Stock Eliminator secrets?

[Jeff Lee]

Tenxal....couple of questions....

1 - why the plastic spacer under the cap screw/bolts in the water pump/front cover photograph a page or two back?

2 - What's the trick to getting a rotating assembly/short block to spin at 8lbs?

In addition to Tenxal’s answer, the rings are back-cut so they are not as deep into the piston. This reduces the axial tension against the bore. Plus the rings are typically much thinner; legally I might ad, through the use of ring spacers.
Regarding ring tension, I would rather give up some great-to-brag-about rotational numbers and not run such an aggressively low-tension oil ring package. My theory is oil is a poor combustion-able once in the chamber; it also reduces octane. Plus loose rings make for a messy underside of the car!

[Jeff Lee]

This reduces the RADIAL tension against the bore.

[jed]

Which rings are back?? The top compression ring and the second ring and how much are they back cut??

[Jeff Lee]

Typically top and second rings are back-cut. The reduction is based on the ring and bore. The amount is the judgement of an experienced race engine builder and / or the ring manufacturer maybe helpful.

[canuc]

I'm I right to guess that stock E can run header crankcase vacs , what about a pump ? Pretty cool to see what performance can be achieved with constant development and I'm sure lots of patience testing .

[tenxal]

I'm I right to guess that stock E can run header crankcase vacs, what about a pump ? Pretty cool to see what performance can be achieved with constant development and I'm sure lots of patience testing.

Per NHRA rules, no header evac. systems or vacuum pump allowed in Stock.

[jed]

I just want to thank you Stock and Super Stock racers for sharing your hard learned engine assembly information and car
preparation. Jeff I hope your car performs well and is competive.
I am assuming that NHRA Super Stock can run a vacuum pump but limit the amount of vacuum.
And Just to confirm LSP mentioned that Super Stocks can run belt drives instead of the conventional timming gear and chain.
When back cutting ring are the Pistons ordered with less ring grove depth or is the space filled with some kind of spacer.
Also is the top ring a moly faced, ductile iron with a coating or some other coated metal.

[canuc]

I'm I right to guess that stock E can run header crankcase vacs, what about a pump ? Pretty cool to see what performance can be achieved with constant development and I'm sure lots of patience testing.

Per NHRA rules, no header evac. systems or vacuum pump allowed in Stock.

Really that makes the performance from your 275/327 even more impressive ! Cam must be a very special piece , is it a f/t or roller ?
Thanks

[tenxal]

Really that makes the performance from your 275/327 even more impressive ! Cam must be a very special piece , is it a f/t or roller ? Thanks

In Stock, you must run the same style lifter as was O.E. in the engine...no roller lifters if originally a flat tappet. The 327-275's were hydraulic flat tappets. You can replace a hydraulic lifter with a solid lifter, if you choose to. Cam must be O.E. for lift but can have any profile. Any valve spring can be used but it must be the same O.D. as the original, which is 1.250 in my case. Retainers can be any material except titanium, unless originally equipped with titanium retainers.

Thank you for the nice comments. I'm fortunate to have a lot of good people involved.

[1972ho]

Both the cams are the same lift and duration one is a stocker and the other isn’t.

[Jeff Lee]

I just want to thank you Stock and Super Stock racers for sharing your hard learned engine assembly information and car
preparation. Jeff I hope your car performs well and is competive.
I am assuming that NHRA Super Stock can run a vacuum pump but limit the amount of vacuum.
And Just to confirm LSP mentioned that Super Stocks can run belt drives instead of the conventional timming gear and chain.
When back cutting ring are the Pistons ordered with less ring grove depth or is the space filled with some kind of spacer.
Also is the top ring a moly faced, ductile iron with a coating or some other coated metal.

Not even in SS can you run a vacuum pump! But you can run a pan-e-vac.
Yes, you can run a timing belt. However, oil pump must be driven same as factory.
Yes, pistons grooves are not as deep to accommodate the back-cut rings. If not, you use shim stock to “fill the void”. Shim stock is usually .015” thick and you can wrap the stock several times if needed.
Rings come in all kind of flavors. I have a good working relationship with Kieth Jones at Total Seal. I would highly suggest you do the same or find somebody that really knows their stuff regarding rings, pistons, and honing. Because it all boils down to these three things in a short block:
Ring seal
Ring seal
Ring seal

[MELWAY]

Tenxal....couple of questions....

1 - why the plastic spacer under the cap screw/bolts in the water pump/front cover photograph a page or two back?

2 - What's the trick to getting a rotating assembly/short block to spin at 8lbs?

In addition to Tenxal’s answer, the rings are back-cut so they are not as deep into the piston. This reduces the axial tension against the bore. Plus the rings are typically much thinner; legally I might ad, through the use of ring spacers.
Regarding ring tension, I would rather give up some great-to-brag-about rotational numbers and not run such an aggressively low-tension oil ring package. My theory is oil is a poor combustion-able once in the chamber; it also reduces octane. Plus loose rings make for a messy underside of the car!

Just wondering if there is and negative disadvantages when running a heavily back cut top ring in a deeper groove with no gas porting?? Is the an issue with response time to build pressure behind ring for good seal ?

[KnightEngines]

James - the spacer to run a narrow ring in the stock width groove has lateral gas ports, taking up the back space with shim stock reduces the response time significantly.
Methinks the top ring in a stocker is damn near as effective as a .031" vertical gas ported SS ring.

[tenxal]

When we order pistons for the back-cut 5/64" rings, we specify the groove depth.

When using the spacer/ring combo, Total Seal advises that they furnish the dimensions to the piston mfg. for the correct fit. We've seen several cases of bad dynamic ring seal caused by poor fitting spacers/rings in standard grooves. Fit incorrectly, the spacers can significantly damage the grooves. Looking at spacers has revealed significant 'stick-spin' issues in several cases.

In one case of a very good 396-375 Stocker engine, it was down 18-20 h.p. after a freshen-up (at another facility) with a spacer/ring combo (pistons originally done for back-cut 5/64" rings). We got involved and inspection revealed the early signs of 'stick-spin' with the spacers. Substituted a good barrel faced, back cut moly 5/64" top ring and went back to the dyno. Power was back up 20 and life was good.

[maxracesoftware]

When we order pistons for the back-cut 5/64" rings, we specify the groove depth.

When using the spacer/ring combo, Total Seal advises that they furnish the dimensions to the piston mfg. for the correct fit. We've seen several cases of bad dynamic ring seal caused by poor fitting spacers/rings in standard grooves. Fit incorrectly, the spacers can significantly damage the grooves. Looking at spacers has revealed significant 'stick-spin' issues in several cases.

In one case of a very good 396-375 Stocker engine, it was down 18-20 h.p. after a freshen-up (at another facility) with a spacer/ring combo (pistons originally done for back-cut 5/64" rings). We got involved and inspection revealed the early signs of 'stick-spin' with the spacers. Substituted a good barrel faced, back cut moly 5/64" top ring and went back to the dyno. Power was back up 20 and life was good.

In one case of a very good 396-375 Stocker engine

what BBC Blocks are Legal for Stocker Classes like A/SA ??
i have a Chevy OEM 4-bolt main 396/375HP bare block STD bore .... need to get rid of a bunch of stuff in my Shop

also , we use to hold the NHRA A/SA record many years ago ( 1969 Camaro )