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455 Finishing Details

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Topic URL: http://psp.aquacomp.net/topic.asp?TOPIC_ID=1882
Printed on: 24 Apr 2014

Topic:


Topic author: Moss Man
Subject: 455 Finishing Details
Posted on: 24 Dec 2007 09:01:50 AM
Message:

Greetings fellow gearheads,

I have been assembling a drive train for a future A-Body build and I need to decide the final details.I am hoping to put the running gear in a 1970 Lemans(can't afford a GTO). Ultimately the drive train will end up in a Pontiac A-Body, it just depends on what becomes available to me. I am not opposed to other Pontiacs, it's just that the Currie rear-end I have is for an A-Body car.

The engine and tranny have 2000 miles on them post rebuild, we drove the car they were in and it made enough power that we bought it on the spot. Here is what I have so far:

1973 Pontiac 455
1976 6x- #4 code heads
068 Cam W/ Hydraulic Lifters
Edelbrock P65 Dual Quad Intake
Dual Edelbrock Carbs with 1" Phenolic Spacers
Factory Cast Iron Ram Air Exhaust Manifolds
Original Ignition Parts
Beefed up TH350
Currie 9" Rear End with 3.50:1 Gears Limited Slip

I have a Melling SPC-3 Cam that came with the motor, but I'm not sure if it would be worth putting in with all the "newer" more efficient grinds available.The previous owner stated around 10:1 compression and I do not know if the heads were milled or what he used for gaskets when he installed them.If he didn't mill them at all and used standard gaskets, I assume the chambers to be 91-92cc.

The car will be mostly for the street and stress relief, but I could see hitting the strip occasionally to see where the performance is at.I'm not really that concerned with gas mileage as it will not be a daily driver. Love the lumpy idle cams, but I'm more interested in making all the power I can while not having it be being so radical that it wouldn't be well mannered enough to drive in traffic to cruise in nights.

Questions:

The optimum cam?

Keep the factory exhaust manifolds or throw considerable money and time at headers?

The best exhaust to run; 2.5"? H-cross pipe or x-cross pipe? Which mufflers for a deep throaty sound and optimal flow at the same time?

Is an electric fan worth the hassle to increase horsepower? I have no fan set-up at present.

What to run for air filtration? I would like to have a cold air intake set-up even if it means fabricating one.

What to run for ignition parts; wires, plugs, coil, etc.? Change to electronic?

I know,lots of questions from a newbie member! I did scan 29 pages of threads looking for answers, but none seemed to cover my specific application.

Hello, my friends call me the "Moss Man".

Replies:


Reply author: mike mcarthur
Replied on: 24 Dec 2007 11:02:06 AM
Message:

Unless you really want the visual impact of the two fours, I would ditch them in favor of a good Q-jet on a stock, or performer intake. It will be more user friendly, and use less fuel. I would look at something like a Comp XE 262 or 268. You will likely get differing opinions on the cam. Everyone has a favorite that works for them. The manifolds you have should be fine for your use. Headers will of course be better, but they can be a hassle. I run an H pipe on my Goat with Dynomax super turbo mufflers and am very happy with the setup. I also still run the original points ignition on it. If you want electronic a good HEI is hard to beat. There are lots of aftermarket options as well, MSD being the best in my opinion. A good clutch fan will be fine unless you want an electric, I don't think you'll see a big HP difference by using one. Good luck on your project, and welcome to the board.


Reply author: Moss Man
Replied on: 24 Dec 2007 11:33:56 AM
Message:

quote:
Originally posted by mike mcarthur

Unless you really want the visual impact of the two fours, I would ditch them in favor of a good Q-jet on a stock, or performer intake. It will be more user friendly, and use less fuel. I would look at something like a Comp XE 262 or 268. You will likely get differing opinions on the cam. Everyone has a favorite that works for them. The manifolds you have should be fine for your use. Headers will of course be better, but they can be a hassle. I run an H pipe on my Goat with Dynomax super turbo mufflers and am very happy with the setup. I also still run the original points ignition on it. If you want electronic a good HEI is hard to beat. There are lots of aftermarket options as well, MSD being the best in my opinion. A good clutch fan will be fine unless you want an electric, I don't think you'll see a big HP difference by using one. Good luck on your project, and welcome to the board.



Thanx for welcoming me!

I have a stock HO cast iron intake off a 68 400cu in and I also have an Edelbrock Performer RPM 850 CFM. I could use those, but I bought the Dual Quad set-up because my friend has the Duals on his Goat and they perform best out of all the combinations he has tried. He had the stock Rochester in the beginning, upgraded to a tri-power and saw gains and then he went to the dual quads and saw even better performance. The quad set-up I have has the progressive linkage and it is said to work quite well considering the total cfm of 1000 is way more than the cfm formulas recommend. I'll try the quads and if I don't like them, I'll try the cast iron intake with the Edlebrock 850 RPM.

You mention the Comp XE 262 or 268 cams, would the XE 268 be that much different than the 068 Pontiac cam that is in there now?


Reply author: Cobrabill
Replied on: 24 Dec 2007 3:11:07 PM
Message:

Thanx for welcoming me!

I have a stock HO cast iron intake off a 68 400cu in and I also have an Edelbrock Performer RPM 850 CFM. I could use those, but I bought the Dual Quad set-up because my friend has the Duals on his Goat and they perform best out of all the combinations he has tried. He had the stock Rochester in the beginning, upgraded to a tri-power and saw gains and then he went to the dual quads and saw even better performance. The quad set-up I have has the progressive linkage and it is said to work quite well considering the total cfm of 1000 is way more than the cfm formulas recommend. I'll try the quads and if I don't like them, I'll try the cast iron intake with the Edlebrock 850 RPM.

