Trying to put together a shopping list for a new engine...

Want to help?

This is "bang for the buck" engine, not an all-out racer. I've got goals I'd like to meet, but not at "any" cost.

I would be dropping it into my 68 Vert. Cruise RPM is about 1800 RPM with the TKO-600. I NEED it to lug along happily at that RPM, cause I do alot of highway cruising. Not interested in forced induction, EFI, or nitrous. I'm good with a clutch, so I'm not much concerned about torque, but would like it to redline around 7,000. That leaves me with a desired power band for the cam between about 2000 and 6500, right? I'd like around 10:1 or 11:1 compression, so it'll run happily on 94 octane.

According to DynoSIM 2001, I should hope for 700 hp...realistic?

I'm not too hip on the raised exhaust ports of most of the performance heads. I'm running sidepipes and that extra .6"-.7" is a lot...

What I already got, so far...
Gen IV Bowtie block, in crate
GM Forged 427 crank
Holley 850 DP
MSD Digital 6 Plus
MSD Pro-Billet dist.
Crane stainless roller rockers, 1.7 ratio


Need yet to select:
Heads (thinking GMPP 400's or 410's)
Cam/Lifters/pushrods
Oilpan & pump/pickup
Conn. rods (I've got a set of GM std. forged, but would consider upgrading)
Pistons
Gaskets
Flywheel...(I've got a L88 10.5" nodular and a 11" cast...which to use?)
Damper (again, I've got a GM damper already, but...)

Questions I've got so far...
For heads, is it best buy bare castings and separate springs, valves, etc. and have everything worked (3-angle, porting, etc.) or better to buy an assembled head and disassemble, do the cutting work, and reassemble (or just not bother with the metal work at all)? I've heard that valve seal is marginal with over-the-counter assembled heads...true?

Cam/lifters...variable duration lifters (Crane, Rhoades, etc)? Roller or flat tappet? Follow DynoSIM recommendations for lobe specs or let the cam grinder make the call?

Oilpan...for a cruiser/occasional auto-x'er, is it really worth it for a $$$ pan from Hamburgers or Milodon? Scrapers/windage trays worth it?

TCI Rattler or Fluidamper worth the extra $$$?

Thanks for helping me spend some money!

 

You are not going to make 700 hp at 6500 rpms without some serious compression, and other non street friendly parts. A 600 hp street 427 is a pretty stout motor. For the parameters you outlined here is what I would recommend.

Rpm Air-gap intake
Brodix Race-rites heads, a 400 cc head is WAyyyyyyyy too big. I did not know GM even made them in a non race head.
Cam: solid roller (or flat tappet) in the area of 245-250 at .050 on a 110, .650 lift
If you are going to run 94 octane I would run 11.5 to 1 compression.
Pro-systems or other 1000 cfm Annular discharge carb. Your 850 is fine also.

A lot of guys are having good luck with Eagle rods, good deal for the price. There are better, but for a sort stroke 7000 rpm motor the Eagles will be fine.

The Rattler is far better than the Fluidamper

 

The GMPP heads aren't nearly that big! The "400" is last three digits of the P/N.

Here's the write-up for the 410:
and for the 400/401:
Chevy High Performance says:

GM Performance Parts 401



This is the smallest rectangular-port GM Performance head, yet it flows extremely well for its size. Having a very similar port volume to the 990 head the 401 head flows dramatically better, especially at higher lifts. With the combination of great flow and being lightweight, this head would make a great mid-priced aluminum head for a hot street rat motor.

 

For stock exhaust port location on an aftermarket head really makes choices harder. I think the best performance is the Edelbrock Vic. Jr heads...i remember reading somewhere that they had the stock locations that weren't raised or anything so that you could sill use your Hooker sidepipes without modifying.
Other than that...why only go 427ci?? That may limit your streetablitly to achieve 700hp and cruise at 1800rpms.

 

I wouldn't settle for just 427 cubic inches. I would build it alot bigger. Cubic inches rule on the street and cost about the same to build.
If a 454 crank works in a 427 block the 4.25 stroker crank would also fit and you get 496 cubic inches and 600 plus horse is no problem with a mild 288 street roller cam a oval heads.
A 427 at close to 700 horse would not run happily along at 1800 rpm on the street.
Go with cubic inches.

 

572 is the way....

 

I'm not actually ~looking~ for 700 hp. That's just what DynoSIM said it would make... I just plugged in the flow numbers (from above) for the 401 heads, set the HP peak at 6500 rpm, set the induction flow for dual-plane with an 850 cfm carb and let the software determine optimal cam timing. I'd have to go home and dig through it to find the actual numbers, but it doesn't really matter at this point...

I don't have a specific HP goal. My only firm goal is a useable power band between 2000 and 6500...

I'm completely open to bumping up the bore, but I'm not sure I want to buy a new crank...

