Hey, I have always been amazed with your guys knowledge on third gens and now have a question of my own! I am currently in the process of buliding a 406 for my 91' z. I have the short block built and it has the stock crank, rods (still the 5.565) and forged pistons that should give me around 10.2:1 compression with 64cc chambers. the cam is a comp cams solid roller xr274r with 236* intake, 242* exaust, .564"/.570" of lift ground on a 110 lsa. I am using holley's stealth ram intake and i wish to use World products sportsman 2 heads or a set of pro action heads with the 200cc runners. Has anybody had any experience with these heads and will they suit my combo? i would love a set of alluminum heads but the rims and everything else kinda drained the pocket book! Also will that cam be to radical for the stock computer with a custom chip? Sorry so long, so many questions!

 

For the price and flow, I got the aluminum Pro Ls.

Should be puttin them on tomorrow, but still need some other things before it's runnin again.

I got them fully assembled and shipped for $870. they were on sale though.

more info here, www.procylinders.com

and i bought them from here www.proshaver.com

 

Flat top pistons and 64 cc heads will result in too much cr
for a street driven 406 on 93/94 octane pump gas.
Depending on your actual piston deck height your cr will be 10:7+.

It would be just ok for aluminum heads.
I'd either get 68 to 72 cc cast iron heads or wait and get alumium. Or you could message the chambers in a 64cc head to lower the final cr to an more practical pump gas level.
Your right on the border line here. Trouble is, a little too much compression (for the fuel used) will result in detonation at full throttle which reduces power and shortenes the life of the motor.
You should be targeting a 9.8/10:1 cr with .040" total quench clearance ( gasket + deck clearance) for this motor with cast iron heads. This will get you more power than trying to squeeze the last bit of compression ratio out of it.

The Pro Action head will outflow the Sportsman heads "out 'o the box"

I'd shop around for a Set of Brodix Track 1's. They'll be worth the extra wait and money. You can easily port these heads to 305+ cfm. Or buy them that way. You won't be dissapointed.

You can download a good compression ratio calc from
www.download.com go there and search for "compression ratio" The program is called Engine CR 1.0....

 

the pistons I am using are Speed pro forged pistons that have a slight .050 dish in them and large valve reliefs. With a 76cc chamber they advertise around 8.9:1 compression. My block has also been zero decked. So with the proper choice of head gasket thickness I should be able to yield a 10:1 compression ratio. Like you said, the few points of compression will not be worth the pain it will bring! I noticed that they have the Brodix Track 1 in a CNC version wwhich I would love but are these heads avaible bare, as I already have all the valvetrain. What kind of power should I expect out of this combo?

 

I am currently dealing with a 406 right now and the only problem that i see is that you went with the stock rods. They put a lot of excessive wear on the engine, over time. I bought a set of sir eagle I beam rods rated at 500-550 hp and paid 550 canadian. pretty damn good for a canadian price. I went with Topline Pro's for cylinder heads, I had them drilled for the steam holes but some people I talked to said I didn't have to but other's said to so I'm not sure what to tell you there. Cooling is one problem they have but if you can swing it i would buy a good water pump and a bigger rad just to be safe. Camshaft is a important item and I would suggest calling comp cams or whoever. I would also suggest 1 5/8 headers at least and a good ignition but a curved HEI will do. If you need any more help email me and I'll try to help

 

I've decided I'm going to wait a bit and get the Brodix Track 1 cnc'd heads. The guy that did all the machining recommened having the steam hole's drilled in the heads for a street application. He said in a drag racing application were cooling is not as much of an issue you can get away with out doind it, but on the street the you need to worry aboult the cooling issue way more! I've got a set of hooker 1 3/4" super comp long tubes for the car. Where did you get those rods from, I live in Winnipeg, that looked like a very good deal! If I could, I'd redo the whole motor with 6"rods, but I was kinda on a budget constraint!

