My Vortec Combo disappoints
Melting Slicks
Joined: Aug 2011
Posts: 3,140
Likes: 262
It is a fast ramp. I use 20w50 VR1. Maybe that helps? A stock 962 cam was tested by GM to last 100,000 mi. XE262 can't be expected to last as long.
With the oil filter bypass plugged, a cam failure usually does not require a rebuild since the shavings get trapped in the filter. So i don't worry about it.
.
I hope the OP chimes in. He has had just enough time to fix it
Good one Matt !! LOL
the 476 cam has really long ramps for long life. 320/324/112.5
That could be the cause of the OP's complaint. Soggy low end, this does not show up on the dyno. So, i would not buy the 476. BUT, someone that drives 25,000/year might love it for its long life.
With the oil filter bypass plugged, a cam failure usually does not require a rebuild since the shavings get trapped in the filter. So i don't worry about it.
.
I hope the OP chimes in. He has had just enough time to fix it
Good one Matt !! LOL the 476 cam has really long ramps for long life. 320/324/112.5
That could be the cause of the OP's complaint. Soggy low end, this does not show up on the dyno. So, i would not buy the 476. BUT, someone that drives 25,000/year might love it for its long life.
I know this is going to sound harsh, but really being direct is the only way I can figure to say this (and it's echoing what was said above).
You put heads on a motor that:flow more, and get the mixture swirling (better mixture and combustion). Then you choke the motor with a smaller cam. I'm not sure why you didn't expect what you've built.
Timing, I don't think, is your issue - but you might be able to get some back with timing. Most motors are happy at 36* total. What did you do for your weights in your distributor? What springs in the distributor? Is your vacuum advance working? Especially in your case, the lightest springs available would help. What vacuum pressure moves the advance? Guessing, again, 16 psi would be the right setting.
Still, for maximum efficiency and power that cam needs to change - the XE262 recommended above is a good one.
By way of comparison - I have a 350 truck bottom end in my Corvette (mid-70s low compression); Vortec heads; Comp Thumpr cam; 4 speed; 3.08 gears; holley 780 (now FAST Efi); DUI distributor (set at what I recommended above - except 10# on the vacuum); MSD ignition; hooker side pipes with reverse flow mufflers. I light the tires at any time in gears 1-3. Prior to the 4 speed, I had a turbo 350 with a 2400 stall - it'd light at any point in 1st, and if you didn't roll into the throttle while it was in 2nd, it'd light the tires.
You put heads on a motor that:flow more, and get the mixture swirling (better mixture and combustion). Then you choke the motor with a smaller cam. I'm not sure why you didn't expect what you've built.
Timing, I don't think, is your issue - but you might be able to get some back with timing. Most motors are happy at 36* total. What did you do for your weights in your distributor? What springs in the distributor? Is your vacuum advance working? Especially in your case, the lightest springs available would help. What vacuum pressure moves the advance? Guessing, again, 16 psi would be the right setting.
Still, for maximum efficiency and power that cam needs to change - the XE262 recommended above is a good one.
By way of comparison - I have a 350 truck bottom end in my Corvette (mid-70s low compression); Vortec heads; Comp Thumpr cam; 4 speed; 3.08 gears; holley 780 (now FAST Efi); DUI distributor (set at what I recommended above - except 10# on the vacuum); MSD ignition; hooker side pipes with reverse flow mufflers. I light the tires at any time in gears 1-3. Prior to the 4 speed, I had a turbo 350 with a 2400 stall - it'd light at any point in 1st, and if you didn't roll into the throttle while it was in 2nd, it'd light the tires.
The GM cam is supposed to be very close to the EX262 cam except the very bottom end performance is unknown/debatable ?
So I don't think he is under or overcammed - to me it sounds like the optimum cam for those heads (GM is building and selling crate motors with that exact combination)
Probably carb tuning , fuel delivery and ignition timing are the culprits here.
Le Mans Master
Joined: Dec 2009
Posts: 6,397
Likes: 649
From: Saskatoon Saskatchewan
I don't think he "choked" the motor at all with that cam - those heads are supposed to be good for supposedly 30-40 hp with no other changes (stock cam).
The GM cam is supposed to be very close to the EX262 cam except the very bottom end performance is unknown/debatable ?
So I don't think he is under or overcammed - to me it sounds like the optimum cam for those heads (GM is building and selling crate motors with that exact combination)
Probably carb tuning , fuel delivery and ignition timing are the culprits here.
The GM cam is supposed to be very close to the EX262 cam except the very bottom end performance is unknown/debatable ?
So I don't think he is under or overcammed - to me it sounds like the optimum cam for those heads (GM is building and selling crate motors with that exact combination)
Probably carb tuning , fuel delivery and ignition timing are the culprits here.
