327_TPI_77_Maro

iTrader: (8)

Hi guys, I'm going to get my datalog laptop setup and start messing with the tune on my 327 again today. I had it running excellent but with a few issues that were masking each other -- my over rich idle masked lean AE due to my stealth ram's big plenum. I've been playing with the upper/low bounds and swing point for the O2 sensor to fine tune idle. It was also suggested that I run more timing at idle to reduce the rich smell. I was running 24-25 degrees idling before, but I cranked it up to 30 to see what I get. Should my timing just be ramped up from 30 at idle? My cam is an old gen 1 SBC hydraulic Isky 280, 232 @0.05, 108 LSA, .485 lift. I'd be interested to see anyone's MAF timing tables with big cams.

funstick

the 108 lsa is whats doing you in for the appearance of a rich idle. its gonna want to run alot of spark advance at idle as long as it doesnt spark knock etc. With the 108 lsa you have lots of overlap shoving fuel etc out of the exhuast. If you really want to kill the stink and keep the power about where it is goto a hyrdulic roller with more lift on a much wider lsa. 113-115 i can tell you that ive done numerous ls1's with 600 lift cam running 230 duration and 115 lsa making in excess of 400whp and running bottom 12's in the 1/4 mile.

327_TPI_77_Maro

iTrader: (8)

A bigger cam isn't necessarily needed when I go to a wider LSA. The cam I have sounds fantastic but is probably making me go slower. This car only runs high 13s/low 14s. How much lift/duration should I be looking for with a 327 if I want to go low 13s? The engine is tight as new and has forged pistons in it (unnecessary but I didn't pick them). I currently have the 1.84/1.5 valved 416 (305 HO) heads which I will either port or replace with better flowing heads at some point.

junkcltr

iTrader: (1)

I have a 327ci in a second gen that does low 13s on BFG street tires. Maybe very high 12s on stickies but never tried it. The 327ci likes to rev and with the cam you have it will make high rpm horsepower. I have a 244 degree duration 106 LSA in mine (carbed going EFI next spring). I expect idle to be very poor on that engine. I run 64cc 2.02I, 1.60E valves on ported fuelie heads. Your engine sounds like it is head limited. If the intake is high rpm and you have decent headers then low thirteens are easily possible with that cam. I would ditch the small chambered, small valved heads.
Sticky tires may get you to low thirteens. The second gen I have with the 327ci is traction limited. It is a street car so it doesn't really matter.
Also, one thing people tend to ignore is fresh air to the intake. Every 10 degree Faren. is roughly 1% additional horsepower.
A 350HP engine would gain about 5% HP from a poor air intake to a good air intake. Roughly, 15HP which equates to lower ETs. When I go to the races I end up stuck in line like everyone else with the car idling sometimes a fair amount. A quicky K&N TPI stuck-on air cleaner would yield IAT temps of about 120 degrees on an 70 degree night........or about 5% free HP wasted.

J

327_TPI_77_Maro

iTrader: (8)

Thanks Junk. I am MAF so I couldn't use one of the stick on K&N filters on the throttle body anyway. I have a 3" ducted intake that is drawing cold air. I had 487X heads on this engine before, but with the 76cc chambers and the Speed Pro forged flat tops I have in this engine I had 7.8:1 compression. I ran a 14.4 carb'ed with a terrbile 60 foot with that setup. I need 58 cc or similar chambers to have enough compression (I'm surprised the car ran as well as it did with way too big of a cam for the compression). I have 9.6:1 compression right now with the 58cc chambers. If your EFI is set up properly the idle will be as good or better than carbed -- mine is. It idles choppy but constant and does not hunt. I know the valves are on the small side but a 327 is short stroke and won't tax the heads as much as a 350. There are plenty of 1.94/1.5 valved 350s running 12s, so I figure the heads shouldn't be killing me that much. I will be looking into better heads or porting these at some point.

Z69

With your current CR, you really ought to change cams.
Your isky would need around 10.5 cr to work correctly in your 327.
A CC 270 magnum or similar Isky would be a closer match w/o going too small.
If you could handle a solid cam, I think you'd like a
Ultradyne 232/232 @.050 or 232/238 w/ about .460 net lift. They are available from Bullet Cams now. Or maybe the Ultradyne cam that Twilightoptics is running. It's a tight lash NF 239/248 112 lsa cam w/ about .500 net lift.

junkcltr

iTrader: (1)

That is a surprise. I have an Ultradyne 244 duration in my 327ci.
You don't hear many people talking about Ultradyne.

