|10-27-2007 01:02 PM|
|F-BIRD'88||using the advertized seat duration of the lunati cam and Kelleys DCR calc i get basicly the same thing as Rippin Ron.. 7.08:1 DCR Should be ok on 91 octane at altitude.|
|10-27-2007 12:37 PM|
RippinRon, I agree with your static CR 9.43:1, but not your Dynamic numbers.
Heads shaved .030" = 4.2cc, 76cc - 4.2cc = 71.8cc ,
6.1cc valve cuts in pistons, .015" head gasket with 4.1" holes, 4.030" bore & 3.48" stroke, .025" deck height, 5.7" rods.
ABDC = 42* @ .050" lift + 15* = 57* (it really S/B + 21* , but to compensate for another error in the online calculator we should use + 15*)
I get a sea level DCR = 7.97:1 & 5,280' elevation DCR = 6.92:1
I have read that this lower DCR is "B/S" above 5K rpm?
Will this ping or knock on the best gas I can buy here in Colorado, 91 octane?
I've read that the Edelbrock Pro-Flo EFI should help with ping & knock?
I bought the David Vizard book How to Build Chevy small blocks on a budget. Good Book! Thanks F-BIRD'88. P.S. I'm having trouble finding the
lower control arm relocation brackets for my 72 Monte?
P 89, He gives these World Products SR Torquer heads his 5 Star award! "The head has excellent port velocity for a torquey engine in the 1,000 to 6,000-RPM range. The swirl developed was about eight to 10% better than the aluminum Corvette head described nearby."
|10-17-2007 07:55 AM|
|RippinRon||I calculate your compression ratio to be 9.43:1 and your dynamic at 7.18. World's web page say mill .007" per cc (to a max of .020" milled flat) and your pistons have valve reliefs of 6.1cc. This is where I got my dcr calculator plus its also a good read.|
|10-17-2007 07:36 AM|
A 4.56 gear seems a little much for that cam. But that car is very heavy so it may be OK. I think a 4.11 would be a little better for a street car.
Isn't a gear vender a 28% OD? That would make a 4.56 to a 3.28. Or maybe it is a 22% and then your calculation with be correct. not sure.
Yes, your heads are the weak link to making power. Bowl smoothing is the low hanging fruit when it comes to head porting. Pull out the valves and smooth out the transition where the bottom of the valve seat meets the port.
|10-16-2007 11:20 PM|
Well getting a machine shop to port a cheapy cast iron head is not very cost effective. Machine shop hourly labout is expensive.
You can actually finish them yourself. You'll need basicaly 1 carbide cutter 3/8" diameter cylinder shaped with a rounded end on a long 6" shaft.
you can completly contour the guide boss using this one cutter on both the intake and exhaust port. you need this long shaft cutter to get deep in the intake port from the manifold side.
The worst that can happen is you touch the valve seats with the die grinder cullet or cutter and need the valve job touched up.
You're not trying to make a prostock head outof them but a thourough complete porting is nessessary to make any power with these heads.
the port walls are nice and thick and will take a good porting.
Buy this book the S/R heads are covered specificly, in it plus a lot more.
You can also search my old post on porting 305 heads. The job is the same.
Yes you can buy all the rear end traction stuff from Summit racing. Its pretty straight forward. You need to modify the rear axle control arm geometry to eliminate axle squat and increase bite. The air bags do a good job of equalizing the right/left wheel traction making the LS differential work all the better.
The lower control arm relocation brackets and stiff lower control arms with stiff poly bushings are key . The adjustable upper control arms allow you to adjust the rear pinion angle. Once set up right the car will really hook up with a sticky tire. A drive shaft loop is recomended.
Can't help you with dialing in the Edelbrock EFI, I;m a old carb guy.
The bolt on track bars don't do much more than bind the suspension on these cars. Keep the sway bars.
|10-16-2007 10:40 PM|
I didn't know what I was doing in around the valve area & was cautious about going too deep & ruining a head. I did smooth off the surfaces that I could get to. I probably didn't accomplish much beyond matching the ports & opening & smoothing that interface area.
The Edelbrock manifold was a disappointment & I called their factory rep back then, he said something about mold shift, or something like that. I ground on the ports & straightened them out & smoothed out the sharp edges.
I wonder if there is a machine shop within 300 miles of me (I-25 & Colorado/New Mexico state lines) that could do a good porting job on my heads, at a reasonable price? Maybe in Denver?
I don't know what those rear suspension parts are, but I want to learn.
Where might I read up on them? Does Summit or Jegs sell them?
|10-16-2007 07:14 PM|
Well the 4.56:1 gear and 3000 stall are just right. Ditch the yeller traction bars and set up your rear suspension like would be done on a stock eliminator car.
(boxed in control arms, new poly control arm bushings. Lower control arm relocation brackets. upper control arm mount extensions. adjustable length upper control arms.) airlift air bags in the rear springs.
"I have port matched the heads to the larger ports on the Edelbrock manifold & opened up what I could get to with the rotary file bits I have. They have 2.02/1.60 SS valves and were advertised to be about 30HP improvement over my stock heads."
