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Parts choice

June 18 2017 at 5:09 AM

Ross  (Login Bad427stang)
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Response to Ross

Arnie, the first thing I would recommend is driving the machine work based on a parts choice, not the other way around.

An uncut FE block has a deck height on 10.170 and is likely not squared to the mains, so quench and compression can differ from cyl to cyl. I would recommend cutting the block, you get a fresh sealing surface on both sides of the gasket and you tell them you want it squared to the mains. Most any shop does that nowadays. The question is, to what deck height?

You can almost be certain that it will like a .010 (10.160) cut to square things up on an old seasoned block, and depending if it was cut before, you may have to go with an even lower deck. Regardless, the nice thing is, if it's 10.170 and you want to go 10.160, but the machine shop says it's already cut, you can use the thicker and cheaper Felpro blue gasket and get your .010 back.

So, lets assume a 10.160 deck with a Felpro 1020 head gasket. About .040 of head gasket, and you'd want the piston to be in the hole .010 or so (at most) to get a decent quench to help against detonation. Not all pistons are the same, in fact they are all over the place from company and even within a company. For a budget build that can boogie now and then, the L2291F30 is a good piston. It's reliable, but not light and doesn't have a modern ring pack, but won't let you down for the level of power you need.

The L2291F30 (.030 over) at a 10.160 would put you at .044 quench and 10.0-10.2 compression depending on where you ended up with the heads using a 1020 gasket. If you had to cut the block to 10.150 because it was cut already and needed a fresh cut or was very crooked, you'd run an 8554 Felpro blue gasket and end up the same, (actually just slightly lower and a quech about .003-.004 more), but the pistons would be slightly above deck, not an issue

Now, if you want to spend a little more money, I'd talk to Brent Lykins about some Racetechs, there are off the shelf and custom options, but, your money gets you a better set of rings (more power and easier break in), potentially the exact pin height you need, so you cut the block to exactly where you want you don't have to be concerned with head gasket choices as much, and a lighter piston with more valve relief room. I don't think your description drives that, but it would make a very nice build if this is a car worth the extra money.

I have done a few of the L2291 combos, that combo at 10.2:1 compression with the L2291s or a custom set of pistons, and a cam with a .006 duration of 276 or bigger on a common 106 ICL (both are likely what you have with 230 @ .050) will run well on pump gas. That engine will run great with a set of headers and a good intake. However, keep in mind, a thicker head gasket will not make it run better on pump gas beyond about .060 in quench (head gasket + deck clearance) after that, you lose the benefit of everything churning around in side from the tight clearances.

I hope I didn't confuse things, but when you choose a piston, you need to look at pin height, also called compression height and know your deck clearance. Lots of us can help, but if it fits your budget, and if my numbers match where you end up, that L2291 can be a good match for a durable budget build



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- 70 Fastback Mustang, 489 cid FE, Victor, SEFI, TKO-600 5 speed, 4.11 9 inch.
- 71 F100 shortbed 4x4, 445 cid FE, headers, RPM intake, 1000 HP series Holley, 4 speed

 
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