Long time Lurker, working on an ’86 iroc-z, LG4 305, 700r4. I’m freshening it up, and trying to give it a little more life (HP). I have it torn mostly apart. The following parts are in hand, or on the way……

Edelbrock Performer intake
Edelbrock 1901 Q-jet
MSD Digital E distributor (I’m ditching the ECM)
Comp Cam/Lifters Hydraulic flat tappet 0.462 int./0.477 exh. Lift - 218 int./224 exh. Duration
Trick Flow 175cc 23 degfree alum heads – 1.94 intake/1.50 exhaust
Summit 1.6 ratio Roller Rockers

My question is about the heads. I’ve heard some say they’re ready to bolt on. I’ve heard others say porting them will help. Which is true? I’ve never done any porting. I don’t want to ruin a new set of aluminum heads. Should I take it to a machine shop? If I wanted to try it, can you guys recommend a source for “beginner porting education”?

Any and all help is appreciated.

 

They won't need a lot of heavy porting. For a 305 you want to keep the port size small.
Never seen these specific heads. Can you post some pics of the ports? and chamber? Are the valves back cut?
Most machine shops don't know much more about porting heads than u do.
This different than porting a stock $2 smog head.
Just about anything will improve a smog head.
This head is much more refined to start with.
Unless they have a flow bench and experience with those heads you probabily can do as good a job as them.
For your purposes. Again heavy reshaping is not what you want. But the mild smoothing arnd tweeking is not hard to do. The most essential skill is patience, planning and willing to invest the time. Time costs $$$.

Leave the machine shop trip for things you cannot do at home. Like valve jobs and other machining.

Other than a carfull port and bowl clean up I don't recomend heavy reshaping without flowbench verification.

Most heavy mods (resulting in big ports) only show a gain at very high valve lifts.
Low mid lift flow and velocity is more important.
Chamber deshrouding around the valves in specific areas can show nice gains here.
It is difficult to cast a cylinder head with the best shaped guide boss contour without getting rejects. Thats why many heads have seemingly huge guide bosses ( Darts in particular)
Can pick up some good flow by streamlning the guide boss some. Sharp edges in the valve bowl below the valve job and short side radius need to be smoothed. But not hogged out. You want a smooth funnel below the valve seat.
Would be nice to see some pics.
Are any "out of the box" flow numbers available?

 

Thanks, 88.

The heads ship tomorrow. I should have them by the end of the week and I’ll post pics then.

Here’s Summtis part number if you want to check them out…..
TFS-30300003

Here’s their pic…..





MW66Nova posted these flow numbers last March from Trick Flow for these heads....

Lift Int. Exh.
.150 99 77
.200 126 102
.250 150 115
.300 175 128
.350 194 142
.400 213 153
.450 230 166
.500 240 170
.550 240 173
.600 240 178

Are these good numbers?

 

Those are very good "out of the box" numbers for a 1.94x 1.50 valve set.
Those heads won't need a lot of work.

Nothing you can't do at home with some stones and rolls.

Need to see actual pics of your heads when they arrive to see how nice the bowls,guide boss and short side radius looks.
Can you remove a few valves and post pics when they arrive. Its a good idea to inspect and clean any assembled head anyways.
What is the chamber size?

 

I'd reccomend picking up a book and doing some reading. Of the three or four books I read on porting, this by far gave the most useful information and it doesn't hurt that it's only 13bucks on amazon.

How to Build & Modify Chevrolet Small-Block V-8 Cylinder Heads (Powerpro Series) by David Vizard (Paperback - October 1991)

 

Id look at getting a better intake manifold.
More gain there than messing with the heads much.

 

Heres a set of ported ones, mine were 2.02 1.6's though. Pretty good numbers for a 185cc head. http://img287.imageshack.us/my.php?i...astscan4va.jpg

 

Which intake would you recommend? I'm using a Q-jet. No emissions (EGR). I already had the 2101 performar in the garage so I thought I'd use it.

Comb Chamber volume - 56cc

Here's the skinny ...

Product Line: Trick Flow 175cc 23 Degree Cylinder Heads
Cylinder Head Style: Assembled
Cylinder Head Material: Aluminum
Cylinder Head Finish: Natural
Combustion Chamber Volume (cc): 56
CNC Machined Combustion Chamber: No
Intake Runner Volume (cc): 175
Exhaust Runner Volume (cc): 67
CNC Machined Intake Runner: No
CNC Machined Exhaust Runner: No
Combustion Chamber Style: Heart
Intake Port Shape: Rectangular
Intake Port Location: Standard
Exhaust Port Shape: Square
Exhaust Port Location: Standard
Spark Plug Style: Angle
Intake Valves Included: Yes
Intake Valve Diameter (in): 1.940
Exhaust Valves Included: Yes
Exhaust Valve Diameter (in): 1.500
Valve Springs Included: Yes
Outside Diameter of Outer Spring (in): 1.460
Damper Spring Included: Yes
Number of Springs Per Valve: Dual
Retainers Included: Yes
Retainer Material: Chromemoly steel
Locks Included: Yes
Lock Style: 7 degree
Valve Stem Seals Included: Yes
Valve Stem Seal Style: Viton®
Rocker Arm Studs Included: Yes
Rocker Arm Nut Thread Size: 3/8-24 in.
Rocker Arms Included: No
Rocker Arm Nuts Included: No
Guideplates Included: Yes
Guideplate Pushrod Size: 5/16 in.
Valve Cover Mounting Style: Perimeter bolt
Accessory Bolt Holes Drilled: Yes
Intake Valve Angle: 23
Exhaust Valve Angle: 23
Valve Guides Included: Yes
Valve Guide Material: Ductile iron
Valve Seats Machined: Yes
Valve Seat Machine Style: 3-angle
Valve Seat Material: Tungsten
Steam Holes Drilled: No
Oiling Style: Through pushrod
Machined for O-Ring: No
Heat Crossover: No
Quantity: Sold as a pair.

