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Topic Review (Newest First)
07-14-2008 06:57 PM
J.D
Quote:
Originally Posted by DoubleVision
200cc heads are too big, it'll be rather soggy in the lower RPM ranges. 180 would have been far better. the smaller 600cfm carb will make up for some of it, but not much. Since you dont know for sure your rear gear I'd find out, as it will be a big influence on how it performs. I always use GM head gaskets that are .028 in thickness, the 64cc chambers will give you a ratio somewhere in the 9:1 area even with the thin head gaskets depending on how far down in the bore the pistons are. rest of the combo looks good, but I think you have a bit too much head for it.
If he shaved the heads and uped the compression would that not help for the large runners?
03-23-2008 07:46 AM
Stroke Probably up and running, but do you have a pic of the guide boss more visible than in the above pic?
03-22-2008 07:41 PM
TheCiscoKid
New Engine Combo - Your Opinions

..........
01-13-2008 02:39 AM
300Deluxe For those interesed, here are a few pics of the heads.





01-12-2008 07:01 PM
roofdawg
Tanks

First I would Like to thank you 300Deluxe for posting this thread. Next I would Like to thank Double Vision, F-Bird'88 and 454C10. I am very very new at this and you guys have answered a lot of questions that I have been asking my self. The four of you have also given me so much to look and thank about. If not for people like you guys my '73 Malibu would be half of what I would like to thank it is going to be. Again THANK YOU so much all of you. RAH!
01-12-2008 05:08 PM
300Deluxe www.lunatipower.com

Found out about the site a day or two ago. Apparantly it's not 100% functional, but there is a pdf catalog.
01-12-2008 09:21 AM
F-BIRD'88 375 to 390hp
01-12-2008 08:34 AM
300Deluxe One more thing: With this combo, is there a ballpark horsepower/torque figure? Just curious.

Thanks.
01-12-2008 08:14 AM
300Deluxe The specs for the 1.47" springs are on a card attached to a spring on each head.

F-Bird, I appreciate your help.
01-12-2008 06:46 AM
F-BIRD'88
Quote:
Originally Posted by 300Deluxe
F-Bird,

I got the spring specs from both Jegs and Summit's product description on their websites. I want to say that I looked them up at one time on Holley's website as well. I'm guessing that they can't be found there anymore.

It's a relief knowing I won't have to purchase new valvesprings. I just wanted to be certain.

What about pushrods? I plan on purchasing a length gauge. I was told that the stock pushrods wouldn't work. I've read that with the proper length, that the tip of the rocker arm should be centered over the pushrod. I *think* this came from article on Comp's website. I may have to dig up the link. Is this something you eyeball to see that it "looks" centered? Or is there a more precise way of measuring?

Also, I'll pose this question again: With such a thin head gasket, do I need to be concerned with valve-to-piston clearance?

Apparently Holley has sold off Lunati Cams to a new company. But the new company has not launched a internet site yet as far as I know. I think thats why most of the Lunati stuff cannot be found on the Holley site any more.
But if you enter a Lunati part number in the Holley search box you get the tech info page you're looking for, for Lunati stuff.
Some, (but not all) after market heads have a thicker overall height from the deck surface to the relative height of the rocker arm stud boss. Usually requiring a +.100 longer push rod by default.
You'll have to assemble the heads on the motor and see what needs to be done for push rods.

Valve to piston clearance will not be a issue. You have tons of room with the cam, heads, gasket,pistons and block you're working with. SBC Valve to piston clearance typically becomes an issue when the (flat tappet) cam is bigger than 250@.050" on tight LSA (lots of overlap) and the heads and block have been shaved quite a bit. I check all roller cams larger than 230@.050" just for grins.

On a previous engine project I built a very hi compression 350 with flat tops with a decked block .018" and the thin .015" head gaskets + maximum flat milled 305 heads + a pretty big solid bracket race/oval track cam 256-264@.050 105LSA and the measured V/P clearance was right at the minimum required for safe high rpm engine operation .090" Thats cutting it close. You're no where near that on your build.

The specs for the 1.47" springs: Did that info come with the Summit heads?
When i checked out these heads at Summit, I did not pay a lot of attention to the literature included in the box. Was more interested on the casting and machining quality of the heads etc.
01-11-2008 06:27 PM
300Deluxe Bump. I'm getting lost in the shuffle, lol.
01-10-2008 11:31 PM
300Deluxe F-Bird,

I got the spring specs from both Jegs and Summit's product description on their websites. I want to say that I looked them up at one time on Holley's website as well. I'm guessing that they can't be found there anymore.

