I would consider 170psi the rough limit of 91 octane. 98 you should be able to go up to 180psi comfortably and 190psi with a good tune.

From what I have experienced cutting a wide lsa ends up being a double edged sword. The grinders cut them straight up or only 2 deg advanced. Not only does the wide lsa drop your cranking comp the "retarded" intake position compounds it making the motor feel lazier than it should.

This combination then means its mandatory to raise your comp to compensate for what the cam is bleeding off. Anything more than 110 I consider a "turbo" grind due to the fact you want to add more psi through boost pressure. Advancing a wide lsa cam brings the intake back into a better position, I try to keep it somewhere between 108-104.

Very informative info gents, so I would like to further tap your knowledge:
 
What cam/specs would you recommend for hillclimbs with a Pinto using only 6000 rpm max?
 
I limit to 6000 to give longevity with cast pistons & standard rods.
Twin 40mm dcoe's, basic Vizard head porting, looking at 10:1 CR or a touch more.
 
What about the Kent FR30 ? (1000-6000 rpm, high torque, 260 deg duration, 110 deg lsa, about 12mm valve lift).
This camshaft never gets mentioned. Or would FR32 be better, even though only using 6000 rpm.
 
Cheers, Gregg

Noono

Very informative info gents, so I would like to further tap your knowledge:

What cam/specs would you recommend for hillclimbs with a Pinto using only 6000 rpm max?

I limit to 6000 to give longevity with cast pistons & standard rods.
Twin 40mm dcoe's, basic Vizard head porting, looking at 10:1 CR or a touch more.

What about the Kent FR30 ? (1000-6000 rpm, high torque, 260 deg duration, 110 deg lsa, about 12mm valve lift).
This camshaft never gets mentioned. Or would FR32 be better, even though only using 6000 rpm.

Cheers, Gregg

 
I would concur with Woz's formula and Spigots further comments above for this application to which end perhaps Woz can recommend an appropriate source for the cam.
 
In the mean time have you considered Piper OHCBP270, should fall in between the two extreames you mentioned?
 
Part No. Power Band Dur. In Dur. Ex V Lift In V Lift Ex Timing Lobe sep
FR30          1000-6000  260 260   0.481" 0.468" 20/60,60/20 110
FR32           2500-7000 272 285   0.434" 0.459" 31/61 79/26 111
OHCBP270 2000-6500 268 268   0.430" 0.430" 23/65,65/23  111
 
In my opinion I believe ultimately it needs to come down to your refered driving style - do you like to 'grunt' it out of the corners at lower revs (FR30) or do you feel more in control pulling down a gear and push out of the corner at higher rpm (FR32) or somewhere in between (OHCBP270)?
 
For reference the cast ACL hypereutectic pistons on std rods have proven to be quite durable for my application, doing a terrific job over the last 16 years and still going strong. The first four running rejetted stock carb, small bore headers, 2" exhaust, first stage Vizard head mods and used as a daily driver with regular 4,000klm + road trips thrown in, next eight years living under a car cover in the garage, last four years sprited weekend driving with dual 40 idfs, Genie large bore extractors and 2 1/4 exhaust; all up over 80,000klms travelled on an unopened engine with just routine maintenance. During that time I have used a max continuous rpm limit of 6,000k though have been known to hold 6,500rpm in the gears as required.
 
PS. suprised myself when I just sat down and worked out how many ks she has done on that engine, back of my mind I was always thinking only 20-25k
edit: formatting

IMO at power level you are chasing you will never damage the pistons or rods at 6500rpm unless you're dentonating the crap out of the motor. Even then you would probably pound out the bearings first.

I never compare cams based on advertised duration, only .050". There is no set standard for the aftermarket and with a mechanical cam lash makes it pointless.

If you are limiting rpm to 6000, peak power would need to be around 5500-5800rpm. Compression ratio works in had with the camshaft, so what is it? Is this std hc bottom end?

