I spelled attention wrong and the editor won't let me fix it?! All I can say is WOW! I got the 3400 aluminum heads today and anybody who is doing a rebuild would be crazy not to use FWD pistons and FWD heads. I happen to come across a set of heads for $25.01 (+45 shipping from Cali to FL) and will post pics later. These hads are far superior to the gen1 design in many ways. The valves are splayed for starters, and when looking down the intake ports the back of the valves are easiy visible (much unlike the iron heads). I took some comparison pics and will post later, but I could hardly contain my excitement. Please feel free to discuss and ask questions. I'm not an expert, but I'm hoping we can all learn from each other...

Yep, genIII heads are THE way to go, IMO the extra effort to use them is definatly worth it.

With .060" compressed height gaskets, removing 1cc of material,and the 12cc dish pistons (RWD), it is possible to obtain a 11:1 SCR. This is on top of all the bennies of the intake and exhaust ports. Next is getting the dizzy to work with the FWD manifold or going to a fabed DIS...HMMM

EDIT: This figure was obtained using .030" over (+.75mm) pistons, it would be slightly higher with stock sized pistons.

you are lucky, i would have sprung for that if i had found them. you lucky dog.

I got a question. Is that amount of milling on the pistons safe? Im no expert, so I dont really know much about how thick the pistons are now.
Also you intend on running boost down the line right? Is the added pressure going to be ok with the thinner pistons?

the pistions are not thick enough to remove any materialit will just weaken the top ringland.thought the combustion chambers can be modified to remove a lil bit of material

Keep your eye out on ebay (I was the only bidder on these), but make sure you look for castings ending in 170 or 487. They will come out of a 3400 or a 2000 and up 3100. These castings have larger ports than their counterparts.

I've also seen machine shops selling reman heads for less than $200.

hey are u having ur buiddie cnc u some headerflanges for those heads?if so can i get a set?

But of course . I'm also going to see about some flanges for the iron heads.

BTW : After the new engine is comming together I might need you to alter that plenum with some flanges to fit the FWD LIM (if I haven't gotten my own TIG by then), so it can be used on the new motor. I also have to remember to ask him for the valve cover gaskets you asked about. I've been considering buying one of those mill/lathe combo machines and he said I can have all the cutters I want and he will show me some "tricks of the trade".

The guys on the beretta.net forum have been doing this for years. What are you doing for the intake manifold?

Plan on using the 3400 LIM and MIM and one of Dave's UIM's. Just don't know if I am going to attempt a DIS (will help that I will have the MegaSquirt installed by the time this motor goes in) or take the route Dave did and mod the dizzy to work.

I am aware the FWD crowd has been doing this, but the RWD 60* is a little different to make it work. I read alot about this at 60*V6.com

Umm, did you just say you wanted to try an duse a RWD middle intake manifold and rwd upper intake manifold?

If you did, that won't work for several reasons. The RWD manifold parts are not swappable with the FWD parts. The FWD uses only a lower and upper intake manifold.
The FWD lower intake manifold is quite a bit taller than the RWD lower intake manifold and would cause hood clearance issues.

I'm not sure why you would want to use any RWD intake manifold parts anway, from what I have seen the runners are smaller in diamater that will restrict flow, as compared to the FWD runners.

I will suggest this:
Use the DIS, it's not that difficult, the hardest part is getting a crank trigger wheel to work. The ECM swap is not that difficult to do, hell it may run on the original ECM.

I will be working on a dizzy that fits the FWD manifold, but I'm still not sure where I'm going to surce particular parts I need to make it work.

No, sorry for any confusion. I said 3400 LIM and MIM (FWD) and a box type plenum and was unaware that the 3400 is only two pieces (unlike the 3 pc RWD). I'm actually having trouble locating a 3400 lower for a decent price, cheapest was $75, does that sound high?

There is no "MIM" for FWD engines, so you'll be looking forever for one.

Besides the FWD UIM, is what you describe. The plenum is large with short runners to attach the plenum to the LIM.

If you want a larger plenum, use the 3500 UIM. Slight port matching needed, but people claim gains using it.

