73C34me

What is the thoughts & experience? I have a good block that i would start slowly building up. Can go 4.040" bore. Is it worth the extra stroke? I don't have a 400 block but thought the 395" would be best use of my 350 block, & get the most cubic inches.

gkull

Definitely, I have a 3.875 project of my own. With a 4.030 bore it's nearly a 396 ci. The cost is same and on the track they are good for a .200 sec in the 1/4 from what I've seen on simularly built cars with a 383 VS 396.

I get my rotating kits from www.flatlanderracing.com

The compression with flat tops and 64 cc heads is to high so look at bigger cc heads or 10-15 cc dished pistons.

Even with big 6 inch H beam rods the pan rail grinding isn't all that much.

gkull

This is the only kit that Flat lander lists.

Crank: 350 Main, 3.875" Stroke, 6.000" Rod Length
Rod: 6.000" 4340 Forged I-Beam Rod w/ARP 7/16" Cap Screw Bolts
Rings: 1/16 x 1/16 x 3/16
Crank # Rod # Piston #
(Type) Bore Size Comp. Ratio Kit # Price
58cc 64cc 70cc
4-350-3875-6000 2-ICR6000-7/16 144995
(srp FLAT) 0.30 12.2 11.4 10.6 1-40900-1 $1380

73C34me

Is there water flowing near the pan rail grinding? Also, .2 tenths in the 1/4 seems like a significant gain, all things being equal. I have a good 4 bolt block un-cut block & have played with the numbers. I was thinking that with 9.025" deck height I could use my current pistons, with .020" machined off the tops (flattop forged j.e.) If i recall, this would place the pistons .012" out of the cylinder for a positive deck displacement. A .050" head gasket would allow for a .038" quench distance. I also wondered if my 3.750" stroke 4340 crank could be welded & offset ground for the additional throw. This way i would not have to purchase new rotating assy parts. Whatz the thoughts on this?

73C34me

Forgotto mention. I think 396 sounds way cool. I would love to run 396 badges on my car. Esp. if it is a small block!!

gkull

I'm not a machinist. You don't hear about pistons above the deck very often. I preferr strong parts. So the idea of machining .020 off the top of piston?????????????

The whole idea of welded cranks, underground, offset ground. If your building a truck motor.... fine. When you get into labor costs VS new correct parts. I buy new parts.

I'm sure that you can find some machinist who could do it all. maybe even a custom ground stroke with 5.85 H beam rods and no piston machining.

I had a 391 ci years ago. It was sold by a less then reputable company. Externally balanced 3.825 stroke 5.600 rods. Cheap everything.

73C34me

I agree with your thoughts on new parts. I can justify a new crank. As far as pistons above the deck it is not too common. I am no expert here sooo, I believe the L/88 pistons were above the deck from g.m. Author David Vizard has published research on a 383 sbc with the pistons .010" above deck. His findings suggest that this helps in the combustion process by reducing the "dirty" amount of undesirable area between the deck & head gasket with its larger diameter area. Or, something to that effect. My rotating assy has less than 1500 miles, hence the desire to reuse. I did check with ross j.e. piston manufactures & they stated for non blower/ heavy nitros apps. that maching upto .020" was o.k. from their experience. Talking to my machinest today. may move forward after my cage is installed. jim

No Go

I assembled a 381 SCAT forged LT4 engine (4.20 bore-more overbores left!).

I think a 395 would be better obviously due to the greater displacement, but only if you can find folks able to do the correct grinding (or yourself).

Knowing my shop had not built an LT1/4 engine, I was not prepared to take any extra risk so the 3.75 stroke was selected-a common build.

Remember I was in Nebraska at the time so...

I am extremely happy with the 381 though. No oil burning whatsoever after 15,000 miles of not so easy use (7000 rpm limiter).

Corvette Kid

Why not compromise, for lack of a better word? A 3.8 crank w/ pistons for a 3.75 stroke. Instant zero deck w/o any machining or milled, one-off heads and intake. With a .030" overbore, you've got a 388. With my 56cc heads, it required -16cc pistons to maintain a realistic CR for everyday street use. SRP inverted domes to the rescue. They are still flat in the quench area. Depending on final measurements and gasket selection, I'm shooting for a quench area of .035"~.

gkull

Instead of machining the pistons .020 why not offset grind the crank to what ever custom length you need.

73C34me

good point on custom offset grind. i would like to run 396 call outs on my l-88 hood. so emotions were driving the build

wesmigletz

I've began assemblig the pieces to put an offset ground 3.875" crank in the 62's SJ 327 block. I was going to build built a 383 using a speed-o-motive SJ stroker kit, but I got a good deal on a used Callies crank. So, I couldn't see giving up the 12-13 cubic inches from the larger stroke. I'd like to get some high 12 sec 1/4 miles through the factory block, heads, intake, and manifolds.

I'll be installing the 377 I built from my 59's 283 (4.00" by 3.75" stroke, with a 6.00" rod) over the next couple of weekends. It will be going in the wife's 62. We (she) decided to tone down the cam, and ended up going with a small base circle Comp 262XS ground on a 112*. We'll also be running pocket ported 1970 186 heads instead of the 59's heads. For now, it will be topped with a #461 intake and an 1850 600 CFM Holley with a milled choke and a secondary jet plate. The exhaust will be 1 5/8" X 3" headers, and a 2 1/2" mandrel-bent exhaust that is currently on the car. It should be a decent driver. If we get done in time, we'll be driving it from L.A. to Bowling Green for CF CI.