Ping and no power rebuilt 455, aluminum heads and intake from mondello
February 7th, 2017, 03:38 PM
#41
Registered User
Join Date: Apr 2014
Location: Winnipeg
Posts: 122
I agree that the carb is jetted lean and I would say that the heat range of the spark plugs is to hot, I've had this problem before. Sounds like the pump shot is ok. A new 750 demon... I have found most 650 & 750 carbs are jetted for 350 sbc's and most people don't realize that they have to set up a new carb for their car, they seem to think that you can just slap one on and go. Also without feedback from the OP we can't help him.
Ray - just my 2 cents
Ray - just my 2 cents
February 7th, 2017, 04:05 PM
#42
Registered User
Join Date: Sep 2013
Posts: 3,574
I agree that the carb is jetted lean and I would say that the heat range of the spark plugs is to hot, I've had this problem before. Sounds like the pump shot is ok. A new 750 demon... I have found most 650 & 750 carbs are jetted for 350 sbc's and most people don't realize that they have to set up a new carb for their car, they seem to think that you can just slap one on and go. Also without feedback from the OP we can't help him.
Ray - just my 2 cents
Ray - just my 2 cents
February 7th, 2017, 06:23 PM
#44
Registered User
Join Date: Aug 2012
Posts: 215
My 455 uses a 750 box stock holley with no issues,on the street.The track,it might need a little tweeking.My new build had problems in the first 100 miles too.turned out to be plugs that were too cold for street use,and a new pertronix distributor that died with less than 100 miles on it.Put in NGK-8 plugs.and another pertronix the builder had at my door the next day,and the motor runs strong as ever.I used Lynn for my build in 2012,and so far they have been my issues with this build.Because of his not so great reputation I don't see a 1/4 miles pass with this motor.....and that SUCKS!!I hope your problems are as simple as mine were.
Last edited by drjr56; February 7th, 2017 at 06:47 PM.
February 7th, 2017, 07:35 PM
#45
Registered User
Join Date: Sep 2013
Posts: 3,574
I don't know copper about your statement on a bbo's . Do you know how many bbo's came out factory with 750 cfm carbs?
February 8th, 2017, 04:15 AM
#49
Once Olds Always Olds
Join Date: Nov 2011
Location: New Matamoras, Ohio
Posts: 1,202
CFM calculations do not consider the technology of these newer carbs. I had this discussion with the Dyno operator that did my engine. Did my 455 need a 850 CFM carb according to the calculation? No. Yet at WOT it was still pulling 1" of vacuum, which is one of the things the Dyno operator looks at when determining if a carb is too big. His philosophy is that newer technology create better circuits and better atomization which result in better performance.
February 8th, 2017, 09:29 AM
#51
Registered User
Join Date: Jun 2008
Location: Chicago
Posts: 1,394
Time to cut the oil filter open and see what's in that too. Either buy a large pipe cutter or oil filter cutter from Summit, don't use a saw because it will add debris.
Here's a similar horror story. I'd pull the whole thing apart with someone that knows what they are doing, before it turns catastrophic, and if it's anything similar to this, I'd be calling a lawyer...
https://www.oldsmobilecentral.com/fo...ngine-had-.php
Here's a similar horror story. I'd pull the whole thing apart with someone that knows what they are doing, before it turns catastrophic, and if it's anything similar to this, I'd be calling a lawyer...
https://www.oldsmobilecentral.com/fo...ngine-had-.php
February 8th, 2017, 09:54 AM
#52
Once Olds Always Olds
Join Date: Nov 2011
Location: New Matamoras, Ohio
Posts: 1,202
Rereading the post and gong back to the fuel issue after the side discussion on carb size. Runs good then goes to crap.
I have a question: Does it have a Holly fuel pump on it from Mondello?
Here is my experience. I had trouble finding a fuel pump for mine as my machine shop was finishing the build. We won't get into all the details of the discussions back and forth, but The machine shop ordered a Holly fuel pump from Mondello thinking he was doing a good thing as it is rated 7.5 psi. At any rate, Dyno day engine runs great using Dyno fuel pump, when went to the Holly engine fell on its nose. Pressure 7.5 at idle 1 psi at about 4,000 rpm. It was sent back.
I have a question: Does it have a Holly fuel pump on it from Mondello?
