Trevor.  You’re right about the timing chain.  Any serious thoughts about raising the camshaft in the Y forces the chain issue to be considered before all else.  Other than this, raising the camshaft in the block sounds relatively simple but ultimately ends up creating some issues in regards to the lifter angles if these are not compensated for.  Simply raising the camshaft and not relocating the lifter bores increases the lobe centerline for a given camshaft.

 

On the Y, there is only 0.080” to 0.130” of lifter clearance to install the camshaft with the lifters placed at the top of their bores.  Core shift during casting typically has each bank of lifters sitting with different clearances to the camshaft so this has to also be taken into account.  Machining the bottom of the lifter bores so the lifter can be raised only compounds the problem in that the lifter bore itself now becomes even shorter.  Relocating the lifter bores so that the camshafts intended lobe centerline angle remains the same when raising the camshaft gives a net gain of zero.  With the stock camshaft journal sizes, the camshaft base circle still ends up being the limiting factor in getting more cam lobe lift while using the stock lifters.  Going to a non mushroom lifter design gets around most of this.

Lorena, Texas (South of Waco)

Ted,

A possible solution to the basecircle/lifter issue could be to overbore the camshaft tunnel and fit offset sleeves or bushes to raise the camshaft higher in the block, closer to the lifters. Not an easy fix, but it works in other engines when done. Inherent problem is the timing chain.

Cheers

Trevor

By definition, the Y-Block utilizes a mushroom lifter.  A mushroom lifter is simply defined as a flat tappet lifter in which the wear face or lifter pad is a different diameter than the lifter body itself.  In the performance world, mushroom lifters are synonymous with being able to run more aggressive camshaft profiles and hence the belief that a mushroom lifter is a performance lifter by design.  Many diesel engines still utilize mushroom tappets but for no particular performance advantage.

 

The wear pad on the Y-Block lifter is is actually larger than most of the other lifters out there in that it measures out at 1.00” so there could potentially be a performance advantage if the camshaft lobes were ground to take particular advantage of this.  But after having a healthy discussion with the EMC representative on the phone, be assured that the Y was not disallowed because of any perceived performance advantage.  The Y-Block engine itself was not disallowed, just the mushroom tappet lifters and this was made clear from the beginning in the rules.

Lorena, Texas (South of Waco)

Trevor.  Thanks for the contact info on Joe Panek.  I had a very good conversation with him and although He’s never made a cam blank specifically for the Y, He’s confident that it shouldn’t pose any more of a problem than the other engines for which he builds them for.  There are some nuances with his billet blanks in regards to journal sizes but I don’t see that being a show stopper.  The billet blanks can possibly alleviate some of the maximum lift at valve issues when using the mushroom lifters if journal sizes are increased but with stock journal sizes, the base circle is still an issue with the maximum lift that’s available without having stock lifter breakage issues.  But knowing that the blanks are potentially available opens up all sorts of possibilities ranging from using a military block with the larger lifter bores in tandem with readily available roller lifters or using stock blocks with specially made composite or ceramic lifters.

Lorena, Texas (South of Waco)

Ted,

Joe Panek from A & B Fords Roto-Faze Ignitions on (310) 325 8844 makes billet cam blanks with the circle the same diameter as the journals.

Hope this helps,

Cheers

Trevor 

John,  You're absolutely right about the large lifter bore blocks.  That would have been an easy out around the mushroom lifter rule.  Unfortunately, those particular blocks are as tough as hens teeth to find today.  I've got feelers out in those wrecking yards that specialize in military hardware but unfortunately, I'm a little late as it would appear that most of those blocks went to the salvage yards back in the eighties or thereabouts and have long since been remelted into something else.

Having some of those blocks available would open up the possibilities for the roller camshaft scenario as readily available roller lifters could likely be used with little modification.  Or even higher lift solid lifter cams could be used with a larger bore lifter as the lift at this point is limited by fact that the current lifter design drops too far down when reducing the cams base circle to increase the lobe lift.

Lorena, Texas (South of Waco)

Ted:

Too bad there aren't more of those blocks around that had enough meat cast in around the lifters to supposedly tolerate hydraulic lifters.  Straight solid lifters could probably be used in one of those to bypass the mushroom lifter rule.  It would still be interesting to see how the engine would stack up against the winner of their series.  Wouldn't it be neat if you could send them a dyno sheet that showed it could run with the rest of them?

John

John - "The Hoosier Hurricane"

Mushroom tappets are being used as a retrofit on the GM and Mopar engines to allow for a increased pad area on the bottom of the lifter which in turn permits for a more aggressive camshaft profile.  It’s a performance advantage for those engines that came equipped with a smaller diameter lifter and a correspondingly smaller pad diameter.  This is seen frequently where the rules require a flat tappet camshaft and roller camshafts are not allowed.

Lorena, Texas (South of Waco)

Ted:  Interesting, the Ford Y-Block has "mushroom lifters" from the factory. So, what is so special about mushroom lifters that E.M.C. bans them? 

Paul

Bummer Ted, I hope that you will dino this engine when you complete it and we can still see how it stacks up with the official crop of EMC engines. An article in YBM on the build would be nice if you have time. Thanks for your hard work.

Glen Henderson



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Letohatchee, AL