548 CI BBC Advice

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David Vizard
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Re: 548 CI BBC Advice

Post by David Vizard » Sat Mar 25, 2017 7:29 pm

zwede wrote:So I just did some googling to make sure I was right, and it turns out I wasn't really right after all. Typically multiplication and division are considered the same priority and you do them left-to-right. So as you had the formula is technically correct.

That said, may I suggest adding the extra parenthesis anyway as it makes it clearer?

Zwede,
You got it.
Thanks for the pointer here.
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MadBill
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Re: 548 CI BBC Advice

Post by MadBill » Sat Mar 25, 2017 7:30 pm

David Vizard wrote:..As soon as I saw this I thought Jeez what a silly mistake. I have looked at that formula hundreds of times not looking for a mistake so I read what I expected to see not what was there...
I think every instruction manual ever written has been proofed by the designer, who's already intimately familiar with the product. Better they should drag people in off the street, hand them the manual and if they can't figure it all out without a single question, it needs work.
Felix, qui potuit rerum cognscere causas.

Happy is he who can discover the cause of things.

TBART1970
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Re: 548 CI BBC Advice

Post by TBART1970 » Sat Mar 25, 2017 8:45 pm

WBR33 wrote:I didn't see it posted anywhere, so I'll ask?

What heads are these? Edelbrock? Which model, what valve size? Looks like they may have had some chamber porting/polishing? Any other work to them?

What model spark plug are you running in them?
Edelbrock Performer RPM. 2.250 Intake. Chambers pushed. Bowl work.

NGK BPRE11 I think.
IMG_20170325_204841.jpg
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Re: 548 CI BBC Advice

Post by TBART1970 » Sat Mar 25, 2017 9:25 pm

Newold1 wrote:I don't think his was a case of import part defects. From his description I think it was just possibly improper part size issue with the oil pump drive shaft. There are only two standard lengths of oil pump drive shafts for a BBC. The shorter standard deck size and a longer tall deck size. There can also be an issue develop if a slip collar distributor is used and the collar height is set wrong. I am pretty sure even Titan and all other main cap mounted oil pumps have the input shaft height the same, at least all the ones I have seen or used. So I think this was just a parts use assembly issue that caused his problems. Not sure what he was reffering to on the extra thick intake manifold but most intake manufacturers also have the distributor sealing pad height pretty standard to a point where it should not cause a distributor, oil pump shaft problem.

As for the defective import performance parts spreading around the after market, don't get me started on one of my stupid rants. It always seems to start out "if its too cheap to be true, it probably is !!"
Lets not muddy this thread with that voluminous post and conversations. Start another thread and there will be plenty of examples and bleeping replies !!
Intake was .100 thicker at the distributor boss. Titan pump uses different shaft than standard pump.

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Re: 548 CI BBC Advice

Post by TBART1970 » Sun Mar 26, 2017 10:01 am

Anyone like to take a guess at what the new dyno numbers would be with new cam compared to old cam? I was told by Chris Straub, the dyno numbers i.e. the torque was that high because of the the 1/8 turn down lifter adjustment. I was never told the Morel hydraulics needed to be adjusted 1 to 1.25 turns down. Also don't forget about the small intake and carb on the dyno, hopefully bigger intake and carb next time, will be upping compression to about 10.2 to 10.5.

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Re: 548 CI BBC Advice

Post by Newold1 » Sun Mar 26, 2017 10:10 am

TBART1970

You are correct about the Titan oil pump , it uses a hex drive shaft which I believe is the Ford type drive shaft, its the same I believe as the Melling Select 10778C pump uses instead of the standard GM drive shaft. I am curious which brand or part of the intake manifold had a distributor pad that was +.100 ? I guess my other head scratcher here is if the pad was high the intermediate shaft would just have some additional end gap which is not a usual problem. Does your distributor have a slip collar.? I am curious how this higher distributor pad of only +.100 wiped out the oil pump if that is what actually happened in your findings.

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Re: 548 CI BBC Advice

Post by TBART1970 » Sun Mar 26, 2017 10:35 am

Oil pump was not wiped out. The distributor was non slip collar, First pump was a moroso with standard shaft, second pump was Titan. Pressure was better but I did not add up all the variables with the intake, distributor, pump and shaft. The Titan pump shaft is cutable for clearance. Hard to do in the car. When it was on the stand for the Titan I didn't truly suspect the distributor alignment, not until it was back in the car and I started messing with machining the distributor, and then buying a slip collar one. Not until I pulled it out and apart did I realize the problem completely.

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Re: 548 CI BBC Advice

Post by fastblackracing » Sun Mar 26, 2017 12:38 pm

TBART1970 wrote:
WBR33 wrote:I didn't see it posted anywhere, so I'll ask?

What heads are these? Edelbrock? Which model, what valve size? Looks like they may have had some chamber porting/polishing? Any other work to them?

What model spark plug are you running in them?
Edelbrock Performer RPM. 2.250 Intake. Chambers pushed. Bowl work.

NGK BPRE11 I think.
IMG_20170325_204841.jpg
Thanks for posting the cylinder head info up.

Engine made 690HP/750TQ. With heads that flow

With heads that flow 323cfm peak and approximately 313cfm at .650 lift,
which is the cam lift the op is using.

