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Discussion Starter #1
1970 WS 400 Ram Air 3/4 434 Build

Am having a rebuild of my 1970 WS/9799915 400 block, dated January 6, 1970. (Ram Air III code up front, with the Ram Air IV modified casting number, of which a few were built.)

Engine parts stored indoors continuously, with the WS block which was stored continuously indoors, and is now in machine shop where it checked out ok for an overbore to 0.40. As we now have a multitude of aftermarket internal engine parts, rebuilding with stronger parts is considerably less money than during the 1900s. The best bang for the buck appears to be a SCAT 4" stroke forged standard weight crankshaft with BBC Callies rods, the latter being only about $250 costlier than Eagle or SCAT 4340s, but with apparently better strength qualities for greater sustained higher rpm operation.

I desire keeping this car with a manual transmission, but want greater flexibility, as the original M-21 close ratio with 3.73 differential gives nice torque multiplication (2.20 first gear), but alas 4000 rpm at 80 mph in top (4th) gear.

Ideally I want to switch to a 5 or 6 speed manual transmission. The most prevalent today appears to be the Tremacs, but I am more intrigued by the Richmond, for two main reasons: (1) its far wider selection of gearing options, and (2) what I read years ago when it was known as the Doug Nash, about the greater efficiency of placing the gear multiplication more within the transmission than in the differential, with steeper transmission gearing coupled with a 2 series rear rather than a high 4 series or 4 series differential coupled with an overdrive. But as I would like to reduce expenses where I already have something which could more easily be swapped later, I plan on switching to an M-20 wide ratio for now, (and with the rear having to come part to re-do the powder-coat) with the 3.73 gears replaced with either 3.31 or 3.07s. See and compare the following comparison between these transmissions:

2.20 1.64 1.24 1.0

with 3.73
8.206 6.1172 4.6252 3.73

2.52 1.88 1.46 1.00

with 3.31
8.34 6.22 4.8326 3.31

with 3.07
7.73 5.7716 4.48 3.07

Note, that the M-20/3.07 combo gives not all that much less overall multiplication than the M-21/3.73 combo, and that the M-20/3.31 combo gives a bit more. With regards to the greater torque of the longer stroke and more modern camshafts, never-mind that Pontiacs were generally more torquey than the Chevrolet engines that led the close ratio trend, this appears to give a great bang for the buck, especially with the 3.31.

But what about the things that should and must be set now?

My basic engine recipe consists of (1) factory 1970 1970 WS 4 bolt main 400 block; (2) aftermarket rotating assembly of a SCAT 4340 forged steel 3" journal, 4" stroke crank swinging BBC Callies rods holding either forged or billet pistons with full floating pins; (3) rebuilt 1970 7040270 (1974 service replacement) Quadrajet; (4) 1971 455HO factory aluminum intake; (5) 2.5 outlet coated RARE Ram Air style exhaust manifolds; (6) 1970 614 heads (1973 service replacements) previously milled thus reducing the combustion chambers from 70-72cc to 65-67cc, with the cross-over ports filled with aluminum), with a moderate degree of porting added, perhaps to 270cfm rater than 330 cfm to minimize adversely affecting lower lift flow.
The basic idea is an externally stock appearing engine with significant internal improvements for far greater power while retaining street-road drive ability and longevity.
But what about?

- Pistons? I know they will be flat top design with added D dish somewhat reflecting the combustion chamber shape for better flame propagation to lower the compression ration from the 12 :1 or so that I would have with my already milled 614 heads, or the II+ that I would have with if they were at their factory 70-72cc sizing. But which brand id most preferable? Ross? Icon? CP/Carolo? Diamond? Or? Benefits and drawbacks of each type, including forged and billet? My machinest dislike Icon, citing inferior sizing tolerance, while a thread I have seen shows a preference for CP and Diamond over Icon or Ross as the choice of serious racers.

- rod length- 6.7 or 6.8? What are the benefits and drawbacks of each? I have seen a reference to the 6.8 rod in a 4" stroke Pontiac as ideal. Does it have any drawbacks with providing less space for the rings?

