[rusted11]

Trouble finding right combination...help

I just recently bought an 87 Monte Carlo SS to use as my daily driver and the 1st thing on the list is to replace the 305 with a 350. I want to be able to achieve the most possible performance on 87 octane while retaining all of the factory emissions equipment.
The 350 is at the machine shop being cleaned up, inspected, & bored.
The 882 heads that were on the motor are in pretty rough shape and the repair cost will probably put me close to $500. So, this got me to thinking about a later style head.
Well, with 4.030 12cc dish pistons and GMPP 64cc Vortec Heads, this puts the compression ratio a little over 9:1 and I'm having a hard time finding a cam that will give this sbc some guts and stay off the premium blend. I've tryed, without success, searching here and montecarloss.com for this particular combination with the same parameters.
I'm about ready to give up and go ahead and spend the money repairing the 882's because this really seems to open up a lot more possibilities in cam choice.
If someone could point me in the right direction, it sure would be appreciated.

PS I forgot to add
stock 1.5 stamped rockers
performer intake w/EGR
CCC Qjet E4ME
Edelbrock shorties made for A.I.R, high flow converter, and catback duals
stock stall 200r4
3.73 limited slip posi

 

[rusted11]

OK, I've all but given up on the 64cc heads. It looks like whatever cam I pick, it will have to bleed off a lot of pressure to keep it on 87 octane.
If this is the case, won't that give it a soggy bottom end?
example: with this cam (advdur 276/283, lift 468/462, 112/108 lsa/icl) and 64cc heads(.041 gasket) with 12cc dish pistons, it puts static at 9.08:1 and DCR at 7.21:1

SO, back to looking at the 882 heads.
I'm considering the CS 268H-10(286/268 advdur, 454/454 lift, 110lsa/106icl) with flat top(5cc) pistons.
It looks like static will be at 8.66:1 with .041 head gaskets and with this cam it puts DCR around 7.19:1

Will this meet my octane goal and still give it strong low rpm torque?

Was my 1st question too broad, should I have called several different cam companies with 4 different head/gasket/piston combinations?
Should I pick one head/gasket/piston combination and commit to making it work?
There just seems to be too many possibilities and at this point any help would be appreciated.
Thanks

 

[rusted11]

Thanks guys.
I realize DCR is just meant to be used as a guide. However, I was thinking I needed to keep it close to 7:1 in order to burn 87 without detonation, regardless of the style head used.
At least starting here, the worst case is I have to go up a grade.

 

[rusted11]

Darn it, someone had to throw a stick in the spokes. :clonk:

RB69
I come up with 9.08:1 static compression with 4.030 bore, 3.48 stroke, 64cc cyl head, 5.70 rod length, same quench distance(that you used), and 12cc dish pistons.
The cam I was talking about was the CS268H single pattern and puts dynamic about 7.5:1.
The XE268 has .477/.480 lift and 54° overlap versus the .454/.454 lift and 48° overlap of the CS grind. The dynamic cr stays virtually unchanged at 7.5:1
The XE262 has more lift at .462/.469 but less overlap at 46° and raises DCR to 7.68:1.

Part of my problem is getting a grasp of what effects the idle quality and what moves the powerband up/down the RPM range.
What's the advantage of the dual pattern?

 

[rusted11]

Thanks for the help guys.
One more question and I think I'll be ready to spend some money, unless someone else throws a kink in the plan.
How will the .480 exhaust lift of the XE268 effect longevity of a head that is designed for a max lift of .480 with press in studs and springs rated for that max lift? That question makes my inexperienced mind want to lean towards the XE262 with its .469 exhaust lift.
The convertor is going to remain stock until sometime next year. I've got to put out some other fires and then later on, plans are to swap to 5 speed w/overdrive . As for the timing, I can set initial but the computer tries to shoot for 33 total.

 

[rusted11]

Vortecs don't have a provision for EGR like the stock late 80s engines do.

They sell an EGR manifold for these heads

 

[rusted11]

The XE262 still puts you at risk. ANYTHING over .460", and you'd better check it before you run it. Don't gamble like I did, or you might LOSE like I did with .470" lift on my 270H.

Check this link: http://markj.home.kih.net/id14.html

Or just buy the Vortecs that have already been setup for more lift.
You'll be glad you did.

Cheers,
mark.

Mark
Did you buy the entire compcam kit and use their springs, seals, retainers...?
The reason I ask is, the heads I'm buying already come complete and they use the umbrella seals. Supposedly, they are setup for up to .480 lift.

 

[rusted11]

It doesn't say on the web site what the limit is, but in the catalog it says good to .480 lift. I called Summit to make sure that was right. They also have a set that has been clearanced for .550 lift and screw in studs for $210 more.