548 CI BBC Advice

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In-Tech
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Re: 548 CI BBC Advice

Post by In-Tech » Mon Mar 20, 2017 2:54 pm

TBART1970 wrote:
In-Tech wrote:Probably means it's an austempered iron core instead of a steel billet.
Billet core. Let's​ pretend I never said anything about hydraulics. Took out the hydraulic cam and ordered full solid roller billet.
There are some nice austempered cores for BBC and are used in mild solid roller applications, and of course, hydraulic roller. I prefer the steel billet two piece(iron gear pressed on back) core myself but again, the mild stuff will probably never know the difference.

newold beat me to it. I meant to comment on that 90mm TB being a bit small for the hp you are trying to achieve, so if the manifold can actually keep up(I am not familiar with the Edelbrock you have), you might look into a 102mm TB.

Oh, and have your tuner experiment with ADDING timing after peak torque, I think you will be pleasantly surprised :)
Heat is energy, energy is horsepower...but you gotta control the heat.
-Carl

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Re: 548 CI BBC Advice

Post by DCal » Mon Mar 20, 2017 4:55 pm

I wouldn't cut the domes any, they look to only be around 15-17 cc's as it is. The spark plug is about .750 above the deck so flame travel will not be impeeded in my opinion. Better to mill the heads ( flat mill) If you mill the heads .036 you will reduce the chamber cc by 6cc. I have a motor very similar to yours, it's 10.5 compression and has 185# cranking pressure. We have 93 octane here and it dyno'd the best at 36 degrees. Camshaft very similar to yours and Edelbrock Victor Jr because of hood clearance but still 689# torque.

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Re: 548 CI BBC Advice

Post by TBART1970 » Mon Mar 20, 2017 7:09 pm

Newold1 wrote:Before we get into hydraulic versus roller cam conflicts, lets talk about your power and torque expectations.

The horsepower expectation you have in my opinion is very achievable and the power limiting factor on this engine will come from, believe it or not, the intake manifold and throttle body. The CFM this engine will consume at about 6000 - 6500 rpms with a good camshaft will either eclipse or come very close to exceeding what a 90 mm throttle body on that small plenum EFI intake from Edelbrock may be able to supply. This manifold is really about a 600-maybe 650 hp combination on a 548 BBC with good compression, good camshaft and a good set of flowing heads. The challenge here may be getting it to a point where it will flow the air required, You might do some research as to what others have achieved with this setup as I have no direct experience with this setup and I am just doing some simple calculations on PipeMax and its' may be a challenge with what I know a 90mm throttle body can flow. It might help you if you happen to be able to identify the heads here and specs. as well as any flow data you may have. It will also help with a camshaft choice.
http://www.edelbrock.com/automotive/mc/ ... -723.shtml , I have this intake and kind of what I was shooting for power wise, the cam is smaller than both of my cams.
Newold1 wrote: As for compression increase and combustion chamber burn patterns, its' my opinion that compression in this engine can only help to a point. Most likely the Holley EFI control system you have has some great tuning capability for both fuel and timing and that being said I don't think its unreasonable to try to use 10.5 to 1 in this aluminum headed BBC in this street type use as long as you have 93 octane fuel available in your area. If you stay with your current pistons then obviously you've got to decrease combustion space CC's to get to that point and that might be doable but it will take some work depending on your dome volume now, deck height of piston when reassembled, head gasket thickness.
Can you give find and give some input here as to those questions so a compression calculation can be done to determine where the engine is now on compression (really) and where with some simpler changes may get close to a higher compression ratio.
We are going to mill the heads, I don't want to touch the pistons because I don't want to re-balance the assembly. Chambers are 131cc, felpro 1073 gasket I think. I forget what the dome is, 9.7 to 1. We are going to redo all the numbers again before the heads get milled.
Newold1 wrote: Also keep in mind that some compression changes might be doable with camshaft design as your requirements on power and rpms leave a little more flexibility of where intake closing and exhaust openings can be adjusted to deliver more dynamic compression and sort of lessen the effects of your current lower cranking compression.

Newold1 wrote:As for milling heads and intake to fit that's a lot more expensive and involved and I am not sure there is enough easily possible there to make a real cost versus benefit. I would not advise going there unless you feel you must.
Newold1 wrote: Glad to hear the oil pump distributor conflicts did not totally wipe things out with metal. Have you carefully determined how this took place and what the exact cause was. Your post on that is a little short on the details.
Newold1 wrote:When you first fired this engine up with either pump what was your cold and hot oil pressures at idle and at higher rpms when measured on your gauge. When did it start dropping and if so did it drop significantly? Did the lifter and valve train noise show up initially or did it happen after the oil pressure drop?
I had so many different sets of lifters in it I lost track. Last time I drove it 19 psi hot at idle and never went over 50 psi even at 6000 rpm.

Lifters were always noisy, got worse with time. Distributor was not in far enough.
Newold1 wrote:Another piece of info missing here is the specs. on your valve springs - spring pressures closed and open, type beehive versus duals and sizes.
195 seat, I don't remember open pressure. Dual spring, all came from Straub with the Hydraulics.
Newold1 wrote:I am not a huge fan of hydraulic roller camshafts in some high performance racing big block applications, but in extended street use and certain other moderate power and rpm applications they are fine if the camshaft is a good build and design, good hi-performance hydraulic roller lifers and proper valve train matches are used. This is even more true when a lower rpm use such as yours is being built and reasonable spring pressures are usable in the application. So don't throw in the towel on a hydraulic roller here yet. If you can use one well they are definitely going to be longer lived and easier to maintain.
Newold1 wrote:Hope some of these questions and thoughts here can help you get to a better place with your re-build and end up with a nice satisfactory result.

Lots to learn here on both sides of this post! :)
definitely getting me to think

found this online calculator

your 2 has an Overlap of 32.00 degrees and has in Intake Duration of
242.00 degrees.
The Exhaust Duration is 254.00 degrees. Your Lobe Separation Angle is
108.00 degrees.
The Inlet Cam has an Installed Centerline of 103.00 degrees ATDC.
The exhaust cam has an Installed Centerline of 113.00 degrees BTDC.

Your 1 has an Overlap of 31.50 degrees and has in Intake Duration of
247.00 degrees.
The Exhaust Duration is 256.00 degrees. Your Lobe Separation Angle is
110.00 degrees.
The Inlet Cam has an Installed Centerline of 108.00 degrees ATDC.
The exhaust cam has an Installed Centerline of 112.00 degrees BTDC.

Inlet Valve Speed of Sound (MACH) Index

Your bore size is 4.600 inches with a stroke of 4.125 inches and has 1
inlet
valves with a diameter of 2.250 inches. Running a Mean Valve Flow
Coefficient
of .336 inches at 6200 RPM, the inlet valve mach index is 0.736 .
The mach index for maximum volumetric efficiency is .6 . Beyond .6 the
volumetric efficiency falls off. As the mach index rises beyond .6 the
volumetric efficiency can be increased by later inlet valve closings
(60 to 90 degrees ABDC).

Camshaft, Rod Length, Boost and Altitude Correction to Compression

Your engine summary is as follows: Bore 4.600 inches,
stroke 4.125 inches, rod c-c length 6.385 inches, with a static
compression ratio of 9.7 :1.
Your camshaft specifications call for an inlet valve closing of 44
degrees ABDC (after bottom dead center).

Your chamber volume is 129.13 cc's. With this camshaft your dynamic, or
effective stroke is 3.71 inches.
Your dynamic compression ratio is 8.82 :1 corrected for cam timing,
altitude, and rod length.
Your dynamic cranking pressure, corrected for cam timing, rod length and
altitude is 180.31 PSI.
Your dynamic boost compression ratio, reflecting static c.r., cam
timing, altitude, and 0 PSI is 8.82 :1.

Camshaft, Rod Length, Boost and Altitude Correction to Compression

Your engine summary is as follows: Bore 4.600 inches, stroke 4.125 inches,
rod c-c length 6.385 inches, with a static compression ratio of 9.7 :1.
Your camshaft specifications call for an inlet valve closing of 51.5
degrees ABDC (after bottom dead center).

Your chamber volume is 129.13 cc's. With this camshaft your dynamic,
or effective stroke is 3.55 inches. Your dynamic compression ratio is
8.49 :1 corrected for cam timing,
altitude, and rod length. Your dynamic cranking pressure, corrected
for cam timing, rod length and altitude is 171.68 PSI.
Your dynamic boost compression ratio, reflecting static c.r., cam
timing, altitude, and 0 PSI is 8.49 :1.

