[Ragtop Man]

Zero decking isn't strictly about the volume, it is about forcing the mixture into an area where it will swirl, tumble and burn more completely. So, even if the static compression was the same between and engine that was zero decked, and one that wasn't, the zero decked engine will have lower EGTs, tolerate slightly less octane, and make more power all other things equal.

Changing out the rings and pistons to get a newer, lighter combo is definitely a good move, and before I put knocking rods back in I would check them verrrrry carefully for twist bending or fatigue. New ring combos are especially good, and give you what is basically free horsepower by keeping more bang inside the cylinder.

[lust4speed]

Here's some discussion matter:

Let me start off by saying my drag car engine is zero decked because I'm looking for anything that will give me the last ounce of performance. If it might help, and I know it can't hurt anything, I'll try it. I keep hearing the joys of zero decking for all applications, but I haven't seen any real test results backing up the assumption that it makes that much difference on a stock or mind performance build. Don't get me wrong, it looks really good on paper, I just don't think there has been a real world back-to-back test to observe the actual difference.

So you zero deck an engine, you still have the width of the gasket, and let's say that it is .039" thick. Let's also say the piston is sitting down in the hole .012" with new pistons. That is a total of .051" of piston to head clearance. Whether an engine can "see" any performance difference between .039" and .051" quench area is the big question. The mixture in that area is going to be pushed out of that area at a terribly fast speed stirring things up really well regardless. Pontiac didn't worry about zero decking their production blocks, and I'm not really that sure that we should. Also, once an engine is zero decked for a particular set of pistons, you then have to watch the rod height on the next rebuild. If you zero decked to a little shorter set of pistons, you will be custom ordering the next set, or possibly milling a few thousandths of the new piston tops. Now let's look at an aluminum rod engine that requires a minimum of .060" clearance, or .009" more than your mild build before you zero deck the block. There's no doubt that the race engine will still be capable of producing a homogeneous mixture, and blow a mild engine build in the weeds.

Last time I checked, no one could even back up the test results published by Singh for his head grooving process - aka "Singh Grooves" -- but his idea also sounds really great on paper.

[69Farburd]

Lust, where can I find the 24cc dished pistons? The most dished I coud find on line were 17cc.

My last rebuild was 15 years ago and cost $1200. I have convinced my wife that everything costs at least twice as much now. So if I can get a rebuild for $2,400 to $3.000, I think I could get away with it .

[69Farburd]

What years do I need to look for to find the 6x-4 heads with screwed in studs?

[b-man]

1976 & 1977 350 engines used the 6X-4 heads, along with the '77 200 HP T/A 400 and the '78 220 HP W-72 T/A 400 engines. The 350 engines with 6X-4 heads will be much easier to find.

The 1975 5C-4 350 heads are equivalent to the 6X-4 heads.

All Pontiac heads from 1974 on will have screw-in rocker studs.

[Ragtop Man]

Right on.

Only thing I've seen on the board are a few instances of engines running the piston farther down the hole and having lots of issues with detonation. Would love to see one of those in-chamber cameras watching what happens when the spark goes off.

Saw one video on you tube of the actual combustion process, the amazing thing was the amount of puddled fuel dripping off the intake valve, no wonder they are going to DI

[lust4speed]

Originally Posted by 69Farburd

Lust, where can I find the 24cc dished pistons? The most dished I coud find on line were 17cc...

Some of the more recent offerings in cheaper pistons seem to be limited to 15-17cc's. So three avenues:

1. Purchase TRW forged pistons and have a 24cc circular dish cut in them and use with new rods. This should be your cheapest rebuild option.

2. Possibility that custom 24cc pistons with a D-shaped dish would be available from our vendors this is a better performance upgrade.

