[S10 Racer]

Ok guys, I'm back for more suggestions. I have listed my combo here numerous times but can't seem to find the old threads. This is in my son's 1989 S10 truck that we only race at the track, no street time. Looking to see what you guys think about the suggestions that Pete @ Hughes Performance gave me. Here is what I currently have.

BBC 454 +.030 - Has not been decked
Stock Stroke & rods w/ARP bolts
Speed Pro L2349F pistons
Comp Cam 294S Cam
Cam Style Mechanical flat tappet
Basic Operating RPM Range 2,500-6,500
Intake Duration at 050 inch Lift 248
Exhaust Duration at 050 inch Lift 248
Duration at 050 inch Lift 248 int./248 exh.
Advertised Intake Duration 294
Advertised Exhaust Duration 294
Advertised Duration 294 int./294 exh.
Intake Valve Lift with Factory Rocker Arm Ratio 0.595 in.
Exhaust Valve Lift with Factory Rocker Arm Ratio 0.595 in.
Valve Lift with Factory Rocker Arm Ratio 0.595 int./0.595 exh.
Lobe Separation (degrees) 110
Intake Valve Lash 0.022 in.
Exhaust Valve Lash 0.022 in.


Stock 215 heads - 101cc closed chamber - resized with 2.19/1.88 Ferrea valves. Light port work & gasket matched.
Victor Jr. 454-O Intake 4500
1150 Dominator

Pete says that with this combo, this engine may be as low as 375-400 HP. I'm looking to wake it up more. Here is what Pete suggests but keep in mind that I am willing to change heads and would need another cam suggestion if I did.

1) I come up with approximately 17% converter slippage based on your trap RPM, MPH, gear ratio, and tire size. This is a rough calculation, but is reasonably accurate. 17% slippage is far too high, but the converter is not always completely to blame in this type of scenario. The converter has a tremendous load against it in your application when you take into account the gear ratio and tire size. For example, if you were simply to install a 5.13 gear in the rear axle, your converter slippage would drop to roughly 8%. I'm sure you can start to see the relationship between gearing and tire size, and how it affects converter efficiency. That being said, 8% is still a bit too high for a naturally aspirated medium-horsepower application, so the converter that you currently use is probably not going to deliver the best performance that your combination is capable of. Realistically, you shouldn't have any more than 4% - 6% slippage with your combination.

2) Depending on the deck clearance (how far the piston sits below the deck surface @ TDC), and the head gasket thickness/bore volume, your static compression ratio could be anywhere from 11.49:1 to 12.51:1. In order to achieve 12.5:1 compression with this combination, your engine block would have to be zero-decked, meaning that the flat part of the piston sits flush with the deck surface of the block, and you would need a true 30cc piston dome. Piston dome volumes on the L2349 piston can vary from 27.9 cc's to 30 cc's.

3) You really need to change the carburetor to a 4150 design, no larger than 850 cfm. That Dominator is actually hurting you with this combination, and is going to contribute to the engine being down on horsepower. Even if it's tuned 100% correctly, it's not going to provide optimized horsepower and torque production with your combination.

4) The Holley Blue fuel pump was originally flow-rated with a 3/8" fuel line, and is optimized for use with a 3/8" fuel line. While many racers use this pump with a 1/2" fuel line, the larger line actually hurts the performance of this fuel pump, and will reduce the volume output of the pump. The larger fuel line holds significantly more fuel compared to a 3/8" line. When you take the additional weight of this added fuel, and you add in the g-forces created during initial acceleration, you end up with a significant increase in the weight of the fuel against the outlet of the fuel pump. The fuel pump not only has to pump enough fuel to support the horsepower production of the engine, but it also has to overcome this column of fuel pushing back against it. This significantly reduces fuel pump volume, and will take your normal 110 GPH rating of the Holley Blue down as low as the 30-40 GPH range in actual operating conditions. With a 1/2" line, you should really run two Holley Blue pumps, or one larger single pump, such as the Holley Black, or Mallory Comp 140. Also, if your fuel filter is installed on the inlet side of the fuel pump, then you need to re-plumb the filter so that the filter is on the outlet side of the pump. The filter you're using has a 10 micron rating, and this is too restrictive to be used on the inlet of a fuel pump. Any filter with a rating finer than 80-100 microns is going to be a restriction on the inlet of the pump, and will cause cavitation, which will reduce pump volume as well as dramatically shorten pump life.

