OhioYJ

Been a while since my last post, buta few of you will remember my axle stuff eariler this year.

I'd like to run my engine build up plan by the experts before I finally commit to assmebly. Since I'd rather give to much information than not enough, I'll try and throw everything out there. Finally picked up a clean 4-bolt main 350 (its a 78 truck block) for my 91 RS (305 TBI currently). I had it bored 0.060" over. The crankshaft and rods are stock, the pistons are flat top cast pieces.

This car will not be driving daily, it’s just a play toy. I want 10 MPG roughly out of it, and it will get premium fuel, but it does have to run on pump gas (92-93 octane).

I've picked up a later style (center valve cover bolts) truck heads. The intake valves are 1.94", the exhaust are 1.5". I've been completing a mild porting on them, and polishing the inside of the combustion chamber part of the head.

I do have the option to pick up an early set of closed chamber heads, but I've been told that my open chamber heads I currently have would be a better selection? Any truth to that?

The camshaft is where I'm really lost on. I've always built Fords, and the cam specs that we run are completely different. I've never used anything less than 0.500 lift in my Fords, but Chevy's don't seem to run real high lift cams for some reason?

The camshaft I'm looking at is

.465" / .488" Lift
224 / 234 Duration @ 0.050"
112 degree lobe center
71 degree overlap

The cam specs say 2000-4800 RPM power range, with decent idle. According to the research I've done, that is a fairly radical cam for a street/strip car. The car is an automatic, its a 700R4, and I have planned on putting a ~2000 RPM stall converter in it? Should that be sufficent? I'll be removing the 3.23s that I just put in the rear end and installing 3.45s as well.

The valve springs I'm ordering match the cam above, 110lbs @ 1.7", 285lbs @ 1.25". Should these be a problem with the factory press in studs? Should I just go ahead and admit it have screw in studs put in the heads?

I do have a couple single plane high rise intakes in the garage, but I've been told for low end power I need a dual plane intake. For that I've just planned on buying a dual plane Edelbrock, or Weiand. I assume the intakes are similar between Edelbrock and Weiand, or is one better than the other; I was just going to buy whatever was cheapest.

On the carbuerator I'm going to run a rochester quadrajet, I've got a buddy who swears buy them, and is going to do the tuning, so I don't think that will be a problem.

I’m swapping in an HEI distributor.

Will I have any air cleaner clearance issues with the stock hood. Once I get the motor out I was thinking about lowering it in the cradle some if that’s possible?

I'll try and post pictures of the work so far later. (Hey everyone likes pictures right?)

sofakingdom

iTrader: (1)

Unless they're casting # 906 or 062, they're probably 193 castings; swirl-port GARBAGE. I hope you didn't pay money for them, because if you did, you got ripped off.

Look inside the intake port, at the bowl area, kind of all around the valve guide. If there's this "ramp" looking thing there, near as tall as the valve guide, they're the ones to avoid.

With flat-top cast pistons, you'll almost certainly have about .045" of deck clearance (how far "down in the hole" the pistons are, at TDC), because VIRTUALLY ALL cast pistons add about .020" to the stock .025" of that. It KILLS compression. With the likely .045" of deck clearance, a .039" head gasket (FelPro 7733PT2 or 1004), 6cc "eyebrow" valve reliefs, and 64cc chambers, your compression will be about 9.4:1. Not too bad for a street motor, except that with all that deck clearance, it'll have no quench whatsoever.

As far as stock heads go, the best/easiest ones to find that will make any power, would be the L98 ones. Either 083 which is the cast-iron (F body) version, or 113 which is the aluminum Vette ones and they also come on the ZZ4. The 113 is about 58cc, which will raose the CR to about 10 flat; again, near ideal for a street motor, with allowance for the heads being aluminum.

Screw-in studs are pretty much a necessity at lifts past about .480". The 113s have them already.

