Cam and intake choice...looking for suggestions...

[TommyShameless1978]

I have a 78 440 out of a motorhome. It has the 452 heads. It has right at 20k on the clock. I am putting it in my 68 Roadrunner clone, with a 727 and a 3.23 sure-grip. I will be using headers with small primary tubes (like a Hooker Comp or something similar). I have a 750 vacuum secondary Holley.

I want stump pulling torque with absolute minimal expense. I was thinking of an RV grind cam and an Edelbrock Performer 440 manifold. Will these even be necessary? I do have the stock cast iron intake. It's ugly as sin, but is it any good? How much will I gain by going with the Performer 440, besides a weight reduction? As for the cam, would the stock one be fine? I mean, this came OUT of an RV, so wouldn't it already be an RV type grind? Or am I just delusional? I think I remember reading somewhere that these things were set up from the factory with the cam not straight up, or something like that. Something about the timing set not being machined straight up, and installing an aftermarket set took care of that. Does that sound familiar? What could be gained by using the stock cam and just advancing it?

I know the compression in this thing is total nonsense. That's something for much later down the road. For now, I just want to have a bunch of fun on the way to school and work and band practice. Maybe I'll just build something absurd in a few years, but for now, I'd like to see what this thing can do with minimal expense. I won't be racing it at all, I just want it to hit me real hard when I hit the gas. Lots of torque is all I care about!

Tommy

 

[1badgtx]

Tommy you are on the right course...A mopar performance purple camshaft is what you can use...I have a 509 lift in my 440...You should get rid of the stock smog heads..The stock heads have really small valves and will not let the engine breath the way it should......Edelbrock performer heads and the intake you are refering too is a good combo...It,s really hard to get alot of power and torque out of a 250 hp smog engine...You,ll also have to remember that the crank in the motor is a cast crankshaft..So it will not handle the rpms like the non smog forged crankshafts...
Lots of luck!!!!
Petty Blue 67 GTX

 

[TommyShameless1978]

I do want to avoid changing out the heads for the time being. I'm really curious about what can be done with what I've got right now. Cam and intake, I don't mind doing at all, if they are necessary. Once I start getting into changing the heads or swapping out the pistons, I know how I can be, and I'll have thousands and thousands of dollars into just the engine alone before I ever get this thing running. I see lots of guys fall into that trap (mostly Mopar and Ford guys...Chevy guys seem to be doing this **** for free somehow). Right now, I want to see what this thing can do, drive it around for a year, get to know the car, and THEN come to whatever conclusions I may. I'll be going from a 98 Ranger with a V6, to this thing, so chances are pretty good even a 250 horse smog big block will impress me! :toothy5:

 

[07charger67]

Just remember, just because they can do it cheap doesn't mean its right "chevy" ha-ha. I think I was planting a garden last week and tilled up a 350 complete engine ha-ha.

 

[1badgtx]

Tommy,
Then stick to the intake,headers...Another way to add a little power is your ignition...Points in a distributor is in the past...An msd setup will also help you with better spark...Check out your local craigs list or even ebay for deals on mopar parts!!!!Hell I built my 67 GTx off of ebay a few years back...I also sold alot of good stuff too!!!
Petty Blue 67 GTX

 

[rumblefish360]

I would use the Performer not for the weight loss, but for a few extra HP that it is better over a stock iron intake. The 750 is big considering the low power nature of the engine. I have a '78 - 400 that is in the same boat. But since your 40 cubes greater and mostly in arm swing, you'll do better.

The Road Runner cam is about as big as I would go. Milling the heads for "Some" compresion would help. Huges engines has an interesting cam for this delima. The cam you have is NOT a RV grind because the engine came from an RV. It is more likely a 260/268 @ mid 400 lifts at best. Generally speaking, IIRC, they had only 2 cams for the big blocks in the closeing years, the one I mention, being the biggest unless they used the R/R cam. (I don't think so, but I could be wrong.)

Also, if you could rid yourself of any parrasidic loss, that would be great. No A/C, loose the belt and compresor, etc....

Oh, also forgot, I have used Rhoades lifters in the passed for a slightly big cam. They take about 8 - 10 degrees out of the cam and will return it around 3000 rpm's.

