Got my latest Street Rodder today and was pleasantly surprised to see a few Nailheads for a change. BUT ... There's a 32 Coupe featured with a 401 that ... and I quote ... "packed with all the right bits." Based on all the stuff I've read on this forum over the last two years I'm not so sure of that statement Egge Machine pistons - been a few comments on some of those Isky cam - well, that will depend a lot on the cam but to just say 'Isky cam' tells me ****. Give me a 091 any day. Offenhauser 2x4 manifold - fail I believe - is that the 'awfulhauser'? Edelbrock Thunder Series AVS 500cfm carbs - no idea Wonder where he got his 'spec' list from - a chevy builder? Certainly doesn't sound like a list I'd be using for my Nailhead.
Agreed, not a good parts list. I wonder what that build would dyno at? 250hp? There is a fix for the Offy manifold, it'll cost ya $200 tho. Russ announced it last year. Things are looking up tho.... The new pistons Tom has been working on will provide a solid foundation for a build.
Tommy Ivo and Tony Nancy both ran exclusively Isky cams. Though not a Buick guy Don Garlits did too. When Ivo and Nancy were running nailheads the late 1950's they most likely were using Polydyne 505's. Those cams set records nearly everywhere they were raced. The 505 got Ed Iskenderian the nickname "Camfather". If you call Isky today and ask them about grinding you a nailhead cam, they will sell you a 280HL. Its a good cam, an excellent step up from a stocker. It is a little small for any kind of serious performance but it does sound nice. The reason they sell you a 280HL is because anything larger requires dropping the base circle and adjustable valvetrain. They don't have new blanks, I inquired about this and I was told that no USA made blanks were available. (Their boxes say 100% made in the USA and they mean it). Even with lowering the base circle its really difficult to .500 lift and an adequate amount of duration. I am with you on the Egge pistons, and the Offy intake. Anybody that spews a blanket knock on Isky cams either has no idea what they are talking about or is mad because they don't give lower volume sellers much of a discount. Through my wholesaler I get 20% off Jobber on Comp Cams products, I don't buy a single one. All of my cams come direct from Isky, you pay a little more but you get a higher quality product. Fair trade off in my book.
have to disagree.cams have come a long ways since isky made the 280hl cams. you will have 10-15 hp loss with that 56*slow ramp speed. plus isky never liked dual pattern cams with more exhaust duration, which might help the nailheads bad flow small exhaust valves .some modern cams have a much faster ramp to make more power with a better idle too. if you don't like comp cams for what ever reason, theres a small co.called camcraft cams in arden,nc. has a 800,000.00 dollar up to date landis cnc cam grinder, for some modern cam designs. I do agree the pistons and intake manifold hurt that engine more than the camshaft did.
Cams are constantly progressing. A 280HL is not the cutting edge of camshaft design, but it is a good step up from stock camshaft 091 or otherwise. I built a 401 and a 364 both with 280HLs. Had very delighted customers with both engines, nice sound and great drivability. The idea that Isky is slowing down the ramps from a stock camshaft, or that it would cost you 10-15hp is just not true. If you are comparing duration or seat to seat timing on the two it is very deceptive. Isky factors advertised duration and lift points at .020 lift where as the SAE method is either .002 or .006 depending on the year it was done. For fun I ran the specs on an 091 camshaft through my desktop dyno. Before you snicker at the idea of a desktop dyno I have built 4 engines, and had customers run them on chassis dynos after they were completed. Output from the program to the wheel dyno dropped between 20-32%. While not right on its an indication. I scanned the printouts; peak power was within 2hp however the 091 gave up at least 20hp and between 20-60 ft lbs of torque under 4500 rpm to the Isky. These figures were calculated on a .040 over 425 with my ported heads 216 and 155 cfm @.500 lift. While the peak numbers are not that impressive the I/E ratio is in the low 70s across the board. This may be helping the Isky a little and hurting the 091 but I dont think it would affect it much. I built a full roller 468 big block Chevy for a good friend of mines boat, all Comp Cams. The first time a tie bar broke on a roller lifter it wiped out two lobes, galled a 4340 Scat crankshaft (we were able to grind it .030), scuffed the skirts on some new JE pistons (threw them away), and nearly destroyed the block by egging out a lifter bore (sent it to LA and had it bronze bushed, all 16). The second time a tie bar broke (different cylinder) it ruined the crank (no regrind left), destroyed a second set of JE pistons, and ruined a lifter bore bushing. This all happened within the course of 3 years. Comp Cams said that incorrect valve train geometry caused the failure. Been running Isky Red Zone roller lifters in that engine since 2005, with no issues, I set up the valvetrain geometry both times and its right.
good post here, am trying to understand why the smaller 091 cam would out perform the bigger isky cam at higher rpms and lose down low. any way of adding. 25 thousands more lift to the 091 cam or taking away .025 from the isky on the desk top? just for the heck of it to see how it helps the 091 cam across the board. no way there can be 60 ft tq more in the real world,those kind of numbers shows the desk top messed up.
