7.550 PR length?
 

Is there anyway that could be right? My calculations say it is right. LS7 lifters, YT non-adj. shimmed up .095" to get good wipe pattern, .040" head gasket (wasn't compressed but we are talking a few thousandths there.... head bolts were snugged), .024" mill on heads . Checker showed between 7.450-7.500

7.450 had a touch of tick. 7.500 was too tight. Add .050-.080" for preload and I'm around 7.550" LSL lobes maybe on a smaller base circle?

It doesn't sound right but the .095 shim on the YTs may be wildcard here. So the pushrod length checker is reading 7.450? (13 turns).

It all depends on the cams base circle, but that seems pretty extreme. I put in the 7.50's that came with my TFS heads and they were so long that the motor couldn't even build compression. I sounded like i was turning it over with no spark plugs

Well I guess it was 13 turns. I was just adding .050" per turn. I ended up with .650" worth of spinning it out to get the light tick. So 13 X .050" is .650" yes. And 6.800 + .650 = 7.450 before preload.

Also the lifters were only in the trays about 1/8" at best when on the base circle of the cam which didn't make me very comfortable.

Sounds correct. 0.095" shims results in the need for 0.151" longer pushrod. If you assume 7.400 as a starting point, that puts you right at 7.550".

That is a fairly long pushrod, I would strongly suggest you see if an 11/32" diameter pushrod will fit and then contact Terry Manton as he has these and will make to the length you need. Other option is if the heads are on yet, open the pushrod holes slightly for 3/8" pushrods. Pushrod flex is a major issue with these motors that most ignore or are unaware of.

I have the AFR's and found that a 0.125" shim is required. Do you have a photo of the wipe pattern? Mine was close at 0.095 but the 0.125" made it perfect. Difference for me is that the Morel lifters are taller and require less preload so my pushrod should come in at around 7.500".

No my dumbass didn't take a picture. I have been taking pictures of all the critical steps and forgot to take a picture of that and the heads are already back off now. :bang: I was pretty happy with .095" I just took a pair of shims off one of the other rocker pedestals and liked it. And if I go more shims, I will add more length to the PR..... and more weight to the valvetrain assembly :barf:


Should I go re-assemble again, vette, and recheck with more shims? I want to get the right pushrods the first time. And would you be comfortable with less than 1/8" of the lifter being in the tray while being on the base circle? I know that it is only keeping the lifter from spinning, but that's not much hanging on there! I know, I know... the morels but just more money :bang:

I just measured my PR holes in the heads and am getting a consistent .480" Would that not clear 3/8 (.375) pushrods?

Neither the rockers or the pushrods will affect the lifter engagement with the tray, so no worries there. What you are really doing is moving the rocker higher relative to the head. The problem you are going to have is the baffles in the valve covers, you are going to need to remove them and grind the inside flush or go aftermarket with valve covers that will clear.

You want to use a single shim, not stacked. Use the shims you have (or even different thickness washers) to figure out exactly what you need for thickness and then buy a single shim (McMaster-Carr has something that will work).

The problem is the angle that the pushrod goes through as it opens and closes the valves, the larger pushrods will contact. Don't worry about added weight on the pushrod side of the rocker.

You can get shims for the valve covers so you don't have to replace them.

JEG's has them.

I had to use 1/2" ones to get enough clearance for my rockers even after I ground out every boss and baffle.

If the heads are off, you can set the wipe pattern up on the workbench if you have check springs.

Oh I knew that :bang: And yes, I'm using the checker springs

I called Terry Manton's shop. Quite the place... they will make any length pushrod, any diameter, any grade you want. However, they were going to be hard pressed to get them to me in time for next weekend. I'm kind of on a time line to get this thing done. So I called Comp Cams and they had a 5/16" 7.550" .105" wall hardened pushrod on their shelf. I told the tech I had LSL lobes and he didn't seem to think I'd have a problem so I ordered them.

Oh, on the lifter tray deal, I wasn't trying to relate it to the PR issue. Just that they weren't in the trays very far at all when on the base circle.

I will play with the wipe pattern again and see what I come up with. I'll probably keep it right around .100" range beings I ordered the length already. I will have a little play cause I am a touch on the long side with the PR. We have a very nice machine shop at work and I'm on nights the next two weeks. I'll see if we can't make some shims the correct thickness so I can avoid stacking washers :D

Thanks for your great help!

That length is not out of the realm of what I've seen needed with shimmed YT rockers and small base circle cams.

Wipe pattern with .095" shim. The line is a little wide as I was checking P/V clearance at the same time so I was using up a lot of stroke on the valves........ or simulating float :D

http://img.photobucket.com/albums/v6...5/IMG_1832.jpg


Exhaust valve didn't leave quite the impression, but it still looks centered to me

http://img.photobucket.com/albums/v6...5/IMG_1833.jpg

Looks good to me.