3. Just about all of our favorite vendors on PY carry several different varieties of 30cc pistons. The problem is the larger 30cc pistons drops the compression down to 8.8:1 (figuring 72cc heads, .039" gasket, and pistons .012" in the hole) on a 4" stroke. The 30's work good on a 455 or larger, but would hurt performance on a 428. Since you need Pistons, Rods, and will have to have the crank turned down (or replaced if it is really chewed up), maybe purchase a 4.25" stroker kit that comes with all new parts and you would end up with a 461ci - the 30cc pistons would then be perfect on this combo giving 9.3:1 compression. Looks like this basic stroker kit is $1,400 - $1,600 with pistons, rods, crank, rings, and bearings.

Any of the above will work good with a larger cam should you decide to up the power output. Final size of the cam depends on the final size of the engine.

[screamingchief]

Now were gonna talk him into a stroker crank here,,,just to get a set of "off the shelf" 30cc dished stroker pistons to work with his current #16 heads???

Why not make it a forged crank then,,,I mean WTH it's not like it's our money being spent here...



Custom dished pistons will be like $650.00 + a set typicaly.

The KB/Icon "off the shelf" forged stuff is typically like $400.00 to $450.00 a set.

And he does'nt need $350.00+ rods here either,Ace's "budget" 5140's I beams will do the job just fine @ $240.00 a set.

I agree the HR cam was a luxury item,said so earlier.

Said there were plenty of flat tappet cams that would get the job done too.

Ones that are much better than that Erson cam he has now.

The 6X cross-over thing is NBD,and one does'nt have to fill the exhaust cross-over completely either,one just needs to fill the small area that's directly above the cross-over (and only on the passenger's side) so the intake gasket can seal completely,and that can easily be done with any of a number of various materials.

And yes,even zero decking is optional when it comes right down to brass tacks.

Just means it would be wise to mill the heads just a little more than one would if they did'nt zero deck the short block,to get to the target CR one is after.

It should'nt cost anymore to mill the heads to 85cc's vs 90cc's.

So right there a fella can save the cost to zero deck.

And when keeping the CR fairly conservative,there should be no major worries from not doing that zero decking either.

Now that we know the budget is pretty tight here,and there are outside pressures to be considered (wife),I'm even more certain the best course of action is the -4 "smog" heads.

Should be less budget "bloat" that way.

Sound judgement dictates that he's gonna hafta go thru his #16 heads anyways on this,so ask me going thru a set of the -4 smog heads should'nt cost him anymore than that would cost,so IMO the head cost situation is pretty much a wash no matter what here,as any money that's spent obtaining the set of the smog castings,is easily recouped by selling the #16 castings.

And getting the current crank turned & prepped should'nt cost as much as a new stroker crank either,so going the stroker route is'nt exactly "budget conscious" here either.

Also,the money saved from not being forced to mix in the race gas should keep the Mrs. happy as well.

JMO/FWIW

Bret P.

[chiphead]

I like the idea of using the 6X-4s and a 10 or so CC dish. He can run pump gas now with the 6X. With the smaller dish can step it up later with a simple head swap (72CC aluminum) to bump his compression & power way up without having to go into the bottom end again. Best of both worlds kinda deal.

6x-4@ 85CC with 12CC dish 9.36 compression

Aluminum @ 72CC with 12CC dish 10.53 compression

That's the hot swap right there. Perfect compression on pump gas with Iron OR Aluminum.

[lust4speed]

Originally Posted by screamingchief

...JMO/FWIW
Bret P.

Bret, I did throw out three possible options. Here's the thing, his current problem is a spun rod bearing. I would like to see him build a bullet proof bottom end for his 428 so the problem doesn't repeat itself.

THE HEADS: It doesn't sound like his current heads are causing any problems. Buying another set of low compression heads is probably going to require a complete rebuild of the 4X or 6X heads he finds. He will be out the cost of another set of heads, and at least the cost of a valve job, but possibly new valves, guides, and seats. Springs will probably have to be changed anyway for the new cam, so that would be a push with the heads.

