|07-05-2012 02:56 PM|
with the AFR heads the car is going to pick up regardless if you change the cam or not. I MYSELF wouldnt waste money on "generic" cam grinds they maybe low cost but Ive seen cam specs way off what they should be from "generic" cam grinds... I trust Comp cams, but id trust Isky more than even comp Cams, I do however like the XE comp cams line, and with the AFR heads the XE 274 although a bit larger in duration with the added lift will make ALOT of difference with what you have...
If you insist on keeping the intake you have do yourself a favor and at least port it... The weiand Stealth intake Flow's decent, but the professonal products single plane, (second time ive recomended that intake today) will work well and not cost you much bottom end with its "ram" effect.. So I recomend..
The Afr heads
CC XE 274 cam
Pro products single plane intake.
if money permits add an x-pipe and aero chamber mufflers
STICKY tires as well cuzz if i drove it with that combo Id be sideways in 3rd gear
|07-04-2012 08:26 PM|
The combo he is giving you is right on for what you wanna do
Cam should be pretty close to 450 460 or so lift n 220 to 230 duration @0.50
Thats about what he recommended
Listen to this guy.....Knows his chit......I been readin his posts
By the way I use 1.6 rockers with this cam,when that wasnt available I used BB rockers n bumped the covers for clearance........But that was Soooooo long ago
|07-04-2012 06:38 PM|
If you are going to run a 27" tire get 4.30's.
The tire diameter has an effect on the overall effective gearing.
No wonder it's a snail.
Your present cam timing open close numbers are -3 47 intake and 45 -1 ex
These are @.050" lifter rise
224-224 115-113 centers 114lsa .450-.461
Should be on the cam card.
that cam was designed for 11:1 +++ cr.
It is dead with anything less than about 10.3:1 compression.
Advancing it by 8deg (39deg intake) closing point will help low end power)
107 in 121 ex centers
This will help some but this cam does not like a stock converter, low compression or stock gears at all.
That cam needs a 3000++ stall converter (9.5" lockup (245MM) with funtional lock up
Your 291 casting heads just need porting (felpro 1205 gasket size.)
The compression ratio needs to be corrected to 10.3:1 10.5:1
may just need a .015" shim style head gasket and a head deck clean up.
Get a perfomer rpm manifold and 750cfm holley.
Isky 270 Mega cam #201271 with 1.6 rockers
270-270 221-221 @.050" .495" .495" valve lift with 1.6 rockers. 108LSA 104In c/L
same idle much more power.
much better cam,,, do all this and be prepared for 12sec ET performance.
4.30 gears 27" ties overdrive
Easy hiway cruise at 2350 rpm 100KLMS (62MPH) 2990 rpm @80 MPH (130KPH)
You can cruise to your hearts content. Be prepared to get nailed to the seat when you rug it.
Don't let your face crack from the perma grin.
This is how a 327 Camaro was intended to go.
|07-04-2012 03:54 PM|
|ap72||You can calculate it but a lot of cam manufacturers provide it. I wouldn't get cheap on the cam, cheap cams have 40 year old lobe profiles and they've improved a lot since then.|
|07-04-2012 03:15 PM|
F-Bird, one more question.
Where do you get the numbers for the cam intake closing? I'm looking through the CAM shaft descriptions for comparison and can't find that number.
Is this something you calculate from the other specs?
(BTW, my tires size is 255-60-15 ..should be a 27" overall height..or close to it)
|07-04-2012 12:30 PM|
I'll pic up a set of 3.73 gears from Summit and start there.
|07-04-2012 12:05 PM|
|ap72||4.30s would be a hair too much around here as the interstates are 70-75mph traffic. 4.10s would be about right though.|
|07-04-2012 11:58 AM|
4.30's would not be too much for this car especially if the tires are tall.
Will hiway cruise in OD sweet sweet sweet.... and haul the mail when you hammer the throttle.
3.00:1 overdrive cruise ratio 2400rpm @62MPH (100KPH) based on a 26" tire diameter.