Race Director
Joined: Oct 2000
Posts: 15,053
Likes: 79
From: central FL, near the beach.
all these high duration cams put out plenty hp at high rpm. 320 degrees! how can that work at low rpm?
In 1990 i had the L79 cam in my 72. also 320 degrees! doggy u bet.
also a 80's crane blazer 288/288/114 at .050 218/218/114 better but still too much duration. PB worked sluggish. All 3 of these cams needed to be advanced 4-6* for any hope.
Guys look at .050" so much, they forget that is just 1/400 of a second. 1 point of dozens, hundreds. The valve has to CLOSE totally or it won't even start! try opening all the valves .001", negative .001" lash. won't run or will run like crap.
For the STREET, seat to seat duration determines manners idle - 2000. sometimes higher.
For DRAGS and DYNO tests it doesnt't matter at all. So can't tell from a dyno test how it will drive on the street in traffic.
Basic cam clues:
1. seat duration
2. duration at .050"
3. Lift
4. LSA
5. single pattern(0-4 spread) or wider spread 5+ degrees on the exhaust?
6. idle vacuum/speed
Those 6 together just give a CLUE, since there are hundreds of combos possible. Best clue for street manners is idle vacuum.
In 1990 i had the L79 cam in my 72. also 320 degrees! doggy u bet.
also a 80's crane blazer 288/288/114 at .050 218/218/114 better but still too much duration. PB worked sluggish. All 3 of these cams needed to be advanced 4-6* for any hope.
Guys look at .050" so much, they forget that is just 1/400 of a second. 1 point of dozens, hundreds. The valve has to CLOSE totally or it won't even start! try opening all the valves .001", negative .001" lash. won't run or will run like crap.
For the STREET, seat to seat duration determines manners idle - 2000. sometimes higher.
For DRAGS and DYNO tests it doesnt't matter at all. So can't tell from a dyno test how it will drive on the street in traffic.
Basic cam clues:
1. seat duration
2. duration at .050"
3. Lift
4. LSA
5. single pattern(0-4 spread) or wider spread 5+ degrees on the exhaust?
6. idle vacuum/speed
Those 6 together just give a CLUE, since there are hundreds of combos possible. Best clue for street manners is idle vacuum.
Last edited by Matt Gruber; Jan 14, 2013 at 01:52 PM.
Drifting
Joined: Jul 2011
Posts: 1,697
Likes: 139
From: Syracuse NY
I don't think he "choked" the motor at all with that cam - those heads are supposed to be good for supposedly 30-40 hp with no other changes (stock cam).
The GM cam is supposed to be very close to the EX262 cam except the very bottom end performance is unknown/debatable ?
So I don't think he is under or overcammed - to me it sounds like the optimum cam for those heads (GM is building and selling crate motors with that exact combination)
Probably carb tuning , fuel delivery and ignition timing are the culprits here.
The GM cam is supposed to be very close to the EX262 cam except the very bottom end performance is unknown/debatable ?
So I don't think he is under or overcammed - to me it sounds like the optimum cam for those heads (GM is building and selling crate motors with that exact combination)
Probably carb tuning , fuel delivery and ignition timing are the culprits here.
Race Director
Joined: Oct 2000
Posts: 15,053
Likes: 79
From: central FL, near the beach.
Not directly comparable from the specs,
since XE262 is 262 at .006"
and 462/151 is 320 at lash.
Even if the 262 has an 18 ramp, 18+262=280, that is 40* LESS!
QUIZ: who knows the compcams ramp? to lash? i sure don't.
since XE262 is 262 at .006"
and 462/151 is 320 at lash.
Even if the 262 has an 18 ramp, 18+262=280, that is 40* LESS!
QUIZ: who knows the compcams ramp? to lash? i sure don't.
Safety Car
Joined: Jan 2009
Posts: 3,736
Likes: 56
From: anchorage ak
all these high duration cams put out plenty hp at high rpm. 320 degrees! how can that work at low rpm?
In 1990 i had the L79 cam in my 72. also 320 degrees! doggy u bet.
also a 80's crane blazer 288/288/114 at .050 218/218/114 better but still too much duration. PB worked sluggish. All 3 of these cams needed to be advanced 4-6* for any hope.
Guys look at .050" so much, they forget that is just 1/400 of a second. 1 point of dozens, hundreds. The valve has to CLOSE totally or it won't even start! try opening all the valves .001", negative .001" lash. won't run or will run like crap.
For the STREET, seat to seat duration determines manners idle - 2000. sometimes higher.
For DRAGS and DYNO tests it doesnt't matter at all. So can't tell from a dyno test how it will drive on the street in traffic.
Basic cam clues:
1. seat duration
2. duration at .050"
3. Lift
4. LSA
5. single pattern(0-4 spread) or wider spread 5+ degrees on the exhaust?
6. idle vacuum/speed
Those 6 together just give a CLUE, since there are hundreds of combos possible. Best clue for street manners is idle vacuum.
