How to prep for head/cam swap?
Thread Starter
Race Director
Joined: Nov 2003
Posts: 12,221
Likes: 446
From: Overland Park Kansas
2020 Corvette of the Year Finalist (appearance mods)
C4 of Year Winner (appearance mods) 2019
How to prep for head/cam swap?
My plan is to deliver the car to a shop for head/cam upgrade. New intake and headers will be mounted in the process (HSR and LTHeaders). Heads will likely be fully ported 113's with a CC 280XFI cam. I have an '89 6-spd with 3.33.
Obviously, it will change my ECM's requirements a lot, but I don't know how to prepare. I need the car to start and get home after upgrades. I also want to avoid damage from running it too lean (or some other problem).
Would it get home with original chip? Should I start with PCM4Less? How close would that be? I'm guessing a custom tune would be better but I'm not finding local guys who are hep to ODB1 dinosaurs.
Obviously, it will change my ECM's requirements a lot, but I don't know how to prepare. I need the car to start and get home after upgrades. I also want to avoid damage from running it too lean (or some other problem).
Would it get home with original chip? Should I start with PCM4Less? How close would that be? I'm guessing a custom tune would be better but I'm not finding local guys who are hep to ODB1 dinosaurs.
Le Mans Master
Joined: Apr 2005
Posts: 6,413
Likes: 9
From: The Old Dominion
Presumably at light throttle the fueling demands would be similar to stock, i.e. it only takes so much power to lightly accelerate or to cruise, regardless of the potential of the engine.
So presumably if you drive it lightly, the stock programming and the feedback loop from the O2 would prevent it from running too lean.
At least that's my thought. Could be I'm mistaken though.
So presumably if you drive it lightly, the stock programming and the feedback loop from the O2 would prevent it from running too lean.
At least that's my thought. Could be I'm mistaken though.
Pro
Joined: Dec 2002
Posts: 522
Likes: 3
From: Rolling Meadows IL
In my 85 I just did a VooDoo 60102 flat cam 219 int./227 exh., old AFR 195 heads, single plane intake, 24lb injectors. With a 32B bin it would not idle, stalled at every stop sign. You will need a chip. I needed to set the idle to 950, add advance down low, changed the fuel tables, and AE to get it to run good. I was surprised how many changes were needed.
Years ago when I went from a stock cam to a Crane 2030 it ran OK without any changes. All I need to change was WOT A/F, but the 2030 is a very mild cam.
Years ago when I went from a stock cam to a Crane 2030 it ran OK without any changes. All I need to change was WOT A/F, but the 2030 is a very mild cam.
Pro
Joined: Feb 2005
Posts: 658
Likes: 1
From: Centerville OH
With stock injectors, I would think that you should be able to cruise home without any major issues. If you are going with larger injectors, there's probably less chance of being able to do this.
IMO, the best bet is to get a baseline mail order tune. For a relatively mild build like this, the good tuners should be able to get you pretty close right out of the box.
IMO, the best bet is to get a baseline mail order tune. For a relatively mild build like this, the good tuners should be able to get you pretty close right out of the box.
