LannyL81

Brians1: I will send you a PM within a few days.

c6silver

Hypertech only sells a standard chip, I don't think they do any customizing at all...but it's worth a shot. I would still get a cam on a 112 or 114 though...and bowl port the heads/back cut the valves and do 3 angle valve job while they're off the engine.

c6silver

I'm going to put up a rather long winded post here just to help illustrate a point here. Years ago, in either Car Craft or Hot Rod magazine (I forget which), Jeff Smith did a buildup of a 420 small block Chevy for an '85 Monte Carlo SS that uses basically the same Q jet and ECM as your '81. They used ported iron aftermarket heads, had the stock intake ported, put on Edelbrock T.E.S. exhaust (tubular manifolds, not full length headers) into the stock cat and then put on a dual 2.5" exhaust system. The Carb Shop worked over the Q jet, the car had a 2500 stall converter installed and they kept the stock 3.73 gears. The cam in use was a "special" 260 degree (adv) cam from Comp on a 112 lobe center to "keep the computer happy" and a long defunct Edelbrock product called the Micro-Plus (basically an intercept box that allowed an end user to pick from a number of different timing curves by setting DIP switches inside the box, another similar product came out later from Crane called the Crane EPS (engine performance system) that had more functions available). That engine had 70 more cubic inches than you have and ported heads, a stall converter, gears, etc...and the best it could muster was a real low 13 quarter (like 13.17) at I want to say around 110-112 mph. They used a 112 lobe center, and they had WAY more inches, head/intake/carb flow and gearing than you, and more tuning choices (with the Micro Plus and the carb was built for the combination). They said they were going to drop the gears back to 3.42 and keep playing with it until they got it in the 12s...never saw that issue (if it exists). I think the deep gears with that many inches/that much low end torque hindered their ability to hook it up off the line, and they were using the stock single snorkel air cleaner which limited top end power. I also feel that with 420 cubes they could have gone to a 270 degree cam (still on a 112 to 114) to make more power and shift it up the RPM band a bit. Take all that for what it's worth, YMMV.

Brians1

C6....thanks for the background (not sure why I didn't get a notice u replied?!?!) so sorry for delayed responce. I know I'm not building a rocket ship here, just going to correct the wiped cam and get some better perf out of her. I already have true duals w/ mangaflows..no cats. MSD coil, wires, cap, rotor (accell 7 pin) CCC dizzy module , rebuilt Qjet. I plan on the hypertech chip after I get her running. If this new cam (and map sensor change) go well I should be pretty happy with her while I decide where I want to take the performance level, etc.

c6silver

I told the story to illustrate that even with a much bigger engine they still stayed mild on the cam, not to say you weren't building a rocket ship...more cubes cushion the effect of a cam being too big, when a cam says "noticeable idle" that means there will be problems with idle quality, which will mess with the MAP sensor and make the computer think there's a vacuum leak and then give a crappy spark advance curve because of it...POOF, there goes your "performance increase". Buy a cam on a 112 or a 114...I'm telling you. The carb is going to have to be re-jetted too by the way...or you'll be lean, which will ALSO make performance less than optimum.

Brians1

Well guys I finally had a day to do the tear down
Fl heat got to us after hour 5...heads are almost off but cam still in...here is what #7 and #4 exhaust lifters look like...pretty big indent on them...root cause at least 50 % here...when I remove the cam I'll find the rest

Brians1

Quick look at all the room ! Lol damn radiator and shroud was a B$@$$&
To remove

Patro46

Yup. Time for an LSx swap

On a more serious note, I can remember working at the Chevy Dealership in 81 when CCC was first introduced, right behind Ford's 1980 release of their EEC3 system, both of which attempted to take a carburetor and convert in to fuel injection. I'll be watching to see how this comes out. Good luck brother!

Amorget

That looks a lot like the cam looked in my 81 when we pulled it out. Did you have any problems pulling the lifters? Two of mine had a ridge around them that I basically had to force them up through.

Brians1

Yes! several lifters were very hard in pull out!! Had to use combo of magnet and pliers.
I'm traveling for work this week so I won't get back at it until the weekend.

Amorget

Man, work gets in the way of everything fun! (Except the needing money part...)

Brians1

Hey fellas...I just got back from a week of work travel and spent a few hours this AM getting the rest of the motor torn down. The cam was a bear to get out, looks a bit worn ( see attached image). The heads came off pretty easy and the cylinder walls all look very clean, no Knicks, grooves, ets. I got my dial gauge out and all bore's still measure 4.000.
We stoped at pulling the cam gear on the crankshaft as I don't have a puller with jaws so going out later today to grab one.

Next step is all the clean up I need to do....I'll post before and after a when I do that.

Brians1

Brians1

Hey guys also i forgot to mention I found this on pass side head....what does this discoloration mean on the valve ? *besides another issue I had coming lol

LannyL81

Ahhh....brings back memories.....nothing says LOW compression like a set of dished, 4 valve relief pistons!!

Not sure if the brown exhaust valve is from a lean mixture or not. Have to wait and see what the experts say.

Amorget

Is that one valve one of the lobes that was wiped on the cam?

Brians1

Actually no....that's #8 cylinder, bad lifters and lobes were. #4 and 7

LannyL81

I know that cylinders 7 & 8 always run hotter due to being up against the firewall, close quarters and all.

What does #7 look like?

Brians1

#7 , the worst of the lifters doesn't look bad, just aged carbon buildup

Side note/question.....what solvent should I used to get the block clean before I put the new head gaskets and heads in ?

81$$pit

I just had mine changed because it had slipped 90 degrees. My 79 had the same issue several years ago. obviously a common problem.