I can only see a RWD based UIM causing a reduction in over all potential power production, and causing yo9u headaches trying to get to fit with the FWD LIM.


If you're tryng to se the RWD UIM, to use a dizzy, stop there, it's teh lower (mostly) that is in teh way of using a dizzy, along with the fuel rail.

$75 is about average, if you don't need it right away, keep looking.

I may have an extra one, but I'll have to check.

I've got a pair of Garrett M24 (T24) .57 trim from a Nissan 300ZXtt I would be willing to trade for it. They need rebuilding, I think I may have shown them to you befor but if you don't recall I could dig up the thread.

I think it would have to be a whole new UIM. I dont think you could alter Daves UIM with new flanges, because the ports on the 3x00 are bigger and spaced farther apart. So you would have to make a whole new UIM.
Also Dave is running the Gen 2 LIM, I believe, the Gen 3 LIM is different. To mod it to be able to run your dizzy you would have to grind out almost all of the #6 runner.

he is right, i wont be able to modify one of my rwd plenums for use on the fwd lim. its actually longer,well i could but it be easier to just make a whole new one ,and i am using a gen 2 lim,but the only thing left of the stock gen 2 lim im using is pretty much a small section of runner were the injector goes,which is about 3/4 inch of runner,and even there there has been so much welding/porting done to the runner to enlarge it to fit a gen 3 head.and the rest of it is all custom fabed up runners and plenum built to suit the needs of the turbo motor.

these are old pics i have to take new ones since i got alot more work done on it



the only reason i used this one was cause i was able to modify the back of it to clear the dizzy without blocking off the rear runner

I would say forget the distributer and run a 3400 lower and upper.

Ther is no accomodations for a dizzy in the 3400 manifold, and no provisions for a DIS in the 3.1 block.
Dave, I have only seen the 3400 plenum and it appeared to be similar except for the evenly spaced ports, so I guess I thought they were more similar than they are.

Some info from the archives so you guys have some reference #'s on those genIII heads compared to professionally ported genI iron heads. These figures for the stock genI & genIII heads come straight from GM.

Stock HO iron heads
1.72"i/1.42"e valves
max flow at .450" lift- 128/120

Alum gen3 heads
1.76"i/1.42"e valves
Max flow @ .450" lift- 149/158

Supersix ported heads-valves unshrouded


1.72"i/1.42"e valves
max flow at .470" lift- 151/145

Supersix heads with larger intake valve
1.80"i/ 1.5"e valves
max flow @.470 lift- 160/150

It is a proven fact that GM was able to acheive 1.5+ hp per cubic inch on the factory iron gen1 heads in their production race motors back in the mid 80's even. All this info is documented in the GM power manual. 2.8l motor is a 173CI. 173ci x 1.5hp per ci = 260 hp out of a naturally asperated iron head 2.8 if proper bench flow porting is done and parts are married correctly.

hp can be made with iron heads if done right we all know that, but u can get well over 230 cfm from ported gen2's if done right and more then that with gen 3's
my gen 2's flowed 233cfm on the intake 190 on the ex i beliveid have to dbl check.one other advantage over the iron heads is lighter valves,specially in the late model stuff.
its been documented of ppl picking up 40+ hp going from iron heads to gen 3 stuff on 3.4 motors with no other changes

Your #'s are impossible on the heads based on GM's own facts.

The stock 2.8 heads that I listed above and will list again have a 128cfm intake and a 120cfm exhaust. This is documented in GM books.

The performance catalog states clearly that the GEN3 heads have a 16.7 % increase over the Gen1 heads ion intake and 31.7% increase on exhaust duewto the d shape exhaust ports.

It is also widely know that the Gen3's flow better than the gen2 heads you are claiming- hence why GM upgraded the gen2's to gen3's on later transverse motors.

I do not have any other facts on gen 2 heads. But based on amatuer reports on bench flow testing, you never see any of these tests done on the same machine using both gen 1, gen2, and/or gen3 heads together in the same test conditions on the same machine. I trust GM's facts in their performance catalogs and power manuals.

Supersix tested the stock heads and then revalved and ported heads on the dsame machine under the same conditions to net their results on the gen1 heads.

