[Z Code 400]

When I built my .060" over 400, I squared the block (.015" removed) and brought the L2262F pistons to .005" out of the hole @ TDC. I cut a very, very minor chamfer on the upper edge of the bore to minimize volume above the top ring.

The 6X-4 heads, uncut when I received them, measured a whopping 98cc's!!! I milled them .015" to get them true and then re-checked the volumes. I measured 95cc's exactly.

Right now I have a total of .030" removed from both the block/heads combined.

By my calculations, this would yield approximately 8.66:1 and I was shooting for 8.85:1, intentionally keeping static compression ratio under 9.00:1 because of varying fuel quality and the fact I will continue to drive this car daily.

If I mill another .015" from these heads (.030" total) I would end up with a 92cc chamber and about 8.88:1 static compression. Adding this .030" from the heads to the .015" milled from the block, which equates to a total of .045" total material removed.

A 90cc chamber would be required for 9.00:1 and that would mean a total of .045" milled from the heads, in addition to the .015" removed from the block, which equals .060" total removed between block and heads. This is certainly do-able, but is it really that much of an improvement (for all the trouble/expense) for 1/4 point in static compression ratio???

With 222°/230° @ .050" on a 111.5° LSA, I am of the opinion the 413 (.060 oversize 400) would probably perform equally well at 8.66:1 as it would at 9.00:1. However, I wanted to pose this question to some of our more experienced engine builders.

Keep in mind, this is an engine that will need to run on 87 octane fuel in a second generation F body with an M-20 4-Speed and 3.23:1 axle. The more I think about it, the more I think KRE's are way more head than this motor really needs and in fact, I think they would actually hurt my low end, when compared to an iron head.

I have had a number of people insist that you can run 10.00:1 compression with iron heads on pump gas, only to read a post by them weeks later trying to eliminate ping on a 10.00:1 compression engine!!! I firmly believe that my decision to use a lower static compression ratio on this engine is the correct course of action. If you refer to the GM power parts catalog, you will find a 8.50:1 compression 454 with 210° of intake duration @ .050" that makes 425 horsepower. Granted it is more of a challenge to make HP with less CID and moderate compression ratios, but I believe this is the correct approach, especially considering the varying quality of fuels I encounter on a daily basis and our +100° summer temperatures.

Your input would be appreciated...Robert

[mchell]

I wouldn't bother...........VERY little, if any difference going from 8.6 to 9.0...............

IF the engine is properly prepared and tuned you can run 10 to 1 with iron heads............I think the big factor in being able to do this is deck height and cam selection......... a motor with a piston that is .020 or more in the hole, with a weeny cam is gonna probably ping on 90 octane fuel........Poor quench and high pressures = ping................I run a zero decked, iron headed 455 at 10 to 1 on 92 pump gas with ZERO ping..............it can be done....

[Z Code 400]

Mchell,

I would be afraid to experiment with this engine (up around 10.00:1) and end up having a pinging problem. I don't have as much experience with Pontiacs (compared to Ford and MoPar) so I am approaching this subject with caution.

My Pontiac 350 is getting ready to be treated to early heads (9.25:1 with stock pistons .020" in-the-hole @ TDC) and my custom .467"/.467" - 220°/226° - 111.5° LSA Hydraulic Flat Tappet Camshaft.

I plan on using the 350 as a sort of 'test bed' to see how the Pontiac responds to changes in compression and camshaft timing.

I think 9.00:1 SCR would be the upper limit for a street driven 413 that is expected to digest 87 octane.

Your 455 is interesting...what camshaft timing are you using with that 10.00:1 motor???

Thanks for your input...Robert

[mchell]

Ultradyne Hydraulic Flat Tappet, 239/244, .507/.530 lift on a 110 lobe, installed at 106ICL.........with 1.6 roller rockers....Comp pro magnum lifters....

[jsd]

Ok, question..

How is a 0.060 over 413ci? By my calculations it comes in at just under 412ci..