Hi 487, those are desk top dyno numbers right? There were a few older threads where a lot of desk top dyno stuff was compared. Its pretty interesting. Seems desk top is always a little low on TQ and little high on HP on nailheads from what I can see.
The issue I see with the Desktop Dyno comparison is that you have the @ 0.050" specs for the Isky cam, and the advertised specs for the 091 cam. To be a meaningful comparison, both should use the @ 0.050" specs, as this provides the most accurate results. I suspect that once that is changed, the 091 cam might make slightly more low end torque, but will be out performed in high RPM horsepower. I've played around with Desktop Dyno quite a bit, both the 2000 and 2003 versions, and it's usually very accurate. This includes some Nailhead builds like Erik's 425, and Ted's 401. It's a great tool for comparing different cam profiles and head flow characteristics.
My desktop dyno will take either SAE seat to seat timing or @.050 specs. Regardless if someone has .050 specs for an 091 post them and I will re run the test. Also if someone has a set of accurate flow numbers for stock 401/425 heads I would like to re run with those. If I remember correctly the I/E ratio on stock heads in in the low 60's. This would probaley help the 091 camshaft, with my head figures the additional duration on the exhaust side may be hurting its numbers.
Somewhere on this site is a collection of stock and ported flow numbers from some big time porters. I don't know how to drag them to this thread. I also have stock flow numbers in my notes if you would like.
Yes, although the program will take either figure, it tends to be much more accurate with the @ 0.050 values. It's even more accurate if you can provide both, as this allows it to also determine the lifter acceleration rate, and determine how aggressive the lobe is. The problem is, Buick rated their advertised duration at 0.002 if I remember correctly, not by the industry standard. Walt degreed a stock '66 cam and I think came up with around 207* @ 0.050. Attached are some screen shots from the dyno program with various flow sets. There is a brief description of what each setup actually is.
[TABLE="width: 1307"] <colgroup><col><col><col span="8"></colgroup><tbody>[TR] [TD="colspan: 10"]This is an interesting flow comparison for various Buick head, valve and porting combinations. I own or owned most of the heads involved and have the flow sheets. Some were before and after porting #s of the same head. All flow #s were at or converted to flow @ 10" of water. Multiply any of the #s by a 1.67 conversion factor to get the flow @ 28" of water (industry standard). I just happened to have more flowed at 10" than 28", and I had to go one way or another for comparison[/TD] [/TR] [TR] [TD="colspan: 10"]Steve Berry[/TD] [/TR] [TR] [TD="colspan: 10"]Buick Intake Flow Comparison[/TD] [/TR] [TR] [TD]Engine, Valve Size and Porting Status[/TD] [TD]Tester and/orPorter[/TD] [TD]Water[/TD] [TD]Conv. Factor[/TD] [TD].100 Lift[/TD] [TD].200 Lift[/TD] [TD].300 Lift[/TD] [TD].400 Lift[/TD] [TD].500 Lift[/TD] [TD].600 Lift[/TD] [/TR] [TR] [TD]401, 1.87, None[/TD] [TD]Mike Kamm[/TD] [TD]10[/TD] [TD]/ 1.67[/TD] [TD]53.4[/TD] [TD]110.2[/TD] [TD]157[/TD] [TD]180.4[/TD] [TD]190.4[/TD] [TD]195.4[/TD] [/TR] [TR] [TD]401, 1.94, None[/TD] [TD]Steve Magnotty / Carmen Faso[/TD] [TD]28[/TD] [TD]NA[/TD] [TD]58.9[/TD] [TD]119[/TD] [TD]164[/TD] [TD]179.4[/TD] [TD]183[/TD] [TD]184[/TD] [/TR] [TR] [TD]401, 1.87, Medium[/TD] [TD]Mike Kamm[/TD] [TD]10[/TD] [TD]/ 1.67[/TD] [TD]56.8[/TD] [TD]111.9[/TD] [TD]158.7[/TD] [TD]192.1[/TD] [TD]210.4[/TD] [TD]202.1[/TD] [/TR] [TR] [TD]401, 1.87, Moderate[/TD] [TD]Greg Gessler[/TD] [TD]10[/TD] [TD]/ 1.67[/TD] [TD]61.6[/TD] [TD]7127.1[/TD] [TD]170.7[/TD] [TD]196.6[/TD] [TD]211.9[/TD] [TD]219.1[/TD] [/TR] [TR] [TD]401, 