In disbelief
Pro
Joined: Sep 2017
Posts: 516
Likes: 72
From: Modesto California
The timing cover is designed for a retro roller cam setup and to make it easier for cam end play.
https://www.summitracing.com/parts/clo-9-221
https://www.summitracing.com/parts/clo-9-221
Okay, I get it. It has an adjustable button in it to control cam walk. I used a Crane Torrington bearing cam button when I put a roller cam into my '82 back in 1996 and was surprised over it's low $9 cost. But I also had to use an earlier timing chain cover that had the three ribs because the '82 timing chain cover was made differently.
Race Director
Joined: May 2005
Posts: 10,674
Likes: 122
From: Millington Illinois
St. Jude Donor '08-'09
So you think the carburetor manufacturers and the factory engineers are wrong when they recommend 1-1/2 cfm per cubic inch? A mechanical secondary carburetor gives a false sense of "increased power" because of secondaries being prematurely opened when they'd normally be closed. But it's no different than putting your foot in deeper with a vacuum secondary carburetor because cfm is cfm regardless of how many barrels or style of secondary a carburetor has. If you put an 1000 cfm one barrel carburetor onto an average 350" engine it would feel REALLY powerful at small throttle openings just because of the larger bore that would pass so much air at a minimal throttle opening. But at only half throttle the engine would already be maxed out because it couldn't swallow any more air.
Last edited by 63mako; Sep 29, 2017 at 11:12 PM.
Pro
Joined: Sep 2017
Posts: 516
Likes: 72
From: Modesto California
The 85% Volumetric Efficiency Is Humbling
"Factory" GM engineers used a 780 Holley on their 302 engines. Blows your "Theory" out of the water. http://www.rickscamaros.com/camaro-c...1968-1969.html BTW my 383 has a Large base Tripower, 840 corrected CFM. Makes 535 HP, Breaks the 13" wide tires loose @ 55 kicking in the outboard carbs in 4th. Got 20.1 MPG cruising 80 in 6th on the interstate.
The 302" Z-28's came with a set of long tube headers in the trunk because the factory engineers assumed (correctly) they would be drag raced. A 302" spinning at 8000 rpm @ 100% volumetric efficiency would consume 699 cfm. The factory engineers opted to equip them with the larger 780 cfm because the 600 cfm was too small for 8000 rpm operation @ 100% volumetric efficiency achieved when running open headers. But once the street legal exhaust system was reattached for the long drive home the 780 cfm became unnecessarily large but a 600 cfm would have been just right for the 594 cfm it could consume at a street legal 85% volumetric efficiency.
If you doubt my word check out the Holley, Edelbrock, and Summit Racing websites showing recommended carburetor sizes for street engines. The figures given reflect the 85% volumetric efficiency that street legal engines can barely achieve running street legal exhaust systems. And mechanical secondary carburetors? As this is America you can use whichever carburetors you want without the fear of being arrested and thrown in the slammer.
Last edited by 71VetteLover; Sep 30, 2017 at 03:39 AM.
Thread Starter
Racer
Joined: Jul 2009
Posts: 344
Likes: 5
From: oak harbor wa
It runs!
Well after many months on a stand, then weeks in the car, it fired up for the first time today. Took little to no time for the Luanti Roller lifters to pump up <--- I've read they can take awhile. I have to get some higher octane fuel, and I will post a video. I haven't posted a video in awhile and it looks like it has changed on the way to do it.
Thank you all for the answers along the way.
Thank you all for the answers along the way.
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Race Director
Joined: Dec 1999
Posts: 11,096
Likes: 990
From: Sierra Foothills CA
When you're creating any post, you can look just above the box that you type into and see a bunch of symbols. The second one from the right is the Youtube symbol. Click that and it will set the format for you, and the cursor will be right where it needs to be. Then you copy/paste the same link for the video that you did above my post. But you're not done yet. The last step is to start at the left end of your video link and erase everything up to and including the = sign. You leave everything to the right of that alone and you're ready to post it. I hope that makes sense.
Thread Starter
Racer
Joined: Jul 2009
Posts: 344
Likes: 5
From: oak harbor wa
Thank you Les
When you're creating any post, you can look just above the box that you type into and see a bunch of symbols. The second one from the right is the Youtube symbol. Click that and it will set the format for you, and the cursor will be right where it needs to be. Then you copy/paste the same link for the video that you did above my post. But you're not done yet. The last step is to start at the left end of your video link and erase everything up to and including the = sign. You leave everything to the right of that alone and you're ready to post it. I hope that makes sense.
Also to All the only thing I can think of and it's not even a complaint, more of just a heads up. The lunati roller conversion lifters with the link bars are loud, I called them and they said completely normal. For the 406 it is a different beast compared to the 350 I built, it feels about the same at a 402 BBC I did for my Dad in an 71 C10. No complaints though.
Race Director
Joined: May 2005
Posts: 10,674
Likes: 122
From: Millington Illinois
St. Jude Donor '08-'09
Yep, and the chart takes the engine's level of performance into account. An L-48 would be about 75% efficient, an L-82 about 80% efficient, and an LT-1 about 85% efficient. It's the restrictive exhaust system that causes the reduction in volumetric efficiency in street engines at the higher rpm's and that's why street engines only require the smaller cfm carburetors. It's pointless to install a 750 cfm vacuum secondary carburetor on an 85% efficient 350" engine because the secondaries would only open about 10% at the very most; even at 6000 rpm because it would only be able to swallow 517 cfm at 6000 rpm. The primaries alone would provide 375 cfm (or 73%) of the 517 cfm needed and that's why the secondaries would barely open.