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Re: 548 CI BBC Advice

Post by TBART1970 » Mon Mar 20, 2017 7:32 pm

DCal wrote:I wouldn't cut the domes any, they look to only be around 15-17 cc's as it is. The spark plug is about .750 above the deck so flame travel will not be impeeded in my opinion. Better to mill the heads ( flat mill) If you mill the heads .036 you will reduce the chamber cc by 6cc. I have a motor very similar to yours, it's 10.5 compression and has 185# cranking pressure. We have 93 octane here and it dyno'd the best at 36 degrees. Camshaft very similar to yours and Edelbrock Victor Jr because of hood clearance but still 689# torque.
I agree about the domes. Builder thinks flatter is better. Which cam old or new? What are your cam specs, just for comparison purposes.

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Re: 548 CI BBC Advice

Post by TBART1970 » Mon Mar 20, 2017 8:41 pm

Part #: #2264 EDELBROCK 555

Vehicle Type: CHEVROLET

Engine Application: 500+ (1996-Later Gen V & VI)

RPM Range: 1500-6500


DURATION AS ADVERTISED INTAKE: 308° EXHAUST: 315°
DURATION @ .050 INTAKE: 248° EXHAUST: 256°
LIFT @ CAM (Lobe) INTAKE: 0.371" EXHAUST: 0.381"
LIFT @ VALVE INTAKE: 0.632" EXHAUST: 0.648"
LOBE SEPERATION: 112° INTAKE CENTERLINE: - IDLE VAC @ 1000 RPM: 10"

The information below is for verification of
opening and closing events.
INTAKE TIMING @ .050" LIFT: Opens: 14.5° BTDC
Closes: 62.5° ABDC
EXHAUST TIMING @ .050" LIFT: Opens: 53.5° BBDC
Closes: 13.5° ATDC

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Re: 548 CI BBC Advice

Post by DCal » Mon Mar 20, 2017 8:46 pm

My cam specs are from a Comp Cams on one of their hyd rollers
lift; int .647 exh .654
dur 242 248
114 lobe sep in at 110

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Re: 548 CI BBC Advice

Post by geraldtson » Mon Mar 20, 2017 8:49 pm

Sounds like your distributor is located to deep in block,if it is it should leave a mark (shaved spot) on the bottom of the distributor shaft on the radius directly above the shims.If its left a mark raise youre distributor with gaskets or if you have an adjustable slip collar drop it down. You can mark the radius i'm talking about with a marker and drop it back down in the hole until it's engaged into pump shaft all the way,now by hand just turn distributor housing not shaft back and forth pull it back out make sure it didn't rub the spot you marked on the radius. If it did you're cam gear is hitting the bottom of you're housing radius and you need to raise it up .050 .075 and try again until its not hitting. Also while you have distributor out look down the hole at you're cam gear for wear ( rotate cam one full turn check for damage) assuming you have a bronze distributor gear it usually only damages the distributor gear and not the cam gear. If car was run with cam to deep it could have been down on power possible misfire too.

Best of luck!!

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Re: 548 CI BBC Advice

Post by TBART1970 » Mon Mar 20, 2017 10:22 pm

DCal wrote:My cam specs are from a Comp Cams on one of their hyd rollers
lift; int .647 exh .654
dur 242 248
114 lobe sep in at 110
How do you think it runs? Would you make a change if you could?

Thanks for the Input.

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Re: 548 CI BBC Advice

Post by DCal » Tue Mar 21, 2017 9:40 am

TBART1970 wrote:
DCal wrote:My cam specs are from a Comp Cams on one of their hyd rollers
lift; int .647 exh .654
dur 242 248
114 lobe sep in at 110
How do you think it runs? Would you make a change if you could?