4.18 bore
3.75 stroke
2.09 * 2.09 * 3.1415926535 * 3.75 * 8 = ~411.6837ci

The difference in power from compression would be almost nil, though going fmor 8.66:1 to 9.0:1 WOULD probably give you a slightly better idle to the point where you could notice it from back to back A-B tests.

However, 222/230 isn't exactly a great deal of duration, and you should have plenty of idle vacuum anyway. I wouldn't bother.

[amcmike]

You should also experiment with colder plugs. Be sure to have your cruise circuit on your carb properly tuned first.

[Z Code 400]

Thanks guys...I guess its not knowing how some engines react to certain conditions that bothers me.

Permit me to make a point:

See, on a 440 MoPar with 9.50:1 and 220°/220° @ .050" on a 106.5° LSA you can run 20° initial advance and 36 total on 87 octane without pinging. I know this because I built this engine in 1987 for my 1969 Charger. 6 months ago, I built its identical twin (from the 1987 assembly notes) for a customer and it runs on todays crappy AM/PM 87 octane without pinging or retuning.

I cannot say the same for a Pontiac 400, but I do know, from a 455 I recently built for a neighbor, a zero-deck .030" oversize 455 with stock 6X-4 heads (about 9.45:1) and a .500"/.500" - 230°/230° @ .050" - 113.5° LSA hydraulic flat tappet will run 18° BTDC @ idle and 34° total on 87 octane without pinging.

Most people I know race their cars or drive them only on special occasions. I drive my 1975 Formula 108 miles a day round trip to work and I buy fuel at a vareity of different stations. I want to be quite sure the 413 (411.9) will digest the worst possible fuel I can find without retuning.

During a recent chat with Jim Butler, he told me sub-9.00:1 SCR's were a wise choice on an engine that is expected to digest low octane fuel. Jim Hand's publication mirrors this approach and Dude's 8.50:1 compression 455 is an prime example, although a bigger engine in terms of CID.

In my case, I want to be sure the SCR and duration @ .050" are compatible. I am mentally comparing my experience with other engines (i.e. Ford & MoPar) and trying to plot out a good combination.

My custom designed hydraulic roller of .547"/.547" - 222°/230° @ .050" on a 111.5° LSA (with 1.52:1 rockers) is a very close match to a commercially available Crane Hydraulic Roller, except I have always used and prefer symetrical lift figures and I avoid high ratio rocker arms as a matter of personal preference.

Judging how people report that camshaft's idle is in a 400 (it is 222°/230° @ .050" on a 112° LSA) and that the Crower 221°229° @ .050" 112° LSA flat tappet seems to be about the biggest camshaft that has yielded good performance in a sub-9.00:1 SCR 400 engine, I felt my HR was a very good match, especially in terms of net lift and port flow figures. I would assume the camshaft to have a slight lope at idel with vacuum in the 12 in/Hg to 15 in/Hg range.

I actually considered KRE's but I have invested so much time (160+ hours) in the 6X-4's that I really want to try them out. I guess my point is, I know I could make more HP and TQ with 10.00:1 SCR and a RAIV, but I am shooting for a more balanced performer, with good street manners, relatively high vacuum and the ability to burn kerosene without retarding the timing.

A Nice lope at idle would be a welcome fringe benefit...:-)

That's where the solicitation of experience from senior forum members (who are building 400's) would be most helpful and appreciated.

Thanks again to all of you...Robert

[Z Code 400]

Originally Posted by jsd

Ok, question..
How is a 0.060 over 413ci? By my calculations it comes in at just under 412ci...4.18 bore
3.75 stroke
2.09 * 2.09 * 3.1415926535 * 3.75 * 8 = ~411.6837ci

JSD,

You are indeed correct. Dyno 2000 shows the formula as 411.9 and I just thought 413 sounded better. Kinda like my uncle's vintage Honda 350 4 cylinder motorcycle. If you look at the emissions tag, it says 350cc's of displacement, But, if you look at the base of the cylinder barrels, it is embossed '348cc'.

