irocbrninrubber

Like the post says, I need help picking a cam. My main goal is to get into the 12's with a 86 iroc. So far what I have is 350 hydraulic roller block w/cast aluminum flat top speed pro pistons, LT1 rods, gm crank, Holley aluminum heads 68cc, and street dominator intake. What cam would you recommend to help me get to my goal? The car will be a weekend car so i want it to be streetable, but i really want to get in the 12's. Oh, also will be mated to a t56 and 373. I have been looking into this cam Lunati 60104LK.what input do any of you have on this cam? Any advise would be appreciated.

sofakingdom

iTrader: (1)

Why the flat-tappet cam?

That's a decent "size", and all that; but look at rollers in a similar vein, instead. Low 230s of intake duration. I don' tknow offhand what those heads' exhaust flow is like; but choose the exhuast lobe accordingly.

irocbrninrubber

Thanks for the advise. The heads are 68cc, 184cc intake and 68cc exhaust. They are the systemax II heads and intake.The only reason i had mentioned the other one is a friend is helping me put this engine together and he had recommended that one. If anyone needs any more info, to help me pick on just let me know thanks again.

5678TA

the holley systemax combo is supposed to put out 425hp right? use the cam that they recommend for the kit.. anything over 375 hp is in the 12's..

irocbrninrubber

I didnt buy the whole kit. I just have the heads and intake. Also, i would like to go with the hydraulic roller cam since my block was made for it. I just dont know what cam to go with. Thanks .

sofakingdom

iTrader: (1)

Look at a Comp XR276HR. http://store.summitracing.com/partde...2D08%2D423%2D8

irocbrninrubber

I called jegs and they recommended the xr288hr http://store.summitracing.com/partde...8&autoview=sku
would that be still streetable? has anyone used this? Thanks

sofakingdom

iTrader: (1)

I had the XR282HR in a 400 for quite a while. It was a handful.

I would say that the 288 would be the ABSOLUTE MAX, in a 400, that would have been streetable.

In a 350, unless you are VERY GOOD and EXPERIENCED at carb tuning, it would be altogether unpleasant to use on the street.

The 282 would be about as much as I'd put in a 350 for street use. Even that would likely cause trouble with power brakes and fuel economy and other street concerns. With those small-port heads, a huge cam isn't going to be a good match, anyway. Once you reach a point where the motor is limited by something else (heads & intake), increasing the cam doesn't "add more" or "make up for" anything; instead, it can actually make you start going BACKWARDS.

Engines work best when all their parts are chosen with similar properties to give a similar result; not so well when the parts are widely different. Small dual plane intakes and street heads on small-displacement motors like a 350 do not play together well in the same sandbox with HUGE cams.

The 276 will give you a very strong-running motor, with plenty of vacuum for power brakes, a possibility of decent gas mileage, and so forth. Bearing in mind, IN CONJUNCTION WITH the rest of the parts. Shouldn't have ANY trouble getting into the 12s, if you can hook it up.

1989GTATransAm

iTrader: (3)

I agree with Sofakingdom. The cam you mentioned is way to big.

Orr89RocZ

iTrader: (20)

tried and true cam right there.. definately a mid 12 second car with the right tune/suspension and those heads and intake. very streetable and will give you good brake vacuum.

I'm not sure what your compression would be with those heads and pistons, i'm guessing 9.5-9.9 to 1, depending on few things. SHould be plenty for that cam, closer to 10 the better, but should still work well.

irocbrninrubber

Thanks for the advice guys. I told the guy at jegs it was going to see 80% street 20% strip. And that was the cam he recommended. The cam that came with the kit was a lunati with 235/240 @.050 so i was wondering if comp cams xr282 has 230/236 @ .050 would work. I know that sofa said that the parts should be matched, so i figured that that cam is almost like the one in the kit so it should work good with the heads and intake right?would it still give me enough vacum for power brakes? thanks again for all the help.

Orr89RocZ

iTrader: (20)

there are some guys running that cam just fine. 282hr will be the biggest i'd go on that motor with those heads and compression. should have decent vacuum for power brakes. You could run abit more LSA for less overlap to be abit more friendly or install it 4 degrees advanced.