 

Why not a crank??? The cost of everything else is the same. A 496 is going to put alot more grunt then say your 435 once bored.
Even based on a mild 1 horse per cubic inches the 496 is ahead 60 horse and way more in torque.. Pistons, rods, cam all cost the same regardless of cubic inches. I would not even bother anymore with a 460.

When looking at flow charts flow in the .800 range is useless. In a street cam I wouldn't go with high lift. I would stick around .625 or so for long roller lifter life.
Also a rough idea of what a head can support in horsepower assuming no intake and flow readings are everything.

.254 x flow in cfm x 8 cyliners = horsepower.

A good intake and carb take away 15 or 20% of this so you are down right away.
Take the head from above at .600 lift. It's maximum horse it can support is .254 x 308 x 8 = 625

Take away 20 % for intake and we get .254 x 248 x8 = 503 realistically.
That is roughly what that head should support if everything else is working well.

 

Can't argue with that logic...but since you have the crank, look into the Comp Cams 288AR Roller that Norval mentioned...am running that now, and the power curve is amazing, I can lug it down to 1000 and stomp on it and it goes like a bat out of hell, in 5th...or something stouter, comp cams 308 roller....both are solid street rollers.

Regarding the crank...if you can swing it, pop in the 4.25 incher, you will have no problems reving to 6500 or even 7000 either the 288 or 308 cams.

Heads...sheeesh...there are so many choices...Brodix, GM, Edelbrock....blah...blah...blah....if you are not going to race, then look for smaller intake runners, stop light to stop light you will have tons of torque...

Pistons....anything in the forged 10-11 C.R. will be fine...I'm running 10.5 and 93 octane is just fine.

Carburation and intake....too many choices and I wouldn't know where to begin.

 

Mostly because I've already got a nice forged 427 crank. I could sell it to get a longer one, but I won't get out of it what it's worth...

 

That's true...you can buy a brand new crank, 3.76 stroke, forged for 100.00

 

The crank would make a fantastic difference. There is no comparison between a 427 and a 496 on the street. You are immediatley limiting yourself with 427.

 

What about running a 496 up to 7000 rpm? Piston velocity goes way up.... Would I have a hard time keeping the bottom end together?

 

Mine is still together......

 

I agree with the 496 idea. I thought you wanted the 427 for nostalgia reasons. About the heads, check the flow #'s on the Race Rites, better numbers in a smaller port, much better head.

 

Race Rites. Roger. Will Check.

So, what's the recipe for a 496 or 509? I kinda dig the idea of a 509, cause that was the last big engine my dad built (about '89)

 

Since you have a Bowtie block, you could do a 479" with the 3.76 stroke and a 4.500 bore. This would be a mega rpm screamer that would be happy at around 8000 rpm. It's a pretty common deal. There was a guy in the Pump Gas Drags a couple of years ago with a beautiful black C-2 with one. He runs mid 9's with his on pump gas (840hp@8100 rpm) and A/C..but it ain't no low $$ deal. But he does have a "blemished" stock GM 427 crank ($149) in it!

Or you could go out to a 4.600 bore and get 500". Still a screamer.

But I would go along with Norval's idea and get a crank. Eagles and SCAT's don't cost too much and are an easy way to at least 540" in your block. That's a proven combo that will rev and live well even with a 4.25 crank. Mine has been together for years now as well as several other buddies. The newest version makes 825HP on dyno and turns over 7000 rpm on 93 octane. The mildest version made 732HP and was a TQ monster.

If you go with stroker, you need longer rods...6.385's at least. They are common.

I'd look at other heads. The GM/Edelbrocks are OK, but the Brodix and AFR's are much better IMHO. The raised ex port isn't that big of a deal..there are Forum members here with the AFR .300 raised ports and no issues. I have the .600 raised Brodix and it seemed to actually help the fit of the Hooker 2-1/8" headers on mine. The Race Rite Bordix have the ports in stock location though.

Get a good oil pan. Get at least the GM LS-7 pan, it does well, but I can tell you the drag race Milodon I have now on mine does much better. Oil pressure stays much better than other pans I've tried. But the LS-7 will do good too for less extreme applications.

The whole cam and head choice comes from what cubes you decide. There are lots of combos here to help pick from.....

But I can tell you a solid flat tappet or roller is better than a hyd anything.

Narrow down the choices some and we'll ehlp all we can!

Jim

 

ARRRGGH, how could I miss the Bowtie block ?? make it a 540-555.

 

Cubes Scat make a very reasonably priced rod/crank set, I belive its their 9000 series, plenty strong and cheap.

Check out www.cncmotorsports.com, you'll be surprised at how reasonable a lot of this stuff is nowadays. Most of the new "cast" Scat parts are stronger than the old GM steel cranks. Good luck

 

Well, I checked out the Race Rites. Those are a winning deal! Thanks for the tip, John!

I also dig the idea of the 540. Let's go with that. I might even have a forged 4.25 crank laying around...I'll have to check.