After extensive reading on here and other sites, (my eyes are bleeding)
and talking with one of their reps. I have settled on an Isky mega 264/270 cam.(pn. 201264/271-12) Before I dive in, does anyone have any history with this grind. I have dart shp 180 heads,and 9.5 to 1 compresson, dcr = 7.65 TH 400 trans. with 3.36 gears. At 60 mph , rpm is around 2800. I know most of you prefer a roller, but I want to stick with a flat tappet.
Thanks

 

Some of Iskys cam lobe patterns are a little dated but, that being said, the quality of parts from Isky is some of the finest in the industry. I run some old Ultradyne patterns in some of builds that I have always had sucess with, by modern standards the acceleration rates aren't super radical, they were back in the 80s/90s when they were created, one thing I can say, they make great power and dont tear up parts. I have never had a defective part shipped to me from Isky, cant say the same for Comp Cams and this has happened more than once, I have had retainers and valve locks that aren't machined properly, stainless steel roller rocker arms that exhibited rapid wear within 1000 miles of use...cams with poor quality lobe grinding from several cam suppliers but, NEVER from Isky. Friends of mine agree, I have a buddy who builds many circle track late model sportsman high dollar engines and he has an old Ultradyne cam he uses as a testing standard against the latest " super duper " lobe profiles, sometimes that old Ultradyne might be 15-20HP down on power but, it has a 500RPM longer rev range and that is what will often win the races

 

Thanks for your reply
From what I've read, Iskys quality is first rate. I was wondering if anyone had any experience with that particular grind. Will there be an issue with a dcr of 7.65 ?
My current dcr is 8.3 and my cranking pressure is way high. (210psi)

 

What is your reason for changing from what you have? 8.3 DCR is preferable to 7.65?? 210 is not too high.

 

With SolidLT1 never had a failure and always liked the way thier cams ran. Unfortunately the handful of Comps Ive tried have all failed very early for some reason (except for one custom billet sr piece), so switched back.

Support the little guy or the only choices we will have will be the giants..and not so great stuff imo.

 

Give Harold Brookshire a call. 662-562-4933
Harold used to own UltaDyne Cams. He also designed cam profiles for just about every major cam company out there. This man knows camshafts!
Mr. Brookshire is a heck of a nice guy and will tell you exactly what you need for what you are trying to do. He is about 75 years old and likes to talk, so have an hour or so to spend if you call. You will be well educated when you hang up the phone!!

 

goin flat!

 

Go roller and you won't have to do this again.
That Isky looks like a good choice if you insist on going flat tappet.

 

in years past i always had very good luck with Iskenderian , Crower and Racer Brown. my only suggestion is Follow the manufacturers recommendation for installation exactly. Isky doesn't sell their cam lube only as a profit builder.

 

thanks mako
I blame myself for the wiped lobe. I guess I didn't break it in long enough. I think there was 4 like that. What about the lower dcr? Will I be sorry?

 

Lower DCR is a sacrifice you make to run less aggressive lobes and maintain comparable operating range. It will cost power. It will be safer on lobes. Proper open, closed and rate spring pressures are critical as is proper geometry. Stock rockers will many times not have a big enough slot to use bigger lift cams without bottoming on the slot. I like this assembly lube. http://www.summitracing.com/parts/CRN-99002-1/

 

It looks like that lifter never rotated in the bore. You may have issues with the bores for the lifters. Have you checked them for any problems. Do you have the head with dual springs now (127122)? If so break in with innners spring removed may help.
If you have the 127121 heads you may be stuck with flat tappet or at least less lift on a roller cam.

I'm with Mako on the roller cams. I really like mine. But it will cost another $1000 or so once all said and done and there are other considerations such as cam walk and the type of timing chain cover to use to handle this, shorter pushrods etc.
It looks like you have hooker side pipes there.
I would go with a minimally spit duration cam or no split with those as long as you're not using a restrictive insert in them.
I'm using the Dart SHP heads as well and have side pipes.
I have a 270/270 - 219 @ .050 on a 108 and make about 380 HP on this cam. More maybe once I get valve train resonance problems addressed.
If you drop your DCR you will lose bottom end torque.
High cylinder pressure is good for torque as long as you can keep deto at bay.
Didn't you have a problem with too much squish or something before? I don't remember exactly what is was.

