There a lot of good info in this thread concerning those awfull swirl port heads, I will say this, even though Im probably not going to build this engine up, I still think if some one was on a tight budget like I was back 6 years ago when I took that 95 TBI SBC, jerked the TBI intake of and dropped that wiend intake and carb on there like I did that they can still have a good running engine. I wish I had upgraded the cam to one of those 2 steps up from stock and tried it in that motor before selling the truck. I could have seen how much difference it would have made.

Thanks to every one that took the time to contribute info, Ill use the info to build the TBI 454 sitting on the stand in the corner waiting on the vette to get bought. That's the next project Ill work on. Ill unearth this thread with pictures of the yoda with the motor in it and maybe a video of it running. I wont do a build thread on it, there just to many v8 yoda threads running around as it is. But would be glad to share if any one wants pictures.

 

While TBI heads have decent volume ports the flow is limited by the vane in the pocket. It obstructs much of the pocket entry and creates a flow direction reversal with respect to flow entering from the manifold into the port opening. The restriction forces an increase in flow velocity while from physics we know that when a flow's velocity is increased its pressure is reduced. This is good for liquids as well as gases. But in the case of gases they are compressible so reducing their pressure also reduces their density. Density tells you how many molecules are there to burn. Density is what makes compression pressure which is in considerable measure independent of compression ratio. The only time there is a direct relationship of pressure to compression ratio is at WOT. The rest of the time the throttle position establishes partial pressures in the engine that with a compression gauge would show a compression pressure less than that expected based on compression ratio.

Since the design of this port increases flow velocity in the pocket and thus through the valve's open curtain area, the increase of velocity also increases turbulence and detached flows across the seats. This makes the apparent valve opening appear smaller than it actually is.

So there is a double whammy going on here that conspires to reduce or cut off flow. The harder you push these heads the worse these conditions become. I've ported several of these heads over the years and can only conclude that while porting them improves their power output performance the result is not worth the effort. These are great heads if you need a moderate RPM torque monster, but if you're looking for power above 4000 RPM you efforts, time and money are better spent on other heads. Especially when you look at the risk of doing a cheapo valve job with lapping compound because the chances of hitting a seat while porting in the pocket are really high and one kiss with the die grinder's chuck or worse with the cutting bit and this valve job becomes one of cutting or stoning new seats, then the cost advantage of do-it-yourself goes up in smoke (dollars actually).

I'd say either don't screw around with porting these heads or find an inexpensive replacement. It turns out that GM makes what are essentially this same head under a different casting number that does not have the vane in the intake. These were used on TBI and non-performance TPI cars as well as marine applications and some crate engines. These heads are castings 14096217 and 14101083; they are essentially the L98 done in iron instead of aluminum.

For a cam the Swirl Ports are more sensitive to duration than lift. Adding duration buys more time for the flow to fill the cylinders. Since you can't do much to improve CFM of these heads then the next step is to increase the fraction of that minute that they are flowing. Additional lift is also helpful because it increases the curtain area of the valve opening which by the law of physics a flow entering a larger area loses velocity and gains pressure which for a gas is also density. But the big thing is by reducing velocity across the seats the turbulence settles down and the flow increases as a result. Back cutting the intake valve above the seat by 30 degrees is also helpful. This improves flow in the mid lift ranges which for the Swirl Port head is particularly important; you may find that factory already did this. The down side of more duration is the torque and power peaks are going up the RPM range which is not a favorable situation with the Swirl Port heads. So cams that open the valve quickly like the Comp XE series or Lunati's Voodoo are much better suited than older muscle car replica cams like the Summit you're looking at that use 10 to 20 degrees more ramp. The importance here is getting the intake on its seat early to prevent back pumping of the intake charge (what is the Dynamic Compression Ratio or DCR which is a measure of cylinder volume lost to stroke used up at the point of intake valve closure). Since the Swirl Ports need all the time they can get to inflow so as to gain mixture density within the cylinder, you don't need a situation where the piston is pushing your hard earned flow gains back into the intake especially with a head that is not going to let the engine rev high enough to gain intake ram velocity to overcome the reverse pumping of the rising piston, which is exactly what long duration cam working with the intake system does to make a high power engine which it does by also making the engine have to rev higher to get this advantage again this is the physics of the beast without a blower of some sort you can't get one without the other. One can argue how much reversion is taking place at the low lifts of the ramp between .050 inch open and truly closed and what significance that has; but it is happening in the case of the Swirl Port that can ill afford much of that event and still produce higher amounts of power.

In the vein of a fast lift cam with higher ratio rockers to further advantage the lift rate a roller cam really become attractive as fast lift flat tappet cams tend to wear themselves and their tappets pretty fast. Your TBI block might have the provisions for a factory roller cam; if it does I'd recommend taking advantage of these to put a roller like the XE --- HR into the thing.

Bogie

 

What plans do you have as far as the truck itself?Frame,suspension,rearend,axles,etc.? You will be adding approx. 3 x's the weight & power that this truck was designed for.