As for stock vs stock and the gen 2's making over 40hp gain? I fully believe that since they do flow better in stock for and ALSO mainly one is generally increasing compression ratio when doing such an upgrade from 8.5:1 to around 11.1 so they would have comparable gains increasing the iron head to 11:1 also netting probably around 20-25hp gain on that alone.

u need to go check 60*v6 and see what other ppl are also getting for flow numbers from ported gen 2&3's 210+ cfm is the norm froma ported aluminum head

I will also add that it has been also proven that the canted valvetrain will not hold up to high lift endurance racing. They use them on short term midget motors, but not endurance motors.

I like reliable builds. I do not like tearing things down and rebuild costs every six months due to things wearing or letting go.

lmao and how so???
besides its not liek any of us our doing 24 hours at lemas or wtf ever it is
.
any high lift valve train that turns high rpm's eats up parts.if its not prperly assembled with all matching hardware.

its just funny how guys are tunning these things 6000+ with lifts over .515+ and never seem to have the probllems u speak of.and they have load of milage on there motors

Midget motors were running Gen2 heads for a few years for weight savings but after the need of a more reliable aluminum head, Potter stepped up and produced the potter Midget racing head thus reliability even on short track racing was no longer a problem for 60*V6 alum heads.

You like to argue alot- learn some facts first rather than refering me to a bunch of hersay on other forums form people you do not know personally. Again, I trust published facts.

hear say lol ive turned my motor 7,000 rpm +, i know firsthand guys who have the gen2&3 topend that turn there motors that high with high lift cams.mainly local fiero guys and they dont have any valve train problems.wether it be a solid cam or a hydraulic roller grind or flat tappet .i know all about the potter racing heads, and they werent only used for midget racing
the point is none of use would ever be going round and round in circles turning that high of an rpm long enough to experiance any of those problems.

my new cam is ground over .550 lift. im runnign valve springs with 110#'s seat preasure and 312#'s open preasure.is it gonna wear stuff out yeah eventually .but its what makes it all work together without those springs id tear everything up on the first pass.do i care every x amount of miles i might have to replace a set of springs or a cam? not really

Your seats and guides are not going to last what is now normal and expected for any modern engine to last 200,000 miles- I bet you do not even make 50k. I like a motor to retain reliabilty day in and day out for at least 5 years of hard use no matter what is thrown at it. The iron heads will last with higher lift pressures and rpms far longer even in daily street use than those genII heads with the same higher lift pressures.Another side note, since most of you are younger, the MTEG stadium series (Thats Mickey Thomspen Entertainment Group for those that do not know) used Chevy 2.8 60*V6 powerplants when the series first started. Toyota dominated the series and even thought the chevy 60*V6 produced good power, the Toyota 2.8's were killing them- Hence the time Ironman Ivan Stewart gained fame. Many still used them in powerboat racing where they destroked them to 2.5L motors and boosted them with turbo setups. Potter heads were very commonly used here also for lightness and longevity over the Gen2 heads.

having to throw away a set of heads after 2 years dosent bother me,for one there so dirt cheap.second if i wanted to id just install new guides and seats but why.50$'s will get ya another set of heads.

the ppl that just want a lil more power arent gonna be installing radical cams,or running very high spring rates,even going to a 260 cam cam would have no ill effects on the aluminum heads.and would last just as long as the motor.

as far as everyone else whos plans are to push them to the limits its a given shits gonna wear out,when u push anything mechanical to its limits its only comon sence its eventually gonna fail/break or wear out.
when u build something for all out power u know u sacrafice longevity,specially when u do something with it it was never meant to do.
and its not like u can just call up and order a set of those potter heads,lol id love to get my hands on a set

Agreed in most cases, but for someones only car and daily driver I am just warning them of potential consequences in reliability. they are not used in road racing type applications.I have search for years for some Potter heads- So far no luck. I almost scored the 60*V6 that was featured on the cover of the Chevy Power Manual off of EBAY a few years back. It still had the original Ryan Falconer hilborn injector setup but the intenals of the motor were gutted for display purposes and sat for years in the corporate GM front lobby. The original full race heads were also replaced- I varified this before bidding on it via casting #. I was still tempted to go for it just for the Falconer intake but there was no fuel management computer to run it so it was pricy for what was being offered.
It was more of a museum piece.