I am really shooting for something different on this Formula. A friend of mine does graphic design work. I was telling him about the engine and he suggested we make a 3-D decal (identical to the wavy checkered flag '421' emblems) that read '412' and he is working on a '412 RAM AIR' decal for the hood, based on photos of the '429 RAM AIR' decals found in old photos of my 1972 Ford Torino 63R.

I am also contemplating adding a replica 3-D full-color decal of the 'Hurst Equipped' "H" emblem (on the RH side of the trunk spoiler) similar to the ones found on some Oldsmobiles.

My son suggested adding a single, tiny 'GM' badge (ala 2007 vehicles) on the trailing edge of the RH fender, similar to how MoPar placed their famous pentastar there.

The Formula concept, at least in my mind, with a fully-functional ram air hood, T/A spoilers, 4 wheel disc brakes, M-20 4 Speed, 412 CID Powerplant & Plain Jane Painted Rallye Wheels, was/is to create a car that would appear (to the untrained eye) to be reminiscant of an early Can-Am or Trans Am car; all business, with a definite attitude, yet nimble, with good handling and braking characteristics.

Thanks are due to my graphic design buddy for my new (retro) Avatar!!! I have re-kindled the old Robert Herndon Racing Engines logo (RHRE) that once adorned every engine we produced in the family shop. It originally read Robert Herndon Race Cars (RHRC) from my Dad's Torrance, California business in the 1950's and 1960s'. At that time, it read 'Flathead Ford/Ardun Specialists' above the race car. It was changed to its present format in the 1980's.

My son wants me to revive the old 3" x 3" RHRE white vinyl full-color window decals and the 3" x 3" silver foil and black RHRE engine decals we used to send out on everything that left the shop.

Actaully, my son wants me to start porting heads and building engines full time and let him take over the business as CEO!!! Can you believe it??? When I was 20, all I could think about was race cars and hamburgers...:-O

Times sure do change...Robert

P.S. I would welcome any and all input on my Formula concept car...

[Z Code 400]

Here is a photo I dug up of the T/A spoilers with a Formula Hood....Robert

[Robert Williams]

Originally Posted by Z Code 400

When I built my .060" over 400, I squared the block (.015" removed) and brought the L2262F pistons to .005" out of the hole @ TDC. I cut a very, very minor chamfer on the upper edge of the bore to minimize volume above the top ring.

The 6X-4 heads, uncut when I received them, measured a whopping 98cc's!!! I milled them .015" to get them true and then re-checked the volumes. I measured 95cc's exactly.

Right now I have a total of .030" removed from both the block/heads combined.

By my calculations, this would yield approximately 8.66:1 and I was shooting for 8.85:1, intentionally keeping static compression ratio under 9.00:1 because of varying fuel quality and the fact I will continue to drive this car daily.

If I mill another .015" from these heads (.030" total) I would end up with a 92cc chamber and about 8.88:1 static compression. Adding this .030" from the heads to the .015" milled from the block, which equates to a total of .045" total material removed.

A 90cc chamber would be required for 9.00:1 and that would mean a total of .045" milled from the heads, in addition to the .015" removed from the block, which equals .060" total removed between block and heads. This is certainly do-able, but is it really that much of an improvement (for all the trouble/expense) for 1/4 point in static compression ratio???

With 222°/230° @ .050" on a 111.5° LSA, I am of the opinion the 413 (.060 oversize 400) would probably perform equally well at 8.66:1 as it would at 9.00:1. However, I wanted to pose this question to some of our more experienced engine builders.

Keep in mind, this is an engine that will need to run on 87 octane fuel in a second generation F body with an M-20 4-Speed and 3.23:1 axle. The more I think about it, the more I think KRE's are way more head than this motor really needs and in fact, I think they would actually hurt my low end, when compared to an iron head.

