Hey all, I have a 401 I’m doing up for my 32 Tudor and I need somevalve train help and insight. To start I’m running an early isky RR3 roller cam and matching solid roller lifters. I came across a set of Tommy telescos roller tip rockers for a good deal and picked them up. Long story short I mocked up one cylinder with a pushrod length checker and it damn near looks like the pushrod is going to jump out of the cup in the rocker just rolling it over by hand. And it almost feels like I’m getting coil bind a little before I reach max lift, but there’s plenty of space between the coils of the spring. Only does it with the roller rockers. Does anyone have any firsthand experience running these? Is there anything in specific I should be looking for or inspecting? I also notice a 5/16” tip pushrod seems to fit much better than the 3/8” tip rod he says it needed. Im just curious why a 3/8” is necessary especially since it looks like it’s going to jump out of the cup when it’s at full lift. Thanks in advance for the help.
A couple of things to check- 1.6" installed spring height, and at least 0.090" valve clearance @ 10 degrees BTDC and ATDC. From the pic of the cup, a 3/8" ball looks large.
I agree a 3/8 ball looks big but I heard a 5/16 will block off the oil p***age ♂️. What exactly do you mean .090” valve clearance 10* BTDC and ATDC. Not valve lash right? Are you talking about valve to piston clearance?
Yes, valve to piston clearance. Another thing to verify is the pushrod clearance in the head hole with 3/8" pushrods. they may be dragging at full valve opening. I ***ume a minimum of .0025" valve stem to guide clearance on the intakes and .0035" on the exhaust.
when adjusting the pushrods on a nailhead, they are to have a preload of 030 thou. how much preload when the lifters are in the engine full of oil. Is it less than .030 thou. and seemed to have become a bit loose.
I know the lash. .030 hot from isky. I just feel like these rockers have bad geometry and I need some re***urance on running them haha.
Find a radius gauge and check the sockets of the rocker arms. If they are 3/8, use the appropriate pushrod. I had a Harley once that ate pushrods, turns out the PO had installed pushrods with tips that didn’t match the rockers. Also, as mentioned, check for interference with the pushrods in the heads and possibly coil bind on the inner springs. That’s cool stuff you’ve got, I hope you can get it all to work well together.
^^^^ If the pushrod is seating in the rocker cup fully, you should be good. IIRC, the ratio on those rockers is 1.7 to 1. Earlier engines with steel rockers had 1.5 to 1 and later when they went to aluminum it was 1.6 to 1. I would ***emble it all and roll it over by hand roughing in the lash and checking for any drag as you described. I ***ume you degreed the cam (I found mine to be off and had to retard the cam 4 degrees) and verified the valve to piston clearance. Unless you decked the block, using composite head gaskets should give you plenty clearance. OEM Buick pistons had a little higher compression height than aftermarket ones, so it lowers the CR some. Going to the composite head gasket vs. the original stamped steel lowers it more.
The heads are cut .040 and the pistons are in the hole some but I haven’t put an indicator on them to se how far in. Using factory Buick steel shim head gaskets on this one. I’m trying to get the compression up on it.
^^^^ If the block has not been decked, the stock Buick pistons will be in the hole about .045" to .050". IIRC, the Buick pistons have a compression height of 1.925". A set of Ross pistons can be made to that height, but they are pricey. I found a set of earlier generation Silv-O-Lite cast pistons in .030 over for my 401. That piston has a CH of 1.912" IIRC. I decked my block .025, a skim on the heads, and with a steel gasket the CR measured 9.95 to 1. Unless you are going to run custom headers, the exhaust manifolds to look for are 1960-61 LaSabre 364 single exhaust ones. That is what the late Hamtown Al had in his 32. They dump just behind the motor mount on either side. Attached pic of what they look like
Hey, Boden; Nice setup. Have you checked the pushrod CL angle to the rocker-cup CL angle, & compared it to factory-stock? If it is too far away from the orig design, it'll need to be changed so it's closer, resulting in less problems. Those Isky lifters are rather tall(really cool, but tall) compared to the stock hyd lifters, the head-cut vs stock, head gasket thickness vs stock(steel shim vs composite), & the design(placement) of the pr cup on the rocker arm; all the tolerances combine to(can) give a different angle at the rocker-cup/pushrod-end. Since you (fortunately)have a removable-pedestal mounted shaft, you can change the height of the shaft(either by adding shims under the pedestals, or milling them to lower them. This's a std check on Stude v8's, that doesn't get done/checked often enough), thereby changing the pr/rockerarm angle relationship. All part of the "fun" building a non-stock mill... ! If this doesn't make quite enough sense, I can find one of the excellent write-ups on the Samba(acvw, & a technique that always needed to be checked, due to the design-variables of that engine, but applicable to others), & drop the link, regarding the requirement of these relationships - How & Why. HTH. FWIW. Btw, Stude v8's will fall into this category too. . Marcus...
I understand what you are saying completely. Great info, thank you very much. The angle is a little alarming but I don’t see any binding between the pushrod and the cup or pushrod and head, or for that matter pushrod to anything. It all looks clear and free of contact. I guess it’s just a little weird looking. But not much about nailhead valve train geometry looks normal Haha.
What I was referring to, specifically, *was* the angle at the pr/ra. It won't always bind or run interference w/something. It's something that most don't think about. ??? Long(er) life of valvetrain, & more hp/torque results from things being in the middle-range, instead of on the outer Limits. Like the Movies??? . Glad you're aware of it... Marcus...
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