JoeMinnesota

Adam... If you think about going down the road to a roller cam with a gen1 SBC, be advised that the roller lifters are only the tip of the iceberg. It won't be the $200 you're seeing somewhere for roller lifters. If those lifters are under $200 I'd also read the reviews and see if you can confirm they are quality products. Yes, there are shortcuts and inexpensive mods to some of the stock parts you can use to make due, but in the end you can easily end up with big $$ invested and lots of screwing around.

Roller cam, roller lifters, decent valve springs, guide plates, rev kit (if you choose), better & custom length push rods, roller rockers and cam button. Aftermarket timing cover to control walk, and aftermarket valve covers to clear the rockers. If the timing cover is billet, the water pump won't clear your cover (too thick... even if Summit says otherwise), so you will space the water pump, and then you will shim the damper to match up the belt pulleys, then you will shim the PS pump (if you have that) so that it matches the pump and crank pulleys, and then you will shorten your PS belt (so that it will clear the cross member in the car when you adjust it out to tighten the belt on the now-shimmed pump). Longer bolts on all of these components. Last, you'll have to replace or modify & shim your alternator mounting set-up, to match pulleys and potentially clear a now non-stock valve cover (that you replaced, to clear the roller rockers).

Just be prepared for the investment to snowball into an additional $800-1K pretty easily for the roller conversion on a gen1.

Ask me how I know - I just finished an 1970 L46 rebuild with a Howards Retro Roller. As my wife says "...it's a hobby...it's a project...it's supposed to take time, and you're supposed to enjoy it...". It's a beautiful motor, but if I had it all to do over again, I think I might go flat tappet hydraulic.

mongoose87

thanks Mako!
All the information you provided, as well as others, helps me out tremendously.
I'll probably do something almost exactly as you described.

Please let me know if you have any other tips for me.

mongoose87

Yeah, I know it will be more than the cost of the lifters. I was looking at this full kit, rather than buying all the other parts separately:
http://www.ebay.com/itm/like/1118859...=ps&dispItem=1

This kit doesn't include the retainers or timing cover though.

I've read a little bit about the aftermarket timing covers, but I don't have all the details. Stupid question, but I thought the purpose of the end play button was to control cam end play. I'm assuming the aftermarket timing cover is is absolutely necessary?
It sounds like a lot of trouble was encountered by the aftermarket timing cover not being the right dimensions.
Do all the aftermarket timing covers require this shimming for the extra space for the end play button, or is there one that will avoid all the accessory pulley shimming you had to do?

(I just read this article)
https://www.corvetteforum.com/forums...oller-cam.html

I've also read you can "modify" the stock timing cover by banging on it with a socket and a mallet where the cam button would be. Obviously over simplifying it with this description, but it doesn't seem impossible.

I've read opposing things about rev kits. Are you racing your engine?
Maybe I should get one?
I wouldn't race the car, and very rarely get it to its red line at 5500 rpm. Is the rev kit necessary?

BKbroiler

Absolutely not.

JoeMinnesota

The aftermarket timing cover isn't essential, but helps keep everything in place without the flex. Yes, the button provides a spinning part/shim between the cam and cover to limit the end play. With flex, your timing and disti gears will wear. As for covers not requiring all the shimming, I can only speak of my experience and my set-up with a short water pump. Maybe would have been better to stick with the stock cover as some others have. When solving my problems I found I wasn't the only one with these issues.

The rev kits are an added to help keep things together if you spin it up high or break a pushrod. Just extra insurance but not a necessity by any means.

My point was that, especially with a mild setup, it's a lot of components and ample investment and personally I'm not sure of the payoff vs. the performance of street and race motors we have built with solid and hydraulic flat tappets in the past.

dmruschell

I just replaced the heads on my 79 Corvette and just had an engine built for a 75 Corvette I'm restoring. I wanted a functional heat riser on both cars for drivability in cold weather, and for the hot air choke on the 75 (the 79 was converted to electric choke).

Basically, there are three options I found:
AFR Eliminator
Edelbrock Performer
Dart Iron Eagle 165cc (Summit branded iron heads are also these heads)

The Performer heads are the same price as the AFRs, and the AFRs perform better from everything I've heard.

For my 79 (manual transmission)!with a Lunati Voodoo 268 cam, I went with AFR 180cc heads assembled with hydraulic flat tappet springs. (The lift with my 1.52 rockers was just too big for the springs used on the Iron Eagles.) I used a GM ZZ4 intake.