You mention the Comp XE 262 or 268 cams, would the XE 268 be that much different than the 068 Pontiac cam that is in there now?
[/quote]


Hmmm,where to start...The HEI is a good idea.www.davessmallbodyheis.com
H-pipe is better than nothing but the X pipe is better.I second the clutch fan idea.But you need the shroud to make it(or any other fan)work.If the tripower ran faster than the Q-jet,then the Q-jet wasn't set-up correctly.If power is the goal.then i would choose a modern intake with a PROPERLY set-up quad over ANY of the choices mentioned including the dual quad.
Street Cobras came with dual quads.The Competition Cars came with single fours.That should tell you something.Also don't worry about CFM formulas.My 427 has a Braswell flowing just under 1000 CFM.And the car gets 17 MPG if i keep my foot out of it.
Air filter-as stuff as much "filter" under the hood as you can.With one exception-DO NOT USE the "Extreme lid".It actually hurts HP.It is the second greatest scam right behind Flowmasters.


Reply author: mike mcarthur
Replied on: 25 Dec 2007 01:29:51 AM
Message:

The 262 is probably closer to the 068, but it is an apples and oranges comparison. The modern stuff is way better than any of the older stuff even though the numbers may not seem to be. I am still trying to decide on the cam for my new engine for the Goat. It will be a 406, and I'm between the 262, and 268. I'm advised that the 268 is the biggest I can use with a stock converter for my application. It will be a little more rumpity rump than the 262, which I like, but still not sure yet. Ditto what CB said on the dual fours and the Tri-Power. I've tried a lot of carbs and nothing is better than a good Q-jet for this type of application.


Reply author: Moss Man
Replied on: 25 Dec 2007 10:38:14 AM
Message:

quote:
Originally posted by mike mcarthur

The 262 is probably closer to the 068, but it is an apples and oranges comparison. The modern stuff is way better than any of the older stuff even though the numbers may not seem to be. I am still trying to decide on the cam for my new engine for the Goat. It will be a 406, and I'm between the 262, and 268. I'm advised that the 268 is the biggest I can use with a stock converter for my application. It will be a little more rumpity rump than the 262, which I like, but still not sure yet. Ditto what CB said on the dual fours and the Tri-Power. I've tried a lot of carbs and nothing is better than a good Q-jet for this type of application.



When you say Q-jet, you mean the Rochester right? Which model Rochester would best fit this application and what cfm would it be?


Reply author: Artic TA
Replied on: 25 Dec 2007 10:52:45 AM
Message:

I really don't think the xe262 or xe268 cam is the best cam for a 455 with 10to1 compression, the cams is best on lower compression engines and I think you can get som problems with detonation. I am using the summit 2802 cam in my 461 9,5compression engine and it is strong from idle to a bit over 5000, it has a bit lumpy idle but not much, ok with vacuum assisted brakes. As I can se is the crower 60919 very popular on the 455 engine. If the idle is important maybe the crower 60916 is better.


Reply author: keith b
Replied on: 25 Dec 2007 9:17:54 PM
Message:

Moss,(my opinion) if i had a 455 neither the 262 or 268 would be in my choices,I have a low compression 400 with the 262 and it is a great cam for a 400 but i am also looking to UPGRADE to something a little more..... , its going to be tooo small for a 455,Dont know what, but not a 262/268 for a 455,in MY oppinion.


Reply author: mike mcarthur
Replied on: 25 Dec 2007 11:41:23 PM
Message:

Hopefully Mr. P will weigh in on this one. I would still go with the 268 on a 455 that is going to be mostly street driven. I would also get with Cliff on a Quadrajet. I've seen a few of the CVMS engines with the Comp XE series cams and they are monsters. Not that something else won't work, I just know what I've seen.


Reply author: Mr. P-Body
Replied on: 26 Dec 2007 08:41:44 AM
Message:


The 10:1 should be verified. At that ratio, XE262H would be good for a smooth idle, but anything larger than that COULD create a detonation situation. As Cliff has pointed out in the past, XE cams and higher compression ratios aren't necessarily a good "mix" unless one is running race gas. If your TRUE compression is under 10:1, XE268H would be a decent choice for a nice sound and broad power band.

The "better" Q-Jets are from mid-'73 to '80. Those are the 800 CFM versions. Cliff also knows how to extract the most from these carbs. The earlier Q-Jets aren't bad... Need some "tweeks".

Agreed, 2 4-bbls. shouldn't outperform either a nice Q-Jet or a well prepared TriPower in a street application.

Jim


Reply author: Moss Man
Replied on: 26 Dec 2007 12:31:07 PM
Message:

Honestly, I would like to verify the compression ratio, but have no way to contact the builder and even then his assesment might not be accurate.

I have read several articles on measuring compression ratios, but it seems like you have to tear the motor apart at least at some level.....right?


Reply author: Mr. P-Body
Replied on: 26 Dec 2007 12:47:32 PM
Message:

MM,

Yup. You gotta pull a head. One cannot "assess" compressoin ratio. This is one of those things where you MUST do "the leg work". That is, actually measure the chamber AND do the math. I would do it, even if I would need a new intake set and head gasket. Some things are better left to NOT guessing.

Jim


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