- compression? I would ideally like to run straight 93 octane pump premium, or at least limit the amount of fuel spiking - E85, Race or Octane Boaster - to retain flexibility for lengthier trips. Some considerations: As my machinist recommends a square cutting of the heads, this shall reduce the now at 65-67cc chambers to say 62-64cc. Thus, I want to minimize any decking of the block for the sake of retaining more of a heat sink, and also minimize the size of the piston dish so as to retain flexibility for swapping heads without having to likewise mill any such replacement heads. For instance, setting the compression at 9.5 with 63 cc heads would mean probably high 8s with 72 cc heads. As I intend to always run this engine with iron Ram Air heads that came with 70-72cc from the factory, together with a more aggressive cam, I would like to set the compression of this engine build for 72cc heads to at least 10 to 1, and thus about 10.75 with 63cc heads.

- Camshaft. My initial idea was a hydraulic roller for the potential for more area under the curve and the reduced rotational friction. But I am told of problems such as of use above 6000 rpm (I would like the capacity for sustained 6500-7000 capability), e.g. pump up, or worse a catastrophic lifter failure. Also, would not much of the friction reduction benefits from the roller be negated by the required greater valve spring pressure. I have had suggested to me the option of a solid roller. Asides from the added maintenance, what is the deal with its friction issues- e.g. are its friction reduction negated by the value springs? What's the issue of the distributes gear with either a hydraulic or solid roller setup? And given how flat tappet camshaft technology evolved by the mid 1980s with lobes considerably more aggressive than those of the 1960s, how much of a bang for the buck would either a hydraulic or solid roller give over the more proven technology of the hydraulic flat tappet cams from the mid 1980s and later, which open and close the valves significantly quicker then the 1960s era cams?

A quick comparison:

1969-1970 Ram Air III automatic
9779068 288/302 212/225 LSA 116.0
1969-1970 Ram Air III manual
9785744 301/313 224/236 LSA 115.5
1969-1970 Ram Air IV
9794041 308/320 231/240 LSA 113.5

Butler recommended hydraulic roller with 9.5cr
CCA-3315 / 3316 282/288 230/236 .340/.347 .510/ .521 .544/.555

Jim Lehert recommended SR
CCA-3315/3316 282/288 230/236 0.510"/0.521"@1.5 0.544/[email protected] 110 LSA,
CCA-3316/3317 288/294 236/242 0 .521"/0.540"@1.5 0.555/[email protected]

Butler recommended hydraulic flat tappet with 10.5 cr
XE284H 284/296, 240/246, .507/.510, 110 Hyd. (112 lsa optional)

Other HYDRAULIC FLAT Tappet Cams

Competition Cams
CCA-51-224-4 274/286 230/236 .488 I - .491 110 1800-6000
CCA-51-225-4 284 /296 240/ 246 .507 I - .510 110 2300-6500
CCA-51-226-4 294/306 250/256 .519 I - .524 110 2800-6500

Lunati Voodoo
10510703 268/276 227/233 .489/.504 LSA/ICL: 110/106 1600-5800
10510704LK 276/284 233/241 504/.527 LSA/ICL 110/106 2000-6000
10510705LK 284/292 241/249 .527/.548 LSA/ICL 110/106 2400-6200

I had to review these figures myself to see that somewhat surprisingly, that the more recent roller cams offer not so much more in opening tand closing he valves then I expected. Sure they do so way more so than the 1960s cams, but not so much with the 1980s+ hydraulic cams. For instance a 1960s [email protected] cam being well over 300advertsied duration (a spread of 70-80degrees), yet both the rollers and the later flat tappets such cams being high 270s/low280s advertised duration (a spread of 40-50 degrees). As I was already aware of this with my circa 1984 Comp Cams 280 flat tappet, I was hoping to see this spread between advertised and 0.50 duration reduced a bit further, perhaps at least down to 30 degrees.

Give that the roller cams are apparently not much more aggressive then the more recent flat tappet cams, I still see a potential benefit in a roller for reduced friction. But again, what is the consensus regarding how much any such friction reduction is negated by the increased valve spring pressure, as well as the reliability issues?
Perhaps a solid roller is better than a hydraulic roller due to it having greater simplicity.

But given the relative spreads between advertised and 0.50 duration lift, is the benefit worth the significantly greater cost of the parts?
And as well, what about the surrender of the added benefits of the long proven technology of having lifters that are variable duration? AKA Rhodes lifters?

Jim Hand apparently got good results with Rhodes lifters, allowing a larger cam allowing greater upper rpm power with the Rhoads variable lifter reducing the duration at lower rpms thus improving power there and thus providing greater power over a broader rpm range.

