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Old 03-06-2013, 05:45 PM
BogiesAnnex1 BogiesAnnex1 is offline
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Originally Posted by Hogg View Post
I get asked this question a lot and there are a lot of ways to answer it.

Can a 400 SBC be installed in place of a Vortec 350 L31, using the Vortec heads, roller cam, the plastic front timing cover(that holds the crank position sensor) with the stock 4x reluctor underneath.
L31 reluctor wheel

Vortec timing cover left/older timing cover right

A Vortec block, notice where the bolt on camshaft retainer goes, this will be absent from a stock 400 SBC

So how do I retain the ROLLER cam in my Vortec headed 400SBC?
What compression would flattop pistons give with the 64cc Vortec chambers roughly, assuming conventional 400sbc gasket comnpressed thicknesses?

Also, the Vortec 350 uses a damper than is thinner than conventional dampers in oder to allow for the thickness of the reluctor wheel under the front timing cover. IIRC the Vortec 350 is a GEEN 1-E engine that uses a neutral damper with a counterweighted flexplate as its a 1 piece RMS engine. What would I need to use for a flexplate and damper as the 400 is a GEN 1 externally balanced engine with a 2 piece RMS.? If a weighted damper is needed I would have to run it in the lathe and trim down slightly. How would I get this attached to my 4l60e trans? Starter?

Thanks in advance guys, your answers will be helping many people beyond myself.

Hog, I've read this over a few times over the past couple days, finding it pretty interesting. I have not built a Gen I with a roller cam to use the plastic timing cover to get the reluctor sensor to run the L31 engine management system. As in the old Laugh In days, "Veeery Interesting"!

I found myself thinking along the lines of Cobalt as to putting a thin sheet steel reinforcement on the cover with some sort of a mechanical fastener that can be sealed up so it doesn't leak oil. I suppose a nut and bolt arraingement or rivets. I think actually a sandwhich of steel with a fairly thin piece on the inside just for the cam button to wear agianst which perhaps a thicker piece on the exterior to provide stiffness. Then I support that with an aftermarket water pump that has the threaded boss on the bottom that is used for a bolt that contacts the cover to actually react the thrust load into a the engine's structure. The real amount of thrust load can vary quite a bit from very little to actually quite a bit this depending on how well aligned the machining of the crankshaft and cam mains are in relation to each other as well as the thrust surfaces of the block and timing gears and the gears themselves in relation to their alignment with each other. The worst case is a load large enough to squeeze the plastic cover out from between the steel sandwich. But in most cases this tends to be a lot less than that.

Of course the next is the old problem of mounting the spider but the included Youtube video is pretty good, I even see some of my own poorly written work comes back to haunt me. What I've done is to drill through the oil galley top into the oil passages that feed 2, 3,and 4 cam and main bearings tapping the upper casting and about 1/2 inch into the oil feed then making a 5/16th bolt for the application that has a reduced diameter where it passes inside the galley passage which extends into that portion that feeds into the upper oil passage. The intent is to provide a two point thread contact to keep the bolt from working on the threads in the upper portion of the main oil passage casting. I've also been mulling drilling and tapping the boss between the lifter bores to install a stud that would pass through a drilled hole made into the dog bone and allowing it to rock on an inverted castlated nut or short length of spring retained by a lock nut. Haven't done this but it sits on my mind for some future test engine project.

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