performance improvements

[rick0312]

My '69 C10 LWB has a '76 305 V8 motor that was rebuilt and installed back in 1988. Runs well, but I have noticed a few problems....
1. When starting after sitting for a few days i get alot of white smoke. the smoke subsides once the engine is warmed up.
2. Classic rear seal leak, not that bad though. A couple of drops on the ground per week. Oil level is stable.
3. valve chatter at part throttle sluggish throttle response in 2nd and 3rd gear.
The p.o mated a saginaw manual 3peed to this engine with aftermarket shifter on the floor. Could this be the problem?
This truck is basically a weekender and I have no intention on a full restore. I have refurbished this truck in order to keep it operational. i have installed new front and rear suspension. New floor pans rocker panels etc.

I quess my question is what can I do to this motor to rectify the sluggish performance I am gettting currently? I have advanced the timing and replace the vac can, although there was some improvement I still get the sluggish response. I am thinking of upgrading the cam????

thanks for all your input!!

Rick

[71meangreenc10]

White smoke could be antifreeze getting into a cylinder, have you checked the vac advance to see if it is working, also try to adjust it, 3/32 allen into the advance turn it counter clockwise until it stops, then 4 turns clockwise, go for a drive and keep turning it one full rotation clockwise until it starts to ping on acceleration, then go back one. I have mine at 5 turns and it seems to be real peppy..

Hope it helps..


Smitty

[rick0312]

thanks Smitty! It seems that the P.O. had the advance can hook to continuous vac. I am going to pickup some additional vac hose and switch it to the ported connection and see what happens.
Rick

[cdowns]

white smoke after sitting is pretty normal it's just the engine burning up the condensation in the cylinders and exhaust pipes//when i lived up in the northeast every winter they'd sell that oxygenated gas that causes white smoke too

[Myself]

Sounds like a typical 305 of that era to me. Swap in a Crane Blue Racer cam with split profile 442/465 lift, A weind stealth intake, A 600 cfm aftermarket carb of your choice, and put a wake-up kit in the distributer. The difference will be like WOW!! Night and Day!! I've found these goodies work well on the 305. The 305 doesn't respond well to huge cams with lots of duration like a 350. This setup with decent exhaust will put a full size truck knockin on 15's in the 1/4.

[65-72 chevytoys]

Super Chevy just did a tech article a while back on a performance build up of 305/307. They used a set of edelbrock Etec 170 aluminum heads, comp cams 262H cam, performer intake and 600 cfm carb with MSD Pro billet distributor and produced 315 HP and over 330 fl-lb of torque. Assuming the short block is ok that is a respectible set up and will get good mileage too with the small displacement.

[WorkinLonghorn]

thanks Smitty! It seems that the P.O. had the advance can hook to continuous vac. I am going to pickup some additional vac hose and switch it to the ported connection and see what happens.
Rick

That looks like a good idea Rick.The Vac-advance ABSOLUTELY must be hooked up to the correct port or it's purpose is completely defeated as it will stay fully advanced at idle and then retard the timing at full throttle,when connected to manifold vac port.
>>Never mind about completely rebuilding the motor with $5000 worth of hi-po parts!! Just a 83 cent vac-hose aught to made a huge difference.

[rick0312]

hey guys thanks for the info. I hooked the vac up to the correct port and no difference in the performance so I pulled her in the garage and did a valve adjustment....Still no difference still get that tic tic tic.........so I took some time to listen when the truck was running at idle. I noticed that the tic was louder on the passenger side. I walked to the rear of the truck and covered up the pass side rear exhaust for a couple of seconds. The ticking got louder!! and not much exhaust force coming out of the pipe. I then walk over to the drivers side and covered up the pipe...Man i could really feel the force of the exhaust........So now I am thinking that all of this sluggish response and ticking is possibly holes somewhere on the pass side exhaust system.........Does this make sense? I know that holes in muffler = loss of horse power and performance. What do you think?

[WorkinLonghorn]

I would say that if switching your vac-advance from manifold vacuum to the correct throttle activated port vacuum didn't make any difference in performance then your vac advance is not functioning at all.
>>When you apply a slight vacuum to the hose after disconnecting it from the carb can you see the breaker-plate move? If you can't maintain a slight vacuum in the line then the diaphragm is shot.
I don't know much about exhaust systems except that a leak in the exhaust manifold will give you a sort of ticking sound sometimes,but I don't think you will lose tons of power with a leaky exhaust.JMO

[rick0312]

the vac can seems to be working. I set base timing and then hook up the vac can and did see a increase in advance timing. just to be certain I replaced the can with a new one. I really think I am losing power through the exhaust on the pass side. I am going to crawl underneath with some muffler tape and see if I can find any holes. I'll keep you guys posted. Thanks for all of your help!!

[Myself]

Sounds like one or more burnt valves. Do a compression check then you'll know for sure.

[Richard H.]

Rick, The cam idea may be a good one if that is the original '76 cam in there. I have heard that the 305 cams were notorious for wearing out. The pic shows a cam out of a '72 350 I just took out...whole lot of duration just NO lift!

[panhandler62]

An exhaust leak makes a hiss/tic kind of sound, like making an exagerated hard "T" sound with your tounge on the roof of your mouth.

A distinct metallic "tic" that is easily distinguishable to one side is most likely a valve train component as "Myself" menitioned. It is notable that an exhaust leak very near the head can *cause* burned exhast valves.

[rick0312]

thanks.....hopefully it is holes and not burned valves. The tick/hiss seems like it is coming from the muffler, it is especially exagerated when I occlude the exhaust pipe for a few seconds. Keith thanks for the great description of the Ticking noise.....it does sound like an exagerated "T". Richard thanks for the pic of the cam and lifters.

Rick