In now reviewing the Rhoads lifter line, I see that in addition to their "Original Rhoads Lifters" that they now offer two extra lines, "V-Pro Street" and "V-Max Race", each of which is adjustable. The V-Pro Street lifters can be adjusted to vary the bleed-down to reduce the lower rpm lift .010" to .025", and the likewise duration between 5 and 15 degrees at .050" cam lift, with full lift and duration coming on by about 3500 rpm. The V-Max Race are likewise adjustable to reduce lower rpm lift by as much as 0.40, and duration between 5 and 20 degrees @0.50, with full lift and duration coming on by about 4000rpm. Each of these newer adjustable lines of lifters offer greater flexibility than the original Rhodes lifters which are non adjustable and which reduce lower speed lift by about 0.10" to .020" and duration about 10-15 degrees, with full lift and duration arriving at about 3500rpm. Since the bleed-down is going to likely increase the engine's dynamic compression at lower rpms, this added adjustable feature could be quite useful in tailoring the duration and lift curves to work better with the higher static compression permitted by the cam's intrinsic duration profile, as well as further fine tuning with the flow of the cylinder head's porting.

Interestingly, Rhoads offers an additional sub variant of these adjustable variable duration lifters- rollers, yet alas not for Pontiac. Ideally I would like to see such developed for Pontiac engines and refined to ensure greater reliability, but alas that has not happened, at least not yet.


3,770 Posts
Interesting. You have obviously got caught up in the "mind trap" of over analyzing your engine build. Trying to bring in everyone's opinion, to include yours, sometimes confuses your choices as you try to put together a build that hopefully works and isn't a dog.

First, build a Pontiac for torque, not horsepower, then find an RPM range you want your engine to best perform at. You want to focus on air flow - carb, heads, exhaust.

Next is matching your drive train to the engine or engine to the drive train.

NO one cam will work best in the entire RPM range. So pick the best RPM range you want to run, ie low to mid-range, mid-range to lower-upper, upper RPM's. There will always be a trade off where some area of the RPM range will not be optimum. That is where your trans/rear gearing comes in to compensate or enhance.

Choosing a cam is probably the most confusing aspect of building your engine. As you have seen, everyone will have an opinion or preferred cam/cam manufacturer, very seldom will you see engine builders or individuals all agree on one specific cam. Look at the factory cams - which worked. Pontiac engineers knew what they were doing and they took them to the tracks/streets to prove it.

Many factors go into cam specs. Some will provide explosive power, but die early in the RPM range which can be a problem when you still have useable engine RPM available through things like forged cranks, rods, and pistons - and as long as your heads have the adequate CFM's/flow to operate at higher RPM's.

Then, let's say you get your engine pushing 500HP and 585 ft lbs of torque, it won't do a bit of good if you aren't running tires wide enough and sticky enough to put all the power to the ground as they go up in smoke each time you drop the pedal from a standing start or down shift hard to race some street car.

So lets say you do get some good sticky tires, the 10-bolt rear is going to pop on you at some point. You will find that the 8.5 10-bolt is the recommended upgrade that can handle big HP IF modified correctly. Next up would be a modified 12-bolt, or the better yet an aftermarket 9" Ford (which would give you the flexibility of swapping out center sections with different gearing as the need arose). You will also have to consider some chassis mods like boxed control arms and upper & lower control arm braces so you don't crack the frame (factory even used these on their 4-speed cars). The GM A-bodies are known for bad wheel-hop when dumping the clutch with sticky tires (heck, with any tire has been my experience). The fix has typically been to reposition the upper control arms with "no-hop" bars - which are readily available aftermarket.

Anything less than the M-22 4-speed could also pose a problem if you hammer on the car. The M-22 was developed for the high torque engines, so keep that in mind in building your engine as well.

Just some things to consider as you plan on this big cube, big HP, big torque engine. Kinda a waste if you can't plant it to the ground, or worse, the HP throws you sideways into a ditch or worse.

Cam selection. I still like the "old school" flat tappet cams. Selections is also based on compression. For a street engine, 9-9.5 compression is about max for pump gas. Racing gas will allow much higher, but at cost and availability of the stuff. I would rather shoot for 9 to 1 to be safe and the power "lost" will be made up in other areas of the engine - ie bigger cubes.