That cam is a relic from the Stone Age. It was a decent piece about 35-40 years ago, when it first came out. It's LONG SINCE been superseded. Granted, it's CHEEEEP (and on top of that, doesn't cost much); but the difference between that and a REALLY GOOD cam, in terms of $$$, is SO TINY that its cheeeepness will disappear as a virtue, and will only be remembered with bitterness every time somebody who picked a better one beats you. I'd suggest a Comp XE262, with the springs Comp recommends; not cheap generic ones like K-motion, not GM, not "Z28" ones.

As to an intake, I'd suggest a Performer RPM, which comes in a Q-Jet version.

OhioYJ

They are, I've cut out that ramp, and smoothed everything out inside. They where free, so no big deal. Will they be fine to run once since I've taken out that ramp? I've only completely done two chambers so far, so its not a big deal, if I stop and go with something else.

F-BIRD'88

The valve lift of chevy cams "seems" low because the rocker arm ratio is 1.5:1 where a ford is 1.6:1. (small block) 1.73:1 (big blocks). That same cam grind for a ford SB windsor motor will have .496" in and .521" exhaust valve lift.
Pick your cam based on the duration @.050" based on the rpm range you are after.
Get some better heads. Sell, or give those heads to some one with a truck.
Don;t waste your time or effort on them.
Get some vortecs or Brodix IK200's or something that has real high performance potential. If you're on a strick budget get some #081,#083(305/350TPI) or 416(305HO) heads and fully port them with larger valves.
That 224-234 deg cam is just "ok" with a stock 2000 stall th700r4 converter. Really wants a 3000 stall.
Same as if it was in a 351W. No different.
If you must use the stock converter get a cam with less duration 214 to 218@.050"
If your rebuilder pistons are .045" in the hole at TDC use a thin .015" steel shim head gasket to maximize compression.
Use a dual plane hi rise and 750cfm carb.
A big cam will not make up for a crappy restrictive cylinder head.
Won't be much of a "toy' using those heads you have.
if you use a Qjet get the hi flow .149" needle and seat set (edelbrock)
The cam you're looking at is not that radical as cams go but same as if it was in a Ford 351W, it wants 9.5-10:1 cr, good breathing heads,a dual plane hi rise-750cfm carb, headers and big exhaust. Needs a high stall converter (+/-3000rpm and some rear gear. 3.73-4.10 That same cam is in the Ford Motorsport book. note the rocker arm ratio difference between a chev SB and a Ford V8. SB chevs respond nicely to a 1.6 rocker on the intake side.
(Requires specific cylinder head mods).

A RPM hi rise will fit under your stock hood with the right aircleaner. Search my old posts on aircleaner clearance using the RPM manifold. keyword L-88 Edelbrock manifold #7104 is just right for a Qjet.

OhioYJ

I'm buying a new converter, I was under the impression that a 2000 RPM stall was a bit looser than stock. But I haven't ordered the converter yet, so I can order something a bit higher, thats not an issue.

I guess too at the moment, the major question is are those heads still bad after that ramp is cut out? That ramp isn't there in the two chambers I've ported. I'm not opposed to buying a different set of heads, but if what I got will work after some porting, am I really gaining anything going to something that doesn't have the ramp in there? (I don't mind the work)

Don't think I'm trying to be hard-headed about the heads, but I'm trying to figure out why the flow is different after that ramp is gone? Are the runners that much different on other head castings?
Am I correct in thinking that milling the heads down some will help correct the quench issue should the piston be to far in the hole? I'll have to run one cylinder up here sometime soon and see where I'm at (the crankshaft is in the motor, but I hadn't put in any rods/pistons yet.).

OhioYJ

These are crappy cell phone pictures, I'll try and get more pictures, but I've completly cut that ramp out, and smoothed everything around the valve guides, then started polishing the chambers. The only part that really seems restrictive to me at the moment, is the little indent there on the intake runner, are the other heads more open there?