For the 75 (automatic transmission) with the Lunati Voodoo 256 cam, I went with the Summit branded Iron Eagles (they even have a Dart part number stamped into them). I used an Edelbrock Performer EGR intake.

Both cars run great with good street manners and good SOTP power. The Quadrajets make them both very responsive to any pedal movement.

If you're staying under 5500rpm, I'd recommend the setup I put in the 75, and you could probably get away with keeping your stock intake.

mongoose87

Thanks for your input!
Do you know what kind of power and torque increase you got from doing the heads and voodoo 256cam (I'd imagine you did the exhaust as well) for your 1975 setup?
The AFR heads, and many of the other name brands, are just too much money for me, especially since I'm looking at low-mid power. Am I wrong in my thinking that better flowing heads are better, but show most of their benefit in the upper rpm ranges when the motor is pulling its peak CFM? So if I'm not looking at racing, is the bang for buck worth it for expensive AFR heads?
The ones mentioned in the previous post seem to be a lot better than stock, and the intake runner size and valve sizes seem best set up for low-mid range power.
I'm not totally married to the hydraulic roller cam conversion, but it just seems like a lot of the parts required will be replaced when the heads and cam are replaced. Most of the things I'm seeing on ebay are saying you can call them up and specify the cam choice you're looking at and they will match the components it comes with to the specs of the cam.
Push rods, lifters, springs, retainers, roller rockers, sprockets, valve covers, (most likely intake & exhaust), etc would all need to match the new engine requirements.
Sure, I may have to modify or buy a timing cover and end play button, but the extra time and money seem worth it to me.
How much could I save by going with the same upgrade but with a hydraulic flat tappet cam?
I would spend like 1500 instead of 1800, maybe?
I don't know, you tell me

I'm estimating around $1500-2k to get the heads and cam worked out. I'd imagine the intake and exhaust will be more on top of that, so if I'm going to do this major change, I want to get the most power improvement possible. It seems like the best way to get the most power throughout the entire rpm range would converting to roller cam, even if the lifts are mild.
Don't the cams last longer with a roller cam as well?
The vortec heads seem best for lifts under .500, even if the valve seats are modified.
I'll be honest, this is all conjecture, because I have never rebuilt an engine like I'm talking about, but this is what I have been reading.
What do think?
Do you agree?

Thanks again for all the great input!

dmruschell

I haven't gotten either on the dyno yet, and the 75 engine is still being broken in. I can say that it pulls pretty well off the line, but it hasn't been over 3500rpms or at WOT yet. I expect 350+ gross hp. The 79 is extremely fun to drive. On the street, it's rare that I rev it past 5500 RPMs because I don't need all of the power that it can give.

Better flowing heads will only benefit you at higher RPM, yes. And larger intake runners (that often help with that flow) can actually be detrimental at lower RPMs. AFR gets a lot of flow with smaller intake runners, which is why their reputation is what it is.

Combustion chamber design is another reason why some of the higher-end heads are sought after.

One thing that set up a red flag on the original heads you posted was that they specify compatibility for intakes differently 3 times throughout the ad. If you're looking to keep the divorced choke, you'll need to keep your stock intake or get an intake with the provisions for that choke. I would bet that later Vortec intakes won't have those provisions. That's why, if I were you, I'd stay with standard SBC heads instead of Vortec heads.

The Summit branded Dart Iron Eagles I used on the 75 (https://www.summitracing.com/parts/sum-152123/overview/) are under $700 for the pair and come set up for a hydraulic flat tappet cam. The cam and lifters I bought were $200. That's $900 for heads that outperform any old-school heads that Chevrolet produced and a cam that will make more power than any flat tappet cam Chevrolet produced. No additional matching of parts is needed, as the assembled heads will work fine with that cam. Push rods may (or may not) need to be replaced, but rockers and even valve covers can be reused.

If you go hydraulic roller, you'll have to buy the Iron Eagles from Dart set up with the correct springs, which will be more $$. Then, there's the cost of the cam and lifter package, which is $850 instead of $200. Add up the parts, but I doubt a hydraulic roller will give you much benefit under 5500rpm.

The benefit of a roller (besides not needing ZDDP) is that you can get greater lift for a given duration. This allows a short duration for smoother idle and low end torque while allowing the higher lift to flow more air higher in the RPM range. So, a cam that is good until 6500RPM can still have a good idle quality and vacuum. But, you're not going to be revving that high. The cam I used in the 75 is advertised to make 19 inches of vacuum at idle (basically what the L48 cam made) and rev to 5500RPMs before it runs out of breath. For what you say you want, I don't think there's any reason to use a different cam.

