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Old 05-10-2021, 05:12 PM
Formulas Formulas is offline
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Now that you have given more details there should be no problem with the combo of parts but its unfortunate you dont know where your cam is actually installed at,

One thing I have always wondered about Rhoads lifters and EFI.
Rhoads are going to provide different valve action between cold start and full heat does any given EFI make the necessary changes based on vacuum and oxygen sensor accordingly? I dont know not my area

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Old 05-10-2021, 05:22 PM
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Yes, map is the load curve on speed density. If the difference is significant enough to show on the map reading, it can be tuned. I would venture a guess that the OP will have a discernible difference in the map reading at idle, than at the problem area. Load is increasing as the clutch engages. A datalog will likely bear this out. I do not know if holley efi offers this feature, but I can enable separate tables just for idle, with regards to both spark and fuel. This helps for those areas you pass through twice, but under different circumstances. Speaking of spark, don't discount what you can do with spark to help manage changing load conditions.
As to the cam, I thought he was going to verify it's position. It would be worth it to know where it is.
ETA: To answer the question with an example, on mine with a 4bar MAP sensor, I can tell the difference at idle, and taking off, in the position of the stator in my switch pitch converter. The map reading will be slightly different depending on if it's in high stall(less engine load) or low stall (more engine load)I have actually switched back and forth by holding the brakes with the line lock to adjust for best combined idle. (The switch pitch is brake pedal actuated) FWIW

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  #23  
Old 05-10-2021, 07:02 PM
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All Good info....
Scott,
Yes, I can and will manually tune the efi. I wanted to degree the cam first because I had the of idle stumble with the Carb also so before I get Into tuning, I wanted to degree the cam 1st.
I will check ICL and compare to cam card.
Question? If it is at 113 as noted, would 111 or 109 be better for my application?
Would you do 109 (4 degree advance) for a starting point?
Thanks Jeff

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Old 05-10-2021, 07:42 PM
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Just an opinion, as I've never used that cam in a 455. I wouldn't go more than 2 advanced and only due to chain stretch. A 455 should handle that cam straight up easily IMO... Hopefully others with first hand experience will make a compelling case one way or another. It could easily be timing curve related since you've had it with both fuel systems. Point being it could be totally un cam related... Now if you find it installed at 116, or something way retarded, there you go... Rule it out.

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Old 05-10-2021, 08:03 PM
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Scott,
The issue I have is a off idle lean hesitation with both a 4bbl and efi.
Rpm between 900- 1300 rpm the engine "surges" lean watching on an AfR gauge regardless of engine load.
I've been holding the throttle in this position and letting the efi l"earn" here, but I feel it's more of cam thing.
I had timing at 12 intial with 10 vacumn (22 total at idle) with the MSD distributor.
Now using the dial sync, the ecm controlling spark, the ecm is running in the same values so I think that's good for initial.
Vacumn at idle using a vacuum gauge, I have 16ish" at idle drops to 5" when you move the throttle.
I think advancing the cam may help a bit.

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Old 05-10-2021, 08:13 PM
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Advancing it may help. It becomes more likely if its currently installed retarded. Verify where it is now first. You may find it in at 115, in which case 2 degrees will make it better, and right! The good news is the lean spot can definitely be tuned out with a few well placed keystrokes. Good luck and report back with results.

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Old 05-10-2021, 08:14 PM
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Will do..... Thanks jeff

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Old 05-11-2021, 09:15 AM
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If you wanted to get an idea of where the cam timing is without getting deep into the engine, we measure the lobe lift at TDC. It is a method we use for folks that do not want to degree in the cam in the car. I should have the that info for that grind you have. Take a valve cover off, find a point of reference for the #1 intake (top of push rod or above the rocker cup), or with the intake off go off the #1 int lifter. Tricky part with it together and just a valve cover off is the lifter preload, on a vmax you should be able to zero the lash. Then check the lift off the base circle, then roll the engine to tdc and check it again and record the lift at tdc. Either can assume the timing marks are correct on the dampener and cover or for higher accuracy use a tdc spark plug stop and mark the dampener for tdc..

We have installed that cam on 113 in a 455 before. Unless the exhaust has some monster porting, I think it is retarded to far in a d port. We always assume that the cam is operating another 2 degrees retarded from where it is installed on a timing chain engine. On a timing chain engine installed at 113 it really isn’t even “running” straight up, it is running closer to 115. On a D port I shoot for installing it either side of 110, so it is operating closer to 112. FWIW

If you have never messed with them, there is quite a bit of adjustment in the tune on vmaxs. We ussually focus on the intake settings. Just my opinion, but I would not go into a street engine for a 2 degree cam timing adjustment. I would rather adjust the vmaxs. But like was meantioned, timing chains can stretch bad, some cheaper double rollers stretch 5* pretty quickly, seen that after 10K miles. 5* on top of the 113 plus the 2* operating slack = 120* ICL. Be difficult to give it a nice tune that far out of wack. You have a lot of head on the engine, I am guessing the cam timing is going to be somewhat forgiving on your combo.


