Also posted in C3 General section:

OK, I've got the block (.060), steel crank, and rods. Pistons are next and I'm shopping and learning about Big Blocks (too cool!!!!).

I need advice on 427 engine combos for the street. I am particularly interested in piston/head/camshaft combos because I want to make sure my compression ratio and camshaft work well together. I'll be using aluminum heads, headers (etc etc the good stuff!). Car has 3.36 rear gears and a 4-speed. NOT a daily driver, so slightly more radical is OK!!! So, could you please share your combo with me?? Piston part numbers and head part numbers are of particular interest!!! THanks!

Thanks to bernie morris for the offer of pistons, but It looks like they will be too high of a compression ratio for my setup. (12.5 to 1!!!) Thanks Bernie!

 

I've had very good luck with Dart and Brodix heads. www.dartheads.com

When you go to their site it gives the use for each cc head. You might get the 310 cc, but call them and ask if they have a 2.30 intake valve option.

with aluminum heads you want to end uo with just under 11:1 compression. right around 10.7

What kind of a cam do you plan on using?

 

I had a 396 .060, full roller valvetrain Comp Cams Xtreme Energy Hyd roller cam #XR288HR with comp cams lifters (very $$$) Air Gap RPM Intake, Holley 750 Mech Sec DP maxed out. I had open chamber heads with 2.20IN/188EX titanium valves since I wasnt as worried about the top end . . . wanted more neck snapping shear low end power. I kept my compression down around 9-9.5 for pump gas use. This was in a 69 Chevelle with a 3500 stall converter, 3.73 gears and a TH400. For a street car it was insanity!! This was nuts but man what a blast! I sure do miss the power!

 

The biggest problem with building 427's are the lack of off the shelf pistons. JE has a lot of nice forged pistons for a 454/502 but not much for the 427, one page at most and the compression ratios are in the 13's. It looks like you have already bought rods or they were the orginals. What I did was pick a 454 piston (same bore diameters) and then deteremined the rod length I needed. Add up half the stroke, the rod length (center to center), and the compression height of the piston you choose. It should equal 9.8" for a standard deck block, or close to it at least, by close I'm talking +/-.010. You may want to have the block decked first then measure the true deck height of your block before making the final selections. I ended up running a "454" je piston with a rod length of 6.535 (+.4" longer than stock bbc rod lengths).

On a side note, my combo works out to 11.5:1 with factory cast iron 114cc open chamber oval port heads. I did have to custom grind the chambers to clear the domes on teh pistons. I'm running 93 octane with 13deg initial and 32 total advance with minor detonation when bogged down in overdrive. I also have a pretty big overlap cam which reduces the dynamic compression a good deal to allow this combo to work. I also have my quench height set at .039".

Dart heads are nice, I've been looking at thier oval port cast iron heads for sometime but the larger chambers will reduce my compression and I'm not really sure I want to do that. The new Trick Flow (aluminum) oval ports look nice too.

If you need help with the piston calculations or have any other questions feel free to email me at egrelle@et-motorsports.cc

 

Your piston choices will depend on whether you choose open or closed chamber heads. Then you can start getting info on how much valve clearance you'll have, which will in turn send you in the right direction for how much cam will work w/ your compression ratio and the valve clearance you have. There are alot more head choices if you go w/ open chambers and they are supposed to breathe better.

 

I lean towards oval port rather then square port. Build the engine where it will be used and force it into the high end.
The alternative is square ports and force it in the low-mid range.
The cam to follow this reasoning.

If moneys in the budget forget the intake and get FI. this also allows you to cheat on compression a bit.

I dropped compression by stoning the lathed grooves off the top of the piston, way back when about the only pistons available were 11.25 and higher. This and a measured reduction in the dome dropped compression to 9.25, thats written down but I for some reason remember 9.5. The pistons were polished. I forgot how much was taken off the dome but it wasn't much. Just the removal of the ridges dropped it some.
I CCed the top of the piston so knew what was happening.

 

My cam will depend on my piston/head combo. I would really like to come in around 10 to 1 on my compression ratio. Since it will be a weekend warrior type car, I'm not opposed to running a solid lifter cam. It will get about 1500-2000k miles a year.

I saw an article in "Corvette Fever" yesterday where they built a 427, using iron heads, TRW pistons, and a solid cam. They also used the original intake manifold and exhaust manifolds. They were very happy with the 455 hp they got, like it was "amazing"! I want more than that! Though I think the intake and exhaust were probably restricting the potential a little. I think around 500 hp at the crank would be perfect, with a nice choppy idle for the drive in appeal. That'll do.

Question: Which is the "better" setup?