Under $1000 for the cam and heads means you can use the rest of the money on a L82 style 2.5" true dual exhaust. On my 79, I used aftermarket Ram's Horn manifolds with 2.5" outlets and didn't notice much difference compared to long tube headers except that manifolds are quieter, not as hot, and don't burn plug wires. On the 75, I used 2" outlet Ram's Horn manifolds with the L82 style 2.5" true dual exhaust. Zip sells Corvette Central exhausts for less than CC sells them. If you can get under the car to install it yourself, you're still less than $1300 into the project.

EDIT: Longevity of hydraulic FT cams: UHarold (the user on various forums who designed the Voodoo cams) has stated that those cams regularly make it past the 100,000 mile mark without issue.

mongoose87

Thanks for the advice!
If you can get 350+ horsepower out of that voodoo 256, then that seems a lot more appealing to stay with the flat tappet lifters. What you said about flat tappet cams makes sense, but can I assume I can find a roller cam with higher lift ramps than what was specified in the earlier posts, while keeping similar LSA will get more power than the voodoo?

I like everything about those heads except for the combustion chamber size. I am hoping to increase compression by using the 64cc chambers.

dmruschell

Remember what you said about air flow and heads? The air flow is only maxed out at higher RPMs. The lift and duration of the camshaft also determine how much air flows into the chamber. A camshaft with a lot of lift won't make more power than a camshaft with less lift if the smaller cam lets in as much air as the heads can handle.

If you have large heads and a small camshaft, the engine will make okay (not great) power until the camshaft chokes off the engine.

If you have small heads and a large camshaft, the engine will be a dog down low and the heads will choke the engine before the camshaft wakes up.

Heads and cams need to be matched.

So, if the Voodoo camshaft is opening the valves enough to max out the flow of the heads, then more lift at a given duration won't make any difference.

Even if the Voodoo is choking those heads, the difference will only be felt when the engine demands more air than the Voodoo can deliver, which will be at WOT above 5500RPM. Since you're not planning to rev any higher than 5500RPMs, you wouldn't see any benefit.

That goes back to what I was saying earlier about one of the benefits of roller cams. If you got a roller camshaft with the same duration specs as the Voodoo, but higher lift, you could have the same street manners in the low and midrange RPMs, but your usable top end might extend to 6,000RPMs. So, you get a wider power band.

About the chamber size, I just looked up approximate compression on Speed Pro's website (http://powerforgedpistons.com/engines.html) for their dished pistons. I'm not sure if they're more or less dished than the stock pistons I assume you have, but it will illustrate my point. With 76cc (stock size) chambers, the compression is 8.18:1. With 64cc chambers, it's 9.14. With 72cc chambers, it's 8.47. Yes, you'll be sacrificing some power, but not a whole lot. In 1970, the ZQ3 was rated at 300hp with 10.25:1 compression. In 1971, it was rated at 270hp with 8.5:1 compression. It lost 30hp because of a 1.75 point of compression loss, which equals about 17hp per point of compression. So, you might be giving up 10 horsepower by going with 72cc chambers instead of 64cc chambers.

I just looked it up, and the smallest chamber size the Iron Eagle 165cc heads have available is 67cc, so you'll be giving up less than 10hp. To get that smaller chamber, you'll have to buy these Dart branded heads heads (https://www.summitracing.com/parts/drt-10024266a) for just under $1100 a pair. That's $400 extra per pair for less than 10 horsepower and the Dart name. I'd spend that $400 elsewhere, which is why I got the Summit branded heads that have a Dart part number stamped into them.