 

just wondering why you picked the cam before you picked the heads

 

Well, I didn't, I had the heads picked out befor I got the cam. i was going to go with a set of Spotsman II due to budget constraints and wanting to get the engine up and running. But after reading all the posts on here I came to the conclusion that If i want to make any kind of decent power the one thing I shouldn't skimp on is the heads. The cam I have will probably be a little small for the heads I am going with now, and a single pattern would deffinitly be better as the cnc's track 1's have an awesome ei ratio. But it shoud still run pretty good, it'll be a torque monster hopefully! Just curios, what is all going into your 406, and what kind of power are you expecting? I am shooting for 450 at the crank, and 500 l'b of torque! I should be able to meet that, but it'll take lots of tuning time! Who knows, maybe after next summer I'll tear it apart and build a short block with the 6"rods like you said!

 

this past summer i put a lot of time into the internals. All arp hardware even the rod bolts. This included main studs because its only a two bolt but supposely two bolts are better than four bolts but im unsure of that. I used keith black dished pistons and the the final compression is about 10.2:1 and had no problems with 93 octane. I have read that with six inch rods that you can run even higher compression without problems. I'll have to look it up why you can. I gapped the rings for nitrious but unsure if it will have it on this year. I also had to profile the rods and the block so they wouldn't hit but it wasn't very much. Balanced and blue printed I used headstuds and guideplates and went with comp cams XE 284 h. It run fine on the street but in my opinion it wasn't the right choice. I think a roller or a solid would have been better but its too soon to to tell because i need the 1 3/4 long tubes and a good 750 carb yet. I had 1 1/2 headers and you could feel the car die at 3000 rpm because it couldn't breath because of the old 600 holley i had on. i won't know until spring how its going to turn out but i believe it will be a hard running car but will still need a torque converter arout 2800 to 3200 stall and a good set of gears at least 3:73. Keep me posted on yours i like to read about 400's because not a lot of people go that route.

 

What kind of intake and heads are you using? I was going to go with a single plane, but decided that I wanted to stick with fuel injection, and the price of the stealth ram sold me right there! After hearing what you are saying I am seriously considering selling the short block and building one with 6"rods! I went with the solid cam just cause I wanted the little extra power. I was like you, I went with all arp hardware, knowing that I was probibly going to spin this motor, and the fact that I was using the stock rods and crank! I don't want this thing spitting parts out the side of the block at 6000! My blocks a 2-bolt main too. I'm not to concerned aboult it. I used miloden main caps for a little extra insurance! I'm planning on using a set of 4/10 gears because they are already in the car, it's a convience thing! But I could probably get away with 3.73 or even 3.55! I am also going with a 2400 stall, which is what comp recommened, but I will probably after time get a custom vigilante after I get the engine running, but for now it's just the b&m holeshot 2400.

 

staying with fuel injection pose a little problem because you will have to get your computer reprogrammed for sure. My personal opinion would be to go carb because it will be a lot easier to tune and I would think cheaper in the long run. You will have to check with other people on these boards because my fuel injection knowledge is limited to what I have read and what my friend talks about with his 94 LT1 z28. I went with topline pro's and a victor jr intake and I think the heads were the best bang for the back and had awsome flow numbers. They cost 830 u.s. through summit and the are very good head. Chevy High Proformance will be doing a vortec headed 406 in the uncoming months and that maybe something to look at as well, these are in my opinion one of the best heads out there and you can't beat the price. Keep me posted

 

Well, I just ordered my heads today, and when they come in i'll be able to start assembling the top end of the motor! They where $2400 american for the heads!! Hopefully they'll be worth it! I'm so excited though, it should be running in less than a month! Aboult the fuel injection, it is a little more expensive initially. But my reasons for sticking with it were, 1, I didn't want to have to rewire all my guages, 2, it's not hard to get a custom chip burned! I'm like you and have very little experience with fuel injection, but this will be something to learn with! I figure I'll get Ed Wright to burn me a custom chip to get it up and running, and I'll learn how to tune it myself as time goes on! Hey, 3 years ago I never new how to tune a carbureator, and now I know it like the back of my hand! I think the fuel injection has more potential than the carbureator does! Let me know how your projects going! I'll have pics of the motor up as soon as it's assembled!