Thanks for the Input.
I'm pleased with mine, it met my goals of good torque, vacuum and 700 HP. It was being used as an R&D piston and rod deal for CP-Carrillo and as such did great, especially with some things that I wanted to try: tighter ring grooves w/gasports, larger ring land diameters that were elliptical in shape and a totally (for CP anyway) different cam and barrel shape for the piston skirts. Piston to wall clearance is .0045 measured .500 from the bottom of the short skirt. 1.220 compression height..
Oil pressure hot at idle is 25 min and 55-60 at anything over 1600 rpm with a Mellings hv77 pump. I kept every dimension and I'm lucky that I found it because I'm moving and if you want anything more I'd be happy to share. I'm still out on the gas ports tho'

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Re: 548 CI BBC Advice

Post by TBART1970 » Tue Mar 21, 2017 10:09 am

thanks, kind of what I was looking for. Anything else you want to share would be great, whenever you get some time. It will be a while before it gets put back together.

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Re: 548 CI BBC Advice

Post by TBART1970 » Tue Mar 21, 2017 10:49 am

https://www.rbracing-rsr.com/camshaft.html

Been messing around with it. I know it is from a bike site......but.

What do you think about pushing the compression up to 10.2 and putting in the new cam so the intake closes at 49.5 instead of 51.5?

Any more thoughts on the piston dome being taken off? I would rather keep the short block spec the same so it can just go back together without a re-balance, and milling the heads too much.

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Re: 548 CI BBC Advice

Post by wyrmrider » Tue Mar 21, 2017 11:08 am

start a new thread- you will get more responses on your bike
I see you are both raising the static-mechanical compression and the dynamic
is bike still together try advancing the cam and see what happens before you make two changes at the same time
see you in new thread
cheers

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Re: 548 CI BBC Advice

Post by TBART1970 » Tue Mar 21, 2017 11:12 am

wyrmrider wrote:start a new thread- you will get more responses on your bike
I see you are both raising the static-mechanical compression and the dynamic
is bike still together try advancing the cam and see what happens before you make two changes at the same time
see you in new thread
cheers
Not for a bike, for my 548. I am the OP, just happened to find this site calculator to play with numbers.

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Re: 548 CI BBC Advice

Post by CamKing » Tue Mar 21, 2017 11:15 am

TBART1970 wrote:Part #: #2264 EDELBROCK 555

Vehicle Type: CHEVROLET

Engine Application: 500+ (1996-Later Gen V & VI)

RPM Range: 1500-6500


DURATION AS ADVERTISED INTAKE: 308° EXHAUST: 315°
DURATION @ .050 INTAKE: 248° EXHAUST: 256°
LIFT @ CAM (Lobe) INTAKE: 0.371" EXHAUST: 0.381"
LIFT @ VALVE INTAKE: 0.632" EXHAUST: 0.648"
LOBE SEPERATION: 112° INTAKE CENTERLINE: - IDLE VAC @ 1000 RPM: 10"
That cam will make more power then both of your cams, because of the added duration.
It's also going to be less noisy.
Mike Jones
Jones Cam Designs
Denver, NC
jonescams@bellsouth.net
http://www.jonescams.com
(704)489-2449

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Re: 548 CI BBC Advice

Post by TBART1970 » Tue Mar 21, 2017 11:30 am

CamKing wrote:
TBART1970 wrote:Part #: #2264 EDELBROCK 555

Vehicle Type: CHEVROLET

Engine Application: 500+ (1996-Later Gen V & VI)

RPM Range: 1500-6500


DURATION AS ADVERTISED INTAKE: 308° EXHAUST: 315°
DURATION @ .050 INTAKE: 248° EXHAUST: 256°
LIFT @ CAM (Lobe) INTAKE: 0.371" EXHAUST: 0.381"
LIFT @ VALVE INTAKE: 0.632" EXHAUST: 0.648"
LOBE SEPERATION: 112° INTAKE CENTERLINE: - IDLE VAC @ 1000 RPM: 10"
That cam will make more power then both of your cams, because of the added duration.
It's also going to be less noisy.
Just trying to learn. The hydraulic roller I had, what would the duration need to be raised to in your opinion to make up for going to solids? Do you think the new cam is way too far off? I have the new cam already, this rebuild is costing me a lot already, I don't want to get another cam if I don't have to. Just trying to make some other changes with compression and cam install to help it. If you guys feel that the new cam is that bad I will see what my options are. Again thanks for the input. I have a ton of money in the car and engine. This set back is not helping the rest of the build that needs to be finished. No unlimited budget here. Plus the time spent. I know live and learn, if you want to play you have to pay, especially when some if not most of the issues are self inflicted.
Again, Thanks.

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