"New" '86 C20 need advice...

[pdxmac]

Hey all,

I bought an '86 3/4 ton 2wd pickup to fix up for my business, and towing my job trailer. I've been driving it around for the last couple weeks trying to work out the bugs, and all of the "fixes" that have been done to it over the years. I've already replaced the master cylinder and booster because the rear portion of the master cylinder was pumping all of it's fluid into the power booster. The truck is really solid, and has absolutely no rust at all. There are a few dents to deal with at some point, but not bad..

All of that said, I would like to start making it run a bit better. It's got a 305 4 bbl, and 700R4 transmission. It's got a sticky lifter that will not let go by the convetional first aid methods ( atf, engine flush, etc..) The engine doesnt smoke and appears to have decent power at times so I think the bottom end is ok for now. My thought is to replace the cam and manifold with an Edelbrock performer setup, and hopefully the carb as well. My problem is I want the truck to be able to pass smog so it doesnt loose it's resale value should I decide to get a different pickup down the line.

Does anyone have experience with these modifications, as they relate to keeping the truck smog legal? Is my truck computer controlled? Do I have to keep it computer controlled? Any experience with high-flow cats?

I know that is a lot of questions.. There will be more :-)

I really appreciate the help!!

Aaron

[bigtruck81]

a 305/700 truck bought specifically to pull a trailer? unless its a really small trailer, i'd seriously look into getting rid of the 700R4.

[Srubydo1986]

agree get your self a th350 or th400 like i did it hlod up better nder a tow. but ur gasmileage wont be as good (no 4th gear)

As for the engine it most likly carberated cause i believe 87 was the first fuel inject/throotle body set up. I put a throtle body engine in my 86 and mad it carberated via edelbrock intake.

as for smog you could up the wieght in the truck so it doesnt have to pass smog. My truck is a 2wd 86 1/2 and has a wieght class of 10,001 so no smog/ emissons. just a thought and you can bring it back down anytime all you have to do is tell dmv.





hope these pictures help a bit.

[scotty101]

hey scrubydo1986 do you have more pics of the engine? i am workin on a truck like that. thanks

[Srubydo1986]

yea i got mose here ill give you a bunch of shots

Shots during the engines build.

how she started her life.

shot of engine out of truck



Shots of engine in truck The orange headers didnt last i found a company to make it last forever but to much for just a daily driver.

Shots after build.



This is all i have right know ill have more later sorry for the high jack but i think these might help you anyway.

P.s. scotty101 if you need more info heres the build thread for the truck. http://67-72chevytrucks.com/vboard/s...17#post2007117.
Also remember to get the right intake if making a throotle bosy engine caberated the heads are catty corned in the middle near carb. youll need a special intake for edelbrock ill get you then numbers if you want them.

[Pyrotechnic]

That Edelbrock performer cam has too much lift for a stock valvetrain. You will destroy your motor with it. By putting in a radical cam, you create new problems, and other mods have to be made to solve them. Stronger pushrods, performance valve springs, screw in studs and guide plates, milled down guides, and high lift capable rockers.

I recommend that if you know for sure that you have bad lifters, remove them and look down at the cam lobes to see if there is any noticeable wear. If the cam looks ok, get a set of stock lifters and replace them all. This is the simplest solution and you will still pass emissions.

For a little extra power I would recommend an Edelbrock Performer aluminum manifold. Get the one with the Q-jet pattern to keep your stock carb.

Get a set of small diameter long tube headers. They will give you a little more power. Get a true dual exhaust with high flow cats. 2.25 inch pipe should be alright. Pick your favorite mufflers. Turbo mufflers are decent for the price at $30 each. If you are on a budget, you can have them put turn downs on the exhaust right before the rear axle and end it there which will save you some money.

Another thing that helps is an open element performance air filter. In order to pass smog you will need the stock one, but as soon as you get home you can put your good filter on. Just keep the old one around for inspection time. This will give you more crisp throttle response and a touch more power.

And of course while towing, keep it in 3rd gear.

[pdxmac]

Thanks for the good words.. It is a small trailer I tow, a 5x10 enclosed Wells Cargo for all of my tools, so I'm not too worried about the tranny.It also shifts as if it has been worked on in the past. Of course, I have no way of knowing that.

I had a 3" high flow cat and 3" exhaust installed today, and that made a nice difference. I don't have to pass DEQ because of permant disabled veteran plates. I just dont want to strip it so that I would be unable to sell it should I decide to do so in the future.

The engine has adequate power for my needs, of course I would always want more. I will likely drop in a stroker at some point, but I'd love to get a couple of years more out of this engine. I'm also considering 4:11s for the rearend, especially since I've got the O/D tranny. It was hot here the other day and the heater core went boom, and the radiator is also seeping. I am going to replace both this weekend, and am also upgrading the radiator to the 3 core HD option. I've got the 19" core in there already, so that should slide right in. I think...

Aaron

[MylilBowTie]

I would start with a tune up before the cam and intake swap. What do you mean it has decent power at times?