5) Horsepower is a function of RPM. You really need to turn the engine more RPM to get the power you need to run the number you're after. This is going to require a larger camshaft, and more rear gear ratio. If the bearing clearances are correct and the connecting rods have good quality fasteners installed, then you should be able to turn your engine 6,500-6,800 RPM without any problems. I would use Comp Cams part number 11-604-5 with your combination. This cam should allow you to comfortably turn 6,500 RPM and provide a significant horsepower increase in the mid-range and top-end. Spec's are: 256/266 @ .050", .580"/.605" lift, 108 lobe separation. The extra RPM will allow you to change gear ratio, which will really bring the whole combination around. However, even with the larger camshaft and extra RPM, you'll still want a smaller 4150-style carburetor.

[ericnova72]

Can you give use current rear gearing, tire diameter, and current finish line rpm?? Currect ET amd MPH?? Vehicle weight??

Torque converter diameter?? Current stall rpm?? Current shift rpm?? what transmission??

Was the closed chamber deshrouded when you had the bigger valves installed?? chamber modified any at all??

Once you answer these questions we'll have a better picture to go with the above advice.

[S10 Racer]

Originally Posted by ericnova72

Can you give use current rear gearing, tire diameter, and current finish line rpm?? Currect ET amd MPH?? Vehicle weight??

Torque converter diameter?? Current stall rpm?? Current shift rpm?? what transmission??

Was the closed chamber deshrouded when you had the bigger valves installed?? chamber modified any at all??

Once you answer these questions we'll have a better picture to go with the above advice.

You have answered most all of my posts on this setup and I thank you again.

9" Ford narrowed 4:30 gears
33x16x15 Hossier slicks (I know I should go smaller but have to keep)
Finish line RPM w/4:30 is 5700 - Had 4:56 and was 6200
ET is 11.6 @ 117mph
Vehicle weight is unknown. Guessing around 3000
Converter is a 9" 4500 stall
Shifting at 5500
TH400 w/transbrake
I worked the bowls and gasket matched the heads myself. The machinist that did the heads and valves said they looked good (for whatever thats worth). I was just smoothing up the casting.

[ericnova72]

I agree with most of what Pete @ Hughes has told you, with a couple exceptions.

He is right, you need to turn more rpm, even with the cam you have now. Shifting at 5500 rpm is cutting 1000 rpm of your best power out of the equation. I'd go back to the 4.56 gear.

Does the engine feel like it really falls off above 5500rpm??

I don't feel the 1150 carb is a problem, yes it is too big at the moment but would be great when the combo runs like it should. O all the things he listed it would be the last I'd look to change.

I'm not sure concerning his reference to the Holley Blue pump, I've used it on 1/2" line and have friends that do so too with no problems. Have you measured fuel pressure during operation, near/at the finish line to see if it isn't keeping up?? He is correct about too restrictive a filter on the inlet side, best too use a 40 micron screen here to protect the pump, then a finer filter after the pump.

The larger cam will help, but I don't think it will do a lot with the present combo, which brings me to the parts I would change if it was mine...The heads.

Two things bother me here, first the Oval port...I am not a Oval port guy, and neither are my friends. Every Oval port engine(using a stock head casting) I have ever seen has left me less than impressed. Sure, they get all the ink in car mags and on forums...but the engines most are using them on are 2500rpm to 5500 rpm engines, and that 5500rpm point is about 500-700 rpm above the point they seem to fall off power on any engine I've seen them on. In your case, you are leaving the line at 4000-4500 rpm, you have already given away 2000 rpm of the Oval heads strong point and are near the engine's torque peak, and with a small head once you go past the torque peak power falls off rather quickly if the head can't flow enough to support the higher rpm.

Second problem with the heads is the closed chamber, along with bigger valves and the chamber not being ground out to a semi-open configuration to unshroud that bigger valve. I would not be surprised that if put on a flow bench that they flow worse than they did with stock valve sizes.