Here is my experience. I had trouble finding a fuel pump for mine as my machine shop was finishing the build. We won't get into all the details of the discussions back and forth, but The machine shop ordered a Holly fuel pump from Mondello thinking he was doing a good thing as it is rated 7.5 psi. At any rate, Dyno day engine runs great using Dyno fuel pump, when went to the Holly engine fell on its nose. Pressure 7.5 at idle 1 psi at about 4,000 rpm. It was sent back.
February 8th, 2017, 10:22 AM
#53
Registered User
Join Date: Oct 2013
Location: Hebron, indiana
Posts: 418
I would invest in books , Learn and build it you self. The money you will spend in the tools and books will be less than having it re re built and you will gain experience you will never have to pay for again. I have never had an engine built and i dont intend to ever have one built for me. have i spent possibly a little more on lessons learned the hard way...... perhaps but its valuable to know even why things fail or go wrong.
February 8th, 2017, 11:36 AM
#54
Registered User
Join Date: Aug 2012
Posts: 215
Troy..I have the same problem with a holley mechanical fuel pump.Same thing 7lbs at idle,but won't handle WOT.Actually it doesn't even have to be wot for the pressure to drop to 2lbs or less.What pump did you end up using to solve that issue.My 455 is buildup a little. Eddy heads,HR Cam 236\244 and 538 lift,750 holley....
February 8th, 2017, 02:43 PM
#55
Registered User
Join Date: Feb 2013
Location: Phoenix, AZ
Posts: 13,734
I once had a Holley mechanical fuel pump and it cracked across the pump body. From what I have read, it's a common failure with this pump.
Engine ran OK at low RPM but would crap out due to lack of fuel at higher RPM and it got worse as the crack grew.
Fuelpump2small.jpg
Engine ran OK at low RPM but would crap out due to lack of fuel at higher RPM and it got worse as the crack grew.
Fuelpump2small.jpg
February 8th, 2017, 06:04 PM
#56
Once Olds Always Olds
Join Date: Nov 2011
Location: New Matamoras, Ohio
Posts: 1,202
Troy..I have the same problem with a holley mechanical fuel pump.Same thing 7lbs at idle,but won't handle WOT.Actually it doesn't even have to be wot for the pressure to drop to 2lbs or less.What pump did you end up using to solve that issue.My 455 is buildup a little. Eddy heads,HR Cam 236\244 and 538 lift,750 holley....
February 8th, 2017, 06:13 PM
#57
Once Olds Always Olds
Join Date: Nov 2011
Location: New Matamoras, Ohio
Posts: 1,202
Interesting, I did not check for a crack. What did you replace it with?
February 8th, 2017, 08:59 PM
#58
Registered User
Join Date: Feb 2013
Location: Phoenix, AZ
Posts: 13,734
A factory replacement Carter M6108 pump from NAPA. If you need the return line, it's the M6109 pump. Prolly available at any of your local auto parts stores, so no need to buy a "muscle car series" pump from the big performance outlets.
February 10th, 2017, 09:16 AM
#60
Registered User
Join Date: Apr 2015
Posts: 59
couple of things, what is the cranking compression?
why don't you take I-phone video of the car accelerating and fauling off so we can see whats happening, we can start diagnosing and quit guessing if you share this info
why don't you take I-phone video of the car accelerating and fauling off so we can see whats happening, we can start diagnosing and quit guessing if you share this info
February 10th, 2017, 07:01 PM
#61
Registered User
Join Date: Apr 2014
Location: Winnipeg
Posts: 122
Ray
P.S. I have had the same Holley 800DP on my car for 25 years, it's now to small and it's time to go EFI.
February 11th, 2017, 06:04 AM
#62
Registered User
Join Date: Nov 2008
Location: Central Fl
Posts: 7,822
It's been my experience that most 650 and 750 Holley style carbs including Demon are sold to people that have a sbc usually a 350. Let's face it, how many carbs are sold to Olds owners as compared to Chevy's. And if you were the one marketing these products who would you set it up for? Yes I know that one should jet to match the air-flow of the carb, but that would be ball parking it. A 455 that's lightly to stout modified should run no problem with a 750 Holley, adjust the idle mixtures and rpm and your done or at least close. I deal mainly with street/strip & strip cars and I find most Holley style carbs need the least amount of tinkering when put on a Chevy. Holley style carbs aren't even close to a quadrajet or better yet a Predator carb for ease when run out of the box. Also Olds engines don't behave like Chevy's, I get tired of telling the speed shop guys that.