The CRANK: The old crank might not be salvageable and will need replacement. Last crank I had ground and polished ran $160, but maybe it's cheaper in other areas. So you are talking $160 vs. $250 for a new cast crank in any stroke. If the crank has to be replaced, then there will be no additional cost difference between 4" and 4.25" stroke.

THE RODS: Brewer has some really cool replacement rods. I was down to his shop last Thursday with a club member that bought a new crank. While the least expensive rods are nicely done and come with ARP bolts, Ken does classify them as stock replacement rods. I'd say they are excellent for "stock" engines, but don't know their limitations and they would make me a little nervous. A much better choice would be his H beam rods. I can't think of a better place to spend additional money than on rods in a Pontiac engine.

THE PISTONS: After looking up the current price on TRW pistons and considering their weight, I have to agree that they are not the best choice. The Ross custom pistons in a dish of the customer's choice are $650 from Butler. So yes, another $200 over Icon flat tops. But the extra money does buy top of the line piston that beautifully finishes off the bottom end.

THE FINISHED PRODUCTS: Looks like your build will run about $1100 or so for the bottom end parts using economy parts throughout the bottom end, while my picking a top line kit from Butler with custom dished Ross pistons, Eagle H beam rods, and new cast crank is about $1,750 -- or about $650 additional for a much healthier bottom end. Machine work cost should be the same for either route. Now subtract the price of 6X heads and additional machine work, and the price difference narrows.
JMO/FWIW

[screamingchief]

Originally Posted by lust4speed

Bret, I did throw out three possible options. Here's the thing, his current problem is a spun rod bearing. I would like to see him build a bullet proof bottom end for his 428 so the problem doesn't repeat itself.

THE HEADS: It doesn't sound like his current heads are causing any problems. Buying another set of low compression heads is probably going to require a complete rebuild of the 4X or 6X heads he finds. He will be out the cost of another set of heads, and at least the cost of a valve job, but possibly new valves, guides, and seats. Springs will probably have to be changed anyway for the new cam, so that would be a push with the heads.

The CRANK: The old crank might not be salvageable and will need replacement. Last crank I had ground and polished ran $160, but maybe it's cheaper in other areas. So you are talking $160 vs. $250 for a new cast crank in any stroke. If the crank has to be replaced, then there will be no additional cost difference between 4" and 4.25" stroke.

THE RODS: Brewer has some really cool replacement rods. I was down to his shop last Thursday with a club member that bought a new crank. While the least expensive rods are nicely done and come with ARP bolts, Ken does classify them as stock replacement rods. I'd say they are excellent for "stock" engines, but don't know their limitations and they would make me a little nervous. A much better choice would be his H beam rods. I can't think of a better place to spend additional money than on rods in a Pontiac engine.

THE PISTONS: After looking up the current price on TRW pistons and considering their weight, I have to agree that they are not the best choice. The Ross custom pistons in a dish of the customer's choice are $650 from Butler. So yes, another $200 over Icon flat tops. But the extra money does buy top of the line piston that beautifully finishes off the bottom end.

THE FINISHED PRODUCTS: Looks like your build will run about $1100 or so for the bottom end parts using economy parts throughout the bottom end, while my picking a top line kit from Butler with custom dished Ross pistons, Eagle H beam rods, and new cast crank is about $1,750 -- or about $650 additional for a much healthier bottom end. Machine work cost should be the same for either route. Now subtract the price of 6X heads and additional machine work, and the price difference narrows.
JMO/FWIW

Sigh...

He's gonna hafta go thru his current #16 heads same as he will a set of -4 smog heads.

I would never go forward with the assumption that the current heads are "fine"...

Especially seeing as he's almost certainly had detonation related issues here.

And sunk exhaust valves are a real possibility here as well,seeing as those #16 heads dont have hardened exhaust seats,and he's only been adding minimal amounts of leaded fuel to this.

So ask me,any potential issues with a set of the -4 smog heads are also very likely to exist in his current #16 castings as well.

That makes the head deal a wash by most accounts.

