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Location: Colorado Springs Colorado/Thousand Oaks Ca
Posts: 1,721
Originally Posted by cutlassefi
Sorry but I couldn’t disagree more. Did GM put Qjets on anything that made any real power? The answer is a resounding no. 370hp LT-1 SBC’s? No, LS6 Chevelles? No. Those all came with Holleys.
I’ve had a half dozen of these “performance tuned” Qjets on the dyno and not one, not one, was correct.
It has its limitations for sure. There are better carbs out there that will give a good balance of power and efficiency.
Although the Q-Jet is not for everybody and every fuel system..........my NHRA stock low HP 455 Buick made a real 531 HP with a real 592 TQ with the factory cast iron intake with of all things the factory Q-Jet a top, so it can work. And make no mistake 531 HP in my world runs well into the 10s @ 3700 pounds in my Buick.
She made 400 HP at 5000 RPM and 513 FT/Lbs at 3300 RPM. Considering I did not have access to the wideband due to my friend being out of town on short notice, I'll take it. There was the slightest bit of detonation at the lower RPMs on this run. I tried using a heavier advance spring and it took the HP down to 382 with no effect on torque, but I still feel it is coming in too quick. I'm going to switch from the HEI to the MSD to get more control of timing. I also feel that the carb is a tick too lean, but didn't change jets today. I'll wait for the wideband to do that to be sure. The thing that concerns me is that the oil pressure is a bit low. After warm up, it was @ 18PSI at idle and running around 30-35 PSI on the pulls. I was running Comp 10W-30 break in oil. Any suggestions on this? I'm sure of all the measurements on bearing clearances were within spec. Should I run something like VR1 20W-50? I have seen where some suggest this.
Sorry but I couldn’t disagree more. Did GM put Qjets on anything that made any real power? The answer is a resounding no. 370hp LT-1 SBC’s? No, LS6 Chevelles? No. Those all came with Holleys.
I’ve had a half dozen of these “performance tuned” Qjets on the dyno and not one, not one, was correct.
It has its limitations for sure. There are better carbs out there that will give a good balance of power and efficiency.
Lets see, obviously the W-30 cars, W-31 cars, 68 Hurst Olds, the Buick Grand Sport Stage 1 (the Hemi killer) lots of GTO and Trans Ams, the Super Duty Trans Am, the list goes on and on. I’m guessing GM used Holleys on high winding engines, or big engines with higher engine speeds that exceed to airflow capacity the Q-Jet. I’m also pretty sure the large float bowls of the holleys were also a benefit.
Years ago, people told me time and time again to get rid of the “Quadra-Junk” and put a real carb on my car. I tried a Holley 750,850, and a 950HP series, none ran as well as the Q-Jet. I’m guessing I could have tuned and tweaked to improve, but I like to be different. If I followed the crowd, I would have swapped in a chebby or LS engine.
Location: Colorado Springs Colorado/Thousand Oaks Ca
Posts: 1,721
I have two Q-Jets I run on my car, one flows 890 CFM the other flows 860 CFM. Next time I have one apart I will take pictures of the Harold Bettes one, a very highly modified carb, infact it had so much work done to it I never ran it until recently.
I'd have to go to my notes to get the clearances. The oil pump is a Melling M22F. That was measured power.
Ok that’s a stock pump so I wouldn’t expect too much more pressure than you have now with the oil you’re using.
I’ve noticed over the years that the gears in the stock pumps seem to be more sloppy than the ones in the HV pumps. That will cost you pressure.
Ok that’s a stock pump so I wouldn’t expect too much more pressure than you have now with the oil you’re using.
I’ve noticed over the years that the gears in the stock pumps seem to be more sloppy than the ones in the HV pumps. That will cost you pressure.
Thanks Mark. Would you suggest switching to an HV pump in this case? Theoretically, all things being equal, more volume would up the pressure a bit. Also, I pulled the pan for inspection purposes and found that my screen is 5/8" from the bottom of the pan, not the 3/8'-1/2" called for...is that contributing to this? (stock style oil pan) Obviously, I will correct that.
Thanks Mark. Would you suggest switching to an HV pump in this case? Theoretically, all things being equal, more volume would up the pressure a bit. Also, I pulled the pan for inspection purposes and found that my screen is 5/8" from the bottom of the pan, not the 3/8'-1/2" called for...is that contributing to this? (stock style oil pan) Obviously, I will correct that.
I’d certainly shoot for closer to 3/8”.
You could just put the pink spring in the pump you have as well. That should add about 8-10#’s.
So I cut the filter open and everything checks out. Not one spec of metal. I'm waiting on the new MSD distributor to arrive, then it will be back to the dyno to get this piece tuned to it's potential! This time I will have access to the wideband. Based on the fact that I will be better able to control the timing curve and have access to the wideband for carb jet selection, I expect the numbers to climb. I was pretty happy with the 400/513 right out of the box, but more is always better. I'm hoping for at least 425/525 this time around. I will be adjusting the oil pump pickup to 3/8" as well.