The only computer controlled things you have would be ESC. Electronic spark control to prevent engine pinging (knocking). If the knock sensor picks up too many knock counts it will retard the timing until the count is lower. Sometimes if the exhaust it leaking it can cause the mess with the knock sensor picking up false readings.

Its a personal choice if you want to keep the ESC unit. But it is not needed to run the engine. You can modify the wiring to disable the ESC or get an older non ESC HEI distributor. Check out this link for a little more info. http://www.73-87.com/7387garage/drivetrain/escrepl.htm

I would get a summit cam and lifter kit from summit racing. http://store.summitracing.com/partde...2&autoview=sku
It has the same specs as the Edelbrock performer. I would stay with the Edelbrock intake.

A better exhaust would help. Headers are a little better for performance but cost more for the emissions legal ones. Using the stock manifolds would be okay to run the dual exhaust. I've used Catco convertors before and didn't seem to have any problem from them. But I did have a head gasket ruin one with the antifreeze that poured into the exhaust. I replaced them with some new pypes converters and all seems well with those.

The 700r4 should be fine for towing depending on the gear ratio you have. I would check the rpo list for the gear ratio. I don't think I would try towing in over drive at all. My 86 has 3.42 and a 700r4 that lasted 220,000 miles. The 700r4 started messing up so I replaced it with a th350. I got a good deal on the th350 so used it rather than getting the 700r4 rebuild. It would have cost a good deal more than what I had in the th350.

[Srubydo1986]

i wouldnt use a 411 gear ratio on a 700r4 id say a 373 would do you fine. by putting in the 411 in you might burn up the trans pull buy putting the 411 it defeats the purpous of having over drive (gas mileage).

But thats just me ive had a bad pass witht he 700r4s and i just dont like them much even if id love to put one im my truck know for the mpg it would have to be heavily modified to withstand the gas/ ass i put through it.

[pdxmac]

Originally Posted by MylilBowTie

I would start with a tune up before the cam and intake swap. What do you mean it has decent power at times?

The only computer controlled things you have would be ESC. Electronic spark control to prevent engine pinging (knocking). If the knock sensor picks up too many knock counts it will retard the timing until the count is lower. Sometimes if the exhaust it leaking it can cause the mess with the knock sensor picking up false readings.

Its a personal choice if you want to keep the ESC unit. But it is not needed to run the engine. You can modify the wiring to disable the ESC or get an older non ESC HEI distributor. Check out this link for a little more info. http://www.73-87.com/7387garage/drivetrain/escrepl.htm

I would get a summit cam and lifter kit from summit racing. http://store.summitracing.com/partde...2&autoview=sku
It has the same specs as the Edelbrock performer. I would stay with the Edelbrock intake.

A better exhaust would help. Headers are a little better for performance but cost more for the emissions legal ones. Using the stock manifolds would be okay to run the dual exhaust. I've used Catco convertors before and didn't seem to have any problem from them. But I did have a head gasket ruin one with the antifreeze that poured into the exhaust. I replaced them with some new pypes converters and all seems well with those.

The 700r4 should be fine for towing depending on the gear ratio you have. I would check the rpo list for the gear ratio. I don't think I would try towing in over drive at all. My 86 has 3.42 and a 700r4 that lasted 220,000 miles. The 700r4 started messing up so I replaced it with a th350. I got a good deal on the th350 so used it rather than getting the 700r4 rebuild. It would have cost a good deal more than what I had in the th350.

Thanks for that write up.. I knew there was some sort of computer behind the glove box, I just didnt know what it did. I'll be getting rid of that I am sure, but at least I know I dont have to worry about it. I also have the 3.42:1 rear end (9.5" 14 bolt). I never tow in overdrive, so thats not an issue. And I've al but decided on dropping in some 4:11s since I plan to have the rearend gone through anyway at some point. My dad had an 85 gmc new back in, 85 :-0 that had 3:73s and the 700R4 and we always wished we had 4:11s.. the O/D would make it plenty tall for short highway trips. Since this is primarily a work truck, I think that would be the ticket. Would do a lot for seat-of-the-pants performance around town as well. I think I'll just replace the lifters and manifold on this motor, and hope it hangs in there for a couple mroe years, rather than messing around with the camshaft.

Oh.. and I'm not sure what the hell I meant by "decent power at times".. must've had a few beers on board :-)

[MylilBowTie]

Originally Posted by Pyrotechnic

That Edelbrock performer cam has too much lift for a stock valvetrain. You will destroy your motor with it. By putting in a radical cam, you create new problems, and other mods have to be made to solve them. Stronger pushrods, performance valve springs, screw in studs and guide plates, milled down guides, and high lift capable rockers.

That might be so for the Performer PRM cam but not the Performer. The Performer is almost stock type grind made for fuel economy and torque. Edelbrock brand for the cam and lifter kit cost 119.88 vs Summit Brand for the same thing is 69.95. That is almost what the lifters alone would cost. Having to go with the trouble of installing new lifters I would also do the cam. Its not much more work to do. I would also grab a timing set from autozone they have Cloyes brand for 20.00 single or a double for about 25.00

I would break it in with some Shell Rotella or Chevron Delo oil, use plenty of GM EOS assembly lube for the cam and lifter and install a good Wix oil filter.