The 2 pc. intake valves are most likely in both sets of heads too,and those for sure are a potential failure right there.

The crux of that matter is that it wont matter even the slightest bit how well he builds his bottom end if he just throws those #16 heads back on there and one of the intake valves pops it's head off and imbeds itself into the piston top and beats the $#!t outta the chamber of his #16 head.

And I also would'nt just assume the crank was toast till that was checked by the crank grinder first.

Not to mention more than a few "new" cranks wont pass inspection outta the box,and often they may need to be machined anyways to use them,that or they'll hafta be sent back for an exchange and you can try your luck again minus the shipping costs to do such.

So no guarantees there either.

Ace's budget 5140 I beams would be fine here,no way this build will be too much for those rods.

And the KB/Icon forgings are fine too.

I personally dont see that much strength being gained for that $650.00 difference.

All I see for that $$$ is a few less grams of RA weight maybe,mostly in the rods.

Ask me that "extra" money is better spent in the heads on new valves & such.

I'm done with the pi$$ing contest,simply wont go any further with that.

Dont really care if this fella ever gets this rebuilt,or if this costs him a fortune,and that inturn costs him his marriage,as none of that will affect my world even the slightest bit.

But I can say this for sure,if your trying to tell us it's only gonna be a $650.00 difference between my way and your way,you better think again Mick,because that's just not the way these deals ever work out,you could probably double or even triple that amount and still come up short when all is said and done.

Anyone here that's BTDT will tell you about that deal.



Bret P.

[lust4speed]

Aw come on Bret, this has been an interesting discussion. I'd like to think that we are just adding some additional insight on picking parts for a rebuild. Most projects run us more money than what we had planned on - not because of the new parts, but all those #$%@ other parts that we find are bad after we get things taken down.

[screamingchief]

Originally Posted by lust4speed

Aw come on Bret, this has been an interesting discussion. I'd like to think that we are just adding some additional insight on picking parts for a rebuild. Most projects run us more money than what we had planned on - not because of the new parts, but all those #$%@ other parts that we find are bad after we get things taken down.

It's cool Mick,I was just saying I'm not gonna go on and on anymore with the back forth over keeping the current heads,or replacing them with some later -4 smog heads.

He's got our pros & cons on that debate.
Now it's for him to figure out what's best for his situation.

No doubt there are all sorts of reasons projects end up costing more,part of it indeed is unexpected/damaged stuff,but often that "well if I'm gonna do this,I might as well do that too" mentality starts to find it's way into that overall dynamic as well.

And anyone that's been in this deal long enough also knows that new parts are'nt necessarily a guarantee of no problems,often it's quite the opposite.

I cant tell you how many "new" things I've had to spend more money on just to be able to use them.

Last one was a torker II intake,had to mill the intake flanges just so the ports & such would line up properly.

So new is not always better,not in my book.

There is a balance to all this,that is all I was saying,and tight budgets often trump other various concerns.

That I know all too well,as my budget is about as tight as it gets.

Do I find places where I can safely "compromise",yep you betcha.

Do I find other places where I wont go that route,again yeah sure.

To guys like me,$650.00 is a pretty big chunk of money to take so lightly.

For me,that sorta money can cover a whole lotta things,and many of those things are far more important in the grand scheme of things than the sorta basic bottom end hardware differences that you & I are talking about here.

But should that be someone else's money I'm spending on a project that I dont even have any connection to,sure I could easily spend that in an instant on just one or two things that will hardly even matter much.

It's a matter of perspective,put yourself in his shoes for a moment.



Bret P.

[69Farburd]

This has definately been an interesting discussion. Thanks guys. I have learned a lot. I would love to go the stroker route, but I'd also like to stay married for a while longer. I pulled a tendon in my elbow, so the teardown is going slow. One of the top trans to engine bolts refuses to budge. I think it's just because I don't have enough strength in my elbow to break it loose. I need to find a strong helper. Keep the comments coming. I am enjoying this!

