71 Cat w/ 400 Ci

[carmen1]

Hello,
looking for some advice. I recently acquired a 71 Catalina 4dr that I am making into a cruiser for the family, love the car, front end looks like it can split wood. I will not be racing the car, no nitrous, just want to have some throttle response. I want to keep the 400 block, not interested in making the displacement any bigger. What have others upgraded this motor with in order to squeeze out 400hp? I have tried to read everything I can "Jim Hands" book included. I need a list of parts so that I can get started, can someone provide this? Do I need forged pistons? Or is stock sufficient? Do I need a Performer Cam? Do I need Edelbrock heads or is stock port and polished sufficient? Do I need headers and if so what is best suited. This is a life long dream of mine to build a car, and I am going to make it happen. I am not a mechanic, but I am a quick learner. Just looking for some help. Any suggestions will be appreciated and thank you in advance for taking the time to review this post. As of this time I do not have any casting numbers, I know this important for specific upgrade parts, and I am sorry I am just trying to get a baseline to start with. Again Thank you.

[Larry]

The 400 is a great engine to build from mild to wild. It has lots of potential.

For what you are trying to do, it would make a great cruiser powerplant without spending an arm and a leg.

You need to define what you want to accomplish and then work around that. If you are not going to be doing any serious racing, stock parts is not a bad way to go, after all, they work well for many miles under normal-to-heavy use... Pontiac engines are STRONG!

For pistons, check stock prices, and if upgrading a bit isn't much more, it can't hurt. Just don't skimp on rings and if you are tearing down that far, buy good bearings and have all journals checked (turned if necessary). Plastigauge the bearings to be sure of any machine work done (I caught a huge error on one asssembly that would have made big problems down the road!).

A Comp Plus or Performer cam is good. Don't go overboard here though. Check for something that would put you in the so-called "3/4-race" category. Perhaps someone has some part numbers, I can't recall what I used. You want a good rumpty-bump but not thrown out of the seat. Don't forget new cam bearings-- that's where good oil pressure comes from in most engines.

Skip the big (enormous!) cost of aftermarket aluminum heads. That is only very serious racing stuff. Check our Head Casting Charts at http://www.pontiacregistry.com/members/online_magazine.php?view=1&article=305 in our On-Line Magazine to determine which heads you presently have. I'm guessing that since you have a 4-door family-type car it is the small valve low compression head. If you have a 2-bbl. that is more certain. Check the charts and see which 400 might have larger valves, but perhaps keep the cc larger to avoid fuel problems from too high of compresion. At least you would get better breathing from the larger valves.

Edelbrock has some good aluminum manifolds, but one is not considered good at low end (where you will spend most of your time). I apologize, but it has been so long since I built using one of their manifolds, I forget which is recommended for the lower end. There is also a stock cast iron manifold that is touted as being as good as any aftermarket hi-rise (I have one somewhere in the top of the garage!). If you want simplicity, I would go with a Holley 600-780 size carb. You don't need more than that.

For headers, I would be surprised to learn that Hooker, Castler, etc. or any other make any for the full-size Pontiacs of that vintage. I hope I am wrong. But, any major supplier's would be good for what you want. I would just concentrate on wall thickness for longevity. Don't reduce down less that 2" either. 2-1/2" is good too for an even deeper rumble... just so it doesn't sound like a school bus!

Going a little further, I would guess your full-size car has pretty high ratio gears in the back. That's not bad for today's gas prices. But if you want to do some tire smoking now and then, get rid of the large torque converter that you most likely have and go with at least a 2800 stall. For your cruisin' needs that should give a lot more zip off the line without having to constantly "pump" the gas pedal when driving through downtown.

I apologize for not having all the numbers you need right now. I can come up with some with a little digging. But I hope some others will be able to fill in some of the gaps. The main point I am trying to make is that the 400 should make a great, strong powerplant with lots of stock and non-exotic parts.

Keep us posted on your project.

[super]

I would definitely steer away from the Edelbrock heads in your particular application. The Edelbrock heads will give you great performance, but it will be expensive in your application. The Edelbrock head is designed for round port exhaust. There may be a source for headers, but I bet they are extremely expensive. If a guy is willing to spend the money $$$$$$$ though on custom headers and Edelbrock heads, it would help you in achieving the 400 horsepower you are wanting.

There are some D-port Pontiac heads that would work good in your application.

