View Full Version : What to change for G head

03-09-2007, 01:09 PM
I currently have a G head on my car, and am running a cal set up for a swirl head. The only way I can get it to run acceptably is by bumping the initial advance up to 18 degrees or so.

Does anyone have a complete table file for an 87 t1 cal? Also, what should I switch over from the G head to the other?

03-09-2007, 01:42 PM
The G-head and Swirl use the same springs, retainers, cams, lifters, rockers but a slider cam will only work on a Swirl head if the squirters are cut into the cam caps.

Valves are longer on a Swirl head but can be used on a G-head if you use PT lifters.

03-09-2007, 01:45 PM
I think he's looking for what to change in the cal when switching from Swirl to G head, Simon. :)

Basically, the only real changes betwen a G-Head and Swirl cal are the G-Head likes a lot of timing in Vac, and a little more advance from rpm.

03-09-2007, 02:35 PM
Hahahaa, sorry, I got caught up in the "what should I change over" part :D

03-09-2007, 10:37 PM
Do you have a 2.2 or a 2.5?

03-09-2007, 11:24 PM
its a 2.2.

I guess I can play around with it. If it blows up, thats just my excuse to build a new engine.

I could still use a 87 T1 cal and table file if they're out there.

OR I could just pull the t2 top end off my other car and slap it in here and use blueberry. hmm....Will the valves smack in to anything if I do that? Seeing as the 85 pistons don't have notches for the valves in them like the later engines do.

03-16-2007, 08:36 AM
There's nothing wrong with running that much timing with that setup, you're compression is like 7.6:1 or so. I ran 22 PSI boost on my G headed 2.2 and the timing so advanced it was out of the window with no detonation. Then I got a TU cal, ran a lot better but I could still even turn the timing up to 15 with no pinging.

03-16-2007, 08:25 PM
I get some pinging in the upper RPMs in full boost. I just got a spare ECU to socket and try changing the timing curves on.

03-16-2007, 09:10 PM
I'm in the same boat as you are, I just installed a G head on my 86 SC and I'm currently trying to work on getting a better calibration for it. I haven't advanced the timing that much just to be on the safe side, but maybe I'll give it a shot. I recently obtained an 87 LM that I started working on it.