Ray
P.S. I have had the same Holley 800DP on my car for 25 years, it's now too small Why? and it's time to go EFI. What's that have to do with it?
Ray
P.S. I have had the same Holley 800DP on my car for 25 years, it's now too small Why? and it's time to go EFI. What's that have to do with it?
And I can tell you categorically that a Holley 750 would not be jetted correctly for your stated degree of builds for a 455. I've done dozens of combinations on the dyno and I will tell you that I typically have to richen even an 850, much less a 750.
And even an 850 equipped 500hp 455 typically pulls an inch or more of vacuum by the end of the pull. A 750 is too small for sure.
Hope this helps.
Last edited by cutlassefi; February 11th, 2017 at 06:17 AM.
February 11th, 2017, 08:25 AM
#63
Registered User
Join Date: Sep 2012
Location: Gilbert, Arizona
Posts: 484
While you guys are arguing and going back and forth about carb sizes and settings, my 425 is running beautifully with its fuel injection. No primary or secondary jet size worries, no metering rods, choke problems, accelerator problems, air valve opening to soon or to late or to slow, no bogging, running to lean or rich, etc. etc. Moral of the story, dump the carb, one less problem.... Just my opinion.........
February 11th, 2017, 08:53 AM
#64
Registered User
Join Date: Apr 2014
Location: Winnipeg
Posts: 122
Sorry but most of what you're saying here is an over assumption. Yes most midsize carbs are jetted for a "350 Chevy". But in reality they're jetted for anything that will make the same HP as a typically modified SBC. The brand of engine means nothing.
And I can tell you categorically that a Holley 750 would not be jetted correctly for your stated degree of builds for a 455. I've done dozens of combinations on the dyno and I will tell you that I typically have to richen even an 850, much less a 750.
And even an 850 equipped 500hp 455 typically pulls an inch or more of vacuum by the end of the pull. A 750 is too small for sure.
Hope this helps.
And I can tell you categorically that a Holley 750 would not be jetted correctly for your stated degree of builds for a 455. I've done dozens of combinations on the dyno and I will tell you that I typically have to richen even an 850, much less a 750.
And even an 850 equipped 500hp 455 typically pulls an inch or more of vacuum by the end of the pull. A 750 is too small for sure.
Hope this helps.
96/front 98/back, need bigger.I could go on and on but, I've said my piece.
Ray
February 11th, 2017, 08:57 AM
#65
Registered User
Join Date: Apr 2014
Location: Winnipeg
Posts: 122
While you guys are arguing and going back and forth about carb sizes and settings, my 425 is running beautifully with its fuel injection. No primary or secondary jet size worries, no metering rods, choke problems, accelerator problems, air valve opening to soon or to late or to slow, no bogging, running to lean or rich, etc. etc. Moral of the story, dump the carb, one less problem.... Just my opinion.........
Ray
February 11th, 2017, 09:23 AM
#66
Connoisseur d'Junque
Join Date: Sep 2010
Location: The Hudson Valley
Posts: 21,183
While you guys are arguing and going back and forth about carb sizes and settings, my 425 is running beautifully with its fuel injection. No primary or secondary jet size worries, no metering rods, choke problems, accelerator problems, air valve opening to soon or to late or to slow, no bogging, running to lean or rich, etc. etc. Moral of the story, dump the carb, one less problem.... Just my opinion.........
- Eric
February 11th, 2017, 11:10 AM
#68
Registered User
Join Date: Oct 2015
Posts: 513
Already double checked dist. Adjusting timing with vacuum gauge and degreeable timing light. Best vacuum 15" @ 32° starts to pull hard for a sec. Then runs like crap pings horribly cranks poorly, no vacuum advance connected to HEI..Back off dist to mid 20° 10" vacuum vehicle starts and idles fine just no power..As I mentioned, I'm also concerned about too much compression? Just not sure of easiest solution? Since everything is new? Thanks again for the great feedback.
We had a local guy here who recently got a 455 from Mondello in Paso Robes.. It was found the lifters were not working, even though brand new. Put in some Comp Cams lifters.
Also note there are 3 Mondello spots. The original in Paso Robles location now run by Lynn, the Tenn location were Joe moved to to do training classes, and Bernard Mondello(Joe's son) in Corona, CA
April 2nd, 2018, 08:17 AM
#69
Registered User
Join Date: Jul 2006
Location: Manassas, VA
Posts: 694
Already double checked dist. Adjusting timing with vacuum gauge and degreeable timing light. Best vacuum 15" @ 32° starts to pull hard for a sec. Then runs like crap pings horribly cranks poorly, no vacuum advance connected to HEI..Back off dist to mid 20° 10" vacuum vehicle starts and idles fine just no power..As I mentioned, I'm also concerned about too much compression? Just not sure of easiest solution? Since everything is new? Thanks again for the great feedback.