 

A little back story on this truck, I bought it to do a v8 but decided to get the 4 banger running just to be able to use it to keep the old lady from complaining about it. Sold my full size chevy in the process, wanted something smaller more trail riding able. It has a well built 22r with webber 38 carb and needs a 42 carb. The tranny has always jumped out of gear in reverse when u power on it from the start, its got lift springs in the front and drop shackles in the rear with 2 inch block. It clears 38.5x15x15 boggers just fine, it has Lincoln locked front back 5.29 gears. Took it out riding at a park and broke a few teeth of in the rear the first night of a long paid for weekend, so commenced doing harry carry to try and finish the job and ripped out reverse while doing donuts backward. A little bit of alcohol was involved:spank:, and the rear end never locked up or gave me a minutes trouble after wards,and I road 2 days just couldn't back up. So only tranny I could find cheap was a 5 speed, but its 4 inches to long, so if im going to have to redo everything for the longer tranny might as well start the v8 swap, spend less in the long run.



The front springs are really stiff, so all I might wind up doing is adding an overload leaf to it till Im ready to put the full size axle under it, 14 bolt rear and im shopping around for a dana 60 for the front but if I cant find that Im going to use a 30 spline 10 bolt front I've got sitting in my shop that needs rebuilt. The rear getting a ladder bar and leaf springs the front will be 4 linked and coil overs. But might do 4 link all the way around with coil overs. Gonna run 44 boggers when done with full size axle swap but will be running the toy axles till then. Figured I would get the engine, tranny and transfer done first and go play with it while I get the axles ready to install and buy the tires.

After pricing the pistons, gaskets, lifters, intake, carb, distributor, and tossing in a couple hundred for unseen stuff Im getting pretty close to the limit were I was going to buy the 5.3. Right now im trying really hard to talk myself out of it. If I take the money for the parts above I could pay for the 5.3 LS , and have 300 hp all day long with a little adjustment to the computer. Toss in an after market computer , cam and larger throttle body and get close to 375.

Im starting to make a case for myself to sell the SBC and the 4 banger, take the money and buy a low 100k 5.3 and spend the money to pump it up because I know I can get my moneys worth of power from that.:mwink:

Bogie write up kinda pushed me in that direction and after re reading all the post it looks like the best decision to make for my long term goal, and will give me the same short term gain of getting the v8 in and set up. I was probably going to go that way any way after a few years of running the SBC in there, Im just going to jump on in and start with that instead of trying to throw good money at bad technology. Ill just have to keep the skinny pedal under control till I get the full size axles in there.

 

Picture of a roller block. Pay attention to the bosses in the lifter valley

 

For the use you describe,other than a port match & cleanup,I wouldn't touch the intake ports.The exhaust can use some work.I'm from Memphis area as well.If you need any help tracking down parts,let me know.

 

That should be a roller ready block,but'trucks got flat tappet cams.The conversion is easy & most parts can be found @ a local pull a part for $40 or so.If going roller,the Ramjet cam(#14097395) would be a good choice & can be found new on EBay often for $120.Specs are 196/206 dur....431/.451 lift w/ 1.5 rocker..109/109. Hitting 300 HP is relatively easy with a 350.There are several GM roller cams that can put you in that range & won't require a lot of headwork to get there.The amount of port work you're speaking of,however,is not gonna raise your powerband by 1000 rpm.If your heads are casting #193,they have approx 65cc chambers.Flat tops of the rite pin hgt on a stock bore will have you close to 10:1,but,with a good tite quench built in,you could make it work.

 

Im not sure if its a roller, probably not given it came from a C 1500 pickup. Im not concerned about MPG, its will be a weekend warrior truck. I honestly though about having the engine dynode after building it to see what the out put and out come of all the parts Ive added would be. The first engine I put together felt like 275 hp But was probably 250. I'm not building a race engine, just want a stought SBC in my yoda that ive got sitting around my shop.

I wish I knew some one with a cam sitting around I could throw $100 buck at them for it. I was looking at a write up on CCT web sit about the difference in the 3 heads, The swirl port has a 185cc intake runner witch explains the good low end aspect, fuel and air getting necked down from such a large space would compress together nicely. Also was reading these heads have a .500 lift max, it got me thinking that a stock cam is in the low .400 so if I increased the lift to .480 or so and ran a 208-210 intake and 212-218 ex I should get good flow up to 5500 with a light shaving of the ramp and good power with flat top pistons, I probably wont see 300 hp .Right? Im not going to flow these heads, ive not got the patience to build a flow bench nor do I have any gumption to have them flowed unless some one in the Memphis area want to do it for free after im done with the little bit of porting work on the ramps.

I think all the parts go together for the rpm range, I will look into some flat tops just not sure what the compression ratio would be, I believe the bowl on these heads are around 70cc, im just not sure my eyes got tired of reading.

With such a light package and low gearing should make for a fun ride.

 

Is the block your working with a factory roller block?

 

The bench that David Vizard talks about will not give total flow numbers though. It will only let you know if your helping or hurting the port and how much you done it.

Sorry about the multiple posts, my phone is being dumb

 

The second book may help also if your going to do work on the heads. I don't recall if the book is specific to any one cylinder head. It's been a while since I've flipped through it.

