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FlynLow
09-29-2006, 06:04 PM
About 3 yr.'s ago slapped on some Vortec's I got from Pace complete with the .550 lift upgrade. At the same time I sought Comp Cam's opinion on a valve train. They set me up with the XM 270 H with Lifters. Asked their advice on rockers and they suggested #1017 Roller's. Sounded good to me. Cam is a real Thumper. Now my dilemma. Toward the end of our last boating season I bought a 23 Turbo to see what rpm gains would be from my 25 Turbo. How about 5200 rpm with 3, 6'+, 220#+ dude's total onboard. This season I noticed I lost 600+ rpm and that was with only 2 dude's onboard. Turns out the rockers are non self aligning. Vortec's require self aligning. Before I start "Tearing Her Down", what do you think I should expect to find? Looking forward to your opinions.:)

Ted Guldemond
09-30-2006, 08:46 AM
Usually when vortecs have the spring pockets machined for extra lift and stem seals, they also swap the pressed in studs for threaded studs with guide plates. With the guide plates you can use standard rockers plus hardened push rods. If you running standard push rods without guide plates the rockers can pivot off the valvestem tip and damage the roller tipped end of the rocker trunion. This will also cause the push rod to rub against the cylinder head possibly wearing weakening and bending a pushrod. The fact that your engine is running with only a loss of power certainly sounds like nothing catastrophic has failed yet. How does the engine sound at low speed? Any clacking or tapping noises?

Ted Guldemond
09-30-2006, 08:51 AM
A gradual loss of power and rpm with the engine otherwise running smoothly makes me also wonder if your valve springs have weakened over time and high lift.

FlynLow
09-30-2006, 10:46 AM
Thanks for your reply Ted. Talked to Pace earlier yesterday and the Tech. said the same thing about weak springs. I just thought that since the .55 lift heads came with the 1.379 O.D. springs and the cam not being that radical the set up would work considering the springs for the 270 cam are1.25 O.D..You are also correct about the Hardened Push Rods and Guides. As far as knocking, the engine is quiet on the top and bottom ends. Now I'd like to get your opinion on the heads. Should I have the Bronze valve guides checked or can I assume that they are OK and just use air to change the springs without removing the heads? Thanks, Jim.

mrfixxall
09-30-2006, 11:12 AM
Are the pushrods scuffing the heads?is their metal in the oil? if so i would yank the engine and freshen her up.

FlynLow
09-30-2006, 11:25 AM
Haven't put a wrench to it yet. The oil has always been clean [Mobil 1]. Just trying to prepare for what I'm getting into. I hope pulling the covers and changing springs to be the extent. But, I want to try to do it right. So if I need to pull the heads I'll probably pull the motor and just check the whole friggin thing.

Ted Guldemond
09-30-2006, 11:58 AM
Swapping valve springs in the boat is a pain in the ---. I can't count how many times I've dropped keepers and other small parts in the bilge. I think it's almost easier to pull the heads off. If your valve guides aren't warn and your not consuming any oil or have oil soaked plugs, I would leave the guides alone. If your in need of a valve job the you might as well do the guides if the heads are already off. Just my thoughts.

FlynLow
09-30-2006, 08:09 PM
After further research, I will have to pull heads and have machine work done for the required Comp. #981 springs. It seems Vortec's appear to be budget friendly, but, with all the added expenses, including intake and covers plus machine work for modest cams, you can get AFR 180's or 195's. Simple math. Definitly would not recommend the Vortec's for more than stock replacements. Again Thanks for your help. Jim