ZD75blue

Hey guys... as a bunch of yall know... I'm working on a whopper parts list!

I need a lil bit of help when it comes to running on 87, I'm not sure my engine plan will...

It contains:
Vortec Cylinder heads 64cc
TRW Forged Flat top pistons/matching rings
Dual plane intake
CompCams 262 Summit # CCA-12-238-2
Self aligning rocker arms
Stock pushrods
And headers
Head gasket is yet to be chosen (http://forums.corvetteforum.com/zerothread?id=663439 )

Thinking about rebuilding the qjet for a second time, and a lars spring kit for the HEI.

Ideally the gearing will let me keep the rpms down on both second and third at 35 and 65-70. So the carb will be adjusted to run off the primarys while on doing both. For extended range between fuel stops :reddevil

Do you think this engine combo will work well on 87? If not, what do yall think needs to be changed for it to love the cheap stuff?

Thanks again :cheers:

Fast81

The most important info is missing....................what's your Compression Ratio ???? Are your Vortec heads iron or aluminum?? I can pretty much already guess with 64cc chambers (& iron heads), your engine will not like 87 -- more like 89 or even 92 with any CR over 9.5:1
Alum gives you an extra .5:1 CR to play with before more octane becomes mandatory.

Just my $.02

bhmyers

DONT use stock push rods. Get a good set of hardened ones. I have a buddy that ruined a motor by using stock push rods, it sharpened them like a pencil on the guides. spend the few extra bucks on that. just my 2 cents.

Fevre

Are you going to run NOS or blower in the in the future? If not I would use hypo piston rather than forged to save some $. The Vortecs are iron heads so depending on the cam you would want a 9/1 comp ration, maybe 9.5/1 if you the cam has long duration and narow lobe seperation.

marshrat99

:iagree: with Fast81. C/R is the important thing

ZD75blue

The thing on summits site for the pistons says i'll have a 9.72:1 compression with the 64cc heads an flat tops...

Heads are gonna be Iron... unless I win the lottery! Well wait that takes money to get money... guess i'm not winning anytime soon :jester

ZD75blue

Is the deck hight on a sbc on smokemup.com for the compression calculator thing supposed to be .25 or 0?

Thanks

ZD :party:

joeveto

Your compression ratio is going to be around 10:1 with that combo. Ask me how I know.

I went with a thicker head gasket to lower compression to below 10. I can run on pump gas, but I've never tried anything in the 80's. I think 91 is the lowest I've run. Given the cost difference, fifteen cents a gallon, it's no big deal, and it's good insurance.

ZD75blue

One of the goals in mind is to make it a cross country/power tour cruiser... so 87 would be nice :cool:

Alot of the late model stuff can run on regular, but I guess they have aluminum heads too :sad:

AlwaysWave

I think you have a good shot at 87 octane. With the Vortec heads chamber and gasket for about an 040" quench. Those heads supposedly like a less advanced timing which would be in your favor.
Read these
http://chevyhiperformance.com/techarticles/94138/
http://chevyhiperformance.com/howto/47075/

ZD75blue

SWEET!

Thanks for the links... I'm thinking to try the flat tops an if it doesnt like 87 to just retard the timing an make it run on it! :blueangel:

Matt Gruber

i'm at 9.65:1 on 87
tips
1. tight .040 quench
2. cold air
3. no heat riser
you will be about 10:1 :lurk:

ZD75blue

Do you think the air gap style intake would help lower the intake charge an help with the 87 idea? :blueangel:

zwede

I'm at 9.5:1 on my 454. 454's tend to ping more than smallblocks due to older style heads and larger bore. I'm also running aluminum heads and EFI, which helps greatly. I started out with 93 octane. Then tried 89. It ran just as good, no difference at all. Haven't tried 87. I'm also running lots of timing.

Matt Gruber

i don't have the air gap as it was not out when i built the motor.
i consider it a necessity on your project, along with cold air. :cheers: and a perfect advance curve

ZD75blue

Hmm...

My best guess is that with no sharp edges in the chambers or on the piston... I may be able to pull it off!

Wonder what heat range I'll need to run when it comes to plugs! :cheers:

LemansBlue68

You might also consider a cam with a little more duration. The later intake valve closing will bleed off some compression at lower speeds where you tend to get in to spark knock, and will gain you a little more top end HP because it allows the engine to breathe better (if your intake and carb are decent) at higher RPMs.

Keep your air and coolant temps low. Use a fresh air induction system and 180' thermostat with a good functioning radiator. Should give you a gain a bit more HP and keep spark knock at bay.

ZD75blue

I would change the cam... but the highway rpm's on a stock 75 with a th400 I think might be to low for a cam thats anything bigger then the 262...

But i'm with ya on bleeding some compression down! Thinking about installing the cam advanced a bit so the valves open a tad later...

Thanks for the input, I'll do some reading on the cold air system!

Larry B.

Trade the vette for a Honda or a lawn mower. :lol: :lol:

ZD75blue

This was my original thought... but through a little bit of research and asking around I may be able to have my cake and eat it too... :smash: