Oval port vs square port BBC heads:
02-06-2002, 03:19 PM
#1
Burning Brakes
Thread Starter
Oval port vs square port BBC heads:
Am interested in perhaps upgrading the heads on my 427/390 L-36. Looking at it from a performance stand point the high HP motors seem to run rect. port heads. This also gives the option to change from the Q-jet type manifold to a Holley style (I want to retain the hood I have & not go the L-88 hood route), unless I'm missing something, there isn't a low-rise dual plane intake that fits oval port heads and uses the Holley. Either stick w/Q-jet & oval port intake & heads or switch to rect. intake (use the LS-6 rect port low rise int) and heads and run a Holley, Demon,etc. Is this correct?
That said, to those who have had experience in this sort of thing, what are your opinions? Can I take a mild mannered 427 and change to rect port heads, put in a decent cam (solid?),add the larger carb,etc. and have a much stronger motor?
While on the subject of heads, I'm running close to 9:7 to 1 with the stock closed chamber oval port heads (approx. 103 cc), with the 2.06/1.72 smaller valves.If I go with say, a Merlin head with 118cc chambers how much comp ratio do I lose? Perhaps the Aluminum Edelbrocks with the 110cc chambers would be the better way to go. Or what about an original head from the early 70's or late 60's (which might be the cheapest way to go)?
So, the ultimate question: Which type head is the best way to go???
Regards, Mark :chevy
That said, to those who have had experience in this sort of thing, what are your opinions? Can I take a mild mannered 427 and change to rect port heads, put in a decent cam (solid?),add the larger carb,etc. and have a much stronger motor?
While on the subject of heads, I'm running close to 9:7 to 1 with the stock closed chamber oval port heads (approx. 103 cc), with the 2.06/1.72 smaller valves.If I go with say, a Merlin head with 118cc chambers how much comp ratio do I lose? Perhaps the Aluminum Edelbrocks with the 110cc chambers would be the better way to go. Or what about an original head from the early 70's or late 60's (which might be the cheapest way to go)?
So, the ultimate question: Which type head is the best way to go???
Regards, Mark :chevy
02-06-2002, 03:42 PM
#2
Racer
Member Since: Aug 2001
Location: Glacier County mt
Posts: 356
Likes: 0
Received 0 Likes
on
0 Posts
Re: Oval port vs square port BBC heads: (marky mark)
All depends on the use of the car. If you use it mainly for street cruising, the low end torque of the oval ports are the way to go. If your car is exclusively for competition, go square port. My ZZ502 has had its oval ports lightly enlarged into a "mini rectangular port" - the MPI 950 commander intake is a slightly enlarged oval. The combo works well for a street machine.
:cheers:
:cheers:
02-06-2002, 04:06 PM
#3
Safety Car
Re: Oval port vs square port BBC heads: (marky mark)
I do not like Rec port heads on a less than radical street car of less than 468 inches or so. I make close to 600 hp (454 +.030) with the oval Edelbrocks. With a 427 you will have to be turning 4500 rpms or so before the motor comes a live. With my ovals I can smoke the tires from a roll in 2nd gear at just over idle.
Only an educated guess, but I believe you would loose close to two full points of compression going to a 118 cc chamber. Edelbrock makes a head with 100cc chambers, since they are aluminum the slight rise in compression would be ok.
I am running the Edelbrock Air Gap with a Holley 850 (flowed to 920) and it fits under my L-88 hood with a 2" drop base, a 2.81" element, and a K and N extreme top. :chevy
Only an educated guess, but I believe you would loose close to two full points of compression going to a 118 cc chamber. Edelbrock makes a head with 100cc chambers, since they are aluminum the slight rise in compression would be ok.
I am running the Edelbrock Air Gap with a Holley 850 (flowed to 920) and it fits under my L-88 hood with a 2" drop base, a 2.81" element, and a K and N extreme top. :chevy
02-06-2002, 05:17 PM
#4
Instructor
Member Since: Jun 2000
Location: Buffalo, NY
Posts: 198
Likes: 0
Received 0 Likes
on
0 Posts
Re: Oval port vs square port BBC heads: (69 N.O.X. RATT)
Negative, you will not gain anything in going to a bigger port in that motor. You want more power, spend the dollar to bring your heads to a shop with a Serdi guide/seat machine and a QUALIFIED operator to open up the valves for you, blend in the bowl/seat area, and relieve the chamber behind the exhaust valve ( key area for a screw up, if they go too far, they'll find water!).