[Old Goat Racer]

Back in the early 80's I put a 428 forged pistons, SD rods, with 670 heads & a complete ram air IV valve train in my 65' with a 4 speed. It never had detonation (that I could hear) & ran on pump gas.
for 20000 + miles. Lucky, I guess. I took the motor apart a few years ago just to look inside. No visible damage. cept the pump screen was in the bottom of the pan.
I still have the complete motor but would not take that chance with pump gas again.

[lust4speed]

Bret brings up a very valid point about the old two-piece valves. I've seen two engines self-destruct because of dropped valve heads (luckily neither were mine). Both engines had lived long happy lives until a new set of stiffer springs were installed. So unless the 16 heads have newer one-piece valves, I will second Bret's recommendation to purchase new valves ($160 or a little less on ebay for Ferrea 5000 Stainless valves). Pretty much need a valve job also. At this point I can feel myself slipping closer to Bret's corner. Those damn weak valves are enough to change my thinking to a lower compression head - which then allows a wider choice of forged pistons since the Ross deep dish won't be needed. The ideal purchase would be a set of 96 heads that have already been gone through, and possibly placed up for sale when the seller moved up to aluminum heads. I prefer the stock 96's over the stock X heads because of the larger 1.77" exhaust valve, and what seems to be a little larger stock exhaust port.

I'll still stand firm on the practicality of a good stroker kit with better rods than a stock upgrade. All our vendors have kits listed for $1,399 that include the better rods and good forged pistons, and they come with rings, bearings, and are balanced.

[chiphead]

I like the stroker kits, for either upsizing 400s or going for max power from 428s. But the 4" stroke in the 428 is such a good balance of torque and RPM on the street, even in the milder combos.

I still say go with the slight dish and 85 CC chambers. This would allow him to step up with a head change later. Heck, price the total cost of reworking and porting the irons and he could about afford the KRE D-Ports.

I'm speaking from experience here. I spent $$$ totally reworking a set of 670s. I dished the pistons way down for 9.3 compression. Now the pistons are dished I can't simply swap on a set of KREs and get a big pump in compression, because the 670s are already 70CC chambers. I gotta either cut the 670s or buy the small chamber alum and cut them down or run a thin head gasket and risk piston to head contact. So that's the flip side of the big dished piston deal. I'm pretty much stuck as long as this engine keeps running good.

But lowering the compression, that's the takeaway. The lower compression has helped this engine live through crappy gas and my learning curve on the tuning items. I've run it 220F, I've run it lean, I've had too much timing, I overrevved it, I ran too hot a plug. 6 years, 10-15K miles and 75 passes later it comes back for more.

[69Farburd]

What ware two piece valves? It has been over 15 years since I rebuilt this engine last, but I'm 99.9% sure they were one piece valves.

[andyg]

Twp piece valves are the factory pieces where the valve head was welded to the stem. My engine blew up last year when one came apart:

http://forums.maxperformanceinc.com/...37#post3757437

[screamingchief]

Originally Posted by 69Farburd

What were two piece valves? It has been over 15 years since I rebuilt this engine last, but I'm 99.9% sure they were one piece valves.

AFAIK all the OE and many of the "stock replacement" valves will be 2 pc.

Most all the "high-perf" stainless steel valves are 1 pc.

Well,the good news here is if they were indeed 1 pc. valves,they could easily be swapped over & used in a set of -4 smog heads.

And by doing so,you would instantly gain .100" of installed height for much better spring selection,and quite a bit more max lift clearance.

Not to mention that would also bring with it an "upgrade" of the 1.66" -4 smog exhaust valves for the 1.77" exhaust valves.

That swap would allow using some Crower #68405-16 springs,as well giving the option to use some 1.65 ratio rockers (providing the pushrod slots get clearanced for the high ratio rockers).

There are almost always options to choose from,one has just gotta be aware of them.

FWIW

Bret P.