1.94, Moderate[/TD] [TD]SteveMagnotty[/TD] [TD]28[/TD] [TD]NA[/TD] [TD]61[/TD] [TD]121[/TD] [TD]172[/TD] [TD]201.4[/TD] [TD]215[/TD] [TD]223[/TD] [/TR] [TR] [TD="colspan: 10"] [/TD] [/TR] [TR] [TD="colspan: 10"]Buick Exhaust Flow Comparison[/TD] [/TR] [TR] [TD]Engine, Valve Size and Porting Status[/TD] [TD]Tester and/orPorter[/TD] [TD]Water[/TD] [TD]Conv. Factor[/TD] [TD].100 Lift[/TD] [TD].200 Lift[/TD] [TD].300 Lift[/TD] [TD].400 Lift[/TD] [TD].500 Lift[/TD] [TD].600 Lift[/TD] [/TR] [TR] [TD]401, 1.50, None[/TD] [TD]Mike Kamm[/TD] [TD]10[/TD] [TD]/ 1.67[/TD] [TD]45.1[/TD] [TD]76.8[/TD] [TD]98.5[/TD] [TD]113.6[/TD] [TD]118.6[/TD] [TD]120.2[/TD] [/TR] [TR] [TD]401, 1.50, None[/TD] [TD]Steve Magnotty / Carmen Faso[/TD] [TD]28[/TD] [TD]NA[/TD] [TD]47.7[/TD] [TD]81.5[/TD] [TD]112[/TD] [TD]119.5[/TD] [TD]123.9[/TD] [TD]125.4[/TD] [/TR] [TR] [TD]401, 1.50, Medium[/TD] [TD]Mike Kamm[/TD] [TD]10[/TD] [TD]/ 1.67[/TD] [TD]40.1[/TD] [TD]78.4[/TD] [TD]101.9[/TD] [TD]121.9[/TD] [TD]131.9[/TD] [TD]131.9[/TD] [/TR] [TR] [TD]401, 1.50, Moderate[/TD] [TD]Greg Gessler[/TD] [TD]10[/TD] [TD]/ 1.67[/TD] [TD]48.3[/TD] [TD]82.7[/TD] [TD]108[/TD] [TD]130.4[/TD] [TD]138.1[/TD] [TD]141.4[/TD] [/TR] [TR] [TD]401, 1.50, Moderate[/TD] [TD]Steve Magnotty[/TD] [TD]28[/TD] [TD]NA[/TD] [TD]52.0d>[/TD] [TD]93[/TD] [TD]126[/TD] [TD]141[/TD] [TD]150[/TD] [TD]153[/TD] [/TR] </tbody>[/TABLE]
looks like just running a big intake valve (1.94) hurts with out porting the head. that's interesting. also that makes sense with the high advertise numbers on the 091 cam and the weird dyno numbers
Yah, after seeing what snake did with a 1.87 I am wanting to start playing with the stock valve. Could be a lot to the shrouding with the 1.94. Snakes numbers are the best I have heard so far :TU:
Good call Cheryl! It appears as if the 1.94" intake valve only hurts relatively high lift flow. Since the low and mid lift flow values are improved (from roughly 4% to 10%), I'm not sure I'd totally discount the larger valve, especially when most Nailhead applications are barely over 0.500" lift. Improving low to mid lift flow can have significant effects on overall power output. It isn't all about peak flow. Bob, do you still have the molds you made of the intake and exhaust ports? I would really love to model them in a CAD package, and utilize some of the Mechanical Engineering software that is being made available to me this semester, primarily ANSYS and its fluid flow simulations. I've seen the power of this simulation software and it would be interesting to see, approximately, the flow patterns, and subsequently, the improvements we could make in port design and architecture.
I myself have found on my test head that as my high lift numbers went up so did all my numbers across the board. This might not be true on all heads. As for the shouding, I had a idea I wanted to try on my test head and last month had a warm day and ran out to the shed and did a little unshrouding on the intake side and back to back test showed only a 600 and 700 gain. I was hoping to get that .500 number up. .600 went from 242 to 246 and .700 went from 252 bto 256. I know no one with a nailhead will ever use 700 lift but I like to see what the port is doing And that is a 1.94 valve. I have been able to match my 1.90 valve in my heads I am doing pretty close to the 1.94. Andy, I still have all them molds. I will send a pm:TU:
I went mild with the chambers, 80 grit on those eye lids and the whole chamber then 120 grit and polished with metal polish and 2500 buffer. the valves I bought from Russ Martin could possibly be Miloden stainless swirl then back cut 30* and buffed polished with valves in.Of course the bigger the valve the more it shrouds. The valves I have are stock size 1.87 but are stainless and design is alot better than stock.