[Pyrotechnic]

Oops. A quick glance at the Edelbrock website lead to to believe that was a huge cam.

Any RV type cam will be fine though. The Summit cam is a good one. Several rebuilders warehouses sell generic performance cams like that and I'm guessing they are all made by the same company. Good cams for the money.

[Slonaker]

Originally Posted by Pyrotechnic

Oops. A quick glance at the Edelbrock website lead to to believe that was a huge cam.

Any RV type cam will be fine though. The Summit cam is a good one. Several rebuilders warehouses sell generic performance cams like that and I'm guessing they are all made by the same company. Good cams for the money.

I put a summit cam and lifters in my '86 305. It had a performance cam with stock gears and exhaust when I bought it, so the stock one actually improved the performance. I don't know which one, I just told them I wanted a stock pre-emissions cam. I had no problems with it. It outlasted the bottom end.

Slonaker

[bigtruck81]

Originally Posted by Srubydo1986

i wouldnt use a 411 gear ratio on a 700r4 id say a 373 would do you fine. by putting in the 411 in you might burn up the trans pull buy putting the 411 it defeats the purpous of having over drive (gas mileage).

the mechanical advantage of 4.10s over 3.73s would actually help the life of the trans, not shorten it.

[pdxmac]

Originally Posted by bigtruck81

the mechanical advantage of 4.10s over 3.73s would actually help the life of the trans, not shorten it.

I would have to agree with that for sure. And for my purposes, makes a lot more sence. Even with the 4:10s I will still be able to cruise down the highway without wrapping it up too far. For me, going back to a 3spd trans doent make sense. I appreciate the perspective though.

[Pyrotechnic]

Originally Posted by bigtruck81

the mechanical advantage of 4.10s over 3.73s would actually help the life of the trans, not shorten it.

I second that one. With 3.42 gears my truck felt as light as a Camaro. I could be rolling at 55 MPH and rev it up like it was nothing without the transmission needing to downshift unless I floored it. Now with 3.08's it feels like i'm pulling a fully loaded trailer.

Gotta run the 3.08's though since that rear is totally rebuilt with brand new bearings and a posi, plus all new brakes. Gonna be doing mostly highway driving next semester.

[Srubydo1986]

i stand corrected. My bad i must have been thing in a different way.

[Slonaker]

The 4:11 gears probably don't have as much of an affect on a 3/4 ton as they do with the 1/2 ton. I haven't done the math, but I suspect the 1/2-3.73 and and the 3/4-4.11 are probably closer than you would expect because the tires are so tall on the 3/4 ton.

Slonaker

[pdxmac]

Originally Posted by Slonaker

The 4:11 gears probably don't have as much of an affect on a 3/4 ton as they do with the 1/2 ton. I haven't done the math, but I suspect the 1/2-3.73 and and the 3/4-4.11 are probably closer than you would expect because the tires are so tall on the 3/4 ton.

Slonaker

Thats a good point.. It probably wont get done till next month I wouldnt guess, but I will be sure to post comments on the results..

Plus I'll have to figure out what speedo gear I'll need as well

[wolfewerx]

Just some quick thoughts for you-
Depending on tongue weight and truck load you will need to have enough tire(load rate) to cover it. Highway DMV are checking this(scale under back tire) and especially if you have a company name on your trailer. Heavy load tires are not available in all sizes. So get your tires and then look at gearing.
Your truck probably came new with 205s or 215s so if you have 235s or bigger-look what you have already done to your gearing.
http://www.4lo.com/calc/geartire.htm
"Designer " wheels are not work wheels so make sure you match up here also.
I know you said its just a little trailer but I know what I put on trailers and now I make sure I'm covered for those "I'll never do that again" !!

[MylilBowTie]

Stock size should be 225/85/16. That is the first time Ive ever heard of anything like that. Semi-Trucks I can see but light duty trucks? Unless you have something over a 1 ton its light duty.

[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.

[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.

[68GMC454]

i know with my 3/4 its alittle differetnt since i got a 454...but as far as little trailer, mine was a 7x12 utility trailer i used to haul my mowers, and used it on any cean up jobs i got i used it...i would load the truck, the trailer and think i didnt have that much weight on the trailer and when i scaled it, i would find i had almost a ton on the trailer..so it doesnt take as much as you think to get a load heavy fast...personaly i wish i had 3:73's or higher, i got 4:11's now,,but i think alot has to do with the granny tranny..ive owned it for 5 yrs now goin gon 6, and i still find my self reaching for the next gear...you would think i would know i dont have any more left by now, but i go by the sound of the engine, and im always reaching..lol...for now id run what you got,,get the valves fixed, then run it till the tranny goes, and look for a turbo 350 or 400 if it ever quits...stock steel 16 inch rims are just right for a work truck..running the sstock size tire,,put a 10 ply tire on them and you wont have to worry about load limits..