New "old" guy here

alloy

alloy

Member
Yes I'm old, get that out of the way right now. Old jokes are fine................I earned the right to be called "old"

Anyway, live in Vancouver, WA, got 6 grand kids, got 5 chevy's, work as an aerospace machinist. Owned a CNC machine shop for 15 years. Now I make aircraft landing gear, have weekends off, 2 weeks of vacation per year.

Been a gear head for about 40 years now. Used to look at engines and wonder how they worked. Been that way all my life, look at it and have to know what makes it tick. I enjoy building engines, transmissions, differentials, creating solutions for problems that others have given up on. My current projects are an 87 IROC-Z28 with a 305/TPI/T56/3.73 rear with eaton posi. Working on a replacement 355 with vortec heads. After the camaro is done I'll get back to working on my 55 chevy.

Hopefully I'll be able to contribute to the site in some small way.

Dan
 
youve picked a project that has both excellent potential compatiable product availability and its comon enought that youll have little trouble finding INFO and help
I don,t know what your performance goals are but with the correct compression, intake and cam that 355 with vortec heads could be an impressive combo.
BTW IVE only got 2 grand kids so far so your ahead on that score
 
Well, I didn't have much to do with how many grand kids I have. That part was out of my hands ;)

From doing some playing with comp cam's camquest software looks like with the stock tpi runners, vortec heads, edelbrock base, 9.6 comp ratio there should be a little over 300 ponies and about 470lb of torque. Good enough for a daily driver I hope. I'd like to maintain the 20 mpg I have now so I'm not going overboard with the cam, and am going to try the stock runners. From all that I read it seems that the stock tpi base is the biggest restriction. And if I do need to upgrade the runners later it's only an afternoon's worth of work to do so.

Cam choice is what's on my mind now. I’m waiting for Ed Curtis at http://www.FlowTechInduction.com to get back to me. The only thing I don’t like about the way he does business is that he designs a cam for you, you pay him and he releases the data to you, then he grinds the cam. Pay first ask questions later type of deal. I myself haven’t kept up with what’s been happening with cams in the last 20 years and don’t feel comfortable in choosing a cam for my combination.
 
the stock tpi runners , plenum and base,start to be a very noticeable restriction to flow rates by about 5000 rpm on a 355 sbc,assuming you'll run a basic flat tappet hydraulic cam like the majority of TPI engines came with, the cams intake duration should fall in about the 212-222 duration range at .050 if your trying to maximize the stock TPI intakes potential, and about 208-216 duration range at .050 if your trying to keep it really easy to drive on the street with no noticeable bad habits or lopey surge idle while still maintaining a wide tq curve and easy streetability, exhaust duration's are typically a bit higher to compensate for restrictive exhaust flow,and the lift will probably be limited to about .475 if your using stock vortec heads, Ive tried about 14 different commercial cams so far in stock and very mildly modded TPI combos, and thats the duration range that works the best, with a basically stock l98 TPI,yes the cam can go a bit larger , with the vortec heads and matching vortec base, but then youll need a manual trans or a higher stall converter, and probably more compression to use the extra duration, effectively and theres not much gained, in a nearly stock combo with typical gearing and compression, past that duration range, as you start to loose more on the bottom of the tq curve than the extra you gain in the upper rpm band, because of the restricted intake plenum and runner flow rates (altho the vortec heads are much better than the stock L98 heads.) if he takes the vortec base and heads into account youll get a bit more duration.
the TPI sensors tend to like a 112-114 LSA but you can run as tight as a 110 with the correct combo in cam timing easily.

let us know your custom specs when you find out please.

this might interest you

http://www.geocities.com/MotorCity/Down ... mspec.html

http://www.nastyz28.com/sbchevy/sbccams.php

how your cam LSA effects your compression ,torque , DCR

TIGHTER 104-110 LSA tend to increase scavenging efficincy but at the cost of less smooth idle LSA lobe separation angle is locked into the cam when its ground and can not change, if its ground at 110,degrees or 114 degrees it will stay that figure and LCA lobe center angle, can be...
garage.grumpysperformance.com

