I have a related thread about this engine here:

https://www.ford-trucks.com/forums/8...ml#post7477179

Getting a little long in the tooth over there about carburetors, so here's a fresh thread about timing.

Any advice and experience is much appreciated. I'm a six cylinder disciple coming back to a V8 after a long hiatus (Ok, only about 5 years).

The engine in question looks to be early 80's. There are a lot of ported vacuum switches on the intake, along with an 02 sensor visible on the passenger side exhaust manifold, maybe both. There appears to be an 80's C5 transmission also dumped into this truck, a 1978 F100. (Looks like a C4, but with "Metric" embossed on the tranny pan -- and it's definitely not an AOD)

I bought the truck from a fellow collector who himself had rescued the truck from a misguided attempt at a re-fit. Someone had this engine converted to points, and my good friend at least converted it back to DS II before I picked it up from him. I did make sure to keep the points dizzy for possible future needs.

Besides my carb adventures from the other thread, I've turned my attention to the ideal timing curve for this setup:

Stock 302. Dual exhaust from stock manifolds. 2100/2150 (Holley 2300 is also a possibility)
C4/C5 Auto (confirmed functional in all gears, but needs kickdown plumbed properly)
2.75 9" rear end. (wow!)
Compression test brought back 150 PSI.

I don't think anything has been done internally, unless a mild compression bump? Haven't been able to get at block or head casting numbers, but I have a small telescoping mirror that can solve that. Engine has 20-22" of vacuum at a very smooth 1000-1100 idle. I haven't been able to get it lower yet in my ongoing carb tuning.

I want this truck to see regular duty, as I run my trucks as daily or weekly drivers, depending on what I need. My fledgling carpentry business is riding on these units. I'm not established enough to buy a new truck for company tax writeoff yet, but that's beside the point.

My 76 highboy does the real work, and with style. This 78 F100 truck will be all about highway driving, estimates, and decent fuel mileage. The 2.75 rear end may help, but I need whatever tourque I can squeeze out of this 302 for the truck to at least get out of it's own way.

I have a 300 and a very fresh NP435 that I'll drop in there in a heartbeat if I don't get the results I want here, but I'm willing to give the 302 the old college try .... since it's already in there, and I want to drive this truck ASAP.

So here's the timing nitty-gritty:

I opened up this distributor, and found a 21L/16L plate, which was set to the 21L option. This means with a base of 10 degrees, and 42 of mechanical advance, I'm pushing 52 degrees of total advance!! This doesn't include my vacuum canister, whatever it's pulling at.

I'm thinking this is a little too much for this engine, with regular grade gasoline - especially if compression is raised above stock. (Again, I don't think it is. 150 just sounds like it's fairly tight seal in a stock engine to me; fairly fresh bores)

For a stock or nearly stock 302, what would you folks, in all your wisdom choose for a timing curve? In that, I'm wondering what would work best for low end tourque in a two barrel engine that will see significant highway time, crusing about 2000 rpm at 65mph. 45 total degrees, all in at 3000 rpm, for example??

Thanks for your patience in reading this mess, and thanks for any thoughts and ideas.

 

Gee I got carried away there. Sorry for such a long post.

Actual question without the big story:

What would people suggest for a timing curve to be used in a stock 302 with stock 2 barrel carburetor - in a truck with 2.75 highway gears?

Trying to dial in something that will maximize what tourque I can shake loose, as I'll need whatever I can get, I think.

 

Your best option is a custom tuned dizzy from Re-In-"Car"-nation High Performance and Automotive Repair/index For about $150, already tuned to your motor, just drop it in. There are numerous sites for tuning that curve. If short on money, like me, I would get a spring kit and change to the 16L slot and swap out the long loop spring to a yellow one. This should bring total advance in between 3500-3800 rpm. With those tall gears, just my opinion, I would try to get my advance coming all in as low as possible in rpm.

 

Thanks for the heads up gfw.

I am going to do the work myself, as I'm trying to keep costs low on an engine that might not even be there in a couple weeks. I might use the 300/NP435 4 speed combination currently sitting in my 85 if there's any mechanical troubles at all with the 302/C4.

I was also thinking a little less mechanical timing, all in at lower rpm. I will get a different spring kit, and switch to the 16L to see what I get, and use an advance timing light to see exactly when it's all in, and at what rate.

 

I would like to see 100% advance in at around 2500 rpm. With a oem vacume dist. typically you can easily get that by removing 1 of the vac advance springs inside the dist.

To fine tune, you can either purchase aftermarket springs from summitt, etc or gently stretch the spring you removed and reinstalll it. This may take a couple of ties but it works.

 

Thanks for the thoughts..

I have re-curved to the 16L side, but havent done anything to adjust the rate of advance yet. I'll do so at first bending tabs, and may try the spring stretch, and eventually, if the results seem worth it, I'll buy the proper springs.

I'm starting to think this engine is going to need a bearing job. Good pressure, but a bit of rod chatter in the higher rpms when no load. When I pull this engine out, it will be to replace it with a 300 six, not to replace the bearings..

I'll know soon enough, the truck will be on the road next two weeks.