F-BIRD'88

A "2000 stall" converter is a "stock converter" if you want a strong launch get a 3000stall. 9.5" (245MM) lock up converter. Do not waste your time or money with a modified cheapy restalled 12" converter. Get a "real" th700 high stall hi performance converter ATI, EDGE, Precision Industries, Yank.

the "TBI swirl port" heads you are playing with were designed for low rpm , low power, low rpm torque/fuel efficentcy. They get a lot of part throttle swirl action with the vane but give up a lot of airflow to get it. You need airflow to make horsepower. The heads you have, suck. They were free cause no one else wants them. Even when you remove the swirl vane. (poor port shape for high airflow) If you want to make horsepower and go fast get other, better heads.
Milling the heads will reduce the chamber volume (increase compression ratio) but will not improve the quench clearance.
You have to deck the block to reduce the deck clearance and/or get the right pistons with the right pin height spec. (1.56") If your pistons have a pin height of 1.54" (typical H345P rebuilder flat tops) your deck clearance will be excessive .045" or more. You can get other pistons with a 1.56" pin height or deck the block .020" to compensate. You really want to deck the block so that the piston comes right flush with the block at TDC "0 deck" as you want a combined piston top/cylinder head clearance of .040" including the head gasket thickness. No different than a Ford motor.

OhioYJ

Ok, thanks for the explanation. I'll go see what else the machine shop has laying around other than the closed chamber heads they showed me.

Sounds like I'll go a bit more radical on the torque converter as well.

I'll run one piston up too, and see where I'm at, perhaps I'll just send the block back and have it decked if the piston is that far in the hole. That or I'll price different pistons?

All other suggestions are greatly appreciated, and thanks for everyones help so far.

F-BIRD'88

[QUOTE=OhioYJ;3577130]These are crappy cell phone pictures, I'll try and get more pictures, but I've completly cut that ramp out, and smoothed everything around the valve guides, then started polishing the chambers. The only part that really seems restrictive to me at the moment, is the little indent there on the intake runner, are the other heads more open there?

The "little indent" is there to make the air tumble as it enter the port. (turbulence) You cannot eliminate the bump without a lot of epoxy. Once you remove the swirl van in the valve bowl you have a poor bowl shape (abrupt right angle directional change) would require a lot lot of epoxy to correct the shape for good flow at high valve lift +.300". (without the swirl vane the port is very turbulent at high(er) lifts) Don;t waste any more time on them. Done waste $$$'s on machine work, screw in studs etc etc on them. Get better heads. At least start with a decent high performance stock casting head that has good basic port shape that you can fully port.
Do not buy what ever the machine shop has laying around just because they are laying around. Most of the stuff laying around will have very limited performance potential. If they happen to have a "jewel" on hand it will not likely be cheap. If you want to go fast, invest in a decent high performance cylinder head.
something like http://store.summitracing.com/partde...5&autoview=sku
is a very good buy.


http://store.summitracing.com/partde...5&autoview=sku
http://store.summitracing.com/partde...5&autoview=sku
other good choices
You won;t be sorry you spent the $$$s for these.
If you're really on a low buck budget look for the 305-350 TPI/HO heads I suggested. They work very well with a full port effort and larger valves.

OhioYJ

This machine shop specializes in SBC's, they have a whole warehouse full of heads, so I think armed with some casting numbers, I'll be able to hunt around till I find something worth having.

OhioYJ

Ok, rather than use my swirl ports, I stumbled across some 461 castings, that are freshly done, screw in studs, Crower springs, 2.02 intake, 1.60 exhaust. Best part is they also came with roller rockers. From my research it appears that 461 casting isn't the best thing as far as factory head castings go, but it appears to be night and day better than those swirl ports I was dealing with.

F-BIRD'88

As long as your don't need the accessory bolt holes on the ends (custom alt brackets) and they are not cracked, they work very well. They respond very well to basic porting for extra power.

OhioYJ

Well technically I need the accessory holes, but I'll have to make due, I'm just going to fab up some brackets if I need them. I'll only have the crank, water pump, power steering, and alternator. The alternator mount is the only part in question at the moment.

F-BIRD'88

http://www.alangrovecomponents.com/

Special mounting brackets that allow post 1969 (long water pump) accessories on heads without accessory bolt holes.