idle circuit and give you some adjustment back.
I have a Quickfuel so everything is adjustable.
I tried air bleeds and it created an off idle stumble so I went back to stock. I'm still working on the tuning but I've got the idle perfect, but cruise is rich at 10.1.
So jets are next. Transfer circuit is a little rich but not bad.
I have a Quickfuel so everything is adjustable.
I tried air bleeds and it created an off idle stumble so I went back to stock. I'm still working on the tuning but I've got the idle perfect, but cruise is rich at 10.1.
So jets are next. Transfer circuit is a little rich but not bad.
Le Mans Master
Joined: May 2006
Posts: 9,993
Likes: 1,136
From: League City Tx
Depends on what you like.
I have it in my 489 with 10:1 and Brodix RR-O heads.
I'm disappointed with it.
When I ordered it I told them that I don't care if the engine makes 400 or 500 HP as long as it idles nicely and makes enough vacuum to operate the brakes.
As I couldn't get it to idle properly and get decent vacuum I contacted them and I was told that I would probably have to lock my mechanical timing advance out and run full 36 degrees at idle and even then not expect more than 11-12 in-Hg vacuum.
Other than that I think it will run great (have only done 30 miles in it) if I can find a race engine specialist to help tune it.
One good thing is that it starts very quickly.
It is however far from what I ordered.
I have it in my 489 with 10:1 and Brodix RR-O heads.
I'm disappointed with it.
When I ordered it I told them that I don't care if the engine makes 400 or 500 HP as long as it idles nicely and makes enough vacuum to operate the brakes.
As I couldn't get it to idle properly and get decent vacuum I contacted them and I was told that I would probably have to lock my mechanical timing advance out and run full 36 degrees at idle and even then not expect more than 11-12 in-Hg vacuum.
Other than that I think it will run great (have only done 30 miles in it) if I can find a race engine specialist to help tune it.
One good thing is that it starts very quickly.
It is however far from what I ordered.
I have the next size or two up from the 229/241 Straub cam... Mine is the 237/245, it's in a 396...(actually 408"), with big square port heads, it idles at 850rpms and drives great..... It's not real torquey below 3500 since it's a short stroke crank and big heads but, from 3500-6500 it pulls nice....
I never have an idle problem.. Using a factory TI ignition that's recurved. It idles at 26* initial, before the vac advance....34* all in by 3000.
I'm pretty happy with it.... It made 441hp with stock intake and exhaust manifolds, with only a 650 carb... Now it has the proper 65' 780cfm Holley... I'm sure with real headers and the new carb it would be real close to 500hp... Out of 408".
I also have an Isky 238/248 in my 71' with the 496", it idles perfect 850 rpms, makes 12" of vacuum and handles all the vacuum stuff fine..(although I don't have power brakes). It has an 850 DP on an RPM air gap intake.. It idles at around 14.5 afr when it's fully warmed up...car drives perfect, and has for 18k miles. I do run the distributor locked out at 31* + 5* of vac advance.
Last edited by ajrothm; Mar 27, 2016 at 07:32 PM.
Burning Brakes
Joined: Aug 2008
Posts: 878
Likes: 55
From: Deep South Denmark
You definitely have something else wrong..
I have the next size or two up from the 229/241 Straub cam... Mine is the 237/245, it's in a 396...(actually 408"), with big square port heads, it idles at 850rpms and drives great..... It's not real torquey below 3500 since it's a short stroke crank and big heads but, from 3500-6500 it pulls nice....
I never have an idle problem.. Using a factory TI ignition that's recurved. It idles at 26* initial, before the vac advance....34* all in by 3000.
I'm pretty happy with it.... It made 441hp with stock intake and exhaust manifolds, with only a 650 carb... Now it has the proper 65' 780cfm Holley... I'm sure with real headers and the new carb it would be real close to 500hp... Out of 408".
https://m.youtube.com/watch?v=Yim71uKmTpk
I also have an Isky 238/248 in my 71' with the 496", it idles perfect 850 rpms, makes 12" of vacuum and handles all the vacuum stuff fine..(although I don't have power brakes). It has an 850 DP on an RPM air gap intake.. It idles at around 14.5 afr when it's fully warmed up...car drives perfect, and has for 18k miles. I do run the distributor locked out at 31* + 5* of vac advance.
I have the next size or two up from the 229/241 Straub cam... Mine is the 237/245, it's in a 396...(actually 408"), with big square port heads, it idles at 850rpms and drives great..... It's not real torquey below 3500 since it's a short stroke crank and big heads but, from 3500-6500 it pulls nice....
I never have an idle problem.. Using a factory TI ignition that's recurved. It idles at 26* initial, before the vac advance....34* all in by 3000.
I'm pretty happy with it.... It made 441hp with stock intake and exhaust manifolds, with only a 650 carb... Now it has the proper 65' 780cfm Holley... I'm sure with real headers and the new carb it would be real close to 500hp... Out of 408".
https://m.youtube.com/watch?v=Yim71uKmTpk
I also have an Isky 238/248 in my 71' with the 496", it idles perfect 850 rpms, makes 12" of vacuum and handles all the vacuum stuff fine..(although I don't have power brakes). It has an 850 DP on an RPM air gap intake.. It idles at around 14.5 afr when it's fully warmed up...car drives perfect, and has for 18k miles. I do run the distributor locked out at 31* + 5* of vac advance.
Shakes a lot. This was with the old Demon carb, I now have a new Quick Fuel SS-850 so I can get started with the tuning.
Last edited by Danish Shark; Mar 28, 2016 at 10:47 AM.