Would be possible with heads that flow just over 400 CFM @ .700 lift intake?(haven't got to the exhaust yet) The compression will be 10.5:1 BBB 464 with this roller cam; Not sure the attachment worked until I post. Anyway this is a project for next year, just trying to get an idea what kind of power I'm getting myself into so I know how strong the components behind it need to be. Thanks for the input. Derek
If, and I really mean "IF" you had heads that flowed over 400 the only way to go would be a custom grind.
Well I got a deal on the cam along with the other parts I have been collecting for this build. Trying to keep it pump gas friendly as well, I haven't done the math yet for the dynamic compression so if I can go higher I will but yeah the cam is a bit small for that flow. So 700ish looks like this thing is gonna need a jock strap! Time to start saving for that piece now. Derek
The intake port does flow just over 400 CFM no ifs ands or buts about it. Maybe I can get the cam I have re-ground with a smaller base circle? Or use more rocker ratio? Not sure, I'm not that far yet. But hell yeah a custom solid roller would be much better! I still want to run on pump gas though, more for the street than for the strip if it goes in one of my cars. If I find a buyer for it then specs may change though. The heads aren't exactly Buick heads(yet) they need a bit of custom work to make them fit, I'll leave it there for now. Derek
Derek What you really need with that kind of airflow is more displacement if it is going to be mainly a street engine. If you had closer to 500 cu inches, the cam could have at least 10* more duration and still have ok street manners with a wide power band. The increase duration would allow more lift without having real aggressive ramp rates. You would have no problem seeing power in the 700+ range Paul
I was thinking about changing to a set of Ford aftermarket 5.4L rods with a set of AutoTecs, stroke the crank for the 2.086" rod journal size they have, they are 6.657" a whole .057" longer than a factory rod plus the big end is .940" so minimal machining to make them the .928" Buick thickness. Here is a link to a set of them; http://www.ebay.com/itm/FORD-MODULA...EAM-ROD-W-ARP2000-BOLTS-/171876797373?vxp=mtr The rod bearings for those rods have a few under sizes too so I could even have the crank stroked a bit extra for one of the under sizes available. Without grinding the crank to an under size bearing and using a virgin crank it can be stroked to 4.060" with a 4.350" bore that would be a 482 cid, close only 18 cid from 500. The block I have may have to go to 4.360" bore so that would be 485 cid only 15 cid away from 500. If I use the rod bearing under sizes I think I can get the stroke to 4.110" for a 490 BBB! Besides I think the velocity these heads have shouldn't slow down a smaller CID engine to much? I found some exhaust flow numbers looks like they are around 290 CFM @ .700 lift. The problem with changing the cam is that I have the cam I posted already($$$). What would 1.9:1 rockers do with durations for that cam? I know the lift will be increased into the .700 range right in the peak flow area, I can also get 2.0:1 rockers as well if that would make the cam I have work better? Wouldn't the smaller duration @ .050" make more torque for the street? If I keep the rockers at 1.6:1 then it won't get into the max flow range will be under 400 @ the .606" lift the cam has with 1.6:1, probably around 360 to 380 range?(I don't have a flow sheet yet just the max flow @ .700 lift numbers) Thanks for your input Paul, its good to see you posting again. I'm good with doing the custom machining to make everything go round and round and up and down but not the best at deciphering camshaft math like you are, thanks again for your input. Derek
The Ford rods look good. I wish there was an off the shelf rod that was 7.00" so the piston CD could be around 1.50". That would cut a lot of weight off the piston as it would be a lot shorter. The Ford flat head rod is too narrow at the big end. Going larger in engine displacement really helps to widen the power band for street use. A lot more fun and you don't have to rev it as high. I would go with the 1.8 ratio rocker to get the lift you want and it will also increase the duration. With a 1.8 ratio you will need solid roller lifters and larger diameter push rods. What type of rocker arms do you need for these heads? What spring pressure is recommended for this cam? It didn't show on the cam card you posted Don't forget the lifter bore girdle. Thanks for the "Welcome back" Paul
Speedmaster was selling BBC 7.100" rods for like $260 a set, I think they ran out of them fast and didn't do another run! Probably should of bought a set when I could, I look for them every once and a while to see if they did another run of them. Their stuff is ok just need to upgrade the bolts to ARP and they're usually good to go, the last set I used in a build the big bores measured good just had to hone the pin bore slightly bigger and swap the bolts to ARP, I have heard stories of bad big bores though. I would of went that way and just stroked it .050", that would make those AutoTecs a lot lighter! Not sure what springs I need with that cam, was thinking of using some sort of beehive type spring though. Why would I need larger diameter pushrods and solid lifters with 1.8:1 rockers? Funny, I was just thinking I will need a lifter bore girdle earlier today. Got a phone call will edit post later. Derek
I am using these to replace my alloy GRPs on my engine freshen up. Went .100" longer because its a common BBC rod with the 2" BE. Cheers
