Carb Question...
09-08-2011, 05:03 PM
#61
Registered
Stock improved ? Is that better ? 
09-08-2011, 09:46 PM
#63
Registered
Some would call bullchit, but many with small block motors like yours (stock improved ) but with bigger heads and in cars, are running 1050 Dom's and using every last bit they have to offer.
Small blocks, big cams, big heads, and big carbs - dogs ????????
Small blocks, big cams, big heads, and big carbs - dogs ????????
09-09-2011, 10:22 AM
#64
Registered
The 302 Camaros came stock with a Holley 830. And yes I ran an 850 on my 355 Camaro. It ran better then my Q-Jet. Of course it was "Stock Improved" also.
LOL
LOL
09-09-2011, 07:52 PM
#65
Registered
Join Date: Mar 2008
Location: TEXAS
Posts: 116
Likes: 0
Received 0 Likes
on
0 Posts
response
LOLLLLLLLLLLLLLLLLLLL. 
See why I said didn't want to get more involved.........
I'll stick with you for one more for some reason
Have we forgotten about the calibration part of carbs ?
If the 850 you mention is a box stock Holley, forget about it. The 850's from Holley are set up for big blocks. Typically 450hp-600hp ones.
Their is an 830 with calibration geared towards small blocks.
Don't get that one though, it's for a different application small block.
This will throw you for a loop since you are stuck on just cfm#'s and unfortunately not part #'s.... I have used and spec'd Holley HP950's for many a 350 and 383. Imagine that ? !
Guess why those work so well ?
=================================
Vacuum leak ????
That saying is so old.
Again, air speed thru the boosters pulls fuel out of them.
Plus there are many booster designs, emulsion circuit packages, venturi vs throat vs blade sizes/designs.etc, etc, etc, that are calibrated/made a certain way to administer the correct amt of fuel for the airflow amt and properties at hand.
Speaking of vacuum, you wouldn't happen to know vacuum secondaries don't work off of intake vacuum would you ?
See why I said didn't want to get more involved.........
I'll stick with you for one more for some reason
Have we forgotten about the calibration part of carbs ?
If the 850 you mention is a box stock Holley, forget about it. The 850's from Holley are set up for big blocks. Typically 450hp-600hp ones.
Their is an 830 with calibration geared towards small blocks.
Don't get that one though, it's for a different application small block.
This will throw you for a loop since you are stuck on just cfm#'s and unfortunately not part #'s.... I have used and spec'd Holley HP950's for many a 350 and 383. Imagine that ? !
Guess why those work so well ?
=================================
Vacuum leak ????
That saying is so old.
Again, air speed thru the boosters pulls fuel out of them.
Plus there are many booster designs, emulsion circuit packages, venturi vs throat vs blade sizes/designs.etc, etc, etc, that are calibrated/made a certain way to administer the correct amt of fuel for the airflow amt and properties at hand.
Speaking of vacuum, you wouldn't happen to know vacuum secondaries don't work off of intake vacuum would you ?
Who asked you to get involved? If you think the question or response is a waste of time don't respond.
THX
09-09-2011, 07:56 PM
#66
Registered
Join Date: Mar 2008
Location: TEXAS
Posts: 116
Likes: 0
Received 0 Likes
on
0 Posts
response
Learn how to disagree with respect to others opinions
THX
09-14-2011, 08:24 AM
#67
Platinum Member
Platinum Member
So, I can run a 850cfm On my 355 350 HP motor according to your points? How is vacuum an old idea? The way I see it, can't you view a carb as sort of a controlled vacuum leak?
I appreciate all the info.
Here is my question then, for a 355cu Vortec cyl, RPM Air Gap, CC XM270 HR, current carb Weber 600cfm A/F ratios dialed in. Has approx 350hp at 5100rpm @ flywheel.
What carb should I be running?
THX
I appreciate all the info.
Here is my question then, for a 355cu Vortec cyl, RPM Air Gap, CC XM270 HR, current carb Weber 600cfm A/F ratios dialed in. Has approx 350hp at 5100rpm @ flywheel.
What carb should I be running?
THX
For a dailey driver street car that is still a hotrod I would use a holley 600 double pumper, for a boat however I would go 10% bigger to the 0477-c double pumper, these double pumpers are more aggressive stock and will be jetted almost spot on for your application. If your really happy however with your current set-up, and its tuned correctly just run it. Like I mentioned previously, I had a jet boat with a mild Pontiac 455, following the carb calulator (which assumes 80% v/e) it told me to run a 650 or 700, I ran a carb that size as motor only turned 5000 at wot and I switched to a 830 annular discharge double pumper and boat was MUCH stronger and gained top end. The punch it had was night and day different.