It's a relief knowing I won't have to purchase new valvesprings. I just wanted to be certain.

What about pushrods? I plan on purchasing a length gauge. I was told that the stock pushrods wouldn't work. I've read that with the proper length, that the tip of the rocker arm should be centered over the pushrod. I *think* this came from article on Comp's website. I may have to dig up the link. Is this something you eyeball to see that it "looks" centered? Or is there a more precise way of measuring?

Also, I'll pose this question again: With such a thin head gasket, do I need to be concerned with valve-to-piston clearance?
01-10-2008 06:18 PM
F-BIRD'88 The Lunati 73943 1.26" springs that are on the Lunati 60102 cam card are the minimum spring requirements for that cam. They are good hi perf stock diameter drop on springs and work very well.
The spring specs that you show for the springs on the Summit heads are on the upper end of what you'd use on a agressive hyd flat tappet cam or a fairly agressive street strip solid flat tappet cam. or most of the hyd roller cams you'll likely use on a street car. They are just right for what you are doing.
But you do want to remove the inner coil as I recomended for the initial fire up and cam break in. Give it about a week of driving around. Get it all broken in and then reinstall the inner springs using compressed air to hold the valves shut, readjust the valve lash and change the oil and filter. Add another bottle of GM EOS on every oil change and you're good to go.
As long as your spring installed height is the same or very close to as speced they are well within the recomended pressures used on high performance hyd flat tappet cams. They are not too much spring for you.
If you're just not going to sleep at night with 130LBS seat pressure, change the valve locks to +.050" to reduce the installed spring pressure. about a $30 cure.
Where did you get the specs from for those springs?
01-10-2008 05:30 PM
300Deluxe Guys I certainly appreciate your input.

I've read horror stories on various forums of cams failing prematurely. This is why I'm trying to go about this build as meticulous as I can. I've read about cam break-in procedures at-length and hope to follow the guidelines provided here and elsewhere.

There seems to be differing opinions on the valvespring issue here. Here are the specs of the springs provided with the heads:

1.47 Dia

Intalled Height (Intake): 1.88 (Exhaust): 1.88

Seat Pressure: 130

Open Pressure: 320

There are various check boxes with the different types of cams on the spring card with "Hyd Roller" checked.

Lunati's recommended valvespring specs:

1.266 Dia - single spring

Installed Height: 1.75

Installed Pressure: 108

Open Height: 1.25

Open Pressure: 339

Coil bind height: 1.060

Spring rate: 462 lbs/in

I realize we need to compare apples to apples here, but the above info is what I found on both springs.

Judging by the numbers, the provided springs are obviously heavier. So F-bird, do you think that these will be OK for my cam? My line of thinking is the fear of having too much pressure on the lobes. You suggested removing the inner springs. What are the specs of just the outers? Are they similar to Lunati's recommended specs?

454C10, you recomment NOT removing the inner spring, right? What would your alternative be?

I apologize for the redundancy. I just want to be confident before I start assembling anything.

You all have already been a big help.

Thanks,
300Deluxe
01-10-2008 12:35 PM
F-BIRD'88
Quote:
Originally Posted by 300Deluxe
The cam was suggested to me form another member on another forum. Being as the bottom end of the engine is basically stock with dished pistons, I didn't want to get too radical of a cam. I'm not knowledgable enough with valvetrain geometry to specify a particular duration for the intake/exhaust; hence I didn't get a custom grind. I was under the assumption that this would be a decent cam for a mild build. Was I wrong? I'm beginning to doubt the cam selection now.....
The cam you chose is a good one for you. it will work just fine with a stock torque converter. It likes a bit of gear, dual plane hi rise and good heads and exhaust (headers) always helps. The break in on the Voo doo and Comp extreme cams is critical. Reread my recomendations. This is the exact procedure I used on my 400 with the Comp Extreme XE28H-10. I use lots of spring pressure. 130+ seat pressure. These fast action "Voodoo/Extreme" cams require a bit more valve spring pressure than most are used to using cause they move the valve faster. Therefore you must follow a strict break in procedure without the inner spring and including both the oil additives I use and recommend.
They both use tried and proven anti-wear anti-scuff Moly and Zinc chemistry. Both have been around for years.
You can maximize the cr you get with dished pistons by selecting a thin .015" head gasket.
Your 200cc heads will not have a "soggy bottom end". Your only problem is going to be keeping tread on the tires.
Pull a valve spring off, measure the retainer installed height and then measure the spring seat and open pressures on a spring tester and go from there. Post some pics of the ports and valve bowls when you get the heads torn down for inspection, spring shim set up and final cleaning and prelubrication of the valve stems.
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