Newb looking for a bit of info on 3A scv

[IHblarp]

good to know! thanks petros. At this point I'm not too concerned about it, The car seems to run OK with decent power but it does smoke a bit, especially on start up, so maybe its more of a valve stem seal problem?? IDK. I didn't get a chance to do a wet test on it either which would be much more informative of where the problem really is.

I also ended up timing it this weekend which was interesting. This is the second time that I've timed any vehicle so i'm not too sure if I did it very accurately. When I first hooked up the timing light the timing was advanced way too far, Which means I've been driving it that way for about 200 miles . I would say it was about 2 in. before even reading on the degree indicator on the front cover. I took it back to 5 degrees BDC and it idled pretty rough, then I remembered someone on here mentioning setting it around 10 BDC so I went with that. Took it for a drive and it seemed to have much better power at the top end 3700~4700 and maybe a couple pulls over 5000, but the lower end performance just seemed to fall apart. Jumping out into traffic was a bit more terrifying. So I ended up taking it back and and fiddled with it a bit more. I finally ended up with it at about 12-15 BDC which seems to give it more power every where. I tried to do a ping check but I'm not too sure about what a "ping" sounds like. I took it out on a flat road got up to about 35-40 and threw it in 5th (~1800 RPM) and listened for knocking or "pinging" didn't really hear any abnormal so I guess it's ok?

[Petros]

typically ping is a cracking sound coming from deep within the engine when at full throttle. When you back off the throttle it goes away, it is worse on hot days. it would sound like having ball bearings rattling around the combustion chamber. IT is caused by sonic shock waves reflecting off the walls of the combustion chamber, it is damaging to the piston and head gasket, and very inefficient. Wasted energy, lots of emissions, and waste heat. It occurs when the peak pressures build up before the piston reaches the top of the stroke, and the up traveling piston causes a sudden rapid uncontrolled buring of the remaining fuel/air mixture, causing sonic shock waves.

A low compression engine has less tendency to ping, as does higher octane gasoline. In fact the octane rating is the measure of how well the fuel resists ping. Hot intake air, and higher pressures in the combustion chambers (as in full throttle) make it worse. But the higher the pressure in the chamber, without ping, the more power and efficiency out of the engine.

[takza]

Mine pings most from around 1200 to 1700 rpm floored in 5th...after this it goes away. If I recall right I had my timing set at around 14* BTDC...but my key is sloppy. Too much advance will cost you mpg...find where it pings and back off a few degrees?

Somebody on here had good luck using Restore with an engine that used oil...got better mpg as a result. I saw a couple of 38 mpg tanks with it.

Might run a pint of water thru the intake using an old soap bottle to control the flow...keep those revs up...then use a pint of kerosene in the oil as a oil flush...change the oil and filter (PL3001)...put in the Restore.

[IHblarp]

thanks tazka and petros. It's nice to hear some real word feedback about the restore and similar stuff. I'm still trying to get my ears tuned properly to know what I'm listening for. From petros' post I gather that a pinging noise is pretty similar to the noise you get when you lug a motor really bad, like to the point of it dying. It's the real bad shaking "ball bearings in the combustion chamber" sound. I think I got it to where its not knocking, probably right around 14-15 BDC.

On the MPG note, I filled the tank on sat before i took a trip out to the desert. In the past two weeks (225 miles) i averaged about 26 mpg. That tank included approx 100 miles of highway/freeway to get out into the desert and back, and 125 of running around town (lots of small trips, 2-7 miles each). I feel like that's pretty good considering all the time i've spent with it just idling in the driveway doing fine tuning and the test drives involved. it seems like maybe its just shaking off some cobb webs and might improve once the motor gets used to running again.

I also Just remebered that I was using my brothers cheap comp tester and it might not be reading very accurately, the pressure release button on it is stuck so it never really builds up to a number and stays, it just jumps and then starts to drop so maybe I can find a better one and re-do the test.

[deejay1272]

i averaged about 26 mpg

I'm also getting around that for combined hwy and city driving with my 3A-SCV motor. I hope I can improve on that...the mystique of ~35mpg was mostly what drew me to the T4WD in the first place!

Regarding your compression test - I would definitely try that again. It'll be useful to have a firm estimate of your engine compression for future reference.

[IHblarp]

I guess I'll see if Auto zone rents compression testers. I hear what your saying with the mpg, my last car (stock 90 honda CRX si) averaged 40 mixed driving and even managed to get 49 once trailing a semi truck on the freeway at about 75 mph for ~250 miles. Oh yea, It also had ~125hp at the wheels and 1000 less lbs. Man that car was fun to drive and cheap, sometimes I wonder why I just had to 'upgrade' to my terc. Then I remember that now I have 4wd, some ground clearance, can carry more than 1 other person, and have a conversation going down the highway at 70 mph. the fact that the terc's a lady killer too is just a perk!!

[sdoan]

I finally got around to doing a compression test, been kinda putting it off because I was worried it would tell me something I didn't want to know, which it did. Each cylinder was reading about 95-105 psi which is kinda disappointing.

Forgive me if you know this. But do your compression check with the throttle and choke plates open all the way. If the throttle plate is closed the compression reading will be lower.

Also, regarding timing (again forgive me if you know this). My timing with the vacuum lines connected to the distributor is very similar to where you set yours. Did you have the vacuum lines connected? The correct timing procedure is to have the engine idling relatively slowly (800 rpm should do) with the distributor vacuum lines disconnected and plugged. It is easy to accidentally swap the vacuum lines on the distributor advance and it is difficult to tell from the vacuum hose diagrams where they really should go (I now label mine with tape ).

Hope this helps.

[IHblarp]

sdoan, no need to be so hasty!! JK!!! Offer up any advice you want you can even tell me I'm doing stuff the long drawn out hard way (because I usually do) I've got pretty thick skin.

On that note though, I should have known both those things you describe but I actually failed to do both I think my comp tester is bad so maybe with both a new tester and a new method my results will improve. I will even try timing it with the vac lines discon. and plugged. If I recall right I already have them marked so hopefully that wont be a problem. With the lines dicon do you set the timing to the 5 deg BDC that the manual suggests?

on another note I think I have a exhaust leak, Ireplaced both the manifold gasket and the exhaust flange gasket in the rebuild but if your standing over the engine bay and blip the throttle you can smell exhaust and even catch a glimpse of it if the lighting is just right. I dont think its coming from the flange and doubt its coming from the manifold, could a clogged egr valve be pushing exhaust into the engine compartment??

[takza]

the fact that the terc's a lady killer too is just a perk!!

It is if they don't see you first?

[IHblarp]

true, true, tazka. If they see me first they melt like butter and there's no need for the car. Ha! I wish!

the car does all the work, the girls pretend to be interested in me but before I know it their asking for the keys?? I think I might be getting used

[sdoan]

on another note I think I have a exhaust leak, Ireplaced both the manifold gasket and the exhaust flange gasket in the rebuild but if your standing over the engine bay and blip the throttle you can smell exhaust and even catch a glimpse of it if the lighting is just right. I dont think its coming from the flange and doubt its coming from the manifold, could a clogged egr valve be pushing exhaust into the engine compartment??

Glad this stuff is helpful.

Mostly people hear exhaust leaks - like a loud splashy ticking sound that increases with engine speed.

If you don't hear it, but see it and smell it, it is probably an oil leak (or dirty finger prints - see below). If it is leaking on the carb side of the engine all the way back it is probably the fuel pump. If further forward, probably the valve cover gasket or blow-by out of the PCV system (cracked hose?).

Also after working on an engine - especially a rebuild - stray grease and oil (like from finger prints) can burn off and smell and smoke a little.