All fine and pretty but did ya get to the critical bowl area around the big ugly as cast valve guide bosses? If not, do that and wack another .030" off the heads decks. (68-70cc chamber volume) These heads can work for ya but need a full port job beyond what is easy to reach by poking a die grinder in the manifold port opening.
|10-16-2007 05:10 PM|
Hello, I bought & installed this cam 13 yrs. ago because Summit & Lunati recomends it for the aftermarket Edelbrock EFI which I also bought.
I had no online advice back then, so the cam is too hot, oh well too late now for this go-around. I will see how it works.
I don't want to break something is why I said 6K RPM I will see how it sounds before going higher.
I have port matched the heads to the larger ports on the Edelbrock manifold & opened up what I could get to with the rotary file bits I have. They have 2.02/1.60 SS valves and were advertised to be about 30HP improvement over my stock heads.
I just adjusted the Crane 1.52 roller rockers, 1 turn past zero lash. The rocker studs are ARP 7/16" The push rods are some HD black aftermarket & probably crane. Most receipts are gone. Springs are Crane dual coil.
I do have a 3,000 RPM stall torque convertor & a B&M T400 on it.
I have all the parts for a good HD rear end. Clean 12 bolt, Strange axles, Moroso posi with 456 gears, not put together yet.
I also have a Gear Vendors OD for it (not installed yet). It will make the 456 act like a 356 on the highway.
I need a good (short) HD driveshaft? I have some kind of yellow ladder bars for the rear end.
Am thinking of putting disc brakes on the rear?
|10-16-2007 02:59 PM|
SR = stock replacement. Don't expect too much.
The cam you have would require a 3.73 or 4.11 gear and a 2800 stall. What gear and stall are you planning on using? Plus you really need about 10:1cr for that cam, maybe even more since you will be at 8500 feet.
a set of 64cc heads would be a better choice. A set of iron eagles (200cc ports) might be a good choice.
why put in a 6500 rpm cam and only rev it to 6000? If you don't want to go past 6000 (for some reason?) then get a cam that only pulls to 6000.
|10-16-2007 01:44 PM|
I would change the cam for something a lot smaller because of the car (weight) and altitude and modest 9.3:1 compression ratio.
Something around 212 to 218@.050"
The S/R heads have modest flow in out of the box form Not much different from a stock GM 76cc head. Porting could fix that.
Why not ditch the EFI and supercharge it? Will more than make up for the lost power caused by the high altitude. If you happen to take a trip out of the clouds, carry a low boost supercharger pulley with ya to adjust the effective cylinder compression at the lower altitude.
A Weiand 177 pro street blower would rock on this motor.
Or keep the EFI and turbocharge it. You're a prime candidate for one of these rear mounted turbos.
|10-12-2007 01:07 PM|
I just looked at: http://www.compcams.com/Technical/DynoSheets/
the 288HR dyno graph might be close to my engine at sea level. A little over 400 HP & 380 ftlbs torque.
I have a little more CR & slightly less cam. Heads similar? my runners are smaller 171cc intake runners vs. 200cc
|10-12-2007 11:18 AM|
|BUFFALOBILLPATRICK||Heads shaved .030" & .015" heads gaskets. BBP|
|10-12-2007 11:06 AM|
It all looks great to me. The cam is a little hefty, especially at altitude. You might notice a pretty wimpy low end.
Also, double check your compression numbers. Flat tops with 76cc chambers should be more like 8.2:1, shouldn't it? I know my flat tops with 64cc vortecs just came in at 9.5:1
|10-12-2007 09:46 AM|
355 Chevy hop-up, will this stuff work together?
Hello, this is my 1st post here. I'm an old fart & not up on all the latest.
I'm trying to get my 72 Monte back on the road. My son took it apart 13 years ago & then discovered girls. Now I have finally found the time to work on it.
Short block was assembled back in 1994. Center bored, original crank & rods balanced, all bolts are ARP. Deck resurfaced & still has .025" above pistons which are balanced flat top forged TRW L2256F30. Deep oil pan with scraper & windage tray. Good oil pump (forgot brand) Fluid Dampener on crank.
Now I'm putting the heads on. World Products S/R Torquer, 76cc, 2.02/1.60 SS valves, 171cc intake runners, shaved .030", ARP head bolts, Felpro rubber coated .015" steel shim head gasket. .040" quench. Static CR about 9.33:1
I really should have about .030" milled off the intake manifold port surfaces, but this would be difficult with all the injector accouterments, so I'm going to try to get it sealed without the milling???
Lunati hydraulic roller cam 110* LSA, advertised 290/300* , (232/242* ABDC 42* @.050) Lift with 1.52 roller rockers is .517/.532 , ARP rocker studs , good quality dual valve springs, pushrods, gears & chain (forgot brands) This is suppose to be a 6,500 RPM cam, but I won't go over 6K.
Dynamic CR at sea level of about 7.9 & at 5,280' where I drive most about 6.8 This might be streetable on the 91 octane gas that is sold here in Colorado?
Edelbrock Pro-Flo fuel injection system (in process of installing). I port matched the intake manifold and the heads. Some of the Edelbrock ports were twisted. I need advice on fresh air intake?
Hedman Elite 1-5/8" headers. I have built 1" thick aluminum anti-reversion plates that go between the heads & the headers & port match. 2-1/2" exhaust system with good open flow mufflers with H-pipe.
I know that I will loose about lots (35%) of power due to the thin air, I live at 8,500'
How should all this work together? Sea level HP & torque estimates?
All advice welcome.
Thanks Bill Patrick