Making your Pontiac breathe is going to be a good start to get you in the neighborhood of 400 horsepower. Camshaft, lifters, intake, carb, exhaust manifolds and exhaust system are all important.

A set of Ram Air III exhaust manifolds would probably work good for your application. Run a good dual exhaust system with 2 1/4" to 2 1/2" diameter. A guy does not need to over do it with 3". Try non-restrictive muffler such as a 2-chamber Flowmaster or a Full Boar Muffler.

I could probably give you a good camshaft, etc. that would work good if you want the suggestions.

[Larry]

From 1970 to 1971 the 400 cu in horsepower for the standard Grand Prix and GTO dropped from 350hp to 300hp, and that was primarily due to a drop in compression from beginning EPA and fuel mileage standards.

If you went with the higher compression heads, you might need to burn at least a mid-range fuel and keep the spark a little below maximum, but I doubt it would be pinging all the time.

If you mimmicked the 400 from '70 (heads-wise) you would be very close to the 400hp you want (i.e. 350). With a slightly bigger cam, good headers (like RAIIIs that Super recommends), a high-rise and Holley, you'd sure be tickling that 400 mark. With a 2800 stall converter people would think you were over it!

[carmen1]

Thank You, Thank You, Thank you
This is just what I was looking for. As far as the cam, I am interested in knowing which one? Also I checked Jegs and Summit and I see torque converters with 2400 to 3000 stall, some are just 3000. should I stay above 2800 or should I be looking for a specific 2800 stall coverter? I will check the chart for the heads, I like that idea. It is a 2bbl, so I will look into the Pontiac intakes, thank you for the suggestion. I am currently checking for the ram air III headers, any suggestions where to get them, found a set on ebaymotors? Also when I find heads, should i be looking for higher compression or lower compression, I always screw that up? And should I have them port and polished? I appologize for rambling on, I am very excited to get this project started. I appreciate all the suggestions, and I am open to any more you may have. Thank you again and I will post a pic as soon as I can.

[super]

Ram Air III manifolds are offered by Ram Air Enterprises. This company has the manifolds available for $329. They are also one of this websites featured suppliers. You should get a discount from them. I would verify through the company that the manifolds do not have any clearance problems, etc.

I recently helped install a set of these manifolds on a friends 1979 Grand Prix. It was originally a 301 automatic car. It has now been converted to a 455 4-speed. Ben wanted to run the manifolds as opposed to headers. He ran the RAR manifolds with no gaskets. They sealed good with no leaks.

I would recommend a dual plane intake if you decide to run an aftermarket unit. Most of the early Pontiac 4bbl intakes work very well too. A guy has several options here. I have actually had good results with factory Pontiac pieces. A good early casting 4bbl. intake with a Rochester carb can yield good performance and streetability. There is nothing wrong with Larry's suggestion either. An Edelbrock dual plane intake with a Holley carb can give you good results too. I like the throttle response from the Holley carb. I have ran a Holley carb on my Pontiac for years now. Very responsive!!

What heads are on your engine??

[super]

One of my Pontiacs I ran a factory intake and 800cfm Rochester and also tried a 850 Demon carb with Edelbrock single plane intake. It ran almost identical times in the 1/4-mile from the factory pieces compared to aftermarket pieces.

Some of your decision may be based off of availability.

[Larry]

If you're looking at RAIII heads as per 1969, those are nice, but you're in the 10.75:1 compression ratio area and may have fuel problems with todays ethanol and such. They have nice big valves too for good breathing. If you go to the lower compression to avoid pinging problems, then you loose the big valves. Answer... some go to the later 455 heads and get the big valves with the lower 8.2:1 compression range (no fuel problems) range. Check our chart and see the larger c.c. shown with the 455 heads. Less c.c. = higher compression.

As for porting and polishing your heads, don't waste your time and money for the cruising application you want. It's kind of like the guy who spends a fortune on his stereo speakers and than blares his music while everyone is talking and drinking beer... who can tell. Porting and polishing is for splitting ET hairs at the track for the all out racer.

The drop in horsepower going with the lower compression heads can be compensated for somewhat by cam. Find out what your present cam lift is and only increase a bit. Most of the 400 GTO engines (high and low compression) are in the 0.41 lift area. However, the valve overlap (intake and exhaust duration)is where you will get the rumpty-bump from.

The real difference can be see in the '70 GTO standard 400 of 350hp having a 54-degree overlap, then the RA 400 of 366hp with a 63-degree overlap, and finally the RAIV 400 of 370hp with 87-degrees. Gitty-Up!

