What should I do?

[crazy4offroad]

If you could get the spec sheet of the crate engine, that would help a lot. Compression ratio, cam specs, horsepower rating, anything you can find. Some of those engines I don't understand why they even produce them, the power numbers are a joke in a 5,000# truck. And a 2.5" exhaust on a weaker engine don't help performance, actually hurts it on the low end. Believe it or not but if you need more bottom end torque a 2" exhaust can get you there.

Try taking the flame tip off a propane torch, and put a section of vacuum hose on it. Start the truck and move the hose around the front and rear of the intake manifold, where those rubber gaskets go that most people throw away for just a big bead of silicone caulk. If the rpms spike, you have a vacuum leak.

Depending on the heads you're currently running, Vortec heads are bolt-on 40 horsepower, so they really are a worthy mod. They even outflow the best 2.02 old school casts right out of the box. Intake manifold compatibility is the reason most don't do it. You can mod your current manifold to work or drop about $160 for one made to adapt between L31 heads and carb.

And yes I saw you had a '79 but just felt there was something more, and admitting you're a F*rd man confirms lol. To crush a truck that has good parts on it even if you take the motor out tells me at least where your loyalty lies before you even said it. You could make more money on good parts than scrap steel (I know, I scrap a lot and it is way down right now) and it shows more of your frustration than anything. I didn't say you were being an ass, but more times than not I've passed on helping people who are down on their truck. Maybe that makes me an ass? Or a hypocrite because I've been there, quite recently really with my trans swap. But when seeking help I try real hard to control it. (coming from someone who has a terrible temper) Sometimes it just don't work out though lol.

 

[HotRodPC]

EEEERRRT !!! Put that brakes on one comment there Curt. I do not believe an OEM old school intake can be modified enough, in fact I'm fairly certain of it. You have no choice but to shell out the cash for the aftermarket Votec head intake.

 

[foamypirate]

EEEERRRT !!! Put that brakes on one comment there Curt. I do not believe an OEM old school intake can be modified enough, in fact I'm fairly certain of it. You have no choice but to shell out the cash for the aftermarket Votec head intake.

Correct. 6-bolt pattern for old school vs. 4-bolt for Vortec. It's TBI manifolds that can be modified to work on old heads, or vice versa, I believe. Not Vortec.

 

[HotRodPC]

Correct. 6-bolt pattern for old school vs. 4-bolt for Vortec. It's TBI manifolds that can be modified to work on old heads, or vice versa, I believe. Not Vortec.

Jep !!! And the ports are so big on the Vortec, there physically is not meat there to take away.

Still a worth while upgrade though. A nice RV cam, Vortec heads which not only flow much better but raise compression ratio, you can potentially, depending on the motor coming from and going to, increase 80-100 hp. This with the bigger cam, increase in head flow and added compression. If you've already got the bigger cam like in the GMPP motors that can be 290 hp with headers and intake, then NO, more like 60-75hp gain, but it's significant enough that it's very worthy. Also the added torque is sure noticeable too. And with the added power, the Vortec heads being more efficient, adds mpg if you can discipline yourself to keep your heavy foot off the skinny pedal.

The only bad about Vortec heads is that there is a ceiling of what you can get out of them and once you've hit that ceiling, you're done. Live with it. There is also a max lift which is fairly low. Is it like .480 IIRC?

In my days, I was more in .510-.525 lift hydraulic cams, sometimes solid in small blocks. Quite honestly, those aren't really street motors though. Gas was cheap enough back then, we didn't care that we got 8mpg, and the speed limit was 55, so we were geared low like 4.88 and 4.56 on passenger car tires and cruising 50-55 at 2900-3200 rpm. Didn't have to worry about tickets from the Hipo. Until we stabbed it and took it up to 6800-7000rpm for a 1/2 mile or so. FUN DAYS !!!

 

[spartman]

Found this link that shows the engine I purchased.

http://sdparts.com/details/gm-goodwrench-replacement-engines/10067353

Hope it helps. If not let me know and Ill try and get more specs from the local GM dealer.

They should have it I think..

 

[spartman]

I was always told that to swap vortec heads on you needed the proper intake and exhaust manifolds.

Also that on some swaps the heads and exhaust manifolds cause clearance issues with things like steering gears and shafts.

Dont think that applies for these trucks, but I could be wrong.

Just ask my wife.....

 

[spartman]

And yes I saw you had a '79 but just felt there was something more, and admitting you're a F*rd man confirms lol. To crush a truck that has good parts on it even if you take the motor out tells me at least where your loyalty lies before you even said it. You could make more money on good parts than scrap steel (I know, I scrap a lot and it is way down right now) and it shows more of your frustration than anything. I didn't say you were being an ass, but more times than not I've passed on helping people who are down on their truck. Maybe that makes me an ass? Or a hypocrite because I've been there, quite recently really with my trans swap. But when seeking help I try real hard to control it. (coming from someone who has a terrible temper) Sometimes it just don't work out though lol.

Oh I wouldnt hesitate to crush a ford if it pissed me off as well.

Ive just had much much better luck with Fords than chevy's. My dad was also a ford man in the cars, but for trucks he thought chevy's were better.