If you have a good squish you could go with more lift and a little more duration, especially with a roller cam.
With the isky cam I'd run at least the 270 mega with 1.6 ratio rockers.
That would give you .496" of lift.
Do you have a higher stall converter? Helps a lot with lower ratio rear ends. Yours is at least a 3.36, better than the 3.08.

 

mako
When I originally broke in the engine, I had the 882s on with comps roller tip rockers.
They are now are junk because the push rod wasn't turning and it ruined the pocket where they ride.
reelav8r
The lifters turned freely in the bores when I removed them, I think I just screwed up.
My heads are 121s My headers are hedmans no side pipes. Isky has a 270/270 mega
I think its 108 lsa. I could advance the new cam and get the dcr higher 7.8ish.
squish ain't good .060
Thanks guys Lots to think about.
Oh and another thing, with a 108 lsa won't I loose vacuum for my brakes?

 

were they 1.6 rockers?

 

no 1.52

 

a lot of times people put 1.6 rockers in and don't elongate the slot. or they don't have guide plates or the guide plates aren't adjusted correctly or the pushrods are the wrong length, lots to remember isn't it?
hopefully you will have no more issues.

 

Vacuum has more to do with overlap in degrees, single vs dual plane intake and state of tune, displacement etc.
To get your overlap; take advertised durations and add together then divide by 4 take that result subtract the LSA and multiply that result by two.
Ie a 270/270 cam with a 108 would be 54*

270+270= 540
540/4=135
135-108=27
27x2=54* of overlap.

I'm at 9.9:1 CR with the cam above but a roller (roller gives a bit more vacuum) instead of flat tappet. I get 14 inches of vacuum at 800 RPM.
Even with 8" of vac I still have brakes and lights operate.
With that 121 head then you are set up for flat tappet and limited to .510 of lift. Try to get close to that .510. 1.6 ratio rockers will open the valve quicker than 1.5 RR. This is good for cylinder filling.
With a full exhaust system if it's not restrictive you might get away with a 270/270. Probably better with a bit of a split though.

A 108 LSA is good for cylinder pressure. So with that .060 quench it might not be your best option. Maybe a 112 LSA? Flat top, dish or D-dish pistons?
I'd give Staub a call and see what they recommend.

 

Good morning
My quench is .060 because the pistons installed are sp 345 which has a height of 1.567
That puts my deck at .045, with a shim gasket, I end up with .060. they are flat tops with 4 reliefs. If you recall any of my previous posts, I have multiple issues. The cam going flat, the high cranking pres., oil drawn into the intake via pcv, the list goes on and on. My plan is to remove the engine, (1) check the cam with a degree wheel, could be installed wrong, (2) do a leak down test with the rockers removed so I can compare tdc and bdc leakage If that checks out, (3) look at the bearings for damage from crap floating around (4) new cam install and valve train. I did talk to strub, I got some delfi lifters from him, he suggested Isky. I'm beginning to ramble on an on so, One more question, the builder installed a cam button during assembly, is it needed for a flat tappet? If the cam can't float a little, could it cause the lifters not to rotate? Thanks guys (I'm getting a head ache)

 

The lobes are ground at an angle on flat tappet cams and are offset from the center line of the lifter bore. This rotates the lifter also keeps the cam pulled backward. If someone put a cam button in a flat tappet there an idiot. Put a black magic marker line on all your push rods rotate your cam cam gear with a speed handle wrench and make sure every lifter with no doubt in your mind its spinning. Be nice before that step if you knew that your lifter bores are still round and in good shape. In like measuring things to know if there right. Isky mega cam is a long proven product. Don't worry about a 108 LSA with a short duration cam you will have enough vacuum.

 

Couldn't say for sure but there sure shouldn't be a cam button there. Could be you did it right and that button is the problem.