Location: Colorado Springs Colorado/Thousand Oaks Ca
Posts: 1,721
Originally Posted by ajr2820
So I cut the filter open and everything checks out. Not one spec of metal. I'm waiting on the new MSD distributor to arrive, then it will be back to the dyno to get this piece tuned to it's potential! This time I will have access to the wideband. Based on the fact that I will be better able to control the timing curve and have access to the wideband for carb jet selection, I expect the numbers to climb. I was pretty happy with the 400/513 right out of the box, but more is always better. I'm hoping for at least 425/525 this time around. I will be adjusting the oil pump pickup to 3/8" as well.
You say measured HP, well if your correct thats good power right there. If you would want to post the dyno data I could make more sense of the testing procedure. Measured HP is in the room uncorrected for the conditions HP, corrected HP takes the in the room number then usually corrects to a 29.92 barometer 60 degrees dry air conditions, sea level perfect conditions. I would set the pickup at exactly .325 off the bottom of the pan, the pickup should be tig welded with silicon bronze.
Last edited by VORTECPRO; January 3rd, 2020 at 05:31 AM.
If you would want to post the dyno data I could make more sense of the testing procedure. Measured HP is in the room uncorrected for the conditions HP, corrected HP takes the in the room number then usually corrects to a 29.92 barometer 60 degrees dry air conditions, sea level perfect conditions.
Please don't try to come off as some dyno expert. You’re the same guy that didn’t even know hp was derived from tq, and not a measured unit in itself. If you like I can post the link from ROP regarding your lack of knowledge on even the basics. Thank you.
Location: Colorado Springs Colorado/Thousand Oaks Ca
Posts: 1,721
Originally Posted by cutlassefi
Please don't try to come off as some dyno expert. You’re the same guy that didn’t even know hp was derived from tq, and not a measured unit in itself. If you like I can post the link from ROP regarding your lack of knowledge on even the basics. Thank you.
Nice build ajr, keep us posted.
I know my way around the SF dyno quite well. I also know how to ck calibration, maybe you should pay attention......................
Last edited by VORTECPRO; January 3rd, 2020 at 06:50 PM.
Location: Colorado Springs Colorado/Thousand Oaks Ca
Posts: 1,721
Originally Posted by cutlassefi
I get that you were just trying to point out the difference between corrected and measured hp/tq. You were correct there.
But moving forward if you stay in your lane and within your REAL areas of expertise I’ll leave you alone, promise.
Thank you.
Unfortunately just yesterday I was approached to build of all things a Oldsmobile 455, when asked when I could start on this build I was quite evasive, because actually I knew this would upset you, and really being backed up about 40 engine builds I really wasn't too excited about it. I offered an alternative, why don't you have cutlassefi build this engine, he wasn't having any of that. And he's a fuel injection guy (the customer) to boot! So I guess I'am building another 455 Oldsmobile, does this mean your not going to leave me alone now......
Sorry Dave I couldn't resist, but you know what motivates me.... I'am out my lane I'am out of my lane
Last edited by VORTECPRO; January 4th, 2020 at 07:45 AM.
That's a beautiful engine and real pretty.
I've never used a degree wheel, and wouldn't know where to start without some reading.
So, again, what carb is on the engine in the photo ? and who's metering blocks ?
I just posted a thread this morning "newbie / old-bie building 455"
I have a '71 F block with the L stamped on the left hand boss on the block. And I purchased another '71 F long block for the "C" heads.
I hope to slip this puppy in place of a Buick 350 in a '71 Jeep Gladiator pickup. Therefore, I will visit this thread again later this week to see your HP ratings.
I have no idea what cam is in my short block yet.
I liked your spark plug wire routing. Very neat and orderly.
That's a beautiful engine and real pretty.
I've never used a degree wheel, and wouldn't know where to start without some reading.
So, again, what carb is on the engine in the photo ? and who's metering blocks ?
I just posted a thread this morning "newbie / old-bie building 455"
I have a '71 F block with the L stamped on the left hand boss on the block. And I purchased another '71 F long block for the "C" heads.
I hope to slip this puppy in place of a Buick 350 in a '71 Jeep Gladiator pickup. Therefore, I will visit this thread again later this week to see your HP ratings.
I have no idea what cam is in my short block yet.
I liked your spark plug wire routing. Very neat and orderly.
thanks
Len
This is the carb: Holley Ultra Double Pumper Carburetors 0-76750BL
I bought it from Holley off eBay. They often list a bunch of "refurb" carbs for cheap, although mine looked new and untouched. They have the same warranty. I got mine for $399.00 instead of $636.00 listed everywhere else. Look at the beginning of the month for these deals. They sell pretty quickly.