Thanks James & spigot,
The full story is:
 
Club rego, so will be driven in city occasionally as well as club level motorsport.
Twin 40mm dcoe webers, 4-2-1 headers, 2.25" exhaust.
Pinto block bored 1mm o/s, decked 0.25mm, standard crank & rods, Hepolite flat top cast pistons which come to 0.3mm below block deck.
Current head decked 2.3mm, Grp1 valves, basic Vizard porting, Waggot cam In 43/80, Ex 80/43, duration 303, lsa 108.5, lift 11.2mm.
The theoretical c/r is 10.8 : 1 which I've read is a little high for cast pistons.
 
It's a dog at low rpm, which I think is due to the large duration & valve overlap.
I have picked up a good untouched head, so I thought would get built with a different camshaft & about 10:1 c/r.
With the current block/piston setup, I would only need to shave the head 1mm max.
 
I liked the look of the Kent FR30 because of 260 duration & 12mm lift. I guess it's great around town, but may have peak power
too low for motorsport.
James, the Piper 270 looks like it could be a good option. Also the Kent website figures for the FR32 are
In 34/71, Ex 68/32, Duration 285/280, Lift 11.6/11.2mm, Lsa 108.
Spigot, the websites don't give 0.050" durations, but I guess only an email away. What does std hc bottom end mean?
 
Cheers, Gregg
 

Noono

Thanks James & spigot,
The full story is:

Club rego, so will be driven in city occasionally as well as club level motorsport.
Twin 40mm dcoe webers, 4-2-1 headers, 2.25" exhaust.
Pinto block bored 1mm o/s, decked 0.25mm, standard crank & rods, Hepolite flat top cast pistons which come to 0.3mm below block deck.
Current head decked 2.3mm, Grp1 valves, basic Vizard porting, Waggot cam In 43/80, Ex 80/43, duration 303, lsa 108.5, lift 11.2mm.
The theoretical c/r is 10.8 : 1 which I've read is a little high for cast pistons.

It's a dog at low rpm, which I think is due to the large duration & valve overlap.
I have picked up a good untouched head, so I thought would get built with a different camshaft & about 10:1 c/r.
With the current block/piston setup, I would only need to shave the head 1mm max.

I liked the look of the Kent FR30 because of 260 duration & 12mm lift. I guess it's great around town, but may have peak power
too low for motorsport.
James, the Piper 270 looks like it could be a good option. Also the Kent website figures for the FR32 are
In 34/71, Ex 68/32, Duration 285/280, Lift 11.6/11.2mm, Lsa 108.
Spigot, the websites don't give 0.050" durations, but I guess only an email away. What does std hc bottom end mean?

Cheers, Gregg

 
Gregg, the cam specs I suggested earlier should be about on the money for that rpm range.
 
Cheers,
Woz
 

What was the timing set at?

Thanks Wozzah.
 
I found the 0.050" timings for the Waggott - In 2/42, Ex 42/2, Duration 224
Is that similar to problem you mentioned with Crow - large advertised duration for small .050" duration ?
 
Spigot - full lift of inlet valve set at 108 deg ATDC,
Ignition timing 14 deg BTDC @ 1000rpm, Max 35 deg BTDC achieved at 3,500rpm
 
Cheers, Gregg

I have had a very bad experience with waggot.

Have you done a compression test?

Have you verified the actual cam position?

Have you tried loosening up the clearance on the lash, this will simulate a smaller cam?

Noono

Thanks Wozzah.

I found the 0.050" timings for the Waggott - In 2/42, Ex 42/2, Duration 224
Is that similar to problem you mentioned with Crow - large advertised duration for small .050" duration ?

Spigot - full lift of inlet valve set at 108 deg ATDC,
Ignition timing 14 deg BTDC @ 1000rpm, Max 35 deg BTDC achieved at 3,500rpm


Cheers, Gregg

 
You're right, it Looks like it suffers from the same issue as the larger Crow grinds, bugger all @.050" and massive amount of advertised. 
 
What you will be finding is the car will be very doughy down low, and because of the size of you carbs it will flatten off up top as well.  Bad combo, as it will lack basically everywhere.
 
Woz