If anything you want to boost compression up a bit. But I'd bet you dont want to mill the heads, and I would agree. If you have the stock cam, its quite lazy, I would replace it with something like an Ultradyne 280/288.
Your 850 is a freckle big unless you, like me, pull the trigger at 6800.
BTW, I run an old L88 motor, de-compressed , and decammed for street use. The engine doenst realize the cam ran out for 500 rpm. its jsut wants to keep revving. Cams' done at 6500. To really use the short stroke/big port combo you need compression ( it runs 10.8 ) and all the cam that compression will take. This gets you to specs like 250/260 on a 110-112 and .580.-.600 on a solid grind. Gears to match. An oval motor that comes on at 2800-6000 would probably still win the race. Because of the high stepping nature of this beast, I had to give it a Richmond 5 speed and KEEP the 3.55s! ( 1st is only a 3.04 though).
No, bigger valves, more compression,faster ramped cam on a tight lsa. And if its the original motor, find yourself a 454 block, buy a 4.25" Callies crank, decent rods, and flatops to give you 10.5:1 with your heads. Put the smallest Crane solid roller in there ( or solid flat tappet of similar specs), and HOLD THE HECK ON! That is a half shaft twister bar none. ( and 1/2 the cost of a Merlin 509)
[Modified by 427TRI, 3:29 PM 2/6/2002]
If anything you want to boost compression up a bit. But I'd bet you dont want to mill the heads, and I would agree. If you have the stock cam, its quite lazy, I would replace it with something like an Ultradyne 280/288.
Your 850 is a freckle big unless you, like me, pull the trigger at 6800.
BTW, I run an old L88 motor, de-compressed , and decammed for street use. The engine doenst realize the cam ran out for 500 rpm. its jsut wants to keep revving. Cams' done at 6500. To really use the short stroke/big port combo you need compression ( it runs 10.8 ) and all the cam that compression will take. This gets you to specs like 250/260 on a 110-112 and .580.-.600 on a solid grind. Gears to match. An oval motor that comes on at 2800-6000 would probably still win the race. Because of the high stepping nature of this beast, I had to give it a Richmond 5 speed and KEEP the 3.55s! ( 1st is only a 3.04 though).
No, bigger valves, more compression,faster ramped cam on a tight lsa. And if its the original motor, find yourself a 454 block, buy a 4.25" Callies crank, decent rods, and flatops to give you 10.5:1 with your heads. Put the smallest Crane solid roller in there ( or solid flat tappet of similar specs), and HOLD THE HECK ON! That is a half shaft twister bar none. ( and 1/2 the cost of a Merlin 509)
[Modified by 427TRI, 3:29 PM 2/6/2002]
02-07-2002, 04:14 AM
#5
Burning Brakes
Thread Starter
Re: Oval port vs square port BBC heads: (427TRI)
Yes, I have forgotton that the old 60's & early 70's motors made all that power with higher compression than we run now. 9&1/2 to 1 is about max I thought w/iron heads.Thanks for the info.
One other question, if I went with a small chamber Edelbrock alum head what type of power increase might I see? :chevy
[Modified by marky mark, 3:15 AM 2/7/2002]
One other question, if I went with a small chamber Edelbrock alum head what type of power increase might I see? :chevy
[Modified by marky mark, 3:15 AM 2/7/2002]
02-07-2002, 05:14 AM
#6
Melting Slicks
Member Since: May 2000
Location: Crescent City, CA
Posts: 2,125
Likes: 0
Received 6 Likes
on
5 Posts
Re: Oval port vs square port BBC heads: (marky mark)
There is a 168 or 169 LS6 intake that is Holley low rise that will fit. From what I understand, the rec port intake to oval head will not decreace Hp.
