Don Terrill’s Speed-Talk

prairiehotrodder wrote: ↑Mon Sep 09, 2019 2:50 pm i have the 1.8 scorpion race rockers on the intake valves. Last winter when the heads were off i ground a little metal out of the inside of the guideplate because those rockers move the pushrod closer to the stud. I'm using the AFR 335 heads.
Brian

Do you have "stock-like" guideplates or the adjustable kind, like the ones that came with my AFR heads when I bought them new? Mine had the adjustable guideplates.

mine are adjust able with a little bolt in the middle. On non- adjustable ones i have cut them and welded them before.

I ended up using the AFR (made by Harland Sharp) 1.7/1.7 aluminum rockers. I had to grind some clearance on #1 and #8 intakes so it would clear my "stock style" valve covers but other than that they fit well. The sweep centered pretty good over the valve tip and I used the midlift or 90 degrees at half lift method. I used the taller studs on the intake only, from ARP, and now have plenty of thread. Gonna check the lash after a couple cruise nights and hope it is still the same. Thank you for the input on this issue. I really appreciate it!

I see this thread popped up again. Good thing since I lost it out of sight.

For giggles and since I have to recheck and retune my engine, I'll try the method Camking said (valve at max lift and then 360° further to set the valve). Will see if there is any difference.

As for the OP's problem. I have a shaft rockers system, so this is quite good at maintaining lash unless something is going bad. However when the engine was new I did see some slight changes of lash between doing the lash setting sessions. It stopped after some miles on the engine. Right now they stay pretty much where I put them. And I know my lifters were still good as I had them out 2 years ago when I had to do work on the intake.
Anyway, I've not seen my lash move as much as yours did, so I would not drive it, take the intake off and check your lifters.

Belgian1979 wrote: ↑Sat Jan 04, 2020 5:39 am I see this thread popped up again. Good thing since I lost it out of sight.

For giggles and since I have to recheck and retune my engine, I'll try the method Camking said (valve at max lift and then 360° further to set the valve). Will see if there is any difference.

As for the OP's problem. I have a shaft rockers system, so this is quite good at maintaining lash unless something is going bad. However when the engine was new I did see some slight changes of lash between doing the lash setting sessions. It stopped after some miles on the engine. Right now they stay pretty much where I put them. And I know my lifters were still good as I had them out 2 years ago when I had to do work on the intake.
Anyway, I've not seen my lash move as much as yours did, so I would not drive it, take the intake off and check your lifters.

It ended up being my PRW rockers. The trunnions started wearing out. I have since replaced them with the AFR's. I will still keep a close eye on them all.

UPDATE: Years later and over 3000 miles my AFR (Harland Sharp) 1.7 rockers are still holding a good "cold" lash. Thank You Straub for the recommendation! Still a perfect sweep pattern on the valve tip.

F-BIRD'88 wrote: ↑Sat Sep 01, 2018 11:40 pm Setting at tdc does not work.

This is an old thread, but this comment always cracks me up. It's kind of like saying " Av-gas doesn't work well in engines at sea level"

Hogwash !!!!!

Please don't get F-Bird fired up This is an old thread created by me. I just updated it for future readers. The content will remain valid for ages. Lets not pollute it with extra arguments. It sucks when a newbie is trying to learn something but has to filter through all the cockfights to find the answers. Thanks!

Use the tried and true EO IC. method.

Bishop540 wrote: ↑Wed May 03, 2023 3:27 pm Please don't get F-Bird fired up This is an old thread created by me. I just updated it for future readers. The content will remain valid for ages. Lets not pollute it with extra arguments. It sucks when a newbie is trying to learn something but has to filter through all the cockfights to find the answers. Thanks!

The comment - "Hogwash" is worth repeating to the comment " Setting at TDC does not work" .... Hogwash.

That comment is pure crap for 95% of camshafts. The actual answer is " It depends"

It depends on the ramps of the cam and it's base circle. The more aggressive the ramps are, and it's base circle, the more accurate that statement May Be.

The cam I ran for 10 years, before replacing it in 2021 with a new grind from Comp, was a custom roller from Dan Crower. That cam was 281/285 @ .050 with .436" and .438" lobe and 1.8:1 rockers. To give you an idea as to how aggressive the lobes were, it was .201 and .205 @ .200" . I could set that cam at TDC or IC, EO and the numbers were just the same.

That cam was way more aggressive than your AVERAGE weekend warrior, or Comp catalog grind that people have been told that they shouldn't set their lash at TDC. You have to check your cam in your engine to see what works, but for the most part that statement is Hogwash !!!!

JC565Ford wrote: ↑Wed May 03, 2023 8:46 pm

Bishop540 wrote: ↑Wed May 03, 2023 3:27 pm Please don't get F-Bird fired up This is an old thread created by me. I just updated it for future readers. The content will remain valid for ages. Lets not pollute it with extra arguments. It sucks when a newbie is trying to learn something but has to filter through all the cockfights to find the answers. Thanks!

The comment - "Hogwash" is worth repeating to the comment " Setting at TDC does not work" .... Hogwash.

That comment is pure crap for 95% of camshafts. The actual answer is " It depends"

It depends on the ramps of the cam and it's base circle. The more aggressive the ramps are, and it's base circle, the more accurate that statement May Be.