Excessively large carburetors will give a false sense of "increased power" because each degree of throttle opening provides more air than the same amount of throttle opening in a correctly-sized carburetor. But as the engine can only swallow a given amount of air at maximum power the larger carburetor doesn't provide any benefit other than bragging rights (or should I say bragging wrongs?).
Excessively large carburetors will give a false sense of "increased power" because each degree of throttle opening provides more air than the same amount of throttle opening in a correctly-sized carburetor. But as the engine can only swallow a given amount of air at maximum power the larger carburetor doesn't provide any benefit other than bragging rights (or should I say bragging wrongs?).
Safety Car
Joined: Nov 2005
Posts: 3,532
Likes: 1,185
From: Arizona - If you don’t know CFI, STOP proliferating the myths around it...
So, I was wondering about the CFM argument here and thought about the 69 Z/28 DZ302 I had back in the day when I was actively racing. I had the GM crossram manifold on it with two 650s and down low it didn't like it so much, but since it was a RPM hound, at 8K it ran like a beast. This manifold was a truck only manifold back then, dealer would not install it. At one time, I converted it to a Proram with two 660s. Ran great. This motor wasn't stock either, just a well built 302. Wish I still had that car now.
Last edited by Buccaneer; Oct 15, 2017 at 02:24 AM.
Thread Starter
Racer
Joined: Jul 2009
Posts: 344
Likes: 5
From: oak harbor wa
Ok guys New news
Well all is well engine is timed in at 36 total didn’t care to try for initial but after the 36 was set, initial sits at about 14-15. I rebuilt the carb because it was just annoying me all is good on it now. The issue I am having it horrible starter kickback, I know the timing is right, along with the balancer mark, it was checked with the heads off on a stand. It has a damn good Frame to block ground along with two ground straps from trans to frame and also another one from the block.
Do I need to just step up to hi torque starter, it didn’t start kicking back until after break in, I took it off and made sure case was not cracked, I have the proper length knurled bolts.... I just don’t want to break a new flywheel... any ideas?
Do I need to just step up to hi torque starter, it didn’t start kicking back until after break in, I took it off and made sure case was not cracked, I have the proper length knurled bolts.... I just don’t want to break a new flywheel... any ideas?
Burning Brakes
Joined: Aug 2013
Posts: 1,071
Likes: 322
From: palm springs ca
Well all is well engine is timed in at 36 total didn’t care to try for initial but after the 36 was set, initial sits at about 14-15. I rebuilt the carb because it was just annoying me all is good on it now. The issue I am having it horrible starter kickback, I know the timing is right, along with the balancer mark, it was checked with the heads off on a stand. It has a damn good Frame to block ground along with two ground straps from trans to frame and also another one from the block.
Do I need to just step up to hi torque starter, it didn’t start kicking back until after break in, I took it off and made sure case was not cracked, I have the proper length knurled bolts.... I just don’t want to break a new flywheel... any ideas?
Do I need to just step up to hi torque starter, it didn’t start kicking back until after break in, I took it off and made sure case was not cracked, I have the proper length knurled bolts.... I just don’t want to break a new flywheel... any ideas?
Sounds like to much initial advance. I remember waaaaay back when we had real gas, the initial on a factory built HP engine was around 12 initial at the most. somewhere between 8 & 12 initial.
But then the higher octane took longer to light off. For what it's worth, I get that kick back when using the CA pump gas, with one more added problem, dieseling when shutting down the engine after it's warmed up.
Just for kicks try retarding about 4 degrees and see if that helps. If so then the experts here will chime in on their thoughts.
Dom
Pro
Joined: Mar 2005
Posts: 635
Likes: 118
From: Lakemont, GA
Have you looked at your advance curve? What RPM is your mechanical advance all in. You have a great looking and sounding car there but based on your move to a roller cam you may want to try a little less advance.
I would also verify that your timing tab is at true TDC for #1. I have seen these off many times and people who think they are running 36 degrees are actually well over 40.
Thanks for the writeup, sounds like you made the best out of a bad situation.
I would also verify that your timing tab is at true TDC for #1. I have seen these off many times and people who think they are running 36 degrees are actually well over 40.
Thanks for the writeup, sounds like you made the best out of a bad situation.
Thread Starter
Racer
Joined: Jul 2009
Posts: 344
Likes: 5
From: oak harbor wa
No news is not always good news
Let me start off by saying the starter did not need shims.
So I finally had time to get the timing backed off as suggested, I turned it over and a horrible racket is the only thing that happened, then came the noise of a free spinning bendix, I thought to myself well it is time to upgrade to a mini starter. I pulled the starter, and the nose was cracked and in pieces as I further looked I noticed it had taken out the flywheel teeth, not just chewed they were gone in one area.
So yesterday afternoon I pulled the transmission and removed flywheel, the new air tools and compressor substantially helped, I had it all out in 2 hours. The flywheel is at machine shop right now getting a new ring gear installed. I was going to do it myself but a 25 dollars labor I can something else to do during that time.
Last edited by lowes-yellow77; Nov 8, 2017 at 08:54 PM. Reason: Picture
Thread Starter
Racer
Joined: Jul 2009
Posts: 344
Likes: 5
From: oak harbor wa