First, let me say I've been hanging aroud this forum for the last 6 months or so, and this place is a real wealth of information and guidance. Having said that, I'm looking for some feedback on the following:

I have a 79 L48 automatic. It's stock except for a K&N breather, headers with true dual side exhaust (no cat), and a 700R4 transmission with the stock rear end. The car has 60,000 miles on it.

The exhaust started to smoke gray/blue smoke at start up, so (with help because I'm stil a rookie) I changed out the valve seals (stock replacements), but it really didn't clear it up - so I'm assuming the valve guides need work too.

If I'm gonna go so far as to pull the heads, I can't imagine not doing some modest performance upgrades while I'm at it.

So here's the heart of my question:

I'm looking at the Jeg's website and am considering the vortec heads, edelbrock performer intake manifold (part #350-7116), and the Comp Cams 'Xtreme Energy' Hydraulic Flat Tappet Camshaft. This cam has a 432''/.444'' lift, 250°/260° duration, and is designed for 600-4600 RPMs.

Where I get lost is matching these 3 major components so that I get what I'm after - a decent horsepower/torque boost, I'm not looking for the big loppy cam sound (as much as I'm tempted to) but just some added pep.

The goal (more or less) is to gain somewhere around an extra 50 HP or so - enough to feel, but not anything too crazy.

My specific questions are:

- Will the stock Rochester Q Jet work wth this setup? I like the rochester, it riuns well, and does not appear to be too close to needing a rebuild yet.

- The vortec heads alone advertise a 20-40 horsepower gain - assuming my current cam is OK, could I go a more cost effective route by sticking to heads only, (or heads and cam) and keep my current intake?

- Knowing my current cam is 31 years old and these have a tendecy to fail, is my cam choice an improvement in terms of performance (horsepower/torque)? I'm mainly concerned I don't go "backwards" in terms of performance, and want something just a bit more aggressive.

I'm green enough to know that I need some guidance for my intended goal - any feedback or insight would be great.

Thanks,

Jim

 

What if it is your pistons causing the smoke?

 

I know that is a possibility - My thought process was to deal with that if I see it is a problem. Either way, the heads have to coem off (at a minimum). I kind of assumed I would probably stumble across something else in there anyway.If I find it's the piston rings or whatever - I will just need to deal with it anyway.

That doesn't really change what I want to do if I have to take the engine apart (except add more things to fix). But I appreciate the point. It's very possible.

 

do a cylinder leak down test at tdc first.....if you have weak ring seal, the smoke and cylinder seal problem if you have one will get much worse with new heads and cam......

 

Jim
You need the 2116 Vortec for the Q-J.
Definitely change cam! Really you should go up a step on the cam to XE-256, should make you very happy.

 

Best bet will be too buy a matched top end kit

Cam, heads, intake, carb all matched and dyno proven

If you dont its just a shot in the dark

Unless you want to pull the motor and run it on a dyno and tune it in with a miss matched unknown combination.

Remember just because a certain part claims X amount of horsepower gain it does not mean you can add up the HP numbers and think it will be so without the complete package they used to get those numbers

 

Thanks - all good feedback.

I agree that I should narrow down possible casues for the smoke at start up and adjust my plan to address that issue. Although I have not really noticed any performance problems like a drop in compression, per se - just smoky start ups.


Midyear vette - Just curious - will a leak down test tell me anything a visual inspection won't (I'll have to pull the heads off anyway). Not thinking about avoiding it, but just wondering.

Also - I like the idea Fonz69 suggested of a top end kit. The heads/intake manifold I originally referred to are sold as a kit through Jegs - but was struggling with nailing down a matching camshaft.

Ganey - Appreciate the reccomendation on the 2116 vortec. I'll look into that one.

Jim

 

the leak down will tell you the shape of the internals better than a visual....if you are just going to pul the heads and rely on the old fashioned way of checking the ridge etc...you still do not know the ring seal...the test will narrow down either bad valves or rings...or just pull it out and go through the short block too..jmo...