I have had a number of people insist that you can run 10.00:1 compression with iron heads on pump gas, only to read a post by them weeks later trying to eliminate ping on a 10.00:1 compression engine!!! I firmly believe that my decision to use a lower static compression ratio on this engine is the correct course of action. If you refer to the GM power parts catalog, you will find a 8.50:1 compression 454 with 210° of intake duration @ .050" that makes 425 horsepower. Granted it is more of a challenge to make HP with less CID and moderate compression ratios, but I believe this is the correct approach, especially considering the varying quality of fuels I encounter on a daily basis and our +100° summer temperatures.

Your input would be appreciated...Robert

The 6X-4 head is approx 93 cc's, the 6X-8 is approx 101 cc's uncut, i think you have 6X-8 heads, not 6X-4's.

http://www.wallaceracing.com/headsearch.htm

[lust4speed]

More power to these people that can run high compression and not ping. Me, well I've never been that lucky. I've had true 9.25:1 455's give me trouble with pre-ignition with 91 octane on really hot SoCal summer days while pulling the grade back up to home, but that's real life. I now stay at or a little below 9:1 for 91 octane and the sweetest engine I'm currently running is a true 8:1 400 that loves 87 octane on any summer day. It also runs mid 13's on regular which is faster than most street goats around here running premium fuel. Also, we pulled our 2+2 421 engine down that was 8.6:1 and running on regular and there were some signs of detonation showing up on the bearings. I remember one tankful of Arco that my son purchased and we ended up draining out the remaining fuel after he complained to me of the pinging - I believe that was when the damage was done. Had the engnine been a little lower compression it would probably have taken the bad gas in stride.

[Z Code 400]

Originally Posted by Robert Williams

The 6X-4 head is approx 93 cc's, the 6X-8 is approx 101 cc's uncut, i think you have 6X-8 heads, not 6X-4's.

http://www.wallaceracing.com/headsearch.htm

6X-4...checked it numerous times. Cliff told me he has seen 6X-4's run from a low of 89cc to a high of 100cc.

There is no exact science to Pontiac combustion Chamber Size...Robert

[Z Code 400]

I just double-checked my static compression ratio on the 412 using the compression calculator on the classicalpontiac.com website.

Of course, I cannot input a positive deck clearance on that calculator, so figuring a true zero-deck @ .060" oversize (my L2262F's are actually .005" out of the hole @ TDC) my 95cc combustion chambers and a .040" head gasket, I come up with 8.62:1 static compression ratio...Robert

[JACK_BURTON55]

Originally Posted by Z Code 400

Here is a photo I dug up of the T/A spoilers with a Formula Hood....Robert

Dominant, dont forget when you build you engine and get your car painted to take a lot of pictures!! that would be SICK!

[BruceWilkie]

My wifes 406 combo is 9.4 static compression(measured) it is NOT zero decked (the pistons are .020+ below I dont have the exact # handy) we run a Crower 60916 cam (221/229@.050 112 LC installed at 108 IC). Ignition timing is 14 initial 35 total all in at 2500. We drive this car anywhere and typically buy 93 octane(most stations here and where we used to live carry 93). However we have run into situations where all we could get was 89 and we topped off with it, we experienced no pinging but suspect there was enough 93 still in the tank to make a difference. We have run consecutive tanks of 91 octane with no consequence. We havent tried 87 at all, but suspect we could get by temporarily if we drove carefully(knowing it would likely ping under stress). Street/highway manners are excellent. 15 inches idle vacuum, (slight lope when first fired then smooths out once warmed up, my wife thinks it sounds too stock) 15-16 mpg highway mileage. Intake is a P65 dual quad with 2 750 edelbrocks on 1 inch 4 hole spacers, currently running in tandem.(city mpg is better if setup progressive) Hooker 1.75 super comps, 2.5" Flowmaster exhaust,T400 w/2200 stall convertor and 2.56 gears. We can drive this car anywhere and drove it from NY to here when we moved to TN without issue. Recent trip to KY to Somerset Cruise then scenic route home through the Appalacians(sp?) on way home over 700 miles total for the weekend including cruising the strip in Somerset(worse than rush hour traffic in nashville). IMO the Crower 60916 cam is the perfect all around cam for a true street driven(with enough for the track too) modest compression 400 based Pontiac.

