Page 1 of 1

Big solid flat tapet cams.

Posted: Thu Nov 02, 2017 4:33 pm
by Berserk
Do the large solid flat tapet cams work well or are there a lage risk of them going flat? I se comp listing cams at 260-270 degree intake duration at 050 and 640 lift. Seems to me that it would be a very cheap way to make some desent power in a big block chevy. will a cam like that last on the street?

Re: Big solid flat tapet cams.

Posted: Thu Nov 02, 2017 6:12 pm
by pdq67
You might want to hunt up the late UDHarold's BBC solid flat tappet lifter cams and chat with some of the BBC guys that run them.

And I really miss Harold on the boards.

pdq67

Re: Big solid flat tapet cams.

Posted: Thu Nov 02, 2017 10:20 pm
by MELWAY
It's no so much the big duration that would make it in reliable but high lobe lift with fast ramps with cause early wear

Re: Big solid flat tapet cams.

Posted: Fri Nov 03, 2017 3:28 am
by Geoff2
High lift = more spring tension to control valve train
More spring = more wear
More lobe lift = smaller overall lobe, 'peakier' nose, less area to carry the load at max lift

Re: Big solid flat tapet cams.

Posted: Fri Nov 03, 2017 7:34 am
by DaveMcLain
Geoff2 wrote:
Fri Nov 03, 2017 3:28 am
High lift = more spring tension to control valve train
More spring = more wear
More lobe lift = smaller overall lobe, 'peakier' nose, less area to carry the load at max lift
More lift does not necessarily mean that you need higher spring loads to control the valvetrain. Often a lobe with more lift can have lower negative accelerations and actually require less load.

Re: Big solid flat tapet cams.

Posted: Fri Nov 03, 2017 10:15 am
by CamKing
It depends on the lobe design, but the longer the duration for a given lift, the less spring pressure you need, and the more reliable the cam will be.
We have a 260@.050" design with .615" lift, and it's very reliable, but I could design a cam with the same lift and duration that would require 100 more pounds of spring pressure, and it wouln't be very reliable.

Re: Big solid flat tapet cams.

Posted: Fri Nov 03, 2017 10:22 am
by Steve.k
We currently running two engines with flat cams. One is .657 and 260-266 @.050. The other .640 and 255-260@.050. Seem fine for reliability. Cam builder calls for 120-320 spring pressure! Hardly aggressive.

Re: Big solid flat tapet cams.

Posted: Sat Nov 04, 2017 5:53 am
by Geoff2
Dave,
Maybe you should read the OPs post...again.

Re: Big solid flat tapet cams.

Posted: Mon Nov 13, 2017 12:53 pm
by Berserk
How do I tell if it is a reliable cam or not? If I would like a cam with slower less agressive ramps that will live on the street. How about something like this?

Brand:COMP Cams
Manufacturer's Part Number:11-613-5
Part Type:Camshafts
Product Line:COMP Cams Drag Race Camshafts
Summit Racing Part Number:CCA-11-613-5

UPC: 036584540151
Cam Style: Mechanical flat tappet
Basic Operating RPM Range: 4,500-7,500
Intake Duration at 050 inch Lift: 270
Exhaust Duration at 050 inch Lift: 280
Duration at 050 inch Lift: 270 int./280 exh.
Advertised Intake Duration: 310
Advertised Exhaust Duration: 320
Advertised Duration: 310 int./320 exh.
Intake Valve Lift with Factory Rocker Arm Ratio: 0.638 in.
Exhaust Valve Lift with Factory Rocker Arm Ratio: 0.638 in.
Valve Lift with Factory Rocker Arm Ratio: 0.638 int./0.638 exh.
Lobe Separation (degrees): 110
Intake Valve Lash: 0.028 in.
Exhaust Valve Lash: 0.030 in.
Computer-Controlled Compatible: No
Grind Number: CB 310C-10

Re: Big solid flat tapet cams.

Posted: Mon Nov 13, 2017 2:27 pm
by statsystems
Berserk wrote:
Mon Nov 13, 2017 12:53 pm
How do I tell if it is a reliable cam or not? If I would like a cam with slower less agressive ramps that will live on the street. How about something like this?

Brand:COMP Cams
Manufacturer's Part Number:11-613-5
Part Type:Camshafts
Product Line:COMP Cams Drag Race Camshafts
Summit Racing Part Number:CCA-11-613-5

UPC: 036584540151
Cam Style: Mechanical flat tappet
Basic Operating RPM Range: 4,500-7,500
Intake Duration at 050 inch Lift: 270
Exhaust Duration at 050 inch Lift: 280
Duration at 050 inch Lift: 270 int./280 exh.
Advertised Intake Duration: 310
Advertised Exhaust Duration: 320
Advertised Duration: 310 int./320 exh.
Intake Valve Lift with Factory Rocker Arm Ratio: 0.638 in.
Exhaust Valve Lift with Factory Rocker Arm Ratio: 0.638 in.
Valve Lift with Factory Rocker Arm Ratio: 0.638 int./0.638 exh.
Lobe Separation (degrees): 110
Intake Valve Lash: 0.028 in.
Exhaust Valve Lash: 0.030 in.
Computer-Controlled Compatible: No
Grind Number: CB 310C-10

Depends on lifter diameter.

Re: Big solid flat tapet cams.

Posted: Mon Nov 13, 2017 2:56 pm
by CamKing
statsystems wrote:
Mon Nov 13, 2017 2:27 pm
Depends on lifter diameter.
????
That cam won't know what lifter diameter is on it, as long as it's bigger then .842"

Re: Big solid flat tapet cams.

Posted: Mon Nov 13, 2017 7:39 pm
by Newold1
Beserk

Your Comp Cams choice for a camshaft with durability for the street seems a bit of a contradiction?

How well does any engine become durable on the street when the operating range is 4500 to 7500rpms??

Think you better ask some one like Mike at CamKing and find a workable design for your application.

Re: Big solid flat tapet cams.

Posted: Mon Nov 13, 2017 8:27 pm
by pdq67
Like I said earlier, hunt up UDHarolds cams here and then talk to the guys that run them.

Might try going over to Team Chevelle and asking because imho, they have more BBC engines in their rides than Team Camaro and NastyZ28.

pdq67

Re: Big solid flat tapet cams.

Posted: Fri Nov 17, 2017 4:43 am
by Berserk
lifter diameter would be stock chevrolet. Yes I will ask at team chevelle to.