HI again

I had said in my earlier post that, I am going to send off my Q-jet probably to national carb, and for like 150.00 they refinish, it rebuild it and put a decent tune, and it is supposed to be like new. I have done a fair bit of reading, and from what I can tell the Q-jet if in good shape and u understand it offers just as much proformance as any holly or elderborck carb. But I was wondering is it worth it to put a Proformer intake on it while I have the carb off, how much HP would that get me if any? Also would there be any advantage to swaping out the cam for something slightly more agressive and any idea's on price? Or is there any other adjustments or swaps I can make when I have the carm and intake off to up the HP without spending a grand or having to have a PHD?

Swaping the heads seems like a good bit of work, do you have to do anything with the pistons or can you just put nicer heads on it have increase the compression or is there more too it than that? Would swaping out the Heads without doing anything under them, have proformance enhancments?

I am not looking to get 400+ horse power from this thing, but if there is any minor adjustment or couple hundred dollar parts you can swap out and get closer to 300, 350 that would be great. It Is an L82 it says it has 220 hp, mine has headers and dual exhaust so I am not sure how much more that would have given me, but you guys get what I am trying to do here. I would appreciate any and all advice because I am always trying to learn as much as I can. I need to understand how all this works together.

Thanks

Brent

 

Brent,

Sounds like you have already opened up the exhaust. I would verify the ignition advance curve is getting you all of the performance 'on tap'.

If you have not sent the carb off yet, I would suggest you send to Lars. Write down everything you know about the combination as it sits and what you plan to add. Lars will set the carb up and even road test it to perform to your goals (or very close).

You already have a decent cam with the L82. However, you may want to look at the 'Thumpr' or Xtreme Energy cams from Comp. They have more aggressive ramps that open the valves more/faster. I would not go higher than .485 lift unless you choose to go retro-roller cam.

What year is your L82? You may have either 624 or 882 casting heads with 76cc chambers. These heads flow 'ok' (around 160cc intake runner). Consider heads with runners in the 180-195cc range for replacements. If you are keeping compression around 9:1 or lower, then cast iron is fine. I would also recommend you get heads with steel seats as 'hardened valve seats' will only last 30-35K miles before you need to rebuild (my experience using with my daily driver).

With just a few improvements, your L82 will really wake up. Enjoy!

 

First off...hold off on the carb rebuild UNTIL you have made a decision of any further parts that may be replaced.(camshaft and heads). This is due to any major changes you plan on making to the engine could and can result in some modifications to the carb to make it work effectively this this new set-up you have.

Sometimes when replacing the intake manifold with a PREFROMER could and can result in some problems due to height, vacuum fitting placement, ported vacuum swith provisions,etc. I am NOT saying it won't work...but in some cases..it creates extra work and figuring out what to do to fix this and that.

Cam and heads will wake this up. BUT a lot of it will depend on the bottom end and what type of components were used. I can not swear by it...but I think that the crankshaft and connecting rods are strong enough to handle the increase of compression due to it being an L-82. Also I believe that this should be a 4-bolt main engine...which gives the bottom added strength. I have seen numerous 2-bolt main engines that hold up well, even with high compression, HP and torque.

I would highly advise you to get to a chassis dyno and see what the engine is producing for HP and torque. This will give you a starting point. BECAUSE...if you are actually getting 180 HP and ??? torque to the rear wheels...and you get it to 350 HP and ???torque. You might also need to possibly look into making sure that the rest of the components down stream from the engine can handle this drastic percentage increase of HP and torque. SO U-joints, transmission, rear differential may need some refreshing/improvements.

Other than the obvious ridge in the cylinders, weak compression, cam bearings, upper valve train components, and possible ignition improvements may need to be investigated and replaced or improved on to get it to be a total package.

DUB

 

It is a 1978, so it is the 25th ofcourse, and it is the Silver Anniversary Editon, with the L82, it has air conditioning, which I desperatly want to get working it was hot in that car with the windows up "the wife's hair" you know what I am talking about.

 

all of the reading I have done, and I have done quite a bit says that. The car was rated at 220 HP & 270lbs torgue, with the factory Exhaust mainfold and single cat to Y pipe setup. They also say that inspite of the rated 220, they actually left the factory with 225 and 272-275lbs in reality. I am not sure how much, switching to true headers and real dual exhaust add, but would i be wrong to guess 25-30HP so maybe I am sitting at 250 hp, would it be any more than that from the exhaust? If I am getting 250 now I would think another 50-75hp for a max of 325 would be perfect, it's fast now, not mind blowing, but fast probably from the amount of torque and the way it is geared. My wife will be driving this car too, this is our corvette, I will get my chance to build mine with the 383 stroker at a later date. I just want to have just a little more than I need, if you know what I mean.

 

o.k, the L-82 was and still is rated by the N.H.R.A at 312 h.p.
put on a new timing chain , advance the cam 4 degrees, put on the thinnest head gasket you can get like the .015 felpro, bowl port the heads while they are off set your advance curve in the distributor , and have Lars set up your carburetor . you won't believe how strong it will run, IF it is an L-82

 

Seriously 312HP all the chevy stuff and read and even the plackard on the cig cover says 220hp and 270lbs torque. So is all that stuff just flulf so Chevy didn't get in trouble with the EPA, so did it make 312 from the factory with the manifold and catalytic converter, or is that with that removed?

 

i think that would be with open exhaust timing optimized etc.