Lets say that the valve spring pressure on the seat is 150 lbs and 400lbs open at .616" lift. That's a spring rate of 406 lbs/inch. With a 1.6 ratio rocker @ 400 lbs the pushrod and lifter see 400 x 1.6 or 640 lbs. Now change to a 1.8 ratio. Valve lift goes to .693" Open spring pressure is .693 x 406 (Spring rate) + 150 or 431 lbs. 431 lbs x 1.8 = 776 lbs. on the pushrod and lifter. That's a 136 lb increase. That's why I recommended solid roller lifters and thicker pushrods. This way you know for sure that there is no loss of power due to hydraulic lifters pumping down and flexing pushrods. One thing you will need to check is if there is enough clearance in the pushrod holes in the head for 1.8 ratio rockers with 3/8" pushrods. There is always Scat or Eagle 7.1" BBC rods for under $500. Paul
Very nice rods! We have a set of BBC 6.8 Callies Ultra for the Blown alky engine in a Vintage 7 Liter hydroplane. We did manage to bend 6 out of 8 right where the side ribs meet the beam coming down from the small end. We had extreme detonation. Paul
Paul, excellent explanation of spring rates. I am going to have to try and remember that for future reference. Great stuff! Sorry Paul I was thinking larger diameter push rods(doh), yeah I would probably get some sort of extreme push rod for this build unless I go with lesser ratio rockers or regrind cam smaller? So if I go with like a 1.3:1 rocker ratio to keep the lift around .500" I could increase low end torque while lowering the RPM the power band will be in. Max flow isn't until .700" so just under .500", flow should be enough less to not kill the low end, should actually rev quite quickly to its max RPM at that lift? Not looking to make max HP, would like it to be more streetable so if I don't use all the high lift flow I should be able to make some good down low torque. Flow @ .500" is 340-350 range for the intake and 240-250 range for the exhaust. Remember that with a lower ratio the valve will open and close slower but should still be opened the same amount of time as with a higher ratio. I would be able to use some inexpensive beehive springs to control the valve train. Using lift as a flow restriction do you think I can get this more streetable by limiting lift by either the rocker ratio or by having the cam reground to a smaller profile? Maybe I can get the power down enough to not have to use a girdle? Not sure about that though because with still close to 350 CFM on tap there would still be a potential of making some good high RPM HP even with smaller durations @ .050"? I am aware there are other brand 7.100" BBC rods available I just liked the price on the SpeedMaster(formerly know as Proform I think). I have Pontiac aftermarket H-beam 6.625" rods with light weight(light for what they are anyway) 2618 flat top Diamond pistons that I can use with this build but was thinking that a longer rod with a even lighter piston would be a good thing to help live without a girdle if I don't install one. There is the 5.4L Ford mod engine rod choice with AutoTec pistons as well to pump up the cubes. On the plus side to my understanding using the Ford mod rods gives a lesser rod ratio and that is supposed to be easier on the bottom end of the stroke and more harsh at the top so that may be a good idea without a girdle? If I use the flat top version of the AutoTec piston and have the top machined to stay a uniform thickness of .150" to .200" thick and the extra stroke and extra rod length .057" more than stock will help lighten the piston with the .866" wristpin the Ford mod rods need helping reduce weight even further getting the compression distance down to 1.880" .100" less than the advertised BBB AutoTec flat tops. Still a whole lot of piston! And that's why I was thinking the longer 7.100" BBC rods for $260 a set were looking very tempting, would of softened the blow of the $639 piston price(includes rings) but the compression distance would be a much more reasonable 1.495". Choices, choices, choices! What's the max HP & torque that a non-girdled BBB block handle dependably before failure? Is it around 600 HP and 600 FT LBS? That would be great numbers to shoot for on the street with some strip duty in a '64 Skylark! Derek
Derek You're killing me. Help me understand. You have heads that flow 400 cfm but you want to detune to keep within a certain budget and waste the potential? Larry's engine made 600 hp @ 6000 rpm and just shy of 600 ft lbs between 4500-5000 rpm without a girdle. (That's corrected HP) Part of this depends on the port volume of the head. Large port volume means low velocity if the engine is detuned. You either go large on the engine displacement or use high rpm in order to have reasonable port velocity and engine efficiency with ports that have larger cross sectional area. Otherwise you will have port reversion through most of the rpm range and power will suck. I take it these are not Buick heads. If not will you need pistons with valve pockets specific for the heads. Also what type of rocker arms. Shaft or stud mount? Paul
Thanks Keep an eye out for cheap 7.1" BBC rods. I'm thinking 470 cid and custom pistons with a dish as described in my PM. CD should be 1.475" since most blocks end up at 10.550" after decking. The cam card shows installation as straight up but even if you advance 4* you can still have 11:1 static compression ratio. To tell you the truth I'm not sure what the effect is on DCR if you go to a 1.5 ratio rocker. The intake valve still closes on the seat at the same place but the valve lift that corresponds to .006" lobe lift (.008" valve lift with the 1.6 rocker) does happen sooner at closing. Paul
Speedmaster is Procomp. Supposedly the same Chinese forgings Eagle starts with, or so I was told. Need way more cubes for the heads, think 351 Cleveland 4bbl. Interesting sounding project.
Procomp 1000 hp rods with ARP bolts. $350 PC-4138 BBC RACE I 7.100 / 2.22 / 0.990 Near bottom of page. http://www.racingjunk.com/Rods/182529014/PROCOMP-RACE-RODS-I-BEAM-H-BEAM.html