Try shopping for a cam with the 0.41 area lift specs and a valve overlap somewhere between the RA and RAVI. I bet you would be happy and still have a tame street car.

Be sure to address the exhaust exit situation well also. The more overlap the more exhaust scavenging needed. Also be aware, the larger the overlap, the higher the power moves up the power range. Don't go crazy here or you will not have good street (lower rpm) power. Super's advise on the RAIII exhaust mainfolds sounds good. Call Ram Air Enterprises and ask them questions too. Remember, our members get a discount there. Check them under "AFFILIATES" then "Member Discounts".

For the stall converter, I went with a 2800rpm in my '69 Lemans wagon and it made all the difference inthe world. I can't seee going up to 3000 as much of a difference. My 2800 is very streetable.

Hope all this info doesn't get you talking to yourself!

Ask any questions... especially before buying and we will chime in.

[carmen1]

Again,
Thank you for the great information! I am getting my ducks in row now and I am checking the affiliates for my purchases. Need to get the budget together before I right any checks. I do have one last question, If you guys don't mind. I live in southern New Jersey, near Philadelphia. Does anyone know of a reputible machine shop in this area to have the engine work done? If not, not a problem I will do my research there. But what should I be spending for the machine work. I know this is a very broad question due to the fact that you cannot see the motor. I guess my question is what should be the ballpark for a motor that has no major issues? Once I get the patio set my wife just bought out of the garage I will be able to get a pic of the "The Beast" as my collegues have named her and will get it posted. Again guys, I do appreciate it, After all god forbid if you walk into a speed shop and not know every term, you would think that some of these guys were born mechanics. Everyone has to start somewhere right?

[carmen1]

Holley Carb, Q-Jet? or something Else?
Thank you.

[Larry]

Mostly a matter of personal preference.

The Q-jet will give you some smaller primaries for some better mileage, but I find them pretty complicated if you go to rebuild... lots of needles and little balls and stuff. But not insurmountable, even if all thumbs.

Now the Holley is simplicity to the max. I have rebuilt them right on the car in the past. Plus there are power valves available for quick, easy changes. And, if you have a small drill bit you can do your own jetting! Just don't get carried away. Oh, and with a small screw and nut-- presto, you have mechanical linkage for your secondaries. Just don't expect the greatest mileage from a good size Holley though.

[super]

The Holley carbs are very simply to work on. As Larry stated, the Q-jet is a little more complicated.

A well tuned Q-jet will give you decent mileage and they are very friendly to use on the street. I have ran a 750 holley for years and have had no problems.

Mileage is not a concern for my street car, as it gets around 3mpg when I am not in the throttle. I run the 750 on this car.

If you run a stock cast iron intake, you will probably want to run the Q-jet. An aftermarket intake will generally be set up for aftermarket carbs. Some will have dual patterns.

[carmen1]

Thanks Gentlemen,
I have furthered my research and I am speaking to a couple of guys who have cylinder heads. I like the simplicity of going with an aftermarket intake (ie: Edelbrock) with the Holley Carb. I will be contacting Holley today to see what they say. I also was given a reccomendation for a machine shop where I live so I will be reaching out to them in the very near future to get the ball rolling. Just need to nail down a cam and check the price difference between cast and forged pistons and I think I will have this project moving off the ground. Thank you again, between your input and the books I have this stuff is now making a whole lot more sense. I went from being confused and building a top fuel dragster to what I really wanted, a cruiser to get burgers in. Thanks again guys, and believe me I will be asking more questions

[carmen1]

Hello,
contacted Holley today, they are reccomending a 670 Street Avenger for my application. Does anyone know anything about this carb? Thanks for the info.

[super]

I have never owned a street avenger carb. I was going to install a used one on my 1979 chevy truck. One of my friends has one and offered it to me. My '79 truck is powered by a 1973 400 Pontiac engine.

The street avenger carb should work well on the street. I know they have an electric choke and I believe they have vac. secondaries. When I looked at Billy's carb a while back, it also had clear site plugs. That is handy for adjusting your float levels properly.

You stated you were going to run 670cfm. That is probably a very good choice considering you are running 400 cubes. That is actually the same size carb my friend has that I am going to try on my 400.

The aftermarket intake and carb will probably be a good choice. Readily available and they are new. You will like the responsiveness of the Holley. Nice and crisp!!

Let me know if you want a camshaft suggestion.