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Old 02-23-2021, 02:52 PM   #85
cmitchell17

 
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Quote:
Originally Posted by oldman View Post
IMO most failure is caused by bounce. Even a twin spring has harmonics that lead to very low spring pressure. Hence the evolution to a conical spring, as it tends to absorb the harmonic within the spring itself. I know it is hard to imagine that a 300 lbs spring will have very little pressure at certain points in the lift cycle.
https://www.streetmusclemag.com/tech...-horsepower-2/

Once the lifter is no longer in contact with the cam, the entire valvetrain is in free fall. There is a whole lot of energy coming down on that valve seat, hence the bounce.

If I were to do all this again, I would definitely go conical. I figure I'll change my TSP dual spring at sub 40K miles to conical.
Right now I am thinking it may be cheaper just to buy some aftermarket castings. Although I don't trust any casting besides the stock one, paying an absurd amount of money you would think you could trust them.

It would give me the added benefit of a smaller chamber. Like you said I want to go to a reliable cam setup under .600 with a better profile. If people can boost these engines to 600-700hp, I don't see why I can get a smaller chamber and run E85, which I run 100% of the time anyway. Maybe it would make up for the loss in lift and cam ramp.
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Old 02-23-2021, 02:54 PM   #86
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Originally Posted by KingLT1 View Post
And there lies your problem which is why I don't recommend porting stock casting without fully reworking the heads...new valve seats, guides, valves are a must imo.
I would just buy their aftermarket casting at that point.

Screen shot below taken off TSP website.
Interestingly enough, I am almost certain I never saw that warning when buying my heads, not sure if they had it up a year or so ago?

That being said, I think there is a pretty big conflict on interest here in them selling aftermarket castings. I've never seen a GM TSB or anything about seats "falling out" especially in stock applications.
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Old 02-23-2021, 02:58 PM   #87
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Originally Posted by cmitchell17 View Post
Interestingly enough, I am almost certain I never saw that warning when buying my heads, not sure if they had it up a year or so ago?

That being said, I think there is a pretty big conflict on interest here in them selling aftermarket castings. I've never seen a GM TSB or anything about seats "falling out" especially in stock applications.
When I was browsing a year or so ago on TSP at their ported factory heads, I don't remember that warning being in the description.
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Old 02-23-2021, 04:09 PM   #88
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It looks like the aftermarket PRC heads start at $2549.00 before springs. So it looks like the Edelbrock heads are a little cheaper. But are they worth it compared to the PRC heads?
They Edelbrock heads also require you to use Kooks headers so if you have headers already I'd skip the Edelbrocks.
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Old 02-23-2021, 06:00 PM   #89
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Quote:
Originally Posted by cmitchell17 View Post
Interestingly enough, I am almost certain I never saw that warning when buying my heads, not sure if they had it up a year or so ago?

That being said, I think there is a pretty big conflict on interest here in them selling aftermarket castings. I've never seen a GM TSB or anything about seats "falling out" especially in stock applications.
From what I have read the stock seats tend to have trouble with increased lift, lobe intensity, and seat pressure. They don't seem to be as problematic in stock applications.

Aside from that GM never acknowledged or issued a TSB for LS7's which were notorious for dropping valves even stock.

Pray, GPI, and TSP have all mentioned at one point that the stock seats are a issue in heads cam applications. Pray has even had a failure in one of his FBO bolt-on hi ram cars.

I also agree with Old man and Parish that valvetrain instability could of also been a player. Your springs might not of been shimmed correctly or incorrect lifter preload. Either way I am just pointing out that the stock seats are a weak point on factory castings.
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Old 02-23-2021, 06:28 PM   #90
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Originally Posted by Puddin View Post
They Edelbrock heads also require you to use Kooks headers so if you have headers already I'd skip the Edelbrocks.
Only the Victor Jr ones I believe. Thought the Performer RPM ones used stock headers.

I’m enjoying my Mast Black Label heads FWIW. Nice product. Support is a little on the slow side unfortunately, but to be fair I haven’t needed any since I bought them.
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Old 02-23-2021, 06:30 PM   #91
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A lot of good info here, my lift is 645 so I have decided to send my heads to Katech for porting and assembly. I have purchased so far the harden push rods BTR, Texas Speed upgraded springs, Smith Brothers Kit, and LS7 lifters. After reading this post and what oldman has said I am getting harden valves and I probably will purchase another set of lifters. GPI has the race LS7 lifters that are an upgrade on the LS7 lifters. My car is not a daily and will be a weekend car, not high mileage so that should help. 1/4 of a Mile at a time. Lol
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Old 02-23-2021, 06:58 PM   #92
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Wow I missed a lot while working. I must say, to me, in that picture it looks like the seat broke...maybe a couple chunks. The burnt seats I have looked at I don’t recall looking like they were missing a chunk. Maybe I’m wrong. Usually aggressive valve seat angles combined with lots of heat will cause the angle to burn. I bet your valve was bouncing and possibly caused that seat to chip.
Regardless again maybe my eyes are playing tricks on me but.....I think that seat chipped from what I can see.
It would be interesting to know how many angles were used for the valve job and what degrees were the angles machined at.?
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Old 02-23-2021, 08:28 PM   #93
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Originally Posted by Scottyz View Post
Wow I missed a lot while working. I must say, to me, in that picture it looks like the seat broke...maybe a couple chunks. The burnt seats I have looked at I don’t recall looking like they were missing a chunk. Maybe I’m wrong. Usually aggressive valve seat angles combined with lots of heat will cause the angle to burn. I bet your valve was bouncing and possibly caused that seat to chip.
Regardless again maybe my eyes are playing tricks on me but.....I think that seat chipped from what I can see.
It would be interesting to know how many angles were used for the valve job and what degrees were the angles machined at.?
It would be extremely interesting to know that as well. TSP will not tell me any of that info, I mean I kind of get it as some might be "proprietary" race info, but then again we are paying them. I can't even find out if they use stock seats or put their own in or what.

