Hey folks,
Truck is 91 C1500, 355, Lunati flat tappet cam, 1.6 rockers, aluminum Vortec style heads, 10.2:1 CR Edelbrock air gap spreadbore
intake, 454 TB sitting on an early factory TB adapter, long tubes with 3" exhaust.
16197427 ECM. Tuning with TunerPro RT V5. $0D XDF
I just dropped a 355 into my old truck and had the bright idea of using the CCC HEI big cap dist. The truck runs but the datalog says it's pulling all the timing out. Currently a dog!!!
Initial timing set at 0, dist set at 0. EGR is disabled. PE is currently turned off.
My timing table,

My datalog,

All biases are factory. Trying to figure out why I'm not getting the advance I'm programming in.
Thanks in advance!!!

 

Your verification by using a timing light ? Spark latency for coil in cap ?

 

Set latency for 90 Vette with big cap. Haven't verified with light. I did the 7427 swap when the 305 was still in it and didn't have this problem. Had that ol worn out motor running like a scalded dog. Anybody having problems with new 7 pin modules?

 

Verified with light, dist. is doing what the ECM is telling it to do. Readings match!

 

Assuming you're not getting in knock retard?

Where at in Florida are you?

For me I would stick with the base SA tables and advance the base timing.

Interesting thing going on - would be interested in hearing more.

 

Yeah no knock retard or an associated code 43??? Actually when I had the code 43, I didn't get any knock retard but I could see that it was pulling a whole bunch of timing as the rpms vs kPas increased.

 

West of Gainesville.

I've left initial timing at 0 for now. I started off by adding 6deg. across the entire table. This cam likes timing. I'm up to 26deg. at idle ramping up to 32deg. at 2800 and 36deg. max at 6000. It can take more. I've just started to get a little knock at WFO.

I figured it out. The XDF I'm using states that main spark bias is accounted for and that advance amounts in the table are actual. Yeah, BS! As I studied what the data was telling me I realized the timing was retarded by the amount of the bias which in my case is 9.84deg. I offset the entire table by the amount of bias and all is well now. Now I'm adding advance in 2deg increments and pulling out four where I get knock, rinse and repeat.
Right now I'm down again because of a cheap chinese POS distributor. I've had to resort to buying a used dist. and rebuild it myself with GM parts.

 

https://www.thirdgen.org/forums/engi...e-gm-made.html

not sure if this would help

 

Thanks but I'm going through this sh#t to get away from the small cap dist. The 'ol big caps rarely ever failed and when they did it was normally a hole burnt through the rotor button. I worked on airboats with Caddy motors on them. Those coil in cap HEI's sat out in the weather and were subjected to salt spray and they never missed a lick. Can't beat that kind of endurance.

 

Good information to know, I’m curious to see how a new coil in cap I bought from
davis unified holds up. But the small cap seemed like a good deal.

 

Are you running FI?

 

my 400 sbc build
4.185 bore, dished pistons, 10:32 compression. Comp cams retrofit roller cam 12-423-8, AFR 180cc Eliminator heads 1.52 rr. Slp ported runners and Edelbrock tpi base 58mm tb using a 1227730 ecm.