In 1990 i had the L79 cam in my 72. also 320 degrees! doggy u bet.
also a 80's crane blazer 288/288/114 at .050 218/218/114 better but still too much duration. PB worked sluggish. All 3 of these cams needed to be advanced 4-6* for any hope.
Guys look at .050" so much, they forget that is just 1/400 of a second. 1 point of dozens, hundreds. The valve has to CLOSE totally or it won't even start! try opening all the valves .001", negative .001" lash. won't run or will run like crap.
For the STREET, seat to seat duration determines manners idle - 2000. sometimes higher.
For DRAGS and DYNO tests it doesnt't matter at all. So can't tell from a dyno test how it will drive on the street in traffic.
Basic cam clues:
1. seat duration
2. duration at .050"
3. Lift
4. LSA
5. single pattern(0-4 spread) or wider spread 5+ degrees on the exhaust?
6. idle vacuum/speed
Those 6 together just give a CLUE, since there are hundreds of combos possible. Best clue for street manners is idle vacuum.
Last edited by bluedawg; Jan 14, 2013 at 02:58 PM.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer
Brett Foote
10 Things Every Corvette Owner Needs (2026 Edition)
Michael S. Palmer
8 Most "Only Corvette Owners Understand" Quirks and Problems
Pouria Savadkouei
10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years
Joe Kucinski
How Much Horsepower Every Corvette Engine "LOST" in 1972
Joe Kucinski
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!
Michael S. Palmer
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Safety Car
Joined: Jan 2009
Posts: 3,736
Likes: 56
From: anchorage ak
We had this conversation about street manners 2 years ago. What I find streetable you might not or vice versa. I'm fine with 6" of vacuum in gear, as you might not be fine with anything under 10" in gear. It was a good thread. Don't remember what it was called though.
Race Director
Joined: Oct 2000
Posts: 15,053
Likes: 79
From: central FL, near the beach.
streetable is just metatalk that an average driver in a new(0-10yrs old) car would, if he drove it, say, it runs like crap. 
To me the gold standard is a C5 or C6, all stock. That is what i rate my car against.
Not that i don't like STRIP/street cars
They are not daily drivers, but can be lots of fun. Plenty of guys drive it to the drags to avoid the expense of a truck/trailer. 
To me the gold standard is a C5 or C6, all stock. That is what i rate my car against.
Not that i don't like STRIP/street cars
They are not daily drivers, but can be lots of fun. Plenty of guys drive it to the drags to avoid the expense of a truck/trailer.
Race Director
Joined: May 2005
Posts: 10,674
Likes: 122
From: Millington Illinois
St. Jude Donor '08-'09
The point everyone is missing is gearing, transmission and intended use. A 3.08 rear gear with stock convertor and TH350 car is streetable and fun to drive with a 325 hp engine with XE 262 flat tappet and 9 to 1 compression.
In my car with a 4.11 and a close ratio 6 speed manual a XE262 and 9 to 1 compression is a waste.
525 hp, 10.4 to 1 and a 288 roller is very streetable (street car) and very fun to drive.
600 hp, 11 to 1 and a solid roller with over 300 advertised duration might be very streetable and more fun to drive. With proper gearing it is not doggy off the line at all or miserable to drive in any way. That would compare to a new Supercharged C6 Z06, over 600 hp, 11 to 1 compression, 6 speed manual, very streetable and fun to drive..
Matt Gruber might not like it.................. he might love it and it could very well change his whole prospective.
Last edited by 63mako; Jan 14, 2013 at 04:00 PM.
Safety Car
Joined: Jan 2009
Posts: 3,736
Likes: 56
From: anchorage ak
streetable is just metatalk that an average driver in a new(0-10yrs old) car would, if he drove it, say, it runs like crap.
To me the gold standard is a C5 or C6, all stock. That is what i rate my car against.
Not that i don't like STRIP/street cars They are not daily drivers, but can be lots of fun. Plenty of guys drive it to the drags to avoid the expense of a truck/trailer.
To me the gold standard is a C5 or C6, all stock. That is what i rate my car against.
Not that i don't like STRIP/street cars
They are not daily drivers, but can be lots of fun. Plenty of guys drive it to the drags to avoid the expense of a truck/trailer. 
Thread Starter
Drifting
Joined: Feb 2005
Posts: 1,583
Likes: 5
From: Richardson Tx.
doesn't seem like 5 years ago....I since added long tube headers to my setup thinking that was the missing piece. --- nope....My car is an absolute joke at low rpms. Not even close to burning out. Now, at 3000 rpm or higher it pulls decently..I decided to have it Dynoed:
260HP at the rear wheels
310ft/lbs torque
there has been so much conflicting advice on here that I decided to just leave it alone
260HP at the rear wheels
310ft/lbs torque
there has been so much conflicting advice on here that I decided to just leave it alone
Le Mans Master
Joined: Dec 2009
Posts: 6,397
Likes: 649
From: Saskatoon Saskatchewan
To me streetable is:
Will it idle without your foot on the gas at less than 800 rpm?
