Thread: BBC questions questions, questions.

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Ok guys i purchased a mid life crisis toy, old 77 nova kinda sort of drag car that im trying to get back on the street. My first question is it has a 468ci, approx 10.5 comp, victor 454r intake with a nitrous plate and a 2inch spacer topped by a holley 4150 carb built by pro systems, msd 7al-2 ign, with a msd hvc 2 coil, lunati #40220 cam...620 in .632 ex ? the heads are old gm factory aluminum heads cast #3946074 that were worked by air flow research, they have the exaust ports welded up and made into "D" ports, do you guys see a prob running this motor on the street ? Any recemended changes ?...... and 2nd question is that i have 1 3/4in o.d. tube headers, but the D port size is "2in" wide X 1 3/8 in" tall. is their going to be a flow prob because of the smaller header size ? do i need bigger tube headers ? This is what happens when you purchase on a whim...

Welcome to CHR!

Sounds like you've got a project car - always fun, but my first impression is that that's way too much cam for the street. Lunati's site says the following:
Solid, rough idle. Good cam for bracket racing in 454 and up cubic inch motors with cast iron heads in a light weight car. Needs 4500 RPM stall converter or better, headers, 12:1 compression ratio or better and 4.56 gearing or better.

Advertised Duration (Int/Exh): 316/324
Duration @ .050 (Int/Exh): 268/282
Gross Valve Lift (Int/Exh): .620/.632
LSA/ICL: 110/108
Valve Lash (Int/Exh): .030/.030
RPM Range: 4200-7600

I believe the heads are the early 70's L88 items - could be great or "not-so-good" depending on just how much work has been done to them. I do know that they were prone to crack at the rocker arm bosses and have to be reinforced or repaired. With that monster cam such has probably been addressed.

Pat McCarthy is our resident BBC master and one of the premier engine builders in this country. He will be able to help you out, re; what to do to dial this one back a bit for street manners!

Have fun and let us see some pictures.
Glenn

it is all a big miss match pile of parts were do you want to start ? all studs towers on GM alum heads can fail many have been fixed old heads Race head that have been ran hard many times .old heads ... old news.i have fix them .if there not crack or busted that,s good . but if so may be better to sell them and buy a new head that ,s up to speed for port size and flow . cam is not right for the CR you have . you will need lot of gear and stall to make it work. for the street . that intake works good.i have used them but not that good for the small engine for street .bump up the CR two points+ . deal with the hi stall and gear = Hi RPM . low speed idle around town with that cam could be less then great . headers could be bigger.i used cams like this for short run street cars they are fine for 10to 20 mile trips but you need better then 12to1 .lower RPM can be soggy you will have to be in the power band of that cam all the time under the cam it will be not much fun and you will be there most of the time on the street

Hey Pat,
That situation sound kind of familiar?
Listen to Mr. McCarthy, he knows more about BBC's then anyone I've worked with before. He just went thru my 509 and "fixed" it. I purchased the engine assembled and it had the exact same heads you have, about 11:1 CR a solid roller cam and a few issues he found after he opened up the motor.
I sold all of the top end stuff and Pat built me a motor that will run on the street and be fun to drive. If that is what you want, give him a listen. Are you in Muskegon? Not that far from Kawkawlin...
Mark

Originally Posted by astroracer

Hey Pat,
That situation sound kind of familiar?
Listen to Mr. McCarthy, he knows more about BBC's then anyone I've worked with before. He just went thru my 509 and "fixed" it. I purchased the engine assembled and it had the exact same heads you have, about 11:1 CR a solid roller cam and a few issues he found after he opened up the motor.
I sold all of the top end stuff and Pat built me a motor that will run on the street and be fun to drive. If that is what you want, give him a listen. Are you in Muskegon? Not that far from Kawkawlin...
Mark

yes sounds like some guys engine i know

Thanks for the input guys, well this is just a winter project that i'm trying to get back up and running on the street, after reading your input it looks like i will be putting in a more street worthy cam, and as for the heads yes one stud boss has been repaired, but thats about all i see right now. I just would like to get it on the street for next year than maybe figure out what i'd like to do with it. Or what $$$ allows me to do with it....

Originally Posted by just putzing

Thanks for the input guys, well this is just a winter project that i'm trying to get back up and running on the street, after reading your input it looks like i will be putting in a more street worthy cam, and as for the heads yes one stud boss has been repaired, but thats about all i see right now. I just would like to get it on the street for next year than maybe figure out what i'd like to do with it. Or what $$$ allows me to do with it....

a smaller cam may help but if heads are hog out on intake runners side at low speed they will not work very good with that intake . you would be better with a old iron 049/781 head re worked O port head s ....you never did say what gear or stall you had ??

Hey Pat, thanks for the input, I belive it to have a 10in stall and a 4.56 gear.

Originally Posted by just putzing

Hey Pat, thanks for the input, I belive it to have a 10in stall and a 4.56 gear.

if thats the case and your do not want some thing your going to drive much what 10 and a 456 i guessing your not. just swap out the piston to 13to1s and run every thing but the small headers .run a stud girdle on the heads

The heads already have stud girdles on them, and yes its only going to be a limited distance driven car,, is their a better cam set up you would recomend than the lunati thats in their ? Damn mid life crisis !!!!!!!!

Originally Posted by just putzing

The heads already have stud girdles on them, and yes its only going to be a limited distance driven car,, is their a better cam set up you would recomend than the lunati thats in their ? Damn mid life crisis !!!!!!!!

i do not use lunati much after they sold it to holley .i only look at the cam numbers i use many companys it more of whos has the numbers or core in stock for a custom grind to my numbers . then are done by Erson cam for my shop , that cam will work have two on the shelf very close to it . but you will need that gear and a 4500 stall and you will need as much CR you can pack in that head

Well Pat I think i'm going to have to just pull this motor apart this winter to see what i really have inside, i'm just going off what the seller told me it had inside as far as internals. the winters are long in wi so i will have plenty of time to pull it apart.... thanks again for the help, at least i have a place to start now.