Hope this helps
Terry
Hope this helps
Terry
02-07-2002, 09:57 AM
#7
Instructor
Member Since: Jun 2000
Location: Buffalo, NY
Posts: 198
Likes: 0
Received 0 Likes
on
0 Posts
Re: Oval port vs square port BBC heads: (marky mark)
Mark, keep in mind that you need more compression with alum heads to make the same power. Any OC head will decrease your compression. the CNC work on aftermarket alums helps mitigate this, but still, I think you'd be better off spending the $600-700 on your heads to really make them work. What castings are they? And once again, if you have the stock 390 cam in there, that is your big performance gain.
DONT DO IT. I can almost guarantee you'll have less performance unless your current heads are tired.
Spend the $$ on your heads and throw something like a Crane H282-08 ( if you can take the idle vacuum) in there, or an Ultradyne 280/288 (. Comp 270S might be a good choice too.) If you really want to get trick, use a custom Crane 13F00001, which is there smallest solid, the F304-2 on a 108. With bigger valves, port work ( ONLY by someone who has a flow bench), and that cam, you;re gonna think you just threw a 502 in. In fact, with that cam, and a bit more compression,a decent intake, headers and an 830 annular Holley, you'll go wll over 500 hp and 500 lbs ft.
Its not the heads. its the cam/intake and compression. You can make wicked power and HUGE mid range torque with ovals, just like yours. If you buy rect port heads, you better bump the CR to 11:1 min and run a cam like the 1st gen L88. Only then will your heads be matched to the power band. IMHO, of course. But since I run them on the street, I should know. But alas, I never tire of pulling the stick at 6800, just missing the 7200 MSD limit chip. But there are oval port cars out there that would smoke me in ET, all in the 60', even though I might out HP them at the big end.
Now, I know alum looks nice. Hell, my old 074 castings are even mirror polished! But do ya wanna look good, or run 11's?:cool:
Good luck Sir.
[Modified by 427TRI, 8:03 AM 2/7/2002]
DONT DO IT. I can almost guarantee you'll have less performance unless your current heads are tired.
Spend the $$ on your heads and throw something like a Crane H282-08 ( if you can take the idle vacuum) in there, or an Ultradyne 280/288 (. Comp 270S might be a good choice too.) If you really want to get trick, use a custom Crane 13F00001, which is there smallest solid, the F304-2 on a 108. With bigger valves, port work ( ONLY by someone who has a flow bench), and that cam, you;re gonna think you just threw a 502 in. In fact, with that cam, and a bit more compression,a decent intake, headers and an 830 annular Holley, you'll go wll over 500 hp and 500 lbs ft.
Its not the heads. its the cam/intake and compression. You can make wicked power and HUGE mid range torque with ovals, just like yours. If you buy rect port heads, you better bump the CR to 11:1 min and run a cam like the 1st gen L88. Only then will your heads be matched to the power band. IMHO, of course. But since I run them on the street, I should know. But alas, I never tire of pulling the stick at 6800, just missing the 7200 MSD limit chip. But there are oval port cars out there that would smoke me in ET, all in the 60', even though I might out HP them at the big end.
Now, I know alum looks nice. Hell, my old 074 castings are even mirror polished! But do ya wanna look good, or run 11's?:cool:
Good luck Sir.
[Modified by 427TRI, 8:03 AM 2/7/2002]
02-07-2002, 10:08 AM
#8
Re: Oval port vs square port BBC heads: (427TRI)
Quote:
"Its not the heads. its the cam/intake and compression"
Thats why I would not hesitate using 310 GM Rectangular port heads on the street with a 468.Cam and intake can overcome this bad reputation Rectangular port heads have.Some gear and 4spd would be needed to work well.Just depends on the kind of performance one is after.To sell a set of Rectangular port heads to obtain a set of ovals? Sell Ovals to get Rectangulars? Nope.More than one way to get things done.
Merlin 345's is a different story.That's a big port.
"Its not the heads. its the cam/intake and compression"
Thats why I would not hesitate using 310 GM Rectangular port heads on the street with a 468.Cam and intake can overcome this bad reputation Rectangular port heads have.Some gear and 4spd would be needed to work well.Just depends on the kind of performance one is after.To sell a set of Rectangular port heads to obtain a set of ovals? Sell Ovals to get Rectangulars? Nope.More than one way to get things done.
Merlin 345's is a different story.That's a big port.