Competition Cams, and others, grind their cams on a 110 LSA. Good for under 9 to 1 compression engines as it builds cylinder pressure in low compression engines. Explosive power & pull, but they RPM early as power falls off quickly. The factory cams, as you have noted, have a wider LSA to provide a broader power curve and work over a wider range of RPM's. Wider LSA's also provide better engine vacuum to operate power brakes - so this must be considered unless you plan to use an electric vacuum pump IF needed. I like a 112 LSA which I feel is a nice compromise. Any of the Comp Cams can be ground on a 112 LSA as any cam manufacturer can do this if requested.

Selecting a cam would also be best IF you know what your heads flow. You would not select a .600" lift cam if your heads flow best for .500". A waste of lift and engine efficiency. For a street engine, I like lower flow numbers due to the fact that it provides better throttle response. Bigger flow numbers, again here is the trade off, might be sluggish on the bottom end where most of your driving will be, but pull hard at the mid to upper RPM range if you were drag racing - or you simply gear to keep your engine in this range, but it'll be tough on all components with your engine screaming at higher RPM's on the street. So my recommendation is not to over do it, especially with a nice set of RARE 614 heads. I would have them "cleaned up" ie port matched, ports evened out to flow same numbers, maybe a little bowl work, and a top quality 3 angle valve job to really improve flow. Of course matching valve components, and I like the Ferrea stainless steel one piece valves.

I have used the Rhodes lifters in one engine, my brothers 360CI Plymouth. The cam selected had close to .500" lift which is a little big for his engine and he wanted street manners and good vacuum for power brakes. The engine idles like stock, nice and smooth, and has a nice sound, but does what it should. He has a 2500 stall converter to match the cam/lifters, so when he nails the gas, tires go up in smoke. No problems yet out of them. So they can work well with higher lift/duration cams and have the slot cut into the bodies for additional oiling to the cam if you feel you need it (which can't hurt). Did not use this feature on his engine and car now has about 25K on the engine.

Many will go with a roller cam because they feel it is "safer" with the lack of zinc in the oil and provides less wear tendencies or that "flat cam lobe" syndrome associated with a flat tappet cam IF you don't choose a roller cam. Roller cams will also keep the valve open longer due to its profile, but it also has steeper ramps in doing this. I don't care for the steeper ramps and don't feel I want to exert the additional side loading onto the lifter bores and take a chance of breaking one. Pontiac's engine's did not have the needed support in this area because they didn't build their engines for such high power big lift roller cams (just look at the lift numbers on a factory Pontiac cam). However, you will note that the RAIV and SD engines did get the additional support to the lifter bores because they were designed to have more potential. That said, I feel a lifter bore brace is a must on any roller cam used, but others will disagree. I would not want to take a chance and blow out a lifter bore if something were to happen, like a roller lifter going sideways. Another plus for flat tappet cams is that they can't break and go side ways, and you don't have to worry about needle bearings breaking and going into your engine.

The cam also gets it lubrication from the splash oil whipped up by the crank which generates and oil mist. The factory uses a windage tray and others go to further extremes to do more to eliminate this "parasitic drag" on the crank. So if you cut it down to the point of little to no oil floating around inside the engine as an oily mist, your cam may suffer from reduced lubrication. Might be ok at lower RPM's, but my guess is as you go into higher sustained RPM's, the heat builds up rather quickly between the cam lobes and lifter faces and contributes to accelerating wear on both - especially with the reduced zinc in most oils used to lubricate. On my 455 build, I am not installing the windage tray, but am going with a crank scraper in its place. I feel this will pull much of the excess oil collected on the crank throws, but still keep the "oil mist" churning within the block to help lubricate the cam and even cylinder walls at higher RPM's - just my theory. You can also notch the lifter bores for more oil flow to the cam or get the lifters with the holes in their face surfaces, but I don't feel I need it.

So for me, flat tappet cams are the way to go, use correct break-in oil like Brad Penn, and follow the cam manufacturers break-in procedure and you should not have a problem.

I would not go any higher than .550" lift on the street if you heads can go that high and still flow CFM's to justify it. Keep in mind that higher spring pressures also means higher wear on all your parts. You can set-up for the 1.65 roller lifters which will open the valve faster in achieving max lift longer. The 1.52 roller lifters, in my opinion, would make sense in building a smoother and better flow at lower lifts as the valve reaches max lift. So you would want to select a cam with its max lift in relation to your rocker arm choice.