I thought they rode like lumber wagons and had the brakes to match.

 

[HotRodPC]

Found this link that shows the engine I purchased.

http://sdparts.com/details/gm-goodwrench-replacement-engines/10067353

Hope it helps. If not let me know and Ill try and get more specs from the local GM dealer.

They should have it I think..

That's not a slouch motor. That one is better than OEM for sure. That appears to be the same motor I have in the K1500. Add Eddy Intake, Headers and 600cfm carb, should get it real close to 290 on the ads I've seen. It should be performing at least at OK standards even with 3.08's. I'd certainly do somethings like check your timing advance, check for vacuum leaks as previously discussed. I'm aslo wondering if you're not having a Trans problem or converter problem. If one of the other is slipping. You shouldn't be this unhappy with that motor so long as you're not expecting it to function like todays cars and trucks and keeping in mind it's a heavy 4wd truck.

I was always told that to swap vortec heads on you needed the proper intake and exhaust manifolds.

Also that on some swaps the heads and exhaust manifolds cause clearance issues with things like steering gears and shafts.

Dont think that applies for these trucks, but I could be wrong.

Just ask my wife.....

Yes, you have to swap the intake for sure to the aftermarket Eddy intake, not sure about the exhaust manifolds, and no problem at all using them on these trucks. Been done many times over.

Oh I wouldnt hesitate to crush a ford if it pissed me off as well.

Ive just had much much better luck with Fords than chevy's. My dad was also a ford man in the cars, but for trucks he thought chevy's were better.

I thought they rode like lumber wagons and had the brakes to match.

That's wierd, I always though GM had better cars, and Ford made better stronger work trucks, even tough GM's were more comfy and failed less. Ford in the late 80's thru the GMT400 did make a stronger chassis. I think about equal now though.

 

[89Suburban]

4 degrees timing??? The stock sticker shows 10 and Ive been told to push it to 12.

The vac gauge shows a nice 15-17 when running constant. Drops to 10 without much effort from the pedal.

Will idle at 17 warm, hits 20 on cold fast idle.

That reminds me, the dizzy is an accell dizzy I bought new for the engine. Its got the stock spring configuration in it as well.

Currently its set for the stock 10 degree advance.

Wow, that is a lot of advance and a low on the vac. You get any pinging at all?

 

[spartman]

No pinging that ive ever heard.

I guess Ive never come across any engine that states 4 degrees adv timing.

Always been 6-8 min with it going all the way up to 10.

Plugs looked clean as well there was nothing to indicate pinging either.

I know its harder to read plugs these days with all the gas etc, but these looked good like they should.

 

[spartman]

I have tried to spray starting fluid around the intake to detect leaks but nothing ever seemed to be out of place.

Ill have to try the propane thing.

 

[HotRodPC]

My motor IIRC is that spec, with Eddy EPS intake, headers, and 600cfm Eddy carb and Th350, in a K1500 with Th350 and NP208. But, it is running 3.73s on 31x10:50 tires, so the tires are bigger than yours too. Should be real close in weight, maybe 400lbs lighter with the Transfer case and yours being the 80 model, this one is 85. Here is a sound clip of a test run after I rebuilt the Th350 with a little shift kit. It's not fast, but not a sled either and I'd have to guess about 12-14mpg. I'm fine with it's performance and mpg.

http://www.youtube.com/watch?v=ieDdUetOyNw&feature=plcp

 

[spartman]

That's wierd, I always though GM had better cars, and Ford made better stronger work trucks, even tough GM's were more comfy and failed less. Ford in the late 80's thru the GMT400 did make a stronger chassis. I think about equal now though.

Ive driven GM and Ford cars and I always thought the fords would stop on a dime and rusted less.

Although if someone were to sell me a 78-88 Monte Carlo................

The ford trucks also seemed to hold up better here I thought. Most of the chevys here looked like swiss cheese.

The only reason the chevy's were more popular here, I think is that the Ford dealership was lacking on personal skills. The GM dealer had the service etc going on for a long time.

Now the roles have switched it seems.

 

[89Suburban]

I wonder if you have a EGR issue. Got to get Jims86 to chime in here on this.

 

[spartman]

My motor IIRC is that spec, with Eddy EPS intake, headers, and 600cfm Eddy carb and Th350, in a K1500 with Th350 and NP208. But, it is running 3.73s on 31x10:50 tires, so the tires are bigger than yours too. Should be real close in weight, maybe 400lbs lighter with the Transfer case and yours being the 80 model, this one is 85. Here is a sound clip of a test run after I rebuilt the Th350 with a little shift kit. It's not fast, but not a sled either and I'd have to guess about 12-14mpg. I'm fine with it's performance and mpg.

http://www.youtube.com/watch?v=ieDdUetOyNw&feature=plcp

Nice sounding shift there.

I had been told that I should be getting at least 12 with my truck, but noone had a clue on how to get it.

I even went so far as to research TBI fuel injection and how to hack those 1st gen ecu's

Hopefully with the new gears it will start to wake up.

In case I didnt mention it before I did do a compression check on the engine and it had 150psi on all eight cyl.