Cylinder heads and intake manifold
 

Like most people with L-48s, I'm looking to get some more power out of it without breaking the bank. I've been idly looking at different cylinder heads and intake manifolds, but I'm still wondering about a few things. (You guys seem to have the answers for everything, so what better place to ask! Also, please excuse any errors -- I'm no mechanic. :cheers:)

With the Dart Iron Eagle heads (64cc chamber, 2.02 intake/1.60 exhaust), what sort of compression ratio would I be looking at? It seems to me like iron heads with such small combustion chambers would be prone to detonation. Would the high-octane pump gas (94) and slightly retarded timing be enough to prevent this? If I can run without fear of detonation, these heads seem like a great idea: they're incredibly cheap! If not, though, I'll start shopping around for aluminum ones. (As far as I can tell there aren't many people making iron performance heads.)

As far as intake goes, can these be mixed and matched pretty freely? I have the stock QuadraJet on there as well as the small block hood. A lot of people seem to be going with the Edelbrock Performer series. Any hood clearance issues with a drop-base air cleaner?

Thanks in advance for the help! (I need it!)

:cheers:
Vetticus Supersonicus

Re: Cylinder heads and intake manifold (VetticusSupersonicus)
 

The Iron Eagles are fine, with flat top piston you will be between 9 - 10:1 CR stock pistons somewhere around 9:1 I believe. You won't have any problems, you could also step up to the Sportsman II heads, fully ported they will support 550 HP :D

Re: Cylinder heads and intake manifold (MotorHead)
 

Why not try a set of GM's Vortec heads and the matching intake? They are cheap, and make great power.

Re: Cylinder heads and intake manifold (MotorHead)
 

I have those heads, although MountainMotor race ported them. I am in the 10.5:1 compression range and I am not having any problems with detonation at all. We put in a tamer cam than what these heads can support and am running in the 490 hp range. MotorHead is correct that these heads will easilly support over 550 hp, as that maybe my next stop on the hp wagon with the hotter cam that the engine was designed for. You won't go wrong with Dart, World, Pro Action, or any of the more expensive heads ie Brodix etc. MountainMotor has tested the Pro Action's and is impressed by their flow rates and performance bang for the buck.

Re: Cylinder heads and intake manifold (gdh)
 

I was going to offer my $.02 but this seems to be an all Canadian thread... :D just joking, no offense meant.

Re: Cylinder heads and intake manifold (7t2vette)
 

http://www.corvetteforum.cc/zeroimg/...withstupid.gif you cant beat the value. :yesnod:

Re: Cylinder heads and intake manifold (VetticusSupersonicus)
 

Okay . . . if you want opinions, I'll give you one. This is a PROVEN (by me) combination . . . Stock bottom end, AFR 190 heads (with 68 cc chambers), Edelbrock Performer intake, stock Qjet (rejetted), recurved distributer, Sanderson shorty headers and Summit 1101 cam for low end power.

Burns the tires, screams like a banshee, pushes you back in the seat and creates a smile a mile wide . . .

Re: Cylinder heads and intake manifold (VetticusSupersonicus)
 

L48 + Vortec heads + Comp XE262 + Vortec Performer = 350hp (conservative estimate) cost less than $1000 US for everything.

Re: Cylinder heads and intake manifold (Smokehouse69)
 

My .02$
XE-262 cam,lifter and spring kit-250.00$
Edelbrock Performer intake- 150.00$
Dart Iron Eagles- 800.00$(??)

Dart Iron Eagles are some of the best iron street heads right out of the box. If the stock L-48 has a 8.5 compression with 76cc, it will probably be 9-9.3:1 area; which you can still run good advance with that. With the setup above you're probably looking at 320-330HP. Add a Demon or Holley a good ignition set up and full dual exhaust with headers, the power is probably 350-360HP range. Look at my sig. I've probalby got around 360HP and still using stock heads but they are EXTREMELY ported and re-worked. And I've probably spent 600.00$ on the motor.

Re: Cylinder heads and intake manifold (VetticusSupersonicus)
 

Where are you going to get your parts from? Is MOPAC pretty much guaranteed to have the best prices in CDN$?