Let this sink in: with 430's you can cruise at 3100rpm @ 80MPH 26" tires (P-245-60-15)
now you are cooking with gas.
|07-04-2012 11:47 AM|
You probabily need to correct the real engine compression ratio. I bet its way too low.
This often is as simple as a head gasket thickness change.
What pistons are in the motor? Deck clearance height @TDC.
|07-04-2012 11:38 AM|
|ap72||Swap cams, swap gears, and leave the rest ALONE for now. Don't get too far ahead of yourself. Id set your cruise rpms for about 2500 or 2600.|
|07-04-2012 11:23 AM|
What is the rear tire diameter? What is the tire size on the side wall.?
The carb is too small and has a generic (universal) calibration that needs improvement.
More power and torque using a RPM stylehi rise dual pane intake manifold over the performer.
Its just a flat out way better intake manifold.
|07-04-2012 11:19 AM|
We are only trying to help, but it does mean changing things "again" and more money but the suggestions will work in this case. Believe me I have been building hotrods of all types for 30 years and did I make a lot of mistakes on my own stuff that cost too much for many years, still learning and listening too. good luck, do the gears first and the current cam will work better, not great but better then change cam as funds allow. later man.
|07-04-2012 11:18 AM|
"idle at hiway speed"
You don;t want o be idleing at hiway speeds.
This is the problem. You want a high performacne cammed motor that likes rpm
yet want o operate the motor at rpms that are below the best rpm range for that cam.
3.73 is a compromise. You should stick in 4.10's in that car.
The OD ratio cuts the gear down by 30% which in fact has a much more profound effect on the higher ratios.
3.73 becomes 2.611 :1 in OD.
You want the car to "cruise on the hiway (100KPH) at around 2200rpm.
The 3.73's are just right for that.
Running the motor slower will not increase efficiently, especially with a cam that wants rpm.
If you want to cruise at 1500rpm you need a "stock cam with very short duration' 185-195@.050" to get any benefit at all.
3.55's is the wrong gear and a waste of time and money.
you want 3.73 or 4.10.
cruise rpm at hiway speeds in OD is just right. Right in the sweet spot.
With 3.36's the cruise rpm is too low.
Acceleration is lame. 3.55''s will not fix that big waste of time.
camshaft prices: You get what you pay for.
Isky Cams are all made in house. Very high quality.
One of my go to first choices for any Hyd and solid flat tappet cams.
You get what you pay for.
Your cam can be improved by degreeing it to verify vam event timing and then advancing it 7-8deg . Intake C/L @107° BTDC.
right now its retarded by 1 deg (115in C/L)
this will close the intake valve sooner and increase efficienty and torque.
You must degree it before moving it.
I'd change the cam thou.
You will notice all the cams I recomended have a intake closing point of 31 to 36deg ATDC.
Your cam has a very late closing point 47deg. needs 11:1++ cr and rpm. and big gears. and a 3000+ stall
Its dead in your motor and car. its a mismatch.
Was not even a good cam in 1968.
|07-04-2012 11:01 AM|
Lets not fight about anything and get back to the discussions.
As AP pointed out, I have always been concerned about putting in ratios like 3.73 in fear of having too high of an idle at highway speeds. Also, we like to use the car when doing vacations and such...so we opted for the 3.36 to get the benefits of extended highway cruising. Hard to get the best of both worlds.
What about a reasonable compromise like 3.55?? (Its available for my rear rear axle).
WRT to the Cam..
The Summit CAM is reasonably priced and affordable especially as a kit (under $100 bucks including lifters)
Summit Racing SUM-K1103 - Summit Racing® Cam and Lifter Kits - Overview - SummitRacing.com
Here is another one that I believe is very similar:
Isky Racing Cams 201264-27112 - Isky Hydraulic Flat Tappet Camshafts - Overview - SummitRacing.com
I have to wonder why the Summit kit..which looks like a very useable product (and fits part of the recipe F-Bird gave) costs a third or half the price of the other cams.
|07-04-2012 10:04 AM|
No way !!!! I'm the most arrogant SOB on this forum.
Lets fight about it.
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