Piston choice is like everything else. Everyone has their favorites. I went with the Keith Black FHR Iconn in my 455 build. If you builder prefers the SR pistons, and he uses them regularly, then his choice should be valid. Again, just have to select the piston to match your head chamber CC's to get the compression you want. You also want to have a "squish" area above the piston in the .040-.045" range to help prevent detonation. Careful measuring of the block and ordering a set of pistons that moves it higher in the block can do this versus milling the block to "zero deck" it - which i rather not do. Pontiac pistons are typically .015-.020" down in the hole, Mine were .020" down. So I compensated by ordering Cometic head gasket that are .027" thick to give me a .045" quench area.

I would add ARP studs to your mains if going with the longer stroke. I like ARP head bolts, but be aware that the RAIV heads have different length bolts that the typical Pontiac head. You will also lose any factory head bolts that have studs used to attach things, like battery ground. So this is a consideration.

Any rotating kit should work. It is typically more cost effective to buy the kit as a whole versus buying pieces at a time and fitting them altogether, but it is a choice. 6.7 vs 6.8 rod length is so inconsequential that it does not matter. I would select the lightest pistons/pins/rods to get as much weight off the reciprocating assembly as possible. Light weight is easier on the parts, especially at upper RPM's.


8 Posts
Discussion Starter #4

Check out the following, which I found today:

excerpt "The 4" stroke has many advantages over all the others. If using it strictly as a "street" engine, the 455 stroke is more attractive. If wanting some high-end power (over 5,000), the 428 is where it's at! The 434 (.030 over 428) will make plenty of low-end for "driving" and still have a short enough stroke that revving it won't kill it. Rick Holladay is adamant about using the 4" stroke in his engines. His 3,700 lb. '65 GTO ragtop has been 10.73 on 93 octane, 4-speed and all. While we MIGHT be able to "squeeze" a little more by going to the 4.21 or 4.25" stroke, he likes to shift over 6,200. His last engine had 10K street miles and over 300 1/4 mile and 1/8 mile passes on it, and was still "going strong" when we upgraded him to a "non-street" engine. Since he's no longer driving the car on the street, no "compromise" was necessary. More compression and a new cam, and he's now going 10.60s and has lost the "handle" regarding traction. He has to re-learn the car. We're thinking it will go some .40s once he's figured out how to apply the new power. MPH is "up" more than 3 WITHOUT traction. "

455 or 428 ?

"Rick Holladay is adamant about using the 4" stroke in his engines. His 3,700 lb. '65 GTO ragtop has been 10.73 on 93 octane, 4-speed and all. "

I would love to know what cam specs etc he used for that.

Premium Member
96 Posts
Just looking for a little clarification on a comment in your first post "Ram Air IV modified casting number." Specifically what do you mean by that? I ask because I have a 1970 9799914 (WS) block which has a hand over-stamp of the 4 to a 5. Is this what you are referring to? Thanks.


1,611 Posts
Quite a few '70 WS engine blocks were originally stamped on the 9799915 block. When I began running across the first instances of these in the late '80's, the first I noted were cast in April & May of '70. Since that time, have had my hands on nearly a dozen more with casting dates running back into Dec of '69, many others noted on internet sales.

Doug on a build centered around a 4" stroke based crank, there are a variety of performance builds. What weight of Pontiac with driver? Purpose build of car? Occasional performance driver? Nostaligia road race build, something else? Performance will to a big degree depend on head flow, cam selection. Eventually, exhaust flow will rise its head, & the use of oversize RA manifolds will definitely hold back performance. 6.7 H beam rods here, (replaced Brooks alum rods).

8 Posts
Discussion Starter #8
All around street-road high performance with occasional 1/4 mile track appearances.

Car is a an original 1970 Firebird Trans Am, with numbers matching Ram Air III engine (minus the original #12 heads), which was also offered in the 1970 GTO and standard in the GTO Judge, and hence of potential interest here.

At this time, I am thinking of the 705 Lunati Voodoo cam with VMAX adjustable variable duration Rhodes lifters, 1.65 rocker arms, and between stage 1 and stage 2 head porting to enhance flow at higher lift flow without compromising such at lower lift. The adjust-ability of the VMax lifters shall allow me to experiment to see what I can get away with contemporary fuels, and I can mix 2-4 gallons or so of E85/and or octane booster with R10 pump premium with the 10.7 compression ratio.

Some time afterwards, I intend on a like rebuild of my other 1970 WS 400 engine, but with its original #12 heads rather than a set of #614s .
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