Re: Cylinder heads and intake manifold (Turbo-Jet)
 

I haven't done much shopping around yet, but I figure it's either going to be MOPAC or Lordco. I'll let you know once I've looked at all the prices, but they both seem to have fairly competitive pricing.

Your car looks great, by the way!

Re: Cylinder heads and intake manifold (Smokehouse69)
 

vortec heads need self aligning roller rockers, the quadra jet wont work with the manifold, so it ends up being pretty pricey? at least that's what I've been lead to believe, otherwise I'd consider the vortec option more...

Re: Cylinder heads and intake manifold (rpounds)
 

rpounds,
That is very close to the combo I was figuring on. Because of the my lower "72" hood, the Performer intake is about as radical as I can get. I ran some cams on the DD2000 program and that 1101 kicks butt for great torque and HP numbers in the usable RPM range. I am still not sure on the heads, Edelbrock Performers maybe... I know the AFR's are very good but $$$. For me, just going to the 64 cc chambers with pick my CR up to about 9.5:1 which alone will improve the low end response. I am please to hear you are happy with your combination. :yesnod:

Re: Cylinder heads and intake manifold (szercer)
 

The Vortec heads require a Vortec intake, square bore carb and the intake is to tall for "wiper door" type hood Vetts. Also the exhaust manifold locations are 1/4" higher than stock. And for the big cam crowd, there are some limitations on lift without doing some spring seat work.

Re: Cylinder heads and intake manifold (KJL)
 

I too have a stock 350 CI, 72 shark. Which Edelbrock performer manifold fits under the hood? Did you use an Edelbrock performer carburator or the stock QJ? What kind of performance increase can I expect by changing just the manifold and carb??
Thanks in advance for your help.
:cheers:

Re: Cylinder heads and intake manifold (l2vette)
 

The Edelbrock Performer (not RPM) will fit under your hood. I don't recall the specific model number, but I believe the number was 4106? I would have to check that. I used my stock GM Q-jet and rejetted it to match my combination, including changing the secondary metering rod hanger to eliminate the "Quadra Bog". Works great now.

The manifold was the first thing that I did. I later tore the top end down and installed the heads and cam. Just changing the manifold did nothing that could be noticed by the 'seat of the pants' other than helping to smooth the transition between primaries and secondaries. The Performer is considered to be a 'stock replacement', so I wouldn't look there for any kind of huge gains.

The heads on the other hand are awesome. They are indeed pricey, but worth every extra penny they cost. If you have access to Desktop Dyno, do a comparison between the Edelbrock Performer heads and the AFR 190s. The difference, especially in the low end, is amazing. The torque curve with these heads and the 1101 cam starts early and really stays flat for a long time. I am running the original TH400 trans and 3.08:1 differential, so that torque was really needed unless I wanted to change the diff. ratio, something that I really didn't want to do. I didn't want my highway RPMs to suffer.

I hope some of this info helps.

Re: Cylinder heads and intake manifold (KJL)
 

yeah, vortec heads are a little more complex than people make them out to be, they are only $500, but with other heads you can keep the qjet, and get a weiand intake for $95 and cam of choice...

Re: Cylinder heads and intake manifold (rpounds)
 

Thanks for the info. Now I have to rethink what I should do for my next mod (and what it will cost)!!
:D

Re: Cylinder heads and intake manifold (VetticusSupersonicus)
 

It would interesting to see who is best to buy from. I have plans to rebuild my motor with new pistons, valves, roller cam, headers, etc, and think that ordering from a well-priced US vendor such as Summit, would still be much for expensive than MOPAC.

Re: Cylinder heads and intake manifold (VetticusSupersonicus)
 

OK... time for my .02. ProTopline iron heads outflow or are comparable to most of the same CC aluminum heads at 2/3 the cost. Performer EPS dual plane intake outperforms the regular performer, but has a square bore carb mount. If the Q'jet is what you want to use, an adapter would be necessary thus changing hood clearance. The EPS Fits under a L-48 hood with a drop base, and has 1.5" to spare. This combo ROCKS... When I get dyno'd next week, I'll post results.
Eddie