The cam I ran for 10 years, before replacing it in 2021 with a new grind from Comp, was a custom roller from Dan Crower. That cam was 281/285 @ .050 with .436" and .438" lobe and 1.8:1 rockers. To give you an idea as to how aggressive the lobes were, it was .201 and .205 @ .200" . I could set that cam at TDC or IC, EO and the numbers were just the same.

That cam was way more aggressive than your AVERAGE weekend warrior, or Comp catalog grind that people have been told that they shouldn't set their lash at TDC. You have to check your cam in your engine to see what works, but for the most part that statement is Hogwash !!!!

Giving @.050" , @.200" , lobe lift and rocker#'s to show your point on lash position setting is not telling the whole tale. You need to give a lot more lobe info to backup this theory. Tons of cams with a lot less than your example @.050" etc definitely do not set correctly at TDC.
The statement you made about being way more aggressive is the statement that sets your eg apart from your hogwash statement.

All this seems pointless if your not on a dyno to test what install position the engine actually wants, The opening and closing on a cam card are only in relation to where the cam company said to install the cam.
This would be like buying a distributor and the instructions tell you to install it at 38 degrees max advance... Does every engine run best at 38 degrees?

cjperformance wrote: ↑Thu May 04, 2023 5:41 am
Giving @.050" , @.200" , lobe lift and rocker#'s to show your point on lash position setting is not telling the whole tale. You need to give a lot more lobe info to backup this theory. Tons of cams with a lot less than your example @.050" etc definitely do not set correctly at TDC.
The statement you made about being way more aggressive is the statement that sets your eg apart from your hogwash statement.

As stated ... (or I'll make it more clear) It has to do with the size/diameter of the base circle the cam is ground on. It's a relationship thing between the base circle, duration and the ramps.

PS. And for my future reference ... Would those cams that TDC doesn't work well with, would they include Sm Blk and BBC's with flat tappet or roller cams in the 260 - 270* duration range at . 050 " ?

Comp Lobe 3192. Listed as 0.069" lifter raise @ 106 ICL 0.056" lifter raise @ 110 ICL

I don't use it but it should check or something is wrong.

Stan

_______I__N__T__A__K__E
Rocker_Arm_Ratio_=_1.500_________Valve_Lash_=_0.00000________Valve_Angle_=_23.0
Cam_____Valve__Crank____Time____Time_____Valve____Valve__Valve__Valve__Piston_Cylinder___User___________L/D
Lift____Lift___Angle____Port____Port___Velocity_Acceler__Lift___Lift___Travel___Volume_Supplied_Valve__Ratio
________________________Area____Area______FPS_____ation__Vert___Horiz_____________cc_____Air__Discharge
________________________cm^2__cm^2/cc_____________FPS^2__________________________________Flow_Coefficient
0.0515___.0772___-5.5___.0811___.0001__14.4369___2.2298_0.0711__.0302__0.0096____1.979___65.66__.9177__.0382
0.0546___.0819___-4.5___.0859___.0001__15.0041___2.2119_0.0754__.0320__0.0064____1.325___69.58__.9177__.0405
----- lifter raise ATDC 110 ICL
0.0578___.0866___-3.5___.0910___.0001__15.5510___2.1328_0.0798__.0339__0.0039_____.802___73.65__.9177__.0429
0.0611___.0916___-2.5___.0962___.0001__16.0768___2.0509_0.0843__.0358__0.0020_____.409___77.85__.9177__.0453
0.0645___.0967___-1.5___.1015___.0002__16.5817___1.9691_0.0890__.0378__0.0007_____.147___82.19__.9177__.0479
0.0680___.1019____-.5___.1070___.0002__17.0655___1.8868_0.0938__.0398__0.0001_____.016___86.58__.9169__.0505
----- lifter raise ATDC 106 ICL
0.0716___.1073_____.5___.1127___.0002__17.5285___1.8054_0.0988__.0419__0.0001_____.016___90.94__.9147__.0531
0.0752___.1129____1.5___.1185___.0002__17.9703___1.7233_0.1039__.0441__0.0007_____.147___95.42__.9128__.0559
0.0790___.1185____2.5___.1244___.0002__18.3912___1.6413_0.1091__.0463__0.0020_____.409__100.01__.9109__.0587

0.3778___.5668__103.5___.5950___.0009____.7481__-1.0029_0.5217__.2215__2.2277__458.749__408.38__.7779__.2806
0.3779___.5669__104.5___.5951___.0009____.4948___-.9877_0.5218__.2215__2.2533__464.009__408.46__.7779__.2807
0.3780___.5670__105.5___.5952___.0009____.2455___-.9723_0.5219__.2215__2.2786__469.217__408.50__.7778__.2807
---- ICL 106
0.3780___.5670__106.5___.5952___.0009____.0000___-.9575_0.5219__.2215__2.3036__474.373__408.50__.7778__.2807
0.3779___.5669__107.5___.5951___.0009___-.2455___-.9575_0.5218__.2215__2.3284__479.474__408.46__.7779__.2807
0.3778___.5668__108.5___.5950___.0009___-.4948___-.9723_0.5217__.2215__2.3529__484.520__408.38__.7779__.2806