You realize that you don't adjust timing with a vacuum gauge don't you? That's idle mix on the carb, that you set to reach the highest vacuum reading.
Total timing is measured at roughly 3000 RPM, and is the max timing mechanical advance can provide, plus initial timing.
Initial timing is set at idle, the timing light zero'd out, as in no advance or retard added, and by viewing the mark on the timing tab on the engine. That should be 12-16 degrees.
It sounds like you are setting initial timing to 32 degrees, that's why you're getting 60+ degrees at RPM. Also why it won't crank, because it's way too far advanced. Probably why it pings too.
So, just to give a basic overview of building an advance curve:
Set Initial timing, set total timing, then determine the rate of advance by using springs (and possibly weights). After that's all done, THEN tune vacuum advance with an adjustable vacuum can.
The only way to adjust total timing on a GM HEI is to fabricate a limiter on the advance plate. Originally, GM HEI weights would limit total advance, but all the crap aftermarket weights these days will push past the flat spot on weights and add advance at higher RPMs. And that's why I say HEI are JUNK. Because you can't get the correct parts to properly tune them.
.
April 2nd, 2018, 08:28 AM
#71
Registered User
Join Date: Jul 2006
Location: Manassas, VA
Posts: 694
So:
Initial timing + Mechanical timing = Total timing (mechanical)
If you are targeting 32 degrees total mechanical timing, it would look something like this example:
Initial - 16 + Mechanical - 16 = 32
Then you start adjusting vacuum by plugging the vacuum line into the can. Generally, start at the lowest setting, and add like 2 or so degrees and drive it. Keep adding until you hear light ping, and back it off 2 degrees (or more).
.
Initial timing + Mechanical timing = Total timing (mechanical)
If you are targeting 32 degrees total mechanical timing, it would look something like this example:
Initial - 16 + Mechanical - 16 = 32
Then you start adjusting vacuum by plugging the vacuum line into the can. Generally, start at the lowest setting, and add like 2 or so degrees and drive it. Keep adding until you hear light ping, and back it off 2 degrees (or more).
.
April 6th, 2018, 11:04 AM
#74
Registered User
Join Date: Jul 2006
Location: Manassas, VA
Posts: 694
How would you suggest you reach optimum timing? Set it by what's in the manual?
.
April 6th, 2018, 11:38 AM
#75
Registered User
Join Date: Feb 2011
Location: Denmark
Posts: 1,591
By far the best option is to put it on a dyno, but that's the dream scenario.
Yes, inaudible detonation. I've seen too many people who think "if it doesn't ping, it's okay."
The factory engineers set timing to where peak cylinder pressure was most effective, while being safe. Where we can experience problems is when our fuel is different from the fuel used in the 60s - especially when you run a high compression engine with lower octane fuel. Initial settings vary wildly depending on the compression. Iirc.
If the engine is stock and low compression, I would stick close to factory specs. If it's high compression, I would make sure the fuel is high enough octane, then go to the factory specs. If it isn't high octane, I'd retard until it doesn't ping.
Yes, inaudible detonation. I've seen too many people who think "if it doesn't ping, it's okay."
The factory engineers set timing to where peak cylinder pressure was most effective, while being safe. Where we can experience problems is when our fuel is different from the fuel used in the 60s - especially when you run a high compression engine with lower octane fuel. Initial settings vary wildly depending on the compression. Iirc.
If the engine is stock and low compression, I would stick close to factory specs. If it's high compression, I would make sure the fuel is high enough octane, then go to the factory specs. If it isn't high octane, I'd retard until it doesn't ping.
April 6th, 2018, 01:09 PM
#76
Registered User
Join Date: Jul 2006
Location: Manassas, VA
Posts: 694
Isn't that basically what I said?
But basically agree with what you said. One of the first things done to improve power back in the day was, recurve the distributor. Because the factor was TOO safe/lazy. And not many run 100% factory configurations anymore.
Go back and read what the original poster posted, and let me know what you think the issue is here. Or was, actually. I found it kind of amusing how many drifted off into a conversation of who the engine should be built by. Heheh!