0607phr_11_z+camshaft_basics+lobe_centerline_angle_determination_chart.jpg


Duration_v_RPM-Range_wIntakeManifold01.jpg


craneq2.gif
 
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What I have for heads is a new set of vortecs modified by scoggins/dickey good for .525 lift. I've got a one piece main roller block I just yesterday finally got back from a machine shop for boring/deck plate hone/balancing, ect. I'm running KB -12cc "D" dish pistons for a 9.6 ratio, 5.7 rods. Block is zero decked for a .040 quench. Trans is a T56 and 3.73 rear. If I'm good til 5000 rpm with the stock runners that would work good for my intended use.

And yes I'd like it to not have any bad habits. It's my main driver because I'd rather push my camaro than drive my wife's grand am. There are times I find myself loafing along in 6th gear following traffic at 1000 rpm with the little 305 and peanut cam in it.

I'm thinking that I'll probably pay for the cam and get the specs and not give the go ahead until I get some input from others more current on cam technology that I am.
 
with those heads, higher cpr, manual trans, etc, and that rear gear ratio, youll be able to run more durration and lift than most guys can get away with and still have a sweet combo, Id say youll be on the upper edge of that durration range listed above and still have no problems, something in a 218-225 durration should
easily add 40-45 plus hp over the stock tpi roller cam
 
Four grandkids here, so in the middle of you two....
Sweet projects there, Dan, will enjoy watching how they develop for you...
Aloha,
Willy
 
Well seems like Ed Curtis has forgotten me. Any suggestions for someone else to contact about a custom cam?
 
I buy about 90% of the cams I use from
erson
crower
or
crane

theres almost no reason to buy a custom cam as one of the three suppliers will almost always have something thats either extremely similar or exactly matching what you need , now they may not catalog, & list that grind, but they most likely have the specs and can manufacture it for you in 48 hours, keep in mind if you get too creative, or markedly differant from the HUNDREDS of combos they have tried and built, your very likely to produce something that the engineers KNOW won,t function correctly.


viewtopic.php?f=52&t=155

viewtopic.php?f=52&t=82

you might also consider that most manufacturers can grind almost any lobe design on almost any LSA betwen about 102-118 if you ask, and are willing to pay thier custom cam fee.

erson
crower
or
crane
EACH have THOUSANDS of cam lobe profiles listed in thier lobe data base, that can be mixed and matched by each manufacturer, but about 99% of the time everything that functions correctly, and meets the durability limits of any reasonably comon engine combo is available from one or more of the manufacturers if you ask.
 
grumpyvette said:
let us know your custom specs when you find out please.
Click to expand...

Here is what I got today.


www.flowtechinduction.com
Custom Camshaft Spec Card

Part Number: NA-08-90S35B-HR11 +3* Customer: Dan

Intake Exhaust
Valve Adjustment: .000” .000”
Lobe Lift: .353” .353”
Gross Valve Lift 1.50 Ratio: .530” .530”
Gross Valve Lift 1.60 Ratio: .560” .565”

Duration @ .050” Tappet Lift: 214* 224*

Lobe Separation: 111*

Recommended Intake Centerline: 108*

Specs at 108 Degree Intake Centerline:
Valve Timing at Open Close
.050” Tappet Lift: Intake: (-1*) BTDC 35* ABDC
Exhaust: 46* BBDC (-2*) ATDC

Degree this camshaft using the specs provided on this sheet. The asymmetrical design of these lobes will not allow for accurate reading using the centerline method.

This camshaft is designed street driven, high torque TPI applications

CHECK and verify rocker arm geometry and lifter preload
This is imperative for optimum performance of this camshaft

The power band is roughly between 1500 to 5000 rpm for 350-358 CID

The preferred valve spring pressure is 130# -135# on the seat
PAC Racing 1218 or 1518 beehive springs highly recommended
Use only quality valve springs with high performance locks and retainers
Hardened push rods required for valvetrain stability

Lubricants with high zinc content required for long term endurance

It is highly recommended to check and verify piston to valve clearance
Failure to do so may result in serious cylinder head and engine damage
 
ID bet youll get a noticably lope to the idle compared to the stock cam, and it makes realy nice power in the 3500rpm-5800rpm band, but let us know the results and your impressions after its installed and you get it tunned for a test drive.
 