This weekend, this build took a turn. I had the pan off because I was concerned about the oil pressure on the dyno. I found no metal in the pan or the filter. After changing the oil pressure relief spring to the bigger spring, it still bothered me. So I decided to pull a main cap just to have a look. I pulled #2 and the bearing showed some scarring. Long story short is that the next run would have likely wiped it out. All the mains showed signs of wear to varying degrees. I'm not sure where the issue lies yet. I'm tearing it back down to have the crank checked as well as the line bore. It could also have been some trash in the galleys that I missed. The rods and bored were untouched it appears. So I consider myself the luckiest unlucky person in the world right now. Since everything appeared to move freely and smoothly, I ALMOST simply put it back together. Moral of the story: Check, recheck, check again, and ultimately....follow your gut.
I think you’re going to find that your bearing clearances may be a little tight, and/or the housing bores weren’t in alignment or round.
Please post pix of the bearings when you get it apart. Sorry for your luck.
Note; as you increase the power level of these blocks there are things you absolutely need to do starting with the correct clearances and overall quality machining and assembly practices.
Again sorry and best of luck.
Last edited by cutlassefi; January 5th, 2020 at 11:24 AM.
Here are the bearings. Tops are on top of the picture and they are right to left #5-#1. I suspect Mark is right about clearances, although I double checked everything...
At the very least you have align bore issues. You can have correct clearance, but if everything isn’t straight and in line it won’t matter.
I’d add ARP bolts and then have it align honed. Then check your clearances. If you’re shy and don’t want to grind the crank again, you should be able to get a bit more clearance by using the Federal Mogul main bearing instead of the Clevite.
Hope this helps.
Already welded them in. That's why they are not on the engine in the pic. I have found someone able to dyno the engine. Just waiting for our schedules to align.
Quick question,do you have the part number for the fitting coming off the fuel pump? The part that allows you to thread on the 90.
Thanks
thanks for the carb info ! it is interesting that you mentioned "refurb's" available, which I could be tempted.
My latest home desktop computer is a HP refurb purchase through Walmart and delivered to our local store. Wow, was I happy.
Geesh, sorry to hear about the bearings. Dag-Nabbit !!
After seeing what they look like, I'd plasti-gauge them to see what the clearances are running, because those could be why your oil pressure is 10-lbs low.
(I was reading on the pressure relief-valve setting for the oil pumps on the old ****** L134 engines and the relief valve opens at 30-lbs pressure, with 6-10 at idle warm if all is in spec for clearances per the factory service manual). Lower than I would think.
Anyone building the 455's often, who see the line-bore requiring correction being a common concern ? _ _ _ I guess each block is different in character depending on what extremes the engine has gone through with build, and service use.
Hang in there !
Last edited by Greaser007; January 7th, 2020 at 08:29 AM.
thanks for the carb info ! it is interesting that you mentioned "refurb's" available, which I could be tempted.
My latest home desktop computer is a HP refurb purchase through Walmart and delivered to our local store. Wow, was I happy.
Geesh, sorry to hear about the bearings. Dag-Nabbit !!
After seeing what they look like, I'd plasti-gauge them to see what the clearances are running, because those could be why your oil pressure is 10-lbs low.
(I was reading on the pressure relief-valve setting for the oil pumps on the old ****** L134 engines and the relief valve opens at 30-lbs pressure, with 6-10 at idle warm if all is in spec for clearances per the factory service manual). Lower than I would think.
Anyone building the 455's often, who see the line-bore requiring correction being a common concern ? _ _ _ I guess each block is different in character depending on what extremes the engine has gone through with build, and service use.
Hang in there !
Those carbs aren't really refurbs. They are new. Holley just does that to get more of the market I'm told.
Thats a Howard’s grind right? I’d do something different but.....
It is Howards. I'm thinking of going Hydraulic roller with a little more duration than the TQ40 I initially had in it. I'm not finding many off the shelf options. Which direction would you go if it were your build? And why? You have much more experience than me.
It is Howards. I'm thinking of going Hydraulic roller with a little more duration than the TQ40 I initially had in it. I'm not finding many off the shelf options. Which direction would you go if it were your build? And why? You have much more experience than me.
Yes not having many off-the-shelf options is one reason why I pick my own combinations. With stock or nearly stock heads I don’t know that I would push the valve open that far. In addition I would do something with a little bit less lift, different duration, and on a slightly wider lobe separation.
You may be able to mimic it on paper, but roller lobes and flat tappet lobes are two entirely different designs.
Yeah that's where I'm coming up with a blank. I'm not familiar with how the design change affects performance on a given profile on a flat tappet vs roller. I just know I liked the TQ40, but feel it leaves a little on the table. I don't want to stray too far from it, but want a roller.
December 25th, 2019, 05:45 AM