02-07-2002, 12:49 PM
#9
Instructor
Member Since: Jun 2000
Location: Buffalo, NY
Posts: 198
Likes: 0
Received 0 Likes
on
0 Posts
Re: Oval port vs square port BBC heads: (mountainmotor)
Mountain, yes, but the loss of compression as he goes from a small chamber to a large OC chamber would negate any perfomance upgrade. Yes?
( Sir, I'm asking, not telling!)
( Sir, I'm asking, not telling!)
02-07-2002, 02:34 PM
#10
Burning Brakes
Thread Starter
Re: Oval port vs square port BBC heads: (427TRI)
427Tri and Mountainmotor, thanks for the advice.Heres some more info:
These are the smaller valve large oval port heads from 1969, #3931063. I had a reputable shop do a 5 angle valve job, hog out the exhaust ports & replace all valves that needed it (2.06/1.72 stock size). Only bad thing they found was that in order to get the intake valves to seat properly they had to clean up the intake valve seat area in the heads which left the intake valves slightly higher up in the chamber than stock location (very slightly).I asked would this reduce lift somewhat and they thought not. These heads cc'd at 103-104cc after work was done.
Cam is Crane H-272 flat tappet hydraulic. @.50 216/228 lift is .515/.510 (not wild, but intake is done by 5300 anyway). Intake is stock aluminum low rise oval port (spreadbore carbs) from '68,it was port matched to heads by same shop. I want to keep stock hood so can't go with high rise intake. Lars is working on rejetting and optiminzing my Q-jet. Stock exhaust manifolds for now going into true 2&1/2" duals w/ X-pipe. Headers are a possibility (what would that do for the motor?).
All this is in a donor 454 4-bolt block with the stock (cast) 427/402/396 crank w/3.76 stroke, stock rods and 427 TRW forged pistons (smallest dome, 14mm?). Block is now .30 over which I think makes it 433 or 434 c.i.Mallory Unilite mechanical dist.( could that be holding the power back?).Comp ratio formula estimates 9:7 to 1 (+/-). Runs ok on 93 octane. 36 deg total timing in @3000 rpm. 4 spd. w/3:36 rear gears.
It's strong, but not scary really. I don't have anything to compare it to so that's part of my problem.... Is this running as good as it should? Sorry, no 1/4 mile times!
Thanks for your help!!!
Regards, Mark :chevy
[Modified by marky mark, 1:37 PM 2/7/2002]
[Modified by marky mark, 1:40 PM 2/7/2002]
These are the smaller valve large oval port heads from 1969, #3931063. I had a reputable shop do a 5 angle valve job, hog out the exhaust ports & replace all valves that needed it (2.06/1.72 stock size). Only bad thing they found was that in order to get the intake valves to seat properly they had to clean up the intake valve seat area in the heads which left the intake valves slightly higher up in the chamber than stock location (very slightly).I asked would this reduce lift somewhat and they thought not. These heads cc'd at 103-104cc after work was done.
Cam is Crane H-272 flat tappet hydraulic. @.50 216/228 lift is .515/.510 (not wild, but intake is done by 5300 anyway). Intake is stock aluminum low rise oval port (spreadbore carbs) from '68,it was port matched to heads by same shop. I want to keep stock hood so can't go with high rise intake. Lars is working on rejetting and optiminzing my Q-jet. Stock exhaust manifolds for now going into true 2&1/2" duals w/ X-pipe. Headers are a possibility (what would that do for the motor?).
All this is in a donor 454 4-bolt block with the stock (cast) 427/402/396 crank w/3.76 stroke, stock rods and 427 TRW forged pistons (smallest dome, 14mm?). Block is now .30 over which I think makes it 433 or 434 c.i.Mallory Unilite mechanical dist.( could that be holding the power back?).Comp ratio formula estimates 9:7 to 1 (+/-). Runs ok on 93 octane. 36 deg total timing in @3000 rpm. 4 spd. w/3:36 rear gears.
It's strong, but not scary really. I don't have anything to compare it to so that's part of my problem.... Is this running as good as it should? Sorry, no 1/4 mile times!
Thanks for your help!!!