The concerns I have are the lope, and the rpm range. This is my daily and gas mileage is a very real concern unfortunately. And the statement that I need to run high zinc oils to keep the from wearing long term. The lift seems kinda high for a daily also. Worried about long term spring life.
 
IF IM not mistaken thats a HYDRAULIC ROLLER CAM, so your concern over use of high zinc oil is unfounded, as too valve springs and lift, if you use the suggested pac beehive springs your fine if the clearances are carefully checked.
as to the rpm band, keep in mind the way you drive and your rear gear ratio and trans gearing, and type of heads all effect your results. but a manual trans and a 3.73:1 rear gear and a 9.6:1 cpr and those vortec heads are all well matched to the cam
 
Grumpy,

I really appreciate your taking the time to give me your thoughts on this. It's easy to live with too small a cam, but too big is a real pain. Been there with a motor somone else built, don't want to go there again. That's why I'm asking experts like you for help this time.

I wrote back to Ed Curtis with a few concerns and here is his reply.

-----------------------------------------------------------------

Ed,

I have a few concerns about the cam specs. From what I understand from advice given to me be someone way more knowledgeable than I, it looks
like there will be a noticable lope at idle, and the power will be mainly
in the 3500 and up range. I need it off idle to around 4000-4500 with my
TPI setup.

~~ The profile should have a very smooth torque curve from 1500 through 4000 where it will plateau. Unless this is a smaller engine than a 355, the cubes will suck this thing up like cold milk and a thirsty cat. It's actually very similar to my Suburban's profile and we tow the car trailer with it.

Also needing to run oil with high zinc content for longetivity. I understand oils will be reformulated again and the zinc will most likely go down even more. After the motor is broken in I'd planned to swith to Mobil 1 synthetic.

~~ The distributor gears need to have the extra zinc to survive. The cam's lobes and lifters are very rarely a problem but the lack of zinc makes the gear meshing build up heat. I prefer the oils with *some* zinc in them for curing this isse but you can also use four quarts of your favorite blend of synthetic with one quart of Royal Purple racing oil Even the wife's SRX gets five quarts of Pennzoil synth and one quart of RP #9 when I change the oil. The VVT system is really smooth because of it.

I drive this car 40 miles per day and a lot more on the weekends. There are times I'll be loafing along at 1000 rpm in traffic. And when I autocross the car I need power and torque down low, and gas prices are going up again unfortunately.

~~ I based my design on the 3.73 gears, 2.66 first gear and the good flowing heads you have. The entire inlet tract is actually quite nice for this quest. I'd be willing to be you can get similar 305-style mileage as well as more HP when she's all dialed in. Please don't blame me for excessive rear tire wear however....
 
let me know YOUR impressions of the engines power and drivability characteristic once its all set up and tuned!

BTW,I never even hinted the car won,t run well, but I think youll find that the cam pulls well higher than 4000rpm that he stated and its noticably more responsive above 2500rpm than below that level,
and really like I said
"ID bet youll get a noticably lope to the idle compared to the stock cam, and it makes realy nice power in the 3500rpm-5800rpm band, but let us know the results and your impressions after its installed and you get it tunned for a test drive.
ID bet youll get a noticably lope to the idle compared to the stock cam, and it makes realy nice power in the 3500rpm-5800rpm band, but let us know the results and your impressions after its installed and you get it tunned for a test drive. "
everything in the combo is designed for torque in the mid rpm band and thats roughtly the 2500rpm-5000rpm range, now Im not saying the car won,t pull smoothly from about 1500rpm in part throttle, Im simply stating that if you nail it at about 3500rpm and shift at about 5500-5800rpm youll be surprised at how responcive it is
 
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