So found more things, #5 exhaust valve appears to be bent, it was hard to take out, and I put another cylinder exhaust valve in and it went in easy:
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Also, every single other intake valve, #5, #3, and #1, all have this same chipping or burning or whatever it is damage:
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So I was thinking with an aftermarket casting I could get a smaller combustion chamber but apparently not the TSP one only goes down to 54 CC chambers. I think I estimated I was around the same 55 or 54 CC or something like that with my .030 mill. My dream build is very high compression E85 motor but everyone I ask gives me a lot of negative feedback or the "just put a turbo on it".
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Old 02-23-2021, 08:43 PM   #94
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Originally Posted by KingLT1 View Post
From what I have read the stock seats tend to have trouble with increased lift, lobe intensity, and seat pressure. They don't seem to be as problematic in stock applications.

Aside from that GM never acknowledged or issued a TSB for LS7's which were notorious for dropping valves even stock.

Pray, GPI, and TSP have all mentioned at one point that the stock seats are a issue in heads cam applications. Pray has even had a failure in one of his FBO bolt-on hi ram cars.

I also agree with Old man and Parish that valvetrain instability could of also been a player. Your springs might not of been shimmed correctly or incorrect lifter preload. Either way I am just pointing out that the stock seats are a weak point on factory castings.
I remember I did call TSP about my preload, and I remember making a thread about it. I think they ended up telling me that the pushrods they sent to me were probably ok with the johnsons and I should just go ahead and run them. Although I think trying to measure using the thread pitch and determining where the thread starts getting tight and bottoms out from person to person is a huge variability that could be interpreted by different people as many different values. I am going to find a better way to check it this time.

Also my springs didn't have shims? TSP installed the springs before it was shipped to me, but there aren't any shims? I do have their supposed "exclusive" "integrated" seat/seal so not sure if they made the seat the correct height for our application?

I mean the whole point of shimming the springs is to get a certain more stable and predictable force range compared to the expected valve travel?
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Old 02-23-2021, 09:15 PM   #95
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That doesn't seem right to me because the Johnson's call for less preload then LS7 lifters so I don't see how standard length pushrods are correct.



Imo while you have it apart get a cam spring package from Cam motion, keep the lift around .600, and get a better set of heads...CID, Mast, Frankenstein...etc. keep the Johnson lifters if they are not damaged, and measure for correct push rod length.

Don't use the thread turn method for finding the correct preload.

Get a adjustable push rod and a digital caliper.

Using the EOIC method, Find zero lash with the adjustable push rod by increasing the length of the APR until there is no slack in the rocker.

Measure the APR with the caliper, add the desired lifter pre load to the Caliper measurement along with .012 for heat expansion. Then order that length of push rod. Manton makes custom pushrods if need be.

For example...if the APR measures 7.8 @ Zero lash, then add .035 for Johnson's recommended preload and .012 for block/head expansion when warm. The measurement equals 7.847 so a 7.85 would probably suffice which is standard length.
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Last edited by KingLT1; 02-23-2021 at 09:27 PM.
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Old 02-23-2021, 09:21 PM   #96
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No expert!

I have been told shining the springs to within .060-.080 of bind at full lift causes the coils to bump into each other and dampens the spring which makes it much more effective.

I can tell you with no shims I could only spin to 6600-6700 depending on boost level. After adding a .050 drop lock I could spin it 300rpm higher. I think I was sill .020+ short of being .060-.080 from bind.
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dropped a valve in the 6.2. now running a drop in rods and piston 5.3
best et 5.83@121 with the 5.3 http://www.camaro6.com/forums/showthread.php?t=465472
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Old 02-23-2021, 09:24 PM   #97
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Originally Posted by KingLT1 View Post
That doesn't seem right to me because the Johnson's call for less preload then LS7 lifters so I don't see how standard length pushrods are correct.



Imo while you have it apart get a cam spring package from Cam motion, keep the lift around .600, and get a better set of heads...CID, Mast, Frankenstein...etc. keep the Johnson lifters if they are not damaged, and measure for correct push rod length.

Don't use the thread turn method for finding the correct preload.

Get a adjustable push rod and a digital caliper.

Using the EOIC method, Find zero lash with the adjustable push rod by increasing the length of the APR until there is no slack in the rocker.

Measure the APR with the caliper, add the desired lifter pre load to the Caliper measurement along with .012 for heat expansion. Then order that length of push rod. Manton makes custom pushrods if need be.

For example...if the APR measures 7.3, then add .035 for Johnson's recommended preload and .012 for block/head expansion when warm. The measurement equals 7.347. a 7.35 would probably suffice.
I have read the total length of the pushrod is not the stated length. I am not sure where exactly they measure from.
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dropped a valve in the 6.2. now running a drop in rods and piston 5.3
best et 5.83@121 with the 5.3 http://www.camaro6.com/forums/showthread.php?t=465472
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Old 02-23-2021, 09:32 PM   #98
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I have used Manley's in the past and the advertised length was spot on with my Digital Caliper. Either way measure the pushrod you order with the digital caliper to make sure it lines up with your measurents taken and everything should be fine. It's what I have done in the past with no issues. Some companies will allow you to swap out pushrods to a different length if they haven't been installed and ran.
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