Regards, Mark :chevy
[Modified by marky mark, 1:37 PM 2/7/2002]
[Modified by marky mark, 1:40 PM 2/7/2002]
02-07-2002, 02:59 PM
#11
Re: Oval port vs square port BBC heads: (marky mark)
Marky,
Your are stuck between a rock and a hard place with that manifold.I would have run a cam with 224-228@.050 intake .230-.235@.050 ex to get a little extra power.It would tend to hit a wall and shut down with the intake and exhaust being as it is but that can be overcome with proper shift points.I think you have a pretty good combo though and to make the kind of power you hear about from other Big Blocks a major rethinking off parts and money would be required.
427,
Doubt the 427 closed chamber pistons would run with out hitting the chamber of a 118cc head so the thought of slapping a set on the motor above never crossed my mind.
Your are stuck between a rock and a hard place with that manifold.I would have run a cam with 224-228@.050 intake .230-.235@.050 ex to get a little extra power.It would tend to hit a wall and shut down with the intake and exhaust being as it is but that can be overcome with proper shift points.I think you have a pretty good combo though and to make the kind of power you hear about from other Big Blocks a major rethinking off parts and money would be required.
427,
Doubt the 427 closed chamber pistons would run with out hitting the chamber of a 118cc head so the thought of slapping a set on the motor above never crossed my mind.
02-07-2002, 05:40 PM
#12
Race Director
Re: Oval port vs square port BBC heads: (marky mark)
Mark: The exhaust manifolds are holding you back. Take a look at my webpage for the dyno results of putting headers on my 454. I think you will see an easy 50-60 hp with a good set of headers and dual 2.5" exhaust.
02-07-2002, 10:05 PM
#13
Instructor
Member Since: Jun 2000
Location: Buffalo, NY
Posts: 198
Likes: 0
Received 0 Likes
on
0 Posts
Re: Oval port vs square port BBC heads: (mountainmotor)
Yeah, if you chose the route of small tube headers, and a X-cross behind them, you could get away with a hi torque single pattern cam like a Crane H282-08. Its falls in Mountainmotor's duration range, and its done on a 108 lsa.Between the headers, "tuned" exhaust, and the peaky feel of a tight centerline cam, you'd certainly get the RIP you're looking for, and DESERVE frankly, with a stout rat. :D And hey, whether you have a M20 or M21/22, 3.31s will better respond to torque than hp.
I havent run that cam, so fwiw, ok. It probably doesnt idle like a kitten, and dont know if Lars wants to fiddle with your carb again.
For the big ports, btw, i'd guess it would like much more gear to keep the combiantion in synch. Now stick a Richie5 in there to give you 4.30s, and then go big. Old cc rect ports shaved down to get 10:1+, some low open plenum manifold ( kinda like a tripower!), and now we're talking! But I foolishly digress...
I havent run that cam, so fwiw, ok. It probably doesnt idle like a kitten, and dont know if Lars wants to fiddle with your carb again.
For the big ports, btw, i'd guess it would like much more gear to keep the combiantion in synch. Now stick a Richie5 in there to give you 4.30s, and then go big. Old cc rect ports shaved down to get 10:1+, some low open plenum manifold ( kinda like a tripower!), and now we're talking! But I foolishly digress...
02-07-2002, 11:01 PM
#14
Re: Oval port vs square port BBC heads: (427TRI)
427,
It is fun building motors in our heads! Speaking of fun,Quote"And hey, whether you have a M20 or M21/22, 3.31s will better respond to torque than hp."
Thats the Chevelle in you.Sharks never heard of a 3.31 gear.
Just kidding :)
There is a 68 Vette here in town with 10.25-1 310 GM heads and 3.73 gear that pulls from 3 on up.It's starting to haze the tires at 2500 then rolls them up in first and second gear.Cam was ground on special order by me for the guy.Bet you would like to know what it's cam card say's :) Oh yeah,forgot the most important part.It's a 439!
It is fun building motors in our heads! Speaking of fun,Quote"And hey, whether you have a M20 or M21/22, 3.31s will better respond to torque than hp."
Thats the Chevelle in you.Sharks never heard of a 3.31 gear.
Just kidding :)
There is a 68 Vette here in town with 10.25-1 310 GM heads and 3.73 gear that pulls from 3 on up.It's starting to haze the tires at 2500 then rolls them up in first and second gear.Cam was ground on special order by me for the guy.Bet you would like to know what it's cam card say's :) Oh yeah,forgot the most important part.It's a 439!