63mako

A hydraulic roller will give you noticeably more power everywhere, idle to WOT. Cam duration @ .050 is a good way to determine where in the RPM range you have power. Heads determine HP capability, at all RPM. If you look at a cam using only lift numbers and Duration @ .050 and .004 or .006 your entirely missing the picture. Duration @ .200, .300 .400 is much more important for power potential. (look at picture, multiply lobe lift by rocker ratio 1.5) since flow below .100 is minimal a roller cam gives you much more area under the curve and more lift at a similar duration. It basically snaps the valve open faster and closes it faster but the time in between is what fills the cylinder. Since the valve lift is constant at all RPM better cylinder filling with similar duration @ .050 will result in similar manners, better vacuum and idle, more power everywhere and less friction and wear. If you increase ramp rate on a performance flat tappet your looking at more lobe to lifter pressures and accelerated wear. As far as heads go look at flow numbers again at .200 .300 .400 not just peak. A 175 CC head will not hurt power anywhere on a 350 with a roller cam. Better flowing heads increase power everywhere as long as you maintain port velocity which they do better. A roller cam increases vacuum, (again, see picture) increasing port velocity so a larger intake port responds like a smaller port with a flat tappet to a certain point. To hit 350 HP with a stock type head and flat tappet is not going to happen with a 256 duration cam, 300 or less. GM needed a 222 duration @ .050 and over 300 advertised duration and 11 to 1 compression to get 350 HP and it is not a low RPM power engine.

dmruschell

There are areas where I agree with you, but a few things I have to disagree with.

If an engine is at a low enough RPM that it can't use all of the air the camshaft is supplying it and the camshaft is within its power band, then the type of cam won't make much difference.

" Better flowing heads increase power everywhere as long as you maintain port velocity which they do better." There are dyno comparisons that show that larger intake ports can hurt power below very close to peak horsepower, so better flowing heads don't necessarily increase power everywhere. Maintaining port velocity is a function of how quickly the air is sucked from the intake into the cylinder. If the engine is not at WOT at high RPMs, the camshaft won't be the limiting factor deciding how much air fills the cylinder. If the cylinder could be filled at certain rpm at a specified cam duration with the flow provided at .100 valve lift, more area under the cam lobe curve isn't going to help it.

Your comparison of the 256 cam to the GM cam ignores your previous (accurate) point about looking at the whole area under the curve. GM ramps are not as aggressive as modern lobe designs, which means there is more area under the curve for a given duration, and more power potential. In researching heads and camshaft combinations, I had one guy tell me that the 165 Iron Eagles could support 400 horsepower in the right engine combination, and that it was difficult to upsell people to aluminum heads as a result. Considering Edelbrock rates their Performer crate engine at 320hp with a smaller camshaft in terms of lift and duration with less aggressive ramps, I don't think 350hp is out of the question. The Comp Cams XE256 cam makes 330hp according to their dyno testing, and the Voodoo line was specifically designed to outperform the XE cams. (The XE hydraulic flat tappet cams actually perform well compared to the XE hydraulic roller cams of similar duration http://www.compcams.com/Pages/401/dyno-sheets.aspx)

63mako

And this is where your point of matching components comes in. Your head choice, compression matches your cam well for the intended use. Those numbers are on an engine dyno with open headers, just swapping cams, matching components and compression . The flat tappet cam will not make use of the bigger ports but a roller with more area under the curve will allow enough extra port velocity to up the port size 10 CC with no loss anywhere and more power everywhere. I'm betting your lucky to see 300 HP on the build you described. I'm also betting the cam and heads I recommended will see 350+ and show no difference or maybe a little more power at low RPM and noticeably more the higher the RPM climbs. I can not in good conscious recommend a fast ramp, high intensity flat tappet hydraulic cam to a guy that is doing it once and wants to optimize power in his chosen operating range. I lost a $6000 302 to flat tappet cam/lifter failure. Never again. There is a reason the GM ramps were lazy. All the cam companies are competing to get the most power compared to the others with the same duration. The only way they can succeed is increasing ramp rate and hydraulic intensity. You use an almost roller cam intensity in a flat tappet design your asking for trouble. It is worth the extra $400 or so to go roller and not worry. JMHO.

63mako

Compare the 256H and the 270 HR HP and Torque at 2000, 2500, 3000, 3500, 4000 RPM. This is where he is looking for power. If you have enough head flow and compression to support it you lose nothing at the bottom. You get up into the larger cams like 288 ect you need gearing, bigger heads, intake and exhaust. and more compression than he can make. The cam, heads and shim gasket I recommended I stand by if the OP wants what he said he wants. Remember the Turbo 400 in 72 has a factory 2000 stall convertor, recommended for this cam. The 108 LSA will increase dynamic compression, pull harder at the bottom and lower operating range than the comp dyno shows and has an operating range 1200-5400.
http://www.compcams.com/Pages/401/dyno-sheets.aspx

dmruschell

Your 300/350 comparison doesn't seem to have anything to back up what you're saying. The heads I used will support almost 400hp, and the roller vs modern hydraulic flat tappet cam comparisons I linked didn't show much increase, if any of the roller cam over the similar flat tappet cam. So, I'm calling BS on your 50+ HP increase.