SpeedPro pistions, 16.8cc dome = 10.1 to 1 with 100 cc Oval port heads

OR
SpeedPro pistions, 34.2cc dome = 10.0 to 1 with 118 cc Rect. port heads

 

Rectangular heads, I like them, they breathe better, though the new style oval port heads are nothing to sneeze at.

 

I ran the same 427 for over 20 years in various cars with just about every concievable combination of heads, compression, cam and intakes at one time or another.

I'm not able to type it all right now.....but unless you plan on screaming it to 7000-7500 rpm regularly, stick with ovals. You can use aftermarket or GM. The rectangulars ran about the same at the track, but I had to shift at 7500 instead of 6500 to get same results. At under 5000 rpm roll-on tromps..it was weak with rect. heads. I've run a gazzilion flat tappets (all solids) through it (it's still in my garage) so I have an idea of what does what.

The last version used 11.1 closed chamber pistons and angle milled/ported Merlin iron heads. Honest 11.2 compression, but it worked fine on 93 octane. It last had a Comp 288 street roller in it and ran 11.20's@123 mph capped up with 2.5" exhaust using 3.36 gears and a Doug nash 5 speed. Probably had a 10.99 in it...just never got that far. It made 423 RWHP in pure street trim at 5850 rpm and still was making 417 rwhp at 7000 rpm. Absolutley beautiful TQ curve..never cared where you shifted.

It also ran mid-high 11's with flat tappet cams and GM oval ports in a 3600+ lb Camaro. Ran mid 10's in Denver Altitude with a little N20. Probably a high 9 at sea level.

I can help you with cams/heads and intake choices as you get deeper into it. The Edelbrock Air Gap would most likely do very well as a dual plane..better than single planes on a motor this small, but I used to run only single planes on it in the past.

JIM

 

OK: Here's the plan:

KB Pistons 25.5cc (4.310 bore)
110 cc oval port aluminum heads
.039 Head gasket - for aluminum heads (4.370 bore)
3.76" stroke steel crank

I used an online compression ratio calculator, and It results in 10.18 to 1 with this setup. Too cool!!!!

I'm now looking at the CompCam CCA-11-318-4. This has 236 intake/exhaust duration, .556" lift, and 110 lobe sep. angle. With a set of roller rockers of course. RPM Air Gap and a 750 CFM Speed Demon, mech. secondaries.

Sound like a winner?

 

Because of my piston .020 down in the block I use a .021 thick head gasket. You want to end up with @ .040 head to piston.

I have 427 ci and a SR cam. But I was out on the Crane Cam shaft site and they give some discriptions about their cams and anything in the 236 class and being a h-flat cam is a radical.

 

Well......

I'm not a hypereutectic piston fan at all for anything you might lean on some. Spend the $$ to get some forged pistons. You'll be happier.


Which heads are you looking at? The Brodix Race rites or Dart ovals would work well. Not too wild about the Edelbrock/GM's either if you're going to spend that much money.

Pay attention to what GKull said....you want to juggle head gaskets and deck height to get .035-.040 max quench distance.

With aluminum heads you can sneak up closer to 10.7-11.0 easily on 93 octane.

I think you can use more cam too. That one is too small to me. You can easily handle .600-.630 lift with no wear issues with a flat tappet cam. With good heads you want all you can get.

The 750 Double Pumper and Air Gap will work fine.

Look for 1-3/4" t0 1-7/8" headers.

427's like to rev...you need to put a cam in there that will like to also. You can easily do that with a streetable solid flat tappet.

JIM

 

When I did my 396 I was pretty limited to pistons, had to go with a .060 over JE I think?? There was no .040 for anyone. With my combination shown above it was WAY more than enough power . . I never used all of it and unless your going racing I highly doubt you will too . . . mine came in at 490 HP with desktop dyno. Stick with open chamber heads and a dual plane intake, for the street you'll be much happier. At 6500 the moter was still pulling like a B***H!

Seriously consider one of Comp Cams Hyd Rollers! they arent cheap but if your spending the cash do it right the first time! The specs dont seem that radical BUT when you consider the lobe shape and how fast a hyd roller opens and closed valves and how long they stay open, it will make a cam with relatively mild looking specs act like a .600 lift cam . . . trust me on this!

But if you do this add an extra 300$ for the comp cams roller lifters too! I never regretted spending the extra cash, the car was extremely fast . . . way more speed than I needed!

 

[QUOTE=427Hotrod]Well......

I'm not a hypereutectic piston fan at all for anything you might lean on some. Spend the $$ to get some forged pistons. You'll be happier.[QUOTE]



[QUOTE=427Hotrod]With aluminum heads you can sneak up closer to 10.7-11.0 easily on 93 octane..[QUOTE]

427 Hotrod knows his stuff...