Last edited by Jay S; 05-11-2021 at 09:48 AM. Reason: Edit
  #29  
Old 05-11-2021, 09:56 AM
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Jeff the hesitation ain't the cam position.

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Old 05-30-2021, 05:23 PM
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Just an update guys,
the timing chain is loose, so definitely running retarded (cam is installed straight up)
Going to order a new chain set and degree.
Thanks, Jeff

  #31  
Old 05-31-2021, 08:40 AM
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I've tested the Crower RAIV cam in a 455 nearly identical to yours and found the best ICL was 109 degrees. It ran equally as well at 111 at the track but just a tad "softer" on the street and didn't make quite as much vacuum at idle. It was "weak" at 113ICL and felt pretty "peppy" at 107. Even so it ran the worst ET and MPH at 107ICL as it just pinched off too much upper mid-range and top end power, and to my surprise advanced to 107ICL it ran slower in 60' not quicker.

Sort of debunks the common praise "advance the cam for more low end torque" because it did NOT pick up in 60" or short times and ran slower in MPH everyplace.

Timing chains do stretch out pretty quickly, especially the "low" end double roller varieties as mentioned. We don't hear too much about this simply because most folks are unlikely to put but a couple thousand miles on their engine in the next 10 years and very few folks end up going back in to take a look at things so would really never know the condition of the timing set.......FWIW........

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Old 05-31-2021, 09:43 AM
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Quote:
Originally Posted by Cliff R View Post
I've tested the Crower RAIV cam in a 455 nearly identical to yours and found the best ICL was 109 degrees. It ran equally as well at 111 at the track but just a tad "softer" on the street and didn't make quite as much vacuum at idle. It was "weak" at 113ICL and felt pretty "peppy" at 107. Even so it ran the worst ET and MPH at 107ICL as it just pinched off too much upper mid-range and top end power, and to my surprise advanced to 107ICL it ran slower in 60' not quicker.

Sort of debunks the common praise "advance the cam for more low end torque" because it did NOT pick up in 60" or short times and ran slower in MPH everyplace.

Timing chains do stretch out pretty quickly, especially the "low" end double roller varieties as mentioned. We don't hear too much about this simply because most folks are unlikely to put but a couple thousand miles on their engine in the next 10 years and very few folks end up going back in to take a look at things so would really never know the condition of the timing set.......FWIW........
So just what ICL would be installed with no advance? You do know that just because some is good does not mean that more is better?

Stan

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  #33  
Old 05-31-2021, 10:04 AM
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Right out of the box the vast majority of the RAIV cams I've installed came in at 112-113ICL.

Knowing this I'll advance them 4 degrees on install.

Since this happens with the Melling, Crower, Crane and most others we've installed it is likely that the companies selling them simply "re-boxed" cams they bought from CMC, but that's just a guess on my part. It still matters not in the big scheme of things and it isn't going to make a lot of difference if you install the cam straight up or advance it. I saw pretty much the same ET and MPH at 109 and at 111ICL, probably because my Continental 10" converter flashes to 3500rpm's at the track with good traction. The ET and MPH was down a bit at 113ICL, but no more than about a tenth and less than 2mph. More important the car "felt" sluggish and a little "flat" right off idle there.

It felt "peppy" as mentioned at 107ICL for "normal" driving, so one would think it would pick up 60' and some short time numbers, but it did not. Once again with a converter that flashes to 3500-3600rpm's at the track pulling more power down to lower RPM"s didn't help anything and hurt ET/MPH simply because the engine is very quickly into the upper mid-range and top end power at the track and didn't like, want or need more "low end torque" to make the vehicle quicker.

I'd also mention that as with all the testing I've ever done the "butt meter" is not to be trusted, IF you drove the car with the cam at 107ICL you'd very quickly bet your next paycheck it would run quicker at the track instead of slower at every point, pretty much the same as any other part or parts I've tested that pull power down and/or narrow it up........FWIW......

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Old 05-31-2021, 11:46 AM
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" You do know that just because some is good does not mean that more is better?"

Stan, I'm one of the guys who are quick to get off of Google, close the laptop and go out and get dirty to find out what really works with these things, but you already knew that.