http://www.thirdgen.org/techboard/at...-falconer1.jpg

http://www.thirdgen.org/techboard/v6...light=falconer (Question On Falconer Intake- ECM Experts Needed)

Wow, from what I read of that posted thread, there are a lot of people that have done very little research, what the guy was after was an Alpha N type ECM set-up, runs on maps, based on TPS and O2 only, but even the people that make and sell them will be the very FIRST to say they are only to be used in race vehicle, where a very narrow power (RPM) band is used, since they are tuned for only a very narrow band, and don't work well other wise. Definatly not for street use.

Also people have been converting ITB manifolds to EFI for years, you just have to know what to use and how to incorporate it. I will be doing this on my Uncles '23 T-bucket within the next year or two, getting rid of the mechanical side of the fuel injection.

Now back to this discussion at hand.

HPE, you contradict yourself in you post about head flow, you say that "professional ported iron heads, flow as much as genIII", THEN you put "stock iron heads" above the 'flow rating' for these said iron heads.

Also it's been PROVEN, that the genIII heads outflow the iron heads, hand down. Especially stock for stock.
In addition to overall flow, it is more important to get a larger area under the curve, than one large number, at max lift. There are many cases where heads will flow less at highest lift, as compared to another head, but flow more overall, at less lift, that will make more power overall, due to more overal air entering the cylinder, so greater area under the curve = more power.

I also have to dispute the canted valve being less reliable part. These engines, can and have run for many hundreds of thousands of miles in stock form, I have also seen many that have ran for several tens of thousands in built form, and even longer than that. The only additinal wear that is seen is on the rocker itself, due to have a slight side load from the pushrod. This side load is generally absorbed by teh rocker itself and the valve sees virtually no side load because of this. On top of that the side load is minimal, not enough to cause premature failure due to a canted valve.

If you look bad at the 2.0 I4 that was used in SCCA racing in Cavaliers, they were built to have over 200 HP with restrictor plates in N/A form using an aluminium canted valve head. Now the other reason I mention this engine is there was a design change in the blocks for those engine in the '87 model year, where the lifters are concerned, they were spaced slightly and pitched on a very slight angle to put the lifter more inline with the pushrod. There was no such change for the 660 however, at lest not one that I have seen documented, but the pushrods are not at very large angles anyway, and I'm sure if there was going to be a reliability issue, GM would have changed the lifter spacing and angle to rectify this situation.

You reeally need to look at what some of the FWD guys are doing with these engines, or what I will be doing with these heads in the not so distant future, large lifts, high valve spring seat pressures, high compression, high boost pressures, etc, everything that you say wil eat these engines up quick, and there has not been one known valve train failure using the genII or III top end, on these abused engines.

The only valve train failure I have seen is on a stock genIII (3400) where the tab on the cam, broke and let the cam spin slightly changing the valve timing events, causing the valves to hit the pistons, since the genIII uses a single large bolt to attach the timing gear instead of 3 smaller bolts like the genI/II.

I said in agreance with just about everything you just reposted- read my posts again about what I posted on flow results stock vs stock and stock vs port- You will relised I did not contridict myself

Yes, I read how you had it typed out wrong for some reason.

But that still shows a gain.

Ported genIII heads have been known to flow well over 200 CFM at peak, and usually have close to 170ish at midlift.

Look idiot, I'll repost it for you since your ingnorance keeps spouting out. Lets translate what I said for you since you can not comprehend anyones statements but your own.

The first line- stock vs stock, yes the gen2's will work better- but 40 hp? NO unless you bump the compression ratio like everyone does.

Last part of my above quote- If you take the stock iron head and bump the compression up you will yeild about 20-25HP alone without headwork- I said stock head vs stock head.

So let me be the one to have to summarize for you- Stock vs stock will yeild about 15-20 hp with stock 8.5:1.