Seems like maybe in this build you overemphasized the importance of compression, and this was the reason for choosing the 215 head?? I think the opposite - emphasize airflow and worry less about the compression ratio. Be 1-1.5 point low on the compression for the cam choice and you loose 30-40 hp...but by comparison, have poor heads and you lose 100+ hp.

If I had your engine the heads would be the first thing changed, before anything else, even the cam or rear gears. Get a Rectangular port head, either iron Merlin, Dart, or RHS bare castings and transfer all the parts out of what you are using now, or even a bare set of the Procomp aluminum castings(PM Bobcrman here at Hotrodders, he has used them many times with good results) fitted with your parts. You are launching at an rpm high enough you don't really care how much low end torque it makes, it's meaningless; the engine is large and you are nearing the rpm it makes peak torque at...now you need airflow so the power doesn't die off just when the rpm is getting good.

Once you have a good head, the 1150 carb won't be a problem, and with a good head the cam you have will run right up to 6500+ rpm just fine. Should be able to port match your Oval port intake to a Rectangle head, usually it is only the last 1.5-2" of port that is oval in the intake manifold.

Again, I would dump the Oval port heads, i have never seen a engine with them that has impressed me.

[S10 Racer]

Originally Posted by ericnova72

I agree with most of what Pete @ Hughes has told you, with a couple exceptions.

He is right, you need to turn more rpm, even with the cam you have now. Shifting at 5500 rpm is cutting 1000 rpm of your best power out of the equation. I'd go back to the 4.56 gear.

Does the engine feel like it really falls off above 5500rpm??

I don't feel the 1150 carb is a problem, yes it is too big at the moment but would be great when the combo runs like it should. O all the things he listed it would be the last I'd look to change.

I'm not sure concerning his reference to the Holley Blue pump, I've used it on 1/2" line and have friends that do so too with no problems. Have you measured fuel pressure during operation, near/at the finish line to see if it isn't keeping up?? He is correct about too restrictive a filter on the inlet side, best too use a 40 micron screen here to protect the pump, then a finer filter after the pump.

The larger cam will help, but I don't think it will do a lot with the present combo, which brings me to the parts I would change if it was mine...The heads.

Two things bother me here, first the Oval port...I am not a Oval port guy, and neither are my friends. Every Oval port engine(using a stock head casting) I have ever seen has left me less than impressed. Sure, they get all the ink in car mags and on forums...but the engines most are using them on are 2500rpm to 5500 rpm engines, and that 5500rpm point is about 500-700 rpm above the point they seem to fall off power on any engine I've seen them on. In your case, you are leaving the line at 4000-4500 rpm, you have already given away 2000 rpm of the Oval heads strong point and are near the engine's torque peak, and with a small head once you go past the torque peak power falls off rather quickly if the head can't flow enough to support the higher rpm.

Second problem with the heads is the closed chamber, along with bigger valves and the chamber not being ground out to a semi-open configuration to unshroud that bigger valve. I would not be surprised that if put on a flow bench that they flow worse than they did with stock valve sizes.

Seems like maybe in this build you overemphasized the importance of compression, and this was the reason for choosing the 215 head?? I think the opposite - emphasize airflow and worry less about the compression ratio. Be 1-1.5 point low on the compression for the cam choice and you loose 30-40 hp...but by comparison, have poor heads and you lose 100+ hp.

If I had your engine the heads would be the first thing changed, before anything else, even the cam or rear gears. Get a Rectangular port head, either iron Merlin, Dart, or RHS bare castings and transfer all the parts out of what you are using now, or even a bare set of the Procomp aluminum castings(PM Bobcrman here at Hotrodders, he has used them many times with good results) fitted with your parts. You are launching at an rpm high enough you don't really care how much low end torque it makes, it's meaningless; the engine is large and you are nearing the rpm it makes peak torque at...now you need airflow so the power doesn't die off just when the rpm is getting good.

Once you have a good head, the 1150 carb won't be a problem, and with a good head the cam you have will run right up to 6500+ rpm just fine. Should be able to port match your Oval port intake to a Rectangle head, usually it is only the last 1.5-2" of port that is oval in the intake manifold.

