"New" '86 C20 need advice...

[pdxmac]

Originally Posted by Roper

Is an old 305 worth putting money into? If it was me I would just run it and save my money to put something bigger in.
Also i tow all the time. My 350 four barrel/th350 has way more power and gets way better fuel mileage since I swapped out the 1/2 ton 308 geared axles and went to one ton 410 geared axles.
If my truck had a 700r4 I would actually want 456 gears.

Really? 4:56s ? I am game, I just dont want it toi be wrapped up to 3000rpm+ at 65-70mph while I'm going down the highway. Is there a way to figure this all out? as far as rpms at speed etc?

I actually flushed the engine and changed the oil yesterday, and the lifter noise is gone! Must've finally flushed whatever was stuck in the check ball out. I agree with you about not putting money into the 305 and waiting to build something bigger, I just have to be able to get this thing to a dependable state for my work truck for the time being. It actually runs quite well now. I've resealed/reattached several vacuum lines that were loose or disconnected, and adjusted the idle mixture. It's still a 305 however, and doesnt have a lot of balls. It tows the trailer much better than my Jeep wrangler did however, which is what it is replacing!

I've done a pile of work to it this month, I've:

-Put new wheels and tires on
-Installed new master cylinder and booster
-Had a 3" cat and Magnaflow exhaust installed
-removed the side mouldings
-buffed out the old paint to get it to shine a bit

I blew out the heater core on a hot day last week, and the radiator is seeping, so I ordered replacements for both, should be in next week. I upgraded the radiator to the 3-core big block option as well. I am considering a flex fan in place of the clutch fan, I've been told they cool better for towing applications. Any input on that?

Thanks guys!


I'll post some pics later today..

[pdxmac]

The tires I put on are 245/75-16 10-ply E rated tires.. so weight should not be a problem.

Also to someone's earlier point about raising the GVW to avoid the DEQ. In oregon that doesnt work, as everyone under 26,000 lbs has to DEQ. Diesels over 8500 dont have to, but it does not apply to gas power vehicles in this state.

[Roper]

Originally Posted by pdxmac

Really? 4:56s ? I am game, I just dont want it toi be wrapped up to 3000rpm+ at 65-70mph while I'm going down the highway. Is there a way to figure this all out? as far as rpms at speed etc?

..

There web site is down today http://www.bowtieoverdrives.com/index.shtml
But from the graph I have printed out a 700r4 with 4/10 gears and 33" tires at 65mph your motor is only turning 1900rpms which is to low.
My th350 is turning 2700rpm with same 33" tires <that actually measure 31" mounted and under the load of my truck and same 4/10 gear ratio. I haul horses and this combo. It works great for me but if my truck was even a bit lower spead that would be even better. Really what I should have is a Gear Venders overdrive.
With the 308 gears the truck sucked gas and had no power.

[Roper]

If I was you I would start looking around for a good deal on a second hand Corporate 14 bolt FF 10.5" ring gear with 456 gears. Your probable only going to be able to find one with 4/10s but thats better than what you have. Those axles sell pretty cheap<think $150-$200> and seals and bearings dont cost that much.
This would give you more bang for the buck than modifying your motor.