Bartje64

It's a daily driver with 90K, fun to play with.
Planning on some upgrades here's what I have in mind.

Comp Cams Kit K12-256-4 (edited 4/16)
Comp Cams full roller rockers 1.6:1 Ratio #17002.
Hedman Headers #68446.
Promax 2169 Aluminum Heads 64cc chamber, 185cc intake runner.
Calculated that the comp ratio bumps up to 10.2:1

Nothing too wild, but it should breathe better.
TPi flattens out at 46 to 4800 from what I've been reading, CamQuest shows peak HP at 4500, peak torque at 2500...

What do you think...any thoughts/opinions?

John A. Marker

One important thing you are leaving out.....do you have a custom tuner in your area. The modifications.....that require a new tune is the cam. The computer can handle most of the other changes. Without a good tuner you will have problems getting this to run well. You could go with a mail order tune, but you will have to provide data logging information for the tuner and will probably send a new chip back and forth several times until it is close to being dialed in.

The 85 is the only year using the 870 chip, so this limits the availability of someone in the market than can accomplish a good tune for you.

You should also consider going to a better intake/plenum/runners to open up air going into the engine. You might want to consider a mini ram which is more available than the SuperRam.

cumbercr

Right on the money. The tune has been the most challenging part of my build. There are very few tuners that will work on an 85 ECM. I've had to do most of the tuning myself. If I were you I would consider an upgrade of the ECM to an 86-89.

Super Rams are harder find but they are still available on eBay from time to time. I personally like the torque the Super Ram delivers. The RPM range is not as high as a Mini Ram. Although I have pulled 6,000 with mine.

The Mini Ram is definitely easier to install.

Muffin

Upgrade the ECM. Big step in the right direction.

Bartje64

What is all involved in an ECM upgrade, I can't imagine its plug and play?

Bart

cumbercr

Several Forum members have done the upgrade and shared the steps. It requires an 86-89 ECM, two relays and some repining of connectors. You can then have a reputable tuner burn you a chip. This upgrade is highly recommended if you need to pass smog.

The total cost to include tuning is around $500. If you had a chip burned for your 85 ECM, you're looking at a minimum of $250.

Bartje64

Sorry guys...

Comp Cams Kit K12-256-4 is the correct part number,
not the 265 I had in the original post.

Since the bottom end already has 90K + on it we were debating rebore or short block.....short block won.
New short-block will be here on the 22nd, 355 (.030) over 4-bolt.

Found an Accel Street Ram set-up used...really cheap. Looks like it has better flow than the stock TPI, may gain a few ponies with it..

Also contacted a couple of folks for chips, seems this set-up won't need it so we'll give it a try.

Bart

John A. Marker

The 85 is a four bolt main and forged pistons. With only 90,000 you could probably get away with just swapping the cam and not touching the rest.

Bartje64

We thought about that as well, but rather not take the chance.
I do need to find if the OEM torque converter will work with the upgrades.

It has a 2000 stall speed I believe, cam quest models show max torque at ~2500 RPM....

Regards, Bart

cumbercr

The cam you're using is very mild. I ran the same duration in my 85 with the stock converter. It will be fine.

John A. Marker

Just something for you to think about. The 700R4 transmission is good for about 110,000 to 125,000 then rebuild time. If you put more power in front of the transmission, you will shorten that life.

I do believe the stock converter in the 85 was at 1400 stall.

Bartje64

Well now I need to get that clarified I guess...
Somewhere in these forums I read that the:
- 85-87 Had a 2000 rpm stall converter..
- 88 and later a 1400 rpm converter...
I cant seem to find that post again, can someone verify this info?

Thanks, Bart

cumbercr

The 85 has a stall of 2050 RPM.

ejscarfo

2 bolt main with 2 piece rear seal like the SBC Corvette engines before it (80-84).

I'd be interested in following your progress as I am in the process of building a mild 355 to drop into my 85 (I'm using an 85 block, the choice of heads TBD) but I do not want to deal with a tune.

Bartje64

I'll keep posting as we make progress. ETA for the block is the 22-23rd of this month.
Head choice....I researched this and found that the stock cast heads on an 85 had 1.94" intake, 1.50" exhaust with a 160cc runner.
I went with 2.02 intake,1.6 Exh, 185cc runner, 64cc chamber. this should take the CR to 10:1 or just slightly over.
Going with large runners (200 and up) will hurt performance on the bottom end (torque) but would help on the top end if the motor spins faster.
However the OEM intake is pretty well petering out at 5K or so, therefore larger runners do me no good anyway.

With the 256 cam, heads, headers, intake (I found a Accel Street Ram), this motor should be able to breathe a lot better, providing better response and an increase in HP and torque.

Models show the peak torque at 2500rpm, so the stock converter with the 2000 stall should work just fine.
And all this without having to change the chip. We'll see what happens.

Bart

ejscarfo

mcm95403

Bart, sounds like you're close to my build. The cam I used is a replica of the LT-4 cam. Drives like stock just more power all over. The Street Ram is a great setup and can definitely rev!

Make sure you do something to improve the exhaust - the stock headers suck like a black hole.

Bartje64

Should have that covered with these.....
Hedman Headers #68446.

ejscarfo

What's the difference between those headers and Hedman Headers #68448? The 68448 say for Corvette.

Bartje64

Coating...one is ceramic..one is thermal