Again, I would dump the Oval port heads, i have never seen a engine with them that has impressed me.

That is great advice, thanks alot. The 215's were used because that is what came on the motor when I bought it and they worked with the dome pistons that were in it so I kept them. I have not personally raced the truck so I don't really know if the RPM's are falling off at 5500 or not. I as always told that BB's were safe to about 5500 - 6000 rpm and so that is where I was trying to keep it (hense the gear change to 4:30). I'm probably going to go back to at least a 4:56 if not a 5.13 and see what happens (after I change heads).
Now comes the question of what size of head should I look for, runner and chamber size and anything else I need to look for in chosing a head for this combo? Also, would a head with even larger valves than what I have now (2.19 x 1.88) work better?
Thanks

[ericnova72]

I'd be looking for a rectangle port head in the 305-320cc range, with 2.19" or 2.25" intake valves and 1.88" exhaust valves. You could use a 2.30" intake valve if the head you like comes with them, but it probably won't need the extra size until you really get the rpm up(7500+).

You could also look at the smaller volume rectangle port (294cc) port Brodix Race Rites or the Edelbrock Rectangle (300cc).

You need to have a 110cc chamber to keep compression at 10.8-1 with the L2349F (as it is a smaller dome shape meant for closed chamber heads), 116cc gets you 10.2-1, 119cc gets you 9.9-1. Looks like just about any head you choose will have to be milled some to get you a decent ratio, as most all aftermarket heads come 118-119cc.

Right now it appears you are around 11.6-1 with the undecked block and 101cc 215 heads chamber, looks like a 119cc head milled .040" should get you to 10.8-1 roughly. You could mill them farther to try to keep as much compression as you can but it may require intake milling also.

[S10 Racer]

Originally Posted by ericnova72

I'd be looking for a rectangle port head in the 305-320cc range, with 2.19" or 2.25" intake valves and 1.88" exhaust valves. You could use a 2.30" intake valve if the head you like comes with them, but it probably won't need the extra size until you really get the rpm up(7500+).

You could also look at the smaller volume rectangle port (294cc) port Brodix Race Rites or the Edelbrock Rectangle (300cc).

You need to have a 110cc chamber to keep compression at 10.8-1 with the L2349F (as it is a smaller dome shape meant for closed chamber heads), 116cc gets you 10.2-1, 119cc gets you 9.9-1. Looks like just about any head you choose will have to be milled some to get you a decent ratio, as most all aftermarket heads come 118-119cc.

Right now it appears you are around 11.6-1 with the undecked block and 101cc 215 heads chamber, looks like a 119cc head milled .040" should get you to 10.8-1 roughly. You could mill them farther to try to keep as much compression as you can but it may require intake milling also.

Thanks ericnova, I knew I could depend on you.

[S10 Racer]

Originally Posted by ericnova72

I'd be looking for a rectangle port head in the 305-320cc range, with 2.19" or 2.25" intake valves and 1.88" exhaust valves. You could use a 2.30" intake valve if the head you like comes with them, but it probably won't need the extra size until you really get the rpm up(7500+).

You could also look at the smaller volume rectangle port (294cc) port Brodix Race Rites or the Edelbrock Rectangle (300cc).

You need to have a 110cc chamber to keep compression at 10.8-1 with the L2349F (as it is a smaller dome shape meant for closed chamber heads), 116cc gets you 10.2-1, 119cc gets you 9.9-1. Looks like just about any head you choose will have to be milled some to get you a decent ratio, as most all aftermarket heads come 118-119cc.

Right now it appears you are around 11.6-1 with the undecked block and 101cc 215 heads chamber, looks like a 119cc head milled .040" should get you to 10.8-1 roughly. You could mill them farther to try to keep as much compression as you can but it may require intake milling also.