Will it acclerate adequately in normal traffic without stalling?
Will it start readily on a cold day and warmup without stalling without your foot on the gas?
If you can answer yes to all three then its streetable.
Will it idle without your foot on the gas at less than 800 rpm?
Will it acclerate adequately in normal traffic without stalling?
Will it start readily on a cold day and warmup without stalling without your foot on the gas?
If you can answer yes to all three then its streetable.
Burning Brakes
Joined: Apr 2007
Posts: 1,039
Likes: 62
From: Kona Hawaii
The point everyone is missing is gearing, transmission and intended use. A 3.08 rear gear with stock convertor and TH350 car is streetable and fun to drive with a 325 hp engine with XE 262 flat tappet and 9 to 1 compression.
In my car with a 4.11 and a close ratio 6 speed manual a XE262 and 9 to 1 compression is a waste.
10.4 to 1 and a 288 roller is very streetable and very fun to drive.
11 to 1 and a solid roller with over 300 advertised duration might be very streetable and more fun to drive.
Matt Gruber might not like it, he might love it and it could very well change his whole prospective.
Best upgrade so far was a 6spd Richmond trans! Quick off the line with that 1st gear and 6th gear OD for cruisin.Roller cam swap next,there is no end for improvements.....
Le Mans Master
Joined: Dec 2009
Posts: 6,397
Likes: 649
From: Saskatoon Saskatchewan
doesn't seem like 5 years ago....I since added long tube headers to my setup thinking that was the missing piece. --- nope....My car is an absolute joke at low rpms. Not even close to burning out. Now, at 3000 rpm or higher it pulls decently..I decided to have it Dynoed:
260HP at the rear wheels
310ft/lbs torque
there has been so much conflicting advice on here that I decided to just leave it alone
260HP at the rear wheels
310ft/lbs torque
there has been so much conflicting advice on here that I decided to just leave it alone
Race Director
Joined: Oct 2000
Posts: 15,053
Likes: 79
From: central FL, near the beach.
Can it drive off instantly, 40F on a cold start without any warm-up? now THAT is a fast car!
(gently when cold, no abuse)
A guy w/1000hp twin turbo got all upset when i made fun of his 3-5 MINUTE warm up
I told him i'd be at my destination by then.
(gently when cold, no abuse)
A guy w/1000hp twin turbo got all upset when i made fun of his 3-5 MINUTE warm up
I told him i'd be at my destination by then.
Instructor
Joined: Jan 2013
Posts: 167
Likes: 0
From: Battle Creek MI
I'll be doing mine in the next week or so. vortec heads with fresh valve job, beehive springs, new locks and retainers and a little trick I thought you guys would know by now... use mopar 2.2l valve seals and touch the bottom of the retainers slightly on a belt sander and you can pull up to .550 lift. I know for sure people are running .525 lift (lt4 hotcam) with this setup and not having issues at all. I don't think I'd run any more than that myself.
I'm using an edelbrock performer rpm intake, holley 670 carb and most likely the XR276hr roller cam. Haven't decided what I'm doing for exhaust yet.
Oh, and my motor isn't the stock l48...guess I should mention that. It's a 95-00 GM replacement. No clue of specs beyond that until I get the intake and heads off. But as of now it will spin the tires without much effort.
I'll probably run a 2000-2500 stall tq converter due to the rpm band of the cam.
I'm using an edelbrock performer rpm intake, holley 670 carb and most likely the XR276hr roller cam. Haven't decided what I'm doing for exhaust yet.
Oh, and my motor isn't the stock l48...guess I should mention that. It's a 95-00 GM replacement. No clue of specs beyond that until I get the intake and heads off. But as of now it will spin the tires without much effort.
I'll probably run a 2000-2500 stall tq converter due to the rpm band of the cam.
Thread Starter
Drifting
Joined: Feb 2005
Posts: 1,583
Likes: 5
From: Richardson Tx.
I would have to say no....not that i can tell....I really thought that since I was almost cloning the 330HO GM crate motor that I would have plenty of power (even at low rpms). i think the stock L-82 was rated @ 225hp. 260hp now at the rear wheels. I have double-checked everything and cannot find anything wrong.
Le Mans Master
Joined: Dec 2009
Posts: 6,397
Likes: 649
From: Saskatoon Saskatchewan
I would have to say no....not that i can tell....I really thought that since I was almost cloning the 330HO GM crate motor that I would have plenty of power (even at low rpms). i think the stock L-82 was rated @ 225hp. 260hp now at the rear wheels. I have double-checked everything and cannot find anything wrong.