 

 

Good to know, thanks!

Jim

 

This is the right place to start.

Harbor Freight Leakdown Tester

 

OK, took some advice from here, and went back to looking at the smoky start up issue to make sure what ever I do with my engine also deals with that problem.

I'm planning on picking up a leak down tester this weekend, but in the meantime, I went back to check some things that might have been obvious to check first (at least to some folks, not necesarily me).

I observed the smoke starts about 30 seconds after start up, then clears within 5-10 minutes. It's worse on the driver side than passenger side, but both smoke somewhat. Passenger side is pretty light, and probably acceptable for 30 degree weather. After it clears, there is still some wisps of smoke on the driver side.

Held a tissue to the exhaust while it smoked, no oily residue - but a very faint sweet smell. I don't think this is condesation.... I know coolant/water tends to be white, but this still seems a bit gray to me (but who knows...).

Next wanted to see if I could confirm a head gasket issue - started the car with the radiator cap off. Starting the car, I could see an occasional bubble in the coolant - a very small one every 2 to 4 seconds. Not really sure that says it's a head gasket, but that came to mind. I've heard this is a good indicator of leaking head gaskets, but I really don't know if that is enough to confirm it. I knda thought I would see more bubbling than the one every 2-4 seconds.

I do expect the leak down test will tell me more, but wanted to get a sanity check here. Any thoughts/insights/experiences I can learn from?

Thanks in advance

Jim

 

Thanks for all the input - did both compression and leak down tests - on the compression the cylinders registered around 140 psi pretty consistantly. Leak down tests did not reveal any cylinder bleeding off too quickly or more than any other.

So now I'm back to pulling the heads off anyway, and might as well get this back on track to my original question(s) -

Ganey - Do you happen to know, on the 2116 Vortec maniflod, will it fit under the stock hood with a drop base air cleaner?

 

Any update to changes made?

 

Unfortunately, no - I got sidetracked checking out different cam options. I plan on tearing into this (with soem help) this fall. I'm figure I'll spend my time this summer working out the plan (and driving ht car) before I pull the Heads/manifold/etc.

I'm just a bit stuck considering the cam options out there. My original intent was to go with a mild (but slightly more aggresive) cam, with at least a near stock idle, and rely on the manifold/heads to really bring the old L48 to life. I actually have a Comp Cams XE250H cam, but thought about returning that and looking for a roller cam. Not sure I want to spend the extra money, but I keep hearing about the easier break in, and much less danger of wiping a lobe - so I'm still thinking about it.

I'm in no real hurry, so I thought why not spend the summer exploring the options...

 

Your cam choice is too small. You are putting on a decent intake and good flowing heads that will bump compression a full point and a cam that is not opening the valve far enough or long enough to take advantage of either.

 

After reading up, that was what I started to believe as well - I'm still pretty cam-illiterate - so I would really like to hear what others have done or would reccomend. I've been slow to do much partly because I'm a rookie with this particular area.

I'm not looking for massive ponies - but as I think about it, I would like to end up around 300 HP at rear wheels. I'm guessing that anything I do will be a real boost in torque as well.

Ganey reccomended the XE-256 - was considering that, then started reading up on the roller cam, but that gets inot a lot of extra work to make the conversion work properly. I think I may just stick with old-school flat-tappet cams.

So if anyone has reccomendations, I'll gladly tak'em - And if not, I also kinda enjoy checking out my options (and like I said, I have all summer to figure it out).

 

Lift is limited to .475 with those heads. This cam fits your lift limitation, will give you gobs of torque and fits your compression and maximum RPM your stock bottom end will handle. It will have a slight lope but will pull hard right above idle and I think is well matched to your use, goals and build.
http://www.compcams.com/Cam_Specs/Ca...x?csid=85&sb=2

 

63Mako - Thanks for the suggestion - I will definately check that out.

 

Yes as you have the med. rise hood & there is a possibility the stock air cleaner would work.