[GOAT490]

Originally Posted by Z Code 400

Of course, I cannot input a positive deck clearance on that calculator,

Put a - in front of the # and I believe it will calculate it as out of the hole.
PHILLYGOAT

[GOAT490]

Stock Bore 4.120
Over Bore 0.060
Stock Stroke 3.75
Stroke Change 0.000
Chamber 95
Piston Dish 6.7
Deck Height -.005
Gasket Thickness 0.040
Cylinders 8
Inches ccs
Total Bore 4.18
Total Stroke 3.75
Cylinder Displacement 51.48 843.63
Engine Displacement 411.85 6749
Total Volume 102.92 109.57

Compression 8.7:1

[Z Code 400]

Thanks Goat490!!!

That would seem to be consistent with most of the calculators I have used. My proposed Hydraulic Roller Camshaft, .547"/.547" - 222°/230° @ .050" on a 111.5° LSA, should produce good performance. It has more duration @ .200" lift than most other lobe profiles I have studied.

One issue I have is idle quality. I have one fellow with a 221°/229° @ .050" - 112° LSA Hydraulic Flat Tappet describe the idle in a 406 as smooth & stock, and another with a 224°/230° @ .050" - 112° Hydraulic Roller describe his idle in a 406 as wild & lumpy. That's quite a contrast on two very similar engines.

Now I am not quite sure what to expect from this 412.

I initally considered a 224°/230° @ .050 HR but after analyzing the Intake lobe's duration @ .200" lift (143°) I found the original 222° intake lobe profile had 146° @ .200" valve lift. The exhaust profile features 153° @ .200" valve lift. I consider both figures to be generous for a mild Hydraulic Roller.

The ported/polished 6X-4 heads flowed very well (IMHO) with 240 cfm intake @ .550" lift and 210 cfm exhaust @ .550" lift respectively. The addition of the '421 style cooling port' between the center cylinders will afford additional coolant circulation into this critical area. This is an important feature in vehicle's expected to operate in our extreme (104° today) climate.

The induction will consist of a Edelbrock Performer with both an 800 cfm Q-jet and a 650 cfm Holley Vacuum Secondary. The engine will be dyno'd with both carbs and then subjected to track testing. Althoug many favor 800 cfm on a street engine, the fact is, a 412 operating at 80% Ve only needs 575 cfm to turn 6000 rpm and even when estimating the Ve @ a generous 90%, only 644 cfm are required.

I know I will be flamed for many of my opinions, but the actual dyno and track testing we have conducted revealed our cars were quickest and produced the most torque (not to mention feel) with smaller cfm carburetors. My partner's 427 Chevrolet ran its quickest 60' time ever with a 600 double pumper. I plan on testing both carburetors back-to-back before making a final decision.

The rest of the drivetrain consists of the M-20 4-Speed with a 2.52:1 first gear and a 3.23:1 rear axle.

Hopefully, all the hard work will soon pay off...Robert

[GOAT490]

"One issue I have is idle quality. I have one fellow with a 221°/229° @ .050" - 112° LSA Hydraulic Flat Tappet describe the idle in a 406 as smooth & stock, and another with a 224°/230° @ .050" - 112° Hydraulic Roller describe his idle in a 406 as wild & lumpy. That's quite a contrast on two very similar engines."


What were the advertised specs and what ICL were they installed at?

PHILLYGOAT

[Z Code 400]

Goat490,

Both were installed at 4.0° advanced I would assume, although an exact specification is not available to me. I install everything at 2.0° advance as a matter of course for eventual timing chain stretch/wear.

I prefer to run a properly sized camshaft as close to 0° index (or stright-up) as possible...Robert