A couple of things here, first I am surprised that these heads do not have higher flow numbers
for the valve size and given they are a bbc head. This puts us at 2.2HP per cfm which is on the strong side, I would think air speed has to be getting up their as well.

Cam #2 (new cam) is closing the intake valve 7.5* later.
The cam is longer duration by 5 degrees (intake) and has a wider lobe separation by 2*
I would like to see the new cam on a 108lsa installed straight up not 2* early which
would keep the intake close at 51.5 atdc and add some overlap which I think will help this deal.

Seems to me like this big engine is somewhat starving for air, and is going to be done at 5600.

Thoughts?

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Re: 548 CI BBC Advice

Post by Bob Hollinshead » Sun Mar 26, 2017 12:52 pm

I was surprised at the low flow numbers for these ported aftermarket heads too... The 049 cast iron heads with 3/8 stemmed valves I ported on flow better than these throughout: +20cfm@.500 and almost +30cfm@.600. I would think the heads would be holding back this motor with the amount of cubes they need to feed?
Pro question poster.

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Re: 548 CI BBC Advice

Post by TBART1970 » Sun Mar 26, 2017 3:55 pm

I really appreciate all the input and information. With that said, I need to just stick to a plan and get this back together. I will raise the compression, I will use my new cam. I would like to know what you would put the new cam in at, and do you think I could at least hit the 700hp mark?

This is not a max effort build, it is a street car, I just want it to run good with the parts I have.

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Re: 548 CI BBC Advice

Post by fastblackracing » Sun Mar 26, 2017 5:06 pm

TBART1970 wrote:I really appreciate all the input and information. With that said, I need to just stick to a plan and get this back together. I will raise the compression, I will use my new cam. I would like to know what you would put the new cam in at, and do you think I could at least hit the 700hp mark?

This is not a max effort build, it is a street car, I just want it to run good with the parts I have.
At the end of the day you have a pretty cool engine build that I am sure will be a lot of fun to drive with the amount of torque and HP that it makes.

Changing the installed center line by 2 degrees will not have a substantial impact on performance and if this engine has an excess of midrange torque I would put it in straight up....if you feel the midrange needs pumped up some I would put it in 2 or even 4 degrees early.

If I were you I would not only check the intake center line....I would also put the time in to find and write down all of the .050" numbers as depending on the lobe master that was used and its original intention the numbers at .050" can grow or shrink a few degrees from what the master was cut at.

So depending on what you feel the most important cam events are...opening or closing points
ICL etc.... sometimes you have to juggle the installed position to get the numbers you want.

Best wishes to you on this build...do you plan on dynoing the engine again?

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Re: 548 CI BBC Advice

Post by Kevin Johnson » Sun Mar 26, 2017 5:40 pm

David Vizard wrote:... When you write as much as I do you tend to read what you thought you put not what is there. Also editing your own work is a boring job since you are reading stuff you may well have read half a dozen times before.
Try reading it out loud. A different part of the brain is processing the information and when you hear it you are more apt to catch the mistake.

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Re: 548 CI BBC Advice

Post by Kevin Johnson » Sun Mar 26, 2017 5:52 pm

zwede wrote:So I just did some googling to make sure I was right, and it turns out I wasn't really right after all. Typically multiplication and division are considered the same priority and you do them left-to-right. So as you had the formula is technically correct.

That said, may I suggest adding the extra parenthesis anyway as it makes it clearer?
I think you are remembering more than you realize:
https://en.wikipedia.org/wiki/Order_of_operations wrote: ... However, in some of the academic literature, multiplication denoted by juxtaposition (also known as implied multiplication) is interpreted as having higher precedence than division, so that 1/2x equals 1/(2x), not (1/2)x. For example, the manuscript submission instructions for the Physical Review journals state that multiplication is of higher precedence than division with a slash,[9] and this is also the convention observed in prominent physics textbooks such as the Course of Theoretical Physics by Landau and Lifshitz and the Feynman Lectures on Physics.[nb 1]
The more you learn about mathematics and logic the more confusing it can become.

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Re: 548 CI BBC Advice

Post by David Vizard » Sun Mar 26, 2017 8:43 pm

TBART1970

I am getting the inference here that the 'new cam' is on a 110 lca. If so I would not even bother to take the engine to the dyno unless I wanted to find out how much less the engine will make compared to a 107. But that said the use of a 2.25 intake on a 540 is not the way to go and it's use would revise my recommendation here to a 106 LCA. This build is bordering on lca limit depending on the profile you may use.

Now you have posted the flow figures and assuming they are right I can tell you within very close limits (about +/- 3%) what it will make given the right cam.

Would you want this info??
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Re: 548 CI BBC Advice

Post by David Vizard » Sun Mar 26, 2017 8:48 pm

Kevin Johnson wrote:
David Vizard wrote:... When you write as much as I do you tend to read what you thought you put not what is there. Also editing your own work is a boring job since you are reading stuff you may well have read half a dozen times before.
Try reading it out loud. A different part of the brain is processing the information and when you hear it you are more apt to catch the mistake.
Kevin,

Tried this and yes it seemed to work. As bad an editor as I am I really appreciated any functional advice. Especially anything might help me spell better!!!

thanks,
DV
David Vizard Small Group Performance Seminars - held about every 4 weeks. My shop or your shop. Contact seminar organizer at marvingvx@gmail.com for details.

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