02-08-2002, 05:17 AM
#15
Burning Brakes
Thread Starter
Re: Oval port vs square port BBC heads: (mountainmotor)
Thanks for the good replys fellas.
A few other questions about the cam. What I have is a dual pattern,right? Would going to a single pattern (where int and exh duration #'s are the same, right?)give me some more power? I would guess the lower LSA of 108 would help mid-range power? Also, if I switch to this type of cam, what lift is reasonable for my set-up, say .550-580? Finally, what about going with a solid cam (not a roller)???
Also, Mountain, I'd like to know the specs on the cam you had built for that guy.
Regards, Mark :flag :chevy
A few other questions about the cam. What I have is a dual pattern,right? Would going to a single pattern (where int and exh duration #'s are the same, right?)give me some more power? I would guess the lower LSA of 108 would help mid-range power? Also, if I switch to this type of cam, what lift is reasonable for my set-up, say .550-580? Finally, what about going with a solid cam (not a roller)???
Also, Mountain, I'd like to know the specs on the cam you had built for that guy.
Regards, Mark :flag :chevy
02-08-2002, 08:29 AM
#16
Re: Oval port vs square port BBC heads: (marky mark)
Mark,
I like solid lifter cams!More power and vacumm.You could use a solid lifter flat tappet or hydraulic with a 110 and advance it 5 degrees or so .That would be better than 108 for your motor.
A single pattern needs good exhaust if you are going to rev it up high.Well so does a dual pattern but more so with a single pattern cam.Is the motor apart now?Intake valve clearance will be an issue.To run the cam I think would work best for you. The Q-jet will need sent to a shop capable of changing the fuel curve and idle feeds.Relatively cheap to do.
Headers on a Big Chevy really works.Best money a guy can spend for sure.Hooker is the brand to go with on Big Chevy IMO
More can be done to make that motor run pretty hard with your manifold.That will take a phone call though.Just like cam specs cause I can't type that much!
[Modified by mountainmotor, 6:32 AM 2/8/2002]
I like solid lifter cams!More power and vacumm.You could use a solid lifter flat tappet or hydraulic with a 110 and advance it 5 degrees or so .That would be better than 108 for your motor.
A single pattern needs good exhaust if you are going to rev it up high.Well so does a dual pattern but more so with a single pattern cam.Is the motor apart now?Intake valve clearance will be an issue.To run the cam I think would work best for you. The Q-jet will need sent to a shop capable of changing the fuel curve and idle feeds.Relatively cheap to do.
Headers on a Big Chevy really works.Best money a guy can spend for sure.Hooker is the brand to go with on Big Chevy IMO
More can be done to make that motor run pretty hard with your manifold.That will take a phone call though.Just like cam specs cause I can't type that much!
[Modified by mountainmotor, 6:32 AM 2/8/2002]
02-08-2002, 08:31 AM
#17
Race Director
Member Since: Apr 1999
Location: CORVETTE 77 385 C.I. TEXAS
Posts: 11,520
Likes: 0
Received 12 Likes
on
12 Posts
Re: Oval port vs square port BBC heads: (marky mark)
Stick w/ oval port heads. You should have went w/ the Comp XE268 suggested a while back for what you wanted.
:cool:
:cool:
02-08-2002, 10:21 AM
#18
Safety Car
Re: Oval port vs square port BBC heads: (marky mark)
Mark, the Merlin ovals will never work right with you pistons. Low compression. I like the Edelbrocks that N.O.X. mentioned for the money. I don't know of any other aftermarket head with those specs. They're tailer made for your engine.
Zwede's right, you need to address your exhaust first. Headers will really help with a larger cam and bigger valves in your stock heads. I wouldn't run a hydraulic myself in a weekend car. You give up power for maintenance, but is adjusting the valves a few times a year really an issue here? For me it isn't. The cams that 427TRI and mountainmotor are recommending sound about right, but I wouldn't go with a 108 LSA myself, more like 110 or 112. This is just a personal preference; I prefer a more mellow idle and broader power. Lots of people won't agree :lol::lol:
If you want to get crazy, I can tell you how to fit a free flowing Edelbrock Victor Jr. single plane intake under your stock BB hood with EFI ;) The L36 intake will always be a bottleneck for you. The LS6 intake would work a little better, but low end throttle response will suffer. I wouldn't go there.