.
But basically agree with what you said. One of the first things done to improve power back in the day was, recurve the distributor. Because the factor was TOO safe/lazy. And not many run 100% factory configurations anymore.
Go back and read what the original poster posted, and let me know what you think the issue is here. Or was, actually. I found it kind of amusing how many drifted off into a conversation of who the engine should be built by. Heheh!
.
April 6th, 2018, 01:14 PM
#77
Registered User
Join Date: Feb 2011
Location: Denmark
Posts: 1,591
Oh no no, we agree completely - the original poster had timing all over the place.
Yes, you said that. I'm nit-picking, because some people apply the ping-and-retard principle to low compression engines too, where it can be dangerous.
The factory had to ensure that people running on crappy fuel would not ruin their engines. They also had to average a variety of conditions like temperature and altitude. Erring to the side of caution makes sense.
Yes, you said that. I'm nit-picking, because some people apply the ping-and-retard principle to low compression engines too, where it can be dangerous.
The factory had to ensure that people running on crappy fuel would not ruin their engines. They also had to average a variety of conditions like temperature and altitude. Erring to the side of caution makes sense.
April 10th, 2018, 09:24 AM
#78
Registered User
Join Date: Jul 2012
Location: Vancouver BC
Posts: 2,788
I would and have in the past run a higher grade of gas then the engine was built for. After the engine was tuned for best performance I would then attempt to de-tune for a lower grade of fuel.
By starting with the higher grade of fuel you eliminate the fuel as being a factor when sorting the fuel and ignition system on a new build.
I also think it provides a safety margin during this tuning period.
By starting with the higher grade of fuel you eliminate the fuel as being a factor when sorting the fuel and ignition system on a new build.
I also think it provides a safety margin during this tuning period.
June 1st, 2018, 04:46 AM
#79
Hello, my name is rob, i ordered a 455 engine from mondello and after install i can not get the pining to go away, the vehicle is very low on power at w.o.t. Pings very bad will not even spin a tire.
Everything is brand new as follows:
455 block bored .030 over forged flat top pistons
aluminum intake
750 cfm demon carb
aluminum heads 2.075 x 1.690 valves
cam jm 20/22 mondello in. 496, ex. 520, running duration 300/310
gross cam lift at .050 intake 300 / 224
exhaust 310/234
lobe centers 112
valve lash hyd.
Hei ignition. Unplugged vacuum advance due to too much timing.
After install, i was told to adjust the total timing at 32 deg. The vehicle pings horribly and immediately jumps to 60 deg making it worse, the only way to get the vehicle to start correctly is retard the timing to total 28 deg, and base at about 15 deg.
Rechecked cam timing, all marks are centered. I'm very concerned about the cam being to big or compression being too high for 92 octain fuel? This is very discouraging since i just spent so much money to have a drop in motor i could run on pumped gas..just looking for some feedback on easiest solutions to fix this problem..and mondello said the motor should be at least 500 horsepower but i cant even get the rear tires to spin? Pings like crazy and now power.
Please help! Thank you!
Rob.
Everything is brand new as follows:
455 block bored .030 over forged flat top pistons
aluminum intake
750 cfm demon carb
aluminum heads 2.075 x 1.690 valves
cam jm 20/22 mondello in. 496, ex. 520, running duration 300/310
gross cam lift at .050 intake 300 / 224
exhaust 310/234
lobe centers 112
valve lash hyd.
Hei ignition. Unplugged vacuum advance due to too much timing.
After install, i was told to adjust the total timing at 32 deg. The vehicle pings horribly and immediately jumps to 60 deg making it worse, the only way to get the vehicle to start correctly is retard the timing to total 28 deg, and base at about 15 deg.
Rechecked cam timing, all marks are centered. I'm very concerned about the cam being to big or compression being too high for 92 octain fuel? This is very discouraging since i just spent so much money to have a drop in motor i could run on pumped gas..just looking for some feedback on easiest solutions to fix this problem..and mondello said the motor should be at least 500 horsepower but i cant even get the rear tires to spin? Pings like crazy and now power.
Please help! Thank you!
Rob.
June 1st, 2018, 04:49 AM
#80
Your initial timing should be around 12 degress BTDC. The total advance could be 32, I personally run 36 total all in by 3400 RPM. if you are setting your initial timing at 32 degrees, lucky you didn't break a piston with the violent detonation you will be having??? Just sayin'
Wayne
Wayne