Now as for ported vs ported on a larger lift cam 'I state my fact finds on the Gen2 heads not being reliable from GM sources'- But of course you clowns are argueing against GM's own published results, not mine- I only posted facts I took out of published articles- Go figure, I should know I am dealing with brain surgeons around here in the V6 board.

I give up- Do what the hell you want around here without my imput.

Good, leave, I use real world results not what someone says they freaking read in some publication that has not been shown.

Beleive or rather don't believe what you want, but dyno numbers and E.Ts speak volumes more than what you are spouting out here.

I don't think anyone, but you has said anything about raising the SCR over stock, or much past anyway. Just look at the stock genIII engine, in STOCK form they have over 170 HP, many gys that have swapped them into other cars using an MPFI computer, untuned, can get upwards of 190 to 200 HP at the wheels, higher with tuning. Yes stock for stock, the SCR is slightly higher, but you can't even trust GM for looking at that, some published articles say 8.5:1 for the 2.8/3.1 in iron head trim, to 8.9:1, hell the published SCRs for the genIII vary between 9.4 to 9.6:1, on the same engine in the same year in the same vehicle, depending on what you use as a source, meaning in what GM source you look at, service manual, owners manual, online, etc.

I don't know why you are trying to argue against the use of genIII parts, they just flat out are superior to the iron counterpart, if they weren't would GM have really dropped the iron head? No, they would have kept it and developed, but wait they already had a superior head (and other parts) that works in the same engine line, it just happens to not be directly interchangable as one single component, there ar a group of parts that need to be swapped to make it all work together.


BTW, not everyone raise the SCR when swapping to these heads, I kept mne at 8.9:1, since I was adding a turbo and played it safe. Unfortunatky I didn't get any dyno results without the turbo, next time the heads go on, I'll be raising the compression via a thinner headgasket, to gain more power and tighter quench, mostly for the quench.

BTW what year were the articles published that you have yet to cite? mid '80s? I have read some similar things to what you read, [i]back then[/bi], but anything from '90s on, supports the use of aluminium heads in racing and endurance racing, due to superior power potential, AND durability, along with teh heat disipation qualities of the material, making it great for hard use.

Hell there are marine applications with supercharged 3400s, where durability and reliability HAVE to be met.

So in short all your arguments against the genIII, hell even genII for that matter having lower reliability, is unfounded. Currently I have a genIII (Small Port 3100) in my '98 Malibu with over 218,000 KMs, and still going, the tranny is about to die, but the engine is fine. My old 3.1 went almost 400,000 before I sold it (IIRC had 380,000 KMs or so), before I sold it to another guy, who put it in another car and drove it as hard as I did, made several hundred Nitrous passes with it, and eventually took out a head gasket, which could happen to any engine at anytime. I think it finally had about 425,000 KMs (or more) when he pulled it and started to replace it with a 3400.

I will admit that my iron head 2.8 never died, I did try to kill it, but that doesn't mean that it's any more durable than a genII or III variant.

So firstfirebird are you planning on keeping your dizzy, or swap to DIS? If you're going to try to keep your dizzy, your manifold design should be interesting.

Tried to quote you , but it kept kicking back your post pre-edited, lmao.
I have been enjoying the comments and I used to love waching the Mickey Thompson trucks, one of my favorite tracks was the Colloseum that had the large hill at one corner that ran up a part of the bleachers. And HPE, I agree that Ironman was the shiznit in his day .

BTT, haven't decided on the DIS or dizzy. Probably going to have to wait for all the parts to get here to decide. Since I got MegaSquirt, I'm leaning towards DIS though...

IMO, the main flaw of the IRON heads is the intake, not the heads. If an intake could be constructed to complement the ported Iron heads, then the 260hp that GM achieved is possible.

IMO again, (and I hate to sound like I'm beating a dead horse(RWD intakes SUCK)) the main advantage to going to the aluminum heads is the better intake, not necessarily the heads. This assumes all things are the same, CR to CR, Cam to Cam, and the like. Apples to Apples people.

