Hey guys,

I was hoping you may have some input here. This summer, I'm going to get back the shortblock of my L69 back, and I have almost all of the stock parts for it except heads on my 350 right now (intake, carb, exhaust, etc). I will be getting some 416 casting heads for the engine this summer if i can find a good set and have a set of short tube headers (1-5/8") in my room right now that will find their way onto this engine when it is done, as well as a new exhaust system.

Anyway, on to my question... Do you guys have any sorta 'low buck' ideas for pulling a few more hp out of my L69? Most of the major parts will be original, but will have headers and exhaust and no emitions stuff at all. I would like to try to get about 240hp out of it.

Thanks in advance.

 

K & N Filter
Synthetic fluid in engine, transmission, diff.
Pulleys
Propper coolant mix, or even better NPG coolant

 

Port the heads. Lots of HP for near free right there.

After that, cam selection is critical. You want all the lift you can get, with .050" duration around 210-214° on the intake and 10° more on the exhaust, and close to .500" lift. I'd recommend a Comp XE262H with 1.6 rockers, and NEW Comp 981 valve springs. Don't try to re-use a bunch of worn-out stock crap ones on a cam with aggressive ramps like that one.

The stock carb and intake are fine. Leave them alone.

My 83, with a pair of old double-hump heads (not the best for the application, but I had them laying around, so what the hey) and a Comp XR264HR with 1.6 rockers and Edlebrock TES, stock carb & intake & exhaust from the cat on back, all emissions devices installed and operating and having just passed California emissions inspection a few days before, put 214 HP and 282 ft-lbs to the rear wheels. That's around 260 HP at the crank. If I had 58cc heads instead of 64cc with equal flow, all else being the same, it should be good for 270 HP or a little more.

That should give you a good idea of what can be done without un-bolting and re-bolting all the stuff you can see but doesn't have much effect, but instead concentrating on stuff that actually makes more power.

 

So you are saying that i should really just concentrate on the valvetrain? That was sorta what i was thinking too...

I'd love to port and/or polish the heads, but since i haven't done it before, i don't really trust myself to do it right. Is there really much power to be gained by doing a port/polish job?

 

There is a lot to be gained. My first attempt was on the Worlds (did one cylinder of a stock head for practice). It was work, but came out better than I had expected (since it was my first attempt), and runs great. Since I did all of the other mods at the same time, it's hard to say how much the porting itself contributed (or how much the heads themselves contributed), but I couldn't be happier with the results.

Just hope I can say the same when the 396 heads are done...

 

How hard would a job like this be to do to a set of 416's for a first timer like me? And if i do end up doing it right (fingers crossed) what kind of gain could i be looking at?

 

First understand that you need to have a real die grinder with speed control - Dremel won't cut it. I have an air die grinder, it takes a lot of air compressing to keep up with it. Others use an electric with a seperate speed control.

I kept tabs of the time I spent on the Worlds. I had both heads end-to-end, did all of a particular operation on all 8 cylinders before going on to the next operation. It took me 10 hours. For reference, the one practice cylinder on the 416 head took me 2 hours. Part of the reduced time on the Worlds was the effeciency of not changing the tool all the time, but more so was that they were much easier to clean up.

 

Well, the shop i'd be working at has an air grinder there, so i could use that. I was usig it just today actually... looks alot like a Dremel, but its much longer and alot more powerful.

So when I do this job, the goal is just to open the ports more right? I really wouldn't trust myself to do any kind of good reshaping of the ports.

 

Buy the Standard Abrasives deluxe porting kit. It has some stuff you probably won't use, and not enough of some of the stuff you do use; but it's a good selection of different sanding and grinding things. And, it comes with a set of excellent instructions.

http://store.summitracing.com/partdetail.asp?part=9175

 

You can download the instructions here http://www.sa-motorsports.com/diyguide.shtm

Excellent guidelines. The deluxe kit is what I used for my heads. Yes, I had to buy more rolls (probably because of the practice head). The pictures are of 305 heads to boot.

I've got another kit on the way for the 396 heads. Figured that would be easier than trying to buy the required stuff piece-meal.

 

Well.. those links, especially the one to the port/polish guide were a good thing to see... I got the idea that this may be a pretty tricky thing to do and really easy to mess up from a book my dad had given me awhile ago that has alot of basic tuning and hi-performance tricks in it, the port/polish job being one of them. After reading that thing, it kinda scared me away from wanting to try this, but after reading a little bit of that guide, it really doesn't seem all that bad and I may yet try this. But it will have to wait untill September at the earliest because I will not have the engine back untill probably after June, I still have to find some decent heads for it, and will be doing 99% of the work at school, because they have a pretty good shop there, with probably most of the tools i'll need to do almost all of the engine work and it and i'll have almost all day to work on it.

So... any other little tips or tricks you guys could suggest aside from the porting and polishing job?

BTW, what should i use to strip all the old paint off the block, heads, pan and valve covers? If possible, i'd like to put the new paint on bare metal, instead of a layer of Chevy red on top of the factory black that is half gone already.

 

Have them "tanked" at the machine shop. That caustic soda will strip 'em nice & clean.

 

Hehe, can't beleive i didn't think if getting it tanked

Ok, got another question... should i use amn open element air cleaner on the engine, or should i stay with the dual-snorkel setup that came with my HO car? I have one of the CAI hoses and scoops for the driver's side, but not for the other.

 

Keep the dual snorkel.

You're in luck, the passenger side scoop and duct are still available. The driver's side scoop is not.

 

Were?

 

Were can i get the scopp and hose?

 

GM dealer

 

Ok thanks.

BTW, why do they only sell one scoop set? why not both?

 

Well it's been nearly 20 years since those cars were last made.... I guess they just ran out

 

Year One (Next Generation) has them, as does Ram Air Box.

 

Does Year One have scoops and ducts for both sides or just one?

 

Passenger only.

At least, still had them about a year ago.

 

Ok, i checked out YO... they have the passenger side scoop and IIRC they have the ducts for both sides.

I was also looking around at other stuff too... mainly cam kits.

What cam kit would you suggest for this motor? Assume mostly stock parts (carb, intake, lightly modded heads) but will have headers too. It has no emitions stuff either.

 

Anyone?

 

XE262

I have a XR264HR in mine, not too bad if you have a roller setup around or feel like springing for it

 

Cool, think i'll check that out... thats a Comp Cams set, right?

 

Hmm... i've been looking around a bit, just because i was curious, and i checked out Comp Cams website. It looks to me like the 270H Magnum cam would be pretty good for this engine. It has a nice lumpy idle but good low/mid range torque. It was meant for a 4 barrel carb and headers (which i will have) and will not affect power accesories. "Great cam for cruising".

Sounds like a good set to me. What do you think?

 

Are you keeping the CC carb and distributor? If so, the computer might not be too happy with the overlap of that cam. On the other hand, CC carbs aren't nearly as persnickity as SD TPI is.

If you are going non-CC carb & distributor, then the cam will be fine.

 

Yea, i'd like to keep the CC carb and distributor. Why would the computer go nuts if i put in a cam like that?