Thunder Racing sells that cam on a 112 lsa. Comp i think is only 110

irocbrninrubber

I dont understand? sofa said that those heads are to small for a cam the size of the xr288 which has 236/242 @.050, but the kit says that it was all matched to optimes performance and the cam that cam with the kit had 235/240 @.050 which to me doesnt seem that big of a diff. or do hydraulic rollers need that much more than flat tappet? If its a dumb ?? sry but i am just trying to understand how these things work. Thanks again for your help and patience.

sofakingdom

iTrader: (1)

1. Roller vs flat-tappet.... a roller cam of any given duration ALWAYS acts "bigger" than an equivalent flat-tappet; ESPECIALLY a modern, aggressive roller like the XE cams, vs an older, gentler flat-tappet like that old Lunati.

2. "Kit".... what does that mean? Does that mean that it's ideal in some way? Does it mean that that's what the mfr could get for cheap? (look at the cams in Edelbrock's "kits" for on object lesson in that concept, by comparing them to the Summit cams) Does it mean that for some reason, whatever it might be, that the mfr expects that that's what a "typical" buyer would demand? Just what DOES a "kit" mean, anyway?

3. What good does it do to create a "kit" that has a set of small-port street heads, an intake with optimum performance from 1500-5000 RPM or so, and a cam that doesn't even BEGIN to make power until it crosses 3000 RPM?

4. What are your REAL goals? I'm kind of reading between the lines here: some of your parts choices speak MUCH louder than the words you typed.Not much of a challenge, really. No great stretch, no problem doing that AND remaining streetable. Think about it... if you went 12.8 and could drive it to work every day and get 18 mpg on the highway, would you be happier if it went 12.5 and every time you drove it something broke and it gets 12 mpg on the highway, or if it only did that 10 times or something and then blew up like a grenade?There's what will break, if you try to go for EVERY LAST HP. And they WILL break, soon, guaranteed. Are those last 20 HP or so, REALLY worth that? How soon are you willing to deal with tearing down a stock street short block and rebuilding it, because it made no power at low RPMs and couldn't survive at the RPMs where some excessive cam forced it up to in order to make power?

You need to stick with a smaller cam than the one that comes in the "kit". I think the XR276HR is PERFECT for the rest of your combo.

It's not a "dumb" question at all. Don't think that. Rather, think of it as, the mfr's goals with the "kit", whatever they may have been, aren't the same as yours.

Orr89RocZ

iTrader: (20)

yep rollers act bigger than the flat tappets. But even that cam in the kit is on the large size for that combo. That doesnt mean its ideal like Sofa said

12's aint hard to get in a properly setup thirdgen. Hell i broke 12.90's with a bolt on L98, with barely 300hp on motor..thats 254 at the wheels A hotcam on that motor would have done 12.6's all day long in the good air. I dont think it would have crested 300whp

503 cam or the 276hr as it is also known, would be great in that setup.

irocbrninrubber

Thanks for the advice guys. I really wanted to go with the xr282, but you are convincing me to go with the xr276, which is most likely what i will go for. on the exhaust I have 2210 hooker long tube headers with a 3" true dual h pipe. what kind of power can i expect with this combo? would it have that chopey muscle car idle? thanks again for all the advice.

Orr89RocZ

iTrader: (20)

get it on a 110 lsa and it will chop pretty good with that exhaust.

you can probly get near 330-340whp with that setup. Its pretty stout

irocbrninrubber

Is there anything else that i am overlooking that can help me get more out of the car? certain carb to use? lifters? rockers? Thanks again. I could live with 330rwhp as long as i can take my brother on a stock ls1. which is why i was originally shooting for 12's. I have read that ls1 camaro's run high 12 stock with sticky tires so as long as i can take him i would be happy.

Orr89RocZ

iTrader: (20)

750cfm carb and a decent dual plane like a performer rpm manifold will match that setup well. roughly 5700-5800 rpm peak power. shift by 6K.

should really ride out, as good as a LS1 stocker