Firstbird, I hope you are going to keep the dizzy. That would be ideal to me. Other wise you might as well swap ECM, wiring, and all. And if you do all that work, you might as well get the FWD motor, redrill the starter holes, and plop it in without worrying about anything.

why use a fwd motor this is no need,just swap in the internals into a rwd block,dizzy will not fit with a stock gen 3 manifold,though it may fit if u lenghten the dizzy and use a custom plenum.he isnt swaping ecms anyway hes doing the same thing i am and are going to megasquirt units

there is nothing wrong with the lower rwd intake,the mid section isnt all to bad till u get to that nasty bend . the upper plenum sucks,and the runners are way to long.

drdave posted flow numbers for a ported manifold,and i think they weer slightly better then the heads.

point is even if u improve the intake for the iron heads now the restriction is once again the heads ur just not gonna get an iron head to flow what an out of the box/or lightlyported aluminum head does

Just swap the internals? I don't think thats a good idea. It would have to be rehoned with new rings for reliability. Plus if you get the GenIII with roller lifters you need the bosses in the block to keep the lifters straight. Plus the new block has the CPS for DIS so its basically a direct swap if you redrill starter holes.

I know I was a big part of that thread. Use an engine calculator to find out the possible HP for an x flow head. 246HP with 160cfm with PP(iron flow) I guess the main problem of the iron head intake is yet to be determined?

http://users.erols.com/srweiss/calcafhp.htm
http://www.wallaceracing.com/calcafhp.php

Regardless, the aluminum FWD setup seems to be better. I don't know what problems they hurdled over when they developed the FWD stuff, but it seams to work better.

Blue89, it's not just the manifold that makes them better. I need to take the valves out of the aluminum's and show you. I can fit one of my fat sausage sized fingers in the port and almost touch the back of the valves (try that with an iron head). The valves are splayed, and the material makes them resist more detonation due to the heat dissipation rate of aluminum. I've been working on the turbo system these past few days, so I have not had time to remove the valves (priorities, lmao). Whan I get the side by side pics, you will see what I am talking about.

pics of said turbo work????

Uploading now, they will be in the 660 thread.

Uhhh, it's not really that difficult. If mild honing is all that is needed, a home mechanic can do that with the ball hone and a drill.

You don't use the FWD cam or lifters, in fact you seem to be able to get better performance and more cam options by using the flat tappet set-up that is used in the genI/II block.

In fact that's just what I did.

The crank trigger is not all that difficult, even easier if you use the 3.4 block from the ('93 to '95) F-body, whihc has that CPS mount.
The custom crank trigger is not overly difficult for a machinist to make up in a day or so, including the CPS mount.

I wouldn't hesitate to do the swap again, using the RWD block, especially since there is more needed than just redrilling the starter, a new driver side mount, and a couple other things that elude me at this point, well there is also the need to retain the RWD timing cover and accessories, that also need a couple parts machined to do so, so the crank trigger, is less of a hurdle then.

Hey Six_Shooter, you said that you put the trigger behind the crank pulley and had to make shims for the other pulleys. What stopped you from using a trigger that mounted in front of the balancer?

Don't worry, I'm not saying dont do it. I just wish the iron head system was better. Remember, i brought you http://www.thirdgen.org/techboard/v6...highlight=head (FWD vs RWD heads (pic))

I had to make adaptors/new accessory mounts anyway, so making one additional shim for the water pump pulley wasn't that much work.

Also the belt changes are MUCH easier, when you don't have to remove the CPS, to slide the belt off. It was also less work and parts to sandshich the trigger wheel between the pulley and balancer, since I wouldn't need a spacer between the pully mounting surfacr and the trigger wheel, that is IIRC about 2" deep.

I am the first person to take a 3.4L OHV motor -- well, any 60* V6 that I know of, and put aluminum heads and the UIM/LIM from a 3100 (3.1L) motor on it.

I didnt port or polish the heads, I did add RKSport headers because i could not get the stock manifolds to bolt up no matter what i did, and this is what i saw:

stock 3.4L heads / intake:
142 rwhp / 183 rwtq

3100 stuff / headers:
170 rwhp / 207 rwtq with open pipes (163 / 203 with the 3 chamber flowmaster).

my compression ratio did go up. but it only went from 9:1 -> 9.6:1. nothing drastic like 11:1.

there are a lot of gains to be had from using the aluminum heads and intake system.