Theory is fine, regurgitating old/outdated information doesn't bother me either, nor does reading books and articles from the "experts"...........even so, DIRECT testing is where you find out what really works. So if/when you get tired of reading copy/pasted information from folks who don't do this for a living and don't even have a Pontiac powered car that moves I'll be glad to put up some useful and accurate information as I know it to be from actually doing it........Cliff

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Old 05-31-2021, 12:19 PM
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Quote:
Originally Posted by Cliff R View Post
Sort of debunks the common praise "advance the cam for more low end torque" because it did NOT pick up in 60" or short times and ran slower in MPH everyplace.


Quote:
Originally Posted by Cliff R View Post
" You do know that just because some is good does not mean that more is better?"

Stan, I'm one of the guys who are quick to get off of Google, close the laptop and go out and get dirty to find out what really works with these things, but you already knew that.

Theory is fine, regurgitating old/outdated information doesn't bother me either, nor does reading books and articles from the "experts"...........even so, DIRECT testing is where you find out what really works. So if/when you get tired of reading copy/pasted information from folks who don't do this for a living and don't even have a Pontiac powered car that moves I'll be glad to put up some useful and accurate information as I know it to be from actually doing it........Cliff
It is not google. It is not theory. It is not regurgitating old or outdated information being post by some others here. It just seem you have a problem if someone does not get the same results as you even when their combination is night and day different than yours.

Stan

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  #36  
Old 05-31-2021, 12:26 PM
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Asking for a friend, how fast does THIS combination run at the track with different intake centerlines?

462 ci
10.2 CR
KRE D ports - 290 CFM
Crane 041 clone
RPM intake.

Thoughts if we had 310CFM heads instead, what would the engine like?

  #37  
Old 05-31-2021, 12:39 PM
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Thanks for the info.
Wasn't sure about 109 vs 111 so thanks Cliff.
109 it is
Just for the hell of it, I may check degree now with the old setup just to see how much retard I have....
Chef,
Haven't ran this combo at the track.... And probably never will... This is more of a weekend cruiser and stoplight killer. Something to show the younger generation what started the muscle wars


Thanks again guys,. Jeff

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Old 05-31-2021, 04:29 PM
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To see the cam timing effects played out back to back on a dyno there is 2 Engine Masters episodes one being Engine Personality test for LCA and Advances in cam timing for ICL event changes

They illustrate the changes in cam timing and its effects on the power curve depending on your experience and understanding they can be enlightening or obvious but it's interesting to see real results and hear why

After watching your not going to know exactly where to degree but you will know more about the direction you want to go to get the results you desire , they state the obvious that they are showing trends and only testing your specific combo will net you best results


Last edited by Formulas; 05-31-2021 at 04:37 PM.
  #39  
Old 06-01-2021, 06:23 AM
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"It is not google. It is not theory. It is not regurgitating old or outdated information being post by some others here. It just seem you have a problem if someone does not get the same results as you even when their combination is night and day different than yours."

Stan, I don't have a "problem" with any of it, just pointing out some obvious flaws in the information provided. I encourage folks to do their own tested vs Google/copy/paste. Testing parts is where we find out what really works and what doesn't. In case you weren't paying attention most of the old/outdated information we see showing up on these threads wasn't Pontiac engine related right to start with. What I've found with these engines is that they really care about the intake closing point. So if you are moving cams around and such the big 455 typically will NOT like a small cam with an advanced intake closing point, or essentially tight LSA and short seat timing with the intake at 106 degrees, for example. I attached a dyno chart showing how much power is left on the table with this sort of thing, not to mention cam # 1 pinged hard enough on the dyno to spin the rod bearings.

At least I have a Pontiac powered car that moves, test a lot of parts and don't mind putting up the results. It just so happens that I've tested ICL with the RAIV camshaft in a 455 and have built quite a few 455's using that cam. At one point I wanted to find out if I was leaving anything on the table with the ICL at 109 so I moved it 4 times, street and track tested it after each movement, and took good notes. If that info fits your needs fine, if not you can make a copy of it and use it for toilette paper, I could really care less......FWIW.......
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Old 06-01-2021, 06:27 AM
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"Thanks for the info.
Wasn't sure about 109 vs 111 so thanks Cliff.
109 it is
Just for the hell of it, I may check degree now with the old setup just to see how much retard I have.... "

You are welcome. Hope it helps and looking forward to the results. I will note here that even clear back at 113ICL my engine still ran fine and not stumble/hesitation/bog or any negatives for "normal" driving. It did loose 2" vacuum at idle speed compared to 109ICL and felt a little "flat" right off idle and at low RPM's.

I'd also add that it did NOT pull hard at high RPM's as one would thing we'd see from retarding a cam vs advancing it. So basically the car slowed down everyplace in both ET and MPH at 107ICL and at 113ICL. Something to consider when you see someone come on here and tell you to advance your cam for more low end torque, or retard it for more high RPM power........FWIW......

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