As far as running rich, idling rich and economy, if idle mixture, float levels are adjusted correctly , power valves are closed while light cruising and carb is jetted properly it will not matter if carb is 10 or 15% too big . I am by no means a carb expert but I do have some personal experience tuning quite a few motors for myself and customers (I own a transmission/rear end shop where we specialize in high performance work and have in the past tuned customers vehicles and built complete drivetrains/tuned them in vehicle) Smitty
09-14-2011, 08:33 AM
#68
Platinum Member
Platinum Member
As far as my personal experience with the weber/edelbrock 600 carbs, I have never been real fond of them and have tuned quite a few with so/so results, 20 years ago guys would rip off there 750 or 800 Quadrajets on pontiac 400's, 455's, 350 small blocks and go to these 600's and tuned perfect a stock quadrajet or properly tuned holley would outperform them in every way including economy, Smitty
09-14-2011, 09:35 AM
#69
Well we just got back from Cumberland so i now have idling experience from a Nickerson carb, we never got to go boating due to the fact that the other engine would not run. I got my carb back last thursday morning from Nickerson, bolted it on and left for Cumberland. We got there thursday evening and that was the only motor that would run. That Nickerson carb motor will start by just turning the key. The other motor I had running and shifting fine in the garage, so I thought or hoped it would work but it didn't. Once in the water it would never shift, forward or reverse without dying even if giving it gas, pumping it. So I guess the other carb needs to go now, just need some more money, lol.
09-14-2011, 09:18 PM
#70
Registered
Join Date: Mar 2008
Location: TEXAS
Posts: 116
Likes: 0
Received 0 Likes
on
0 Posts
Thanks for info
Are you happy with the weber 600 cfm? what rpm do you want motor to pull to? My personal choice with a 355 small block if you want or like a vacuum secondary is a holley 3310. Take the checkball out of the vacuum secondary so it responds faster, put a spring that comes in a vacuum secondary spring kit that is 1 spring from the lightest, change the original primary jets from the original 72's to 73's if your near sea level, change out the # 25 squirter to a # 31 to help cover the secondarys opening quicker along with a more aggressive accelerator cam (buy a trick kit), adjust the idle mixture until you get the highest vacuum then turn the screws 1/4 to 1/2 turn richer. With your cam a 6.5 power valve should be fine. I have been very happy with this carb on a couple of small blocks that had cams very close to a the comp 270.
For a dailey driver street car that is still a hotrod I would use a holley 600 double pumper, for a boat however I would go 10% bigger to the 0477-c double pumper, these double pumpers are more aggressive stock and will be jetted almost spot on for your application. If your really happy however with your current set-up, and its tuned correctly just run it. Like I mentioned previously, I had a jet boat with a mild Pontiac 455, following the carb calulator (which assumes 80% v/e) it told me to run a 650 or 700, I ran a carb that size as motor only turned 5000 at wot and I switched to a 830 annular discharge double pumper and boat was MUCH stronger and gained top end. The punch it had was night and day different.
As far as running rich, idling rich and economy, if idle mixture, float levels are adjusted correctly , power valves are closed while light cruising and carb is jetted properly it will not matter if carb is 10 or 15% too big . I am by no means a carb expert but I do have some personal experience tuning quite a few motors for myself and customers (I own a transmission/rear end shop where we specialize in high performance work and have in the past tuned customers vehicles and built complete drivetrains/tuned them in vehicle) Smitty
For a dailey driver street car that is still a hotrod I would use a holley 600 double pumper, for a boat however I would go 10% bigger to the 0477-c double pumper, these double pumpers are more aggressive stock and will be jetted almost spot on for your application. If your really happy however with your current set-up, and its tuned correctly just run it. Like I mentioned previously, I had a jet boat with a mild Pontiac 455, following the carb calulator (which assumes 80% v/e) it told me to run a 650 or 700, I ran a carb that size as motor only turned 5000 at wot and I switched to a 830 annular discharge double pumper and boat was MUCH stronger and gained top end. The punch it had was night and day different.
As far as running rich, idling rich and economy, if idle mixture, float levels are adjusted correctly , power valves are closed while light cruising and carb is jetted properly it will not matter if carb is 10 or 15% too big . I am by no means a carb expert but I do have some personal experience tuning quite a few motors for myself and customers (I own a transmission/rear end shop where we specialize in high performance work and have in the past tuned customers vehicles and built complete drivetrains/tuned them in vehicle) Smitty