Anyways, both books talk about building a homemade flow bench on the cheap with a shopping trip to the hardware store.

 

https://www.youtube.com/watch?v=oW1ENNqF0AI (part 2)

https://www.youtube.com/watch?v=OYxD1GvgoEY (part 3)

https://www.youtube.com/watch?v=G654y5nj-H4 (part 4)

 

The motor will rev to 5500 rpm,but,it's HP/Torque peak @ given RPM for the parts used.Since your heads die out pretty quik,you want a cam that has an operating range that matches & compliments the rest of your combo.As for lift,you need to know @ what lift your heads continue to gain flow & maych your lift to that.If they reach max flow @ .500 lift,then taper off,it's of no benefit to install a cam w/.600 lift.You also have to set the heads up for your max lift & proper springs spec'd by the cam mfr.There no way to tell how much flow your porting work has helped w/o a flowbench,but,I wouldn't expect miracles from these heads.If not experienced w/ exactly what needs to be done to improve them,you could easily make them worse.I can't post a link,but,go to Youtube & look up videos by "Headbytes".This guy is a little unorthodox,but,he gets amazing results.He has a video where he spent many hours doing extensive work to swirlport heads.He made great improvements,but,IMO,not worth it.You may pickup some ideas tho on how to proceed,or,least,"what not to do.You can make this strong motor,but,you have to match the parts & realize that it's not gonna make power out to 5500/6000 rpm.

 

SA Design How-To and Reference Manuals SA24 - Free Shipping on Orders Over $99 at Summit Racing

SA Design How to Port and Flow Test Cylinder Heads SA215 - Free Shipping on Orders Over $99 at Summit Racing

The first link is probably the best engine building book I've ever read. The book is way under priced for the info you getting.

The second book may help

 

. Thanks for creating your own new thread... if you're specific what you have, want, doing in your thread title, you'll get a quick, specific response here as you've seen... don't have to piggyback on somebody else's 'popular' thread...

. That 214/214 cam would feel a little soggy with the stock compression ratio and be a bit of a gas hog... I'd suggest maybe some strong, popular-priced 4-eyebrow KB claimer flat top pistons (KB9901) with it... and remove the swirl ramps completely if they aren't hollow... I don't know...

. If keeping stock pistons and that engine is roller cam compatible, I'd look around for someone's take out 207/213 TPI 350 roller cam or a 208/221 ZZX - ZZ4 crate engine roller cam... many racers replace them with bigger cams... or go with Summit's K1102 204/214 flat cam...

. Lift isn't mentioned in the link above because generally we go with the highest lift readily available for a given duration and newer flat cams have more lift per duration (because of computer design) and roller cams have even more lift per duration... more lift without increasing duration tends to increase torque/efficiency/MPG at that duration...

 

Ok let me climb up on my soap box here, I know a set of vortecs or a 1200 dollar set of high flow heads would be the cats meow, Id rather spend the money on an LS then through that kind of money at a small block. I took a 95 TBI motor a few years ago that had 145k on it, throw a wiend high rise dual plane with a 670 street avenger on it. I did not change the cam nor the heads, a cheap $50 HEI dizzy and a cheap electric fuel pump. It had a th350 set up for a bbc had 38.5x16x16.5 TSL on it with 4.11 gears. It needed 4.88 or 5.13 because it did not pull good in 4wd high, but pulled like a mad man up past 5000 in 4wd low. I put a set of street tires on that truck and put it on the pavement and it would burn the tires down. It had vacuum secondary's and would only open them about 1/4 of an inch. Now Ive never driven a car with a lot of horse power so I wouldn't know how a big motor feels like, but that motor wasn't no slouch. All im trying to do is repeat that but with a little better cam. Ive read that I can take the top of the ramp down, that will open up the flow a little and possibly give me better flow at 5500 and make a little bigger cam work better.If more compression is needed Id be willing to drop a set of flat tops in there when I rering it.

Every person that saw the truck run though I had a big exspensive motor in there, and it was a blast to drive once I got all the kinks out of it. From reading that wiki page looks like ill need to drop the intake duration down a bit, but what about the lift, it don't cover the lift in that article, do I need more lift or less lift with 9.5:1 compression? Thanks for the link and the help, its not falling on def ears Im just not throwing a lot into this motor.

 

Also,a cams operating range is approx 3000 rpm,despite what the mgfr states.(2000 to 5000...1500 to 4500,etc).With your setup,you will be looking for for something in the lower rpm range.Cam,compression,heads,all need to be matched for optimum performance.

 

I would have those heads magged before I put a dime,or,1 minutes work into them,especially since you say it blew a headgasket.Those heads are out of breath by 4500 rpm,so,choosing a cam that has an operating range up to 5500 won't do much good.If the port work is good,you can extend the rpm of the heads,but'that all depends on the quality of the port work.Read thru the tutorial Tech linked.Good reading.

 

Please read through this wiki tutorial.....
http://www.crankshaftcoalition.com/wiki/Cam_and_compression_ratio_compatibility