Thanks 1983. I'll get that book.

 

if you got to stick with the Qjet, either a performer RPM with the Qjet flange. or pick up David Vizards book on
building sbc's on a budget and see what he did with a Weiand Team G Street Ram. It's a low rise street single plane for a Qjet.He fully ports it and there is room for playing with various "Qjet" carb spacers.
The model number is 7525.
there is not a lot available for the Qjet.

 

I know the Qjet may not be the best choice for top performance, but I have this 1901 I paid $500 for just sitting in my shop, and it has an electric choke. This will be a daily driver.

Thanks for all the input. I'll get pics up of the heads when they get here.

Thanks,

Geno

 

The way to look at your heads is, they will come to you with various casting irregularities, and "steps" and weird angles where machined surfaces meet as-cast surfaces, especially right immediately behind the valves and around the guides.

THe goal of head porting isn't to "hog them out"; it's to make air flow around them as smoothly as possible. That goes double for a small motor. You don't need, and can't use, monster flow numbers; what you DO need, and CAN use, is for as much air as possible to flow smoothly into and out of the cylinders, with as little turbulence and obstruction as possible, and at as high a velocity as possible without frictional losses.

ALL heads need work "out of the box". Some need it more than others. Some need it in different places, for different reasons, than others.

You want to eliminate sharp edges and corners, smooth the short-side radius WITHOUT LOWERING THE FLOOR, and reduce the interference to flow from the guides. The guides work best if you taper them along the direction of flow, as an airfoil, sort of like an airplane wing, rounded facing the bowl and coming to a point on the outside toward the port entry or exit; and necked down as they meet the valve stem. Intake flow is partly along the "common" wall, where the port is next to its neighbor, and mostly along the roof of the port. Relatively little goes along the push rod wall or the floor. Exhaust flow is almost entirely along the roof of the port. You should imagine shooting a garden hose through the port and visualize where the water will go; or just do that, and watch the path it takes. Concentrate your efforts there. Remove the least amount of metal possible, while easing the path for the water. Intake ports should have "port bias", such that the water is sort of circling around the valve seat as it comes out; this makes for better fuel distribution in the chamber, and improves the BSFC and efficiency in general. You should leave the intake port surface somewhat rough to prevent fuel pooling out of the mixture in the port, 100 grit or so is about right.

Another intake you might want to look at is the ZZ4 one. It works well on a 305, in the RPM range that your cam will work best in. You can pick them up brand-new on ebay and elsewhere for pretty cheap. The Performer will act as a restriction to the rest of the engine.

 

Sounds like excellent advice on the porting. I'll also look into the ZZ4. Thanks very much for the guidance.

This is just an awesome forum.

 

The ZZ4 is looking good, but it has the provision for the EGR. My setup will be without an EGR. Is there a block-off plate available?

Thanks,

 

The one I have came to me with a cover plate bolted to it. Looked sort of manufactured. So I guess it came from somewhere.

Even so, it's just a piece of 3/16" flat stock about 2" square with some edges cut off and 2 holes drilled in it. I've made them from various different raw materials over the years. It's not exactly something you would have to "buy" if you wanted one.

 

Porting Trick flows will help. If you look at the exhaust side, around the valve guide and the port, you will see they can be improved upon very easily. Open the exhaust port up to a regular sized header gasket. They are made to fit stock equipment, which is why they are smog passable. The intake bowl can use a little improving, at the back of the valve guide. this is at least what I was able to do with the KD series heads. I tried to take digital pics, not good enough quality though.

 

ZZ4 is on the way from Summit. Thanks for the advice, Sofa.

 

YIKES! This ZZ4 intake looks tall! Is this going to give me hood clearance problems? I'm using an L69 dual snorkel setup on the quadrajet.

 

Not a problem.

I'm not driving my car that's like that, today; but I did over the weekend. It was fitting just fine. ZZ4 intake, Q-Jet, L69 intake.

In fact, GM used to sell a "kit" for installation into LG4/auto cars; it was, the ZZ4 motor, the L69 intake, a whole exhaust system, carb & ECM parts, and so on. Basically turned a weenie car into a L69'ed ZZ4.

 

I have that intake on my L98. Seems to work good, But i need a bigger cam and better heads. It also fits under the hood with a drop base air cleaner and my holley 750.

Genob4c, Glad to see another fellow kentuckian on the board! You are not far from me at all!!

 

I have a victor jr intake, 1/2' nos plate, and a 3" cleaner and it clears.

 

Yeah, I've been to London many times. My Company has done a lot of tile work at the Flav-O-Rich dairy there. I've done a couple of schools there (Colony and Keavy) and a Church also. Oops. Off topic.

My Trick Flow heads will be here tomorrow. My UPS guy thinks I'm building a car from the ground up. I get something from Summit about every day. I told him I took it easy on him because I got aluminum heads instead of cast iron.

 

Got the trick flows. They sure are pretty. I took them to a local guy who is supposed to be a "head" expert. He said, aside from the nick, they're just about the cleanest set of new heads he's seen (referring to burrs and such). He said he could improve them some, but probably it wouldn't be worth the trouble and cost. I took that as a swipe at my puney 305. Anyway here are some pics....









They came with a pretty good nick. See these pics. If I smooth it, will it be okay. It seems to be in a safe spot.



What do you think?

 

Just smooth off any raised metal. Can you remove a valve or two so I can see the bowls under the valves.
you'll need a valve spring compressor tool.
The combustion chamber looks real nice.

Anything this set of heads needs in the way of porting to get them ready you should be able to handle yourself at home. Very nice...