-Joe
[Modified by Flareside, 9:21 AM 2/8/2002]
Zwede's right, you need to address your exhaust first. Headers will really help with a larger cam and bigger valves in your stock heads. I wouldn't run a hydraulic myself in a weekend car. You give up power for maintenance, but is adjusting the valves a few times a year really an issue here? For me it isn't. The cams that 427TRI and mountainmotor are recommending sound about right, but I wouldn't go with a 108 LSA myself, more like 110 or 112. This is just a personal preference; I prefer a more mellow idle and broader power. Lots of people won't agree :lol::lol:
If you want to get crazy, I can tell you how to fit a free flowing Edelbrock Victor Jr. single plane intake under your stock BB hood with EFI ;) The L36 intake will always be a bottleneck for you. The LS6 intake would work a little better, but low end throttle response will suffer. I wouldn't go there.
-Joe
[Modified by Flareside, 9:21 AM 2/8/2002]
02-08-2002, 10:46 AM
#19
Race Director
Member Since: Apr 1999
Location: CORVETTE 77 385 C.I. TEXAS
Posts: 11,520
Likes: 0
Received 12 Likes
on
12 Posts
Re: Oval port vs square port BBC heads: (mountainmotor)
Joe
You must have missed all his previous topics on this. Not sure why he finally went w/ the Crane at 112.
by Mountainmotor
The XE-268 is 224/230 @ .050 & 110.
You must have missed all his previous topics on this. Not sure why he finally went w/ the Crane at 112.
Marky,
Your are stuck between a rock and a hard place with that manifold.I would have run a cam with 224-228@.050 intake .230-.235@.050 ex to get a little extra power.It would tend to hit a wall and shut down with the intake and exhaust being as it is but that can be overcome with proper shift points.I think you have a pretty good combo though and to make the kind of power you hear about from other Big Blocks a major rethinking off parts and money would be required.
427,
Doubt the 427 closed chamber pistons would run with out hitting the chamber of a 118cc head so the thought of slapping a set on the motor above never crossed my mind.
Your are stuck between a rock and a hard place with that manifold.I would have run a cam with 224-228@.050 intake .230-.235@.050 ex to get a little extra power.It would tend to hit a wall and shut down with the intake and exhaust being as it is but that can be overcome with proper shift points.I think you have a pretty good combo though and to make the kind of power you hear about from other Big Blocks a major rethinking off parts and money would be required.
427,
Doubt the 427 closed chamber pistons would run with out hitting the chamber of a 118cc head so the thought of slapping a set on the motor above never crossed my mind.
The XE-268 is 224/230 @ .050 & 110.
02-08-2002, 10:53 AM
#20
Safety Car
Re: Oval port vs square port BBC heads: (Ganey)
Joe
You must have missed all his previous topics on this. Not sure why he finally went w/ the Crane at 112.
Marky,
Your are stuck between a rock and a hard place with that manifold.I would have run a cam with 224-228@.050 intake .230-.235@.050 ex to get a little extra power.It would tend to hit a wall and shut down with the intake and exhaust being as it is but that can be overcome with proper shift points.I think you have a pretty good combo though and to make the kind of power you hear about from other Big Blocks a major rethinking off parts and money would be required.
427,
Doubt the 427 closed chamber pistons would run with out hitting the chamber of a 118cc head so the thought of slapping a set on the motor above never crossed my mind. by Mountainmotor
The XE-268 is 224/230 @ .050 & 110.
You must have missed all his previous topics on this. Not sure why he finally went w/ the Crane at 112.
Marky,
Your are stuck between a rock and a hard place with that manifold.I would have run a cam with 224-228@.050 intake .230-.235@.050 ex to get a little extra power.It would tend to hit a wall and shut down with the intake and exhaust being as it is but that can be overcome with proper shift points.I think you have a pretty good combo though and to make the kind of power you hear about from other Big Blocks a major rethinking off parts and money would be required.
427,
Doubt the 427 closed chamber pistons would run with out hitting the chamber of a 118cc head so the thought of slapping a set on the motor above never crossed my mind. by Mountainmotor
The XE-268 is 224/230 @ .050 & 110.