With all this being said, would you recommend aluminum or cast heads? I know that the cast heads are heavier but I think they are also more durable, agree? I'm stuck between choosing. With the cam lift I have now I don't see a problem with rocker studs in the aluminum heads but what if I wanted to go a higher lift roller in the future? I really can't afford a Jesel system so I would have to stick with roller rockers and stud girdles for the meantime. I also have a another cam that I bought new from Comp a while ago. Would this cam help my setup more than what I have now with better heads? I forgot to mention in my earlier posts that I am running factory 1.7 ratio rockers on both sides (if that makes a difference). Thanks in advance

Summit Racing Part Number CCA-11-220-4
UPC 36584540168

Cam Style Mechanical flat tappet
Basic Operating RPM Range 3,000-7,000
Intake Duration at 050 inch Lift 260
Exhaust Duration at 050 inch Lift 260
Duration at 050 inch Lift 260 int./260 exh.
Advertised Intake Duration 306
Advertised Exhaust Duration 306
Advertised Duration 306 int./306 exh.
Intake Valve Lift with Factory Rocker Arm Ratio 0.629 in.
Exhaust Valve Lift with Factory Rocker Arm Ratio 0.629 in.
Valve Lift with Factory Rocker Arm Ratio 0.629 int./0.629 exh.
Lobe Separation (degrees) 110
Intake Valve Lash 0.022 in.
Exhaust Valve Lash 0.022 in.
Computer-Controlled Compatible No
Grind Number CB 306S-10

[ericnova72]

Not really any difference in durability of aluminum heads vs cast iron, that is mostly a wives tale. With the aluminum head you get light weight(big plus with BBC) and repairability if something goes wrong(you can weld them). You just have to not be ham handed with the threads in aluminum is all...follow recommended torque specs. Antiseize on spark plugs and exhaust bolts. Plus there are always helicoils if a thread gets hurt, a helicoiled hole is stronger after the repair than a simple threaded hole in the aluminum casting is in the beginning. Some companies helicoil all fastener holes in their heads from the get-go(I think Brodix comes to mind).

About the only plus to iron is the lower buy-in cost. Both will perform the same if they are an identical port casting, like comparing Dart Iron Eagle and Dart Pro 1.

A stud girdle is good protection for the stud posses in the aluminum, along with preventing flex in the studs with the BBC compound angle and big 1.7 ratio, so it is good to have a girdle on both Aluminum or Iron.

I like the bigger cam grind. I would definatle put a face-oiling lifter on it though if you use it, BBC is hell on flat tappet cams.

I've used that Comp grind in a 460 Ford years ago, it worked well with the large port Super Cobra-Jet heads. Went mid-10's in a 2800lb '66 Mustang with an 8" converter and 4.30 gears w/31.0 x 16.50 tires. Shift point at 6000 rpm.

[S10 Racer]

Originally Posted by ericnova72

Not really any difference in durability of aluminum heads vs cast iron, that is mostly a wives tale. With the aluminum head you get light weight(big plus with BBC) and repairability if something goes wrong(you can weld them). You just have to not be ham handed with the threads in aluminum is all...follow recommended torque specs. Antiseize on spark plugs and exhaust bolts. Plus there are always helicoils if a thread gets hurt, a helicoiled hole is stronger after the repair than a simple threaded hole in the aluminum casting is in the beginning. Some companies helicoil all fastener holes in their heads from the get-go(I think Brodix comes to mind).

About the only plus to iron is the lower buy-in cost. Both will perform the same if they are an identical port casting, like comparing Dart Iron Eagle and Dart Pro 1.

A stud girdle is good protection for the stud posses in the aluminum, along with preventing flex in the studs with the BBC compound angle and big 1.7 ratio, so it is good to have a girdle on both Aluminum or Iron.

I like the bigger cam grind. I would definatle put a face-oiling lifter on it though if you use it, BBC is hell on flat tappet cams.

I've used that Comp grind in a 460 Ford years ago, it worked well with the large port Super Cobra-Jet heads. Went mid-10's in a 2800lb '66 Mustang with an 8" converter and 4.30 gears w/31.0 x 16.50 tires. Shift point at 6000 rpm.

Ok so with all this being said, can I use the closed chamber pistons I have installed with a set of open chamber heads or should I change the pistons? If I change the pistons, what would a recommended piston be? A dome I assume would keep my compression up.