327_TPI_77_Maro

iTrader: (8)

Thanks. Z69, I can't believe that the car was running low 14s with under 8:1 compression with this cam. I pull 20 mpg on the highway with the 0.64:1 OD in my T5 too with the 58cc small valved heads. I can deal with a solid, this car sees very very few miles, it is only driven on sunny days, so re lashing would be a seldom event. Is it safe to say this old tech, too big cam is slowing me down? That would make me a happy man. It says 2500-6800 power band on the cam card. I didn't pick the cam, but I did get the part # off it when I popped the cam plug changing clutches a couple months ago, and Isky still had a cam card for it.

Z69

I have a lot of the specs for the ultradyne lobes if interested. I'm running the 243/251 solid 110 lsa currently in my 383.

I did a few calcs and that 108 lsa saved you on your CR.
While it's on the low side, it's not terrible.
The cheapest route would be to put a set of the GM .028 thick head gaskets on for 9.9cr or the .015 steel shim gaskets
for 10.2 ish. Taming the idle by going to a smaller cam and widening the lsa would give you more torque but your dynamic cr would stay similar to what it is now.
If your getting 20 mpg, I wouldn't swap cams unless you can't stand it now that I look at it more. Your current heads don't really support the current duration in a 350, but I haven't done any calcs to compare it to a 327.
If you swap heads then that cam will come into it's own more.
But you should pick up midrange by loosing 10 deg of duration. Depends on how interested you are in testing making it faster.

327_TPI_77_Maro

iTrader: (8)

The problem with heads is that basically I have to go aftermarket. I don't think there is a such thing as a 58cc chamber factory 1.94/1.5 head that ALSO has hardened valve seats. By the time I put hardened seats in an old set of small chamber fuelies (which would not be cheap to purchase either) I could already get a used set of aftermarket heads.

junkcltr

iTrader: (1)

Yes, I put a lot of money in a set of fuelies. I should have just bought aftermarket.
If you know the cam specs and the piston dome/dish, you can go to the keith black website and calculate the dynamic compression of your engine.

Z69

Here's the DCR calc I use.
http://cochise.uia.net/pkelley2/

RBob

iTrader: (1)

MY '89 -'91 Corvettte '113 heads. Aluminum, 58cc chamber, 1.94 x 1.5" valves, screw in studs, center bolt valve covers, and use the old style intake manifold bolt angles. I have 'em on my 331 with an older version of the Isky 280HL hydraulic cam (224° @ 050, .465 lift, 108 LSA).

I'm happy with them. Used the stock '91 Corvette heads gaskets. These are thick at .052" but was the only thing available back in '91. Fel-pro has a coated shim gasket that is .015" specifically for aluminum heads ( # 1094).

Then the 1043 at .039". Stay away from 1010's.

RBob.

gmgod

Rbob, your scaring me...... Why stay away from 1010's?

RBob

iTrader: (1)

They fail. The fire ring tends to turn inside out and leak. When I say inside out, it is a failure where the ring delaminates from the actual gasket and gets pulled in toward the chamber, gets mangled and leaks.

A head gasket that fails from too much cylinder pressure blows outward. 1010's like to delaminate.

RBob.

gmgod

They revised these gaskets somtime in the recent past. Is this a recently discovered problem or somthing that has been going on for a while?

RBob

iTrader: (1)

It has been going on for years. Yes, I recall the claim that they are revised, but how is one to know when a 1010 fails whether it is the revised version or the old version? Without knowing that there is no way to build history. IOW: does the revised version still fail?

And, how does one know if the 'new' set being installed is the original revision or the new revision head gasket?

This is why I recommend that folks just avoid them.

RBob.

MonteCarSlow

Ditto here. I have the same heads, and used the factory gasket. My train of though: if GM bothered to make a head gasket specifically for this cyclinder head, I should use it...

gmgod

I have seen two versions of the 1010. The old, or older gasket, looks like any other printoseal type fel-pro with the lite blue background and fel-pro lettering over it. The newer ones are black with raised blue lines throughout the gasket and no lettering whatsoever.
I unfortunatly used these on the motor I am about to drop in my bird. Have you or anybody else heard of the black ones failing?

DM91RS

This is the one that I "read" was used on the Vette heads.

GM #10105117

I've used it twice With Vortec heads with no prob.

.028 thick composite............

DM