Your statement about a roller cam being able to support an extra 10cc of intake runner size is because that cam will have more lift at a given duration and will support more power at WOT, so it needs more head flow to match it. But, anywhere other than WOT at high RPM, where the flow through the head and valves is near maximum, it won't make any difference. I feel like I'm repeating myself here.

I have 8 cars with non-roller cams. 2 are OHC without any hydraulic function with aggressive ramps, one is a solid flat tappet Duntov cam, two currently have a stock GM cam, one used to have a Comp XE cam, but now has a different cam (fuel pump arm broke and wrecked the camshaft, which wasn't the camshaft's fault), and two have Voodoo cams. These are the only cars I drive, all but one have had the cams installed under my ownership, and I've never had a cam failure in over 75,000 miles on these cars. I don't drive them gently, either. The ones with manual transmissions have all seen over 6,000RPMs.

If you'd do some research on the Voodoo line, you'll see lots of posts by UDHarold (the guy who designed the cams) talking about camshaft ramp angles, opening and closing rates of the ramps, and about camshaft longevity. The XE line is more aggressive, and the valvetrains that use those cams are pretty noisy. The Voodoo line outperforms the XE line, but is more gentle on the valvetrain.

Everyone is entitled to their opinion, and if I lost a $6,000 engine because of a camshaft failure (I did need a full rebuild thanks to a fuel pump arm failure, which wasn't cheap), I'd probably be more hesitant to go with a FT cam. But, as someone who daily drives cars with FT cams without a failure, in my experience, they work perfectly fine. Full disclosure: my next engine in my 79 Vette will probably be a roller cam, but it will also be a roller block and built to handle some higher RPM, and might be a stroker, too. In order to get more power than what I've got and keep the street manners, I'd have to go roller. But, for someone who won't spin the engine above 5500RPMs and is working on a limited budget, the FT cam makes a lot more sense, IMO.

Since it appears we are at a disagreement and going back and forth at this point doesn't seem to be productive, I'm going to refrain from responding to your posts on this issue. The OP knows both of our opinions and can figure out what each of them costs and what path works best for him.

63mako

Voodoo has an asymmetrical lobe design and a parkerized coating. I have sold dozens of them. I do agree they are a better choice than comp.

mongoose87

I took a closer look at the comp cams site with the graphs of the roller cam vs flat tappet, and found the same thing, horse power and torque curves are pretty similar. The graphs don't really show the HP and torque figures below 2500 rpm though. I know most people dont care about these ranges, but I would think this plays a big part to judge when the camshaft's power band starts. This is important to me, because I want low end power. Call me a redneck, but I like the ability to smoke the tires without having to put it into neutral to rev it up and drop it into drive. (I don't intend on smoking the tires, but you get what i mean)

Can i assume the roller cam will maintain the lower end power better than the flat tappet?

Can putting in a 1.6 roller rocker give me some (understandably not as much) of the advantages of the roller cam?
I would think the duration and LSA would stay the same, but the lift would be increased, including when a the cam is not yet at maximum at lift. So wouldn't that provide the faster opening and closing of the valves?
I've read that alone, the 1.6 roller rockers don't provide too much power increase, but if i have to buy them anyway, it seems like a good idea.

If i use the heads previously mentioned by 63mako:

http://www.ebay.com/itm/Chevrolet-35...hUkH4f&vxp=mtr

And get 1.6 rockers, it seems like flat tappet voodoo 256/262 would produce some good power increases, and still stay below the 0.520 maximum lift of the heads.

http://www.ebay.com/itm/Chevy-SBC-35...JZZdpf&vxp=mtr

(Any reason the aluminum rockers wouldn't work?)

http://www.lunatipower.com/Product.aspx?id=1774

Although, i'm still not getting away from adding ZDDP to every oil change, or the somewhat "risky" cam break in procedure.

I've read so many articles about doing the break in on flat tappets, and it seems people commonly don't do it right, and ruin their cams and engines.
It seems pretty simple; just put the special lube on the cam lobes and journals and add break in oil.
Any additional info you can provide on the break in so I don't add myself to the list of boneheads who ruined their engines during break in?

dmruschell

I haven't taken the 75 much above 2500rpms, and haven't even opened the secondaries yet, and it pulls as soon as the stock TH350 torque converter catches, even with 3.08 gears. If you have a 2,000 stall converter (which 63mako says you do with the stock TH400), then the engine will rev up to 2,000 as soon as you hit the gas, before the car even starts moving. So, power under 2,000RPMs is irrelevant.

A roller cam of a similar duration and valve overlap will make virtually identical power as a flat tappet cam down low (the roller will have less friction to overcome, but the difference is not going to be much, if any). Power is made by airflow. The amount of air flowing at low RPMs is not anywhere close to the limits of a cam that can rev to 5500RPMs. None of the cams recommended to you are so big that the engines will still be choking on themselves under 2,000RPMs. Even my 268 Voodoo cam will pull from 800RPMs in my 79 with a manual transmission.

I don't know anything about the heads that he recommended. I'm wary of off-brand heads, especially from eBay sellers. Dart is a well-known brand of cylinder head, and Summit Racing is well known for their customer support, and the heads I recommended will also cost less. The reviews on the site speak for themselves - 41 5 star reviews, six 4 star reviews, and no reviews lower than that.

1.6 ratio roller rockers will increase lift, but will also increase duration. Duration is measured at a certain lift point, usually .050 lobe lift. .050 lobe lift * 1.5 ratio rockers = .075 valve lift. With 1.6 ratio rockers, the valve will reach .075 valve lift more quickly opening and will stay open more than .075 for a longer duration. All it does is make your camshaft seem like it has a little more lift and duration than it actually does, and is a quick way to get a little more power out of a small camshaft without changing the cam.

EDIT: Increasing lift without changing duration only increases the maximum amount of air the cam will let into the engine. It won't affect much of anything at low RPMs.

I personally don't like aluminum roller rockers because aluminum fatigues with no lower limit. If aluminum is stressed repeatedly, it's not a question of if it will break, but when it will break. Aluminum roller rockers were first used by racers who were rebuilding the engines and replacing parts every season because they're lightweight.

Steel, when stressed repeatedly (and not so hard that it immediately causes a catastrophic failure), will fatigue to a point, and then it will hold its strength forever, as long as the amount of stress doesn't change. So, I replaced my cheap aluminum roller rockers with stamped steel (but roller tip, which doesn't do much) rockers from Comp on my 79, and used the same rockers on the 75. They allow the use of stock valve covers. Comp also makes steel full roller rockers, but they don't guarantee valve cover clearance.

As for ZDDP, just buy oil that is made for a flat tappet cam (and made for use on the street) like Lucas Hot Rod Oil or Valvoline VR-1 (VR-1 is only marketed as a racing oil because it doesn't conform to current API standards; it's actually made for street use and standard oil change intervals). Both of those oils can be used during cam break-in without any extra additive, and don't require any additive after break-in, either.

I broke in the Duntov cam on my 61 Corvette (also from Lunati) by putting the lube supplied by Lunati on the cam and then filling the engine with Lucas Hot Rod Oil. I cranked the engine until it started and revved it up to 2,000 RPMs for the better part of a minute. Then, I exited the car and adjusted the idle screw as quickly as I could to get the car to run at 2,000-2,500RPMs for a half hour. I changed the oil after the break-in.

The DeLorean engine I put cams in didn't even get a real 2,000RPM break-in. The cam had lube on it, but it took a lot of cranking to get the engine started. There's no real idle adjustment, so we just got it running and idling for a little while (which is generally not recommended). Then, it was driven on a 500 mile trip. We had to adjust the valves after break-in (no hydraulic lifter mechanism), which was expected, but we didn't have any issues.

63mako

Enginequest heads are not offbrand. They are use extensively in circle track engines in specific classes limiting port size and requiring iron heads. They are cast in New Zealand and machined and assembled in the USA. The eBay seller is the manufacturer. The flow number are quite a bit higher than vortecs with thicker decks. They also come with head bolts. I seen a 430 Hp street build with the exact head I linked with a LT4 hot cam which is fairly mild. Here is a build using these heads with a little bigger 224 cam on a 108 lsa. http://www.hotrod.com/articles/0611e...c-small-block/ OP can do what he wants, I'm out.

dmruschell

Based on that article, those heads seem to be good performers. I had never heard of them before, so thanks for the info!

I did notice that those heads require a Vortec style intake manifold, though, which might make it difficult to keep the divorced choke the OP talked about in his first post. The Edelbrock Performer Vortec intake manifold doesn't even have provisions for the heat riser crossover.