With those lifters, you could install a R/R cam or slightly larger unit and get away with the stock stall and gear easy while increasing torque on the low end.

 

[TommyShameless1978]

I just noticed I wrote "can" instead of "cam" in the title. This is what happens when you do this at 3am.

I'm digging the Road Runner cam idea...which one is that and where do I get it? Is that a factory Mopar piece?

I could, of course, leave the cam it has in it now and see what it will do. Hell, I may think it's just fine!

I was initially concerned that the carb was too big as well, considering it is on the mild end, big cubes notwithstanding. I have read in many places that a vacuum secondary carb is much more forgiving when it comes to overcarbing, and the next size down is the 1850 Holley, which is 600cfm. That seems like I'd be starving it, so I don't want to go that route.

Talked to a guy a few hours ago here in town that had the exact same engine, even down to the year, and he put it in a 68 Coronet. He said all he did was headers, carb, and a Torker intake, and it was all kinds of fun with plenty of pulling power. He personally assured me I'm gonna love it, and if I do go up a step in the cam, it will be even more fun. I was surprised when he mentioned the Torker. I would think that runs counter to everything I've ever been taught. Dual plane for bottom end, single plane for top end Performer RPM if you want to try to split the difference. I asked him about that and he said it would take an act of god to kill the low end torque on this thing, and to just bolt a Torker on there and go to town. He even said he may have one laying around I can use. What do you guys think of that? Awesome dude, too, by the way. It's nice to meet people like that right here in town!

Tommy

 

[Meep-Meep]

The Road Runner cam will want a bit more compression to run well. What I recommend is using a cam that is specific to a low CR engine because you have something like 8:1 - if you're lucky. STD Edelbrock performer grind or similar. The 452 heads will work fine as is and the stock TQ intake probably will be fine as well. You want to boost cylinder pressure up to about 160 PSI cranking. It will run great on regular 87 R+M/2 gas and probably go flat at 450-5000 RPM, but it will satisfy your realistic goals for a good driver. 1-7/8" headers with 2.5" exhaust will be an asset as well.

The term "RV cam" I believe is generic for an aftermarket mild cam that boosts performance on late model bone stock smogger engines. A general pick-me-up for RV's, trucks and behemoth mid 70's cars.

Before you pull it apart do a compression check to get a base line. I'm thinking you will have 140-150 PSI as is.

 

[Meep-Meep]

I just noticed I wrote "can" instead of "cam" in the title. This is what happens when you do this at 3am.

I'm digging the Road Runner cam idea...which one is that and where do I get it? Is that a factory Mopar piece?

I could, of course, leave the cam it has in it now and see what it will do. Hell, I may think it's just fine!

I was initially concerned that the carb was too big as well, considering it is on the mild end, big cubes notwithstanding. I have read in many places that a vacuum secondary carb is much more forgiving when it comes to overcarbing, and the next size down is the 1850 Holley, which is 600cfm. That seems like I'd be starving it, so I don't want to go that route.

Talked to a guy a few hours ago here in town that had the exact same engine, even down to the year, and he put it in a 68 Coronet. He said all he did was headers, carb, and a Torker intake, and it was all kinds of fun with plenty of pulling power. He personally assured me I'm gonna love it, and if I do go up a step in the cam, it will be even more fun. I was surprised when he mentioned the Torker. I would think that runs counter to everything I've ever been taught. Dual plane for bottom end, single plane for top end Performer RPM if you want to try to split the difference. I asked him about that and he said it would take an act of god to kill the low end torque on this thing, and to just bolt a Torker on there and go to town. He even said he may have one laying around I can use. What do you guys think of that? Awesome dude, too, by the way. It's nice to meet people like that right here in town!

Tommy

I had a Torker on a bone stock 289 Ford and it ran great. The key to noticeable power is not killing your cylinder pressure with too much cam and not enough CR! This is very important!

 

[TommyShameless1978]

Hey Meep Meep, I already had to pull the heads off. It rained on the way home, the kind of torrential rain we get here in Southwest Florida. Enough to get some water in the heads. I pulled them off the second I got home, of course. I was pleased by how clean and tight the cylinders were. This thing is like a brand new engine inside.

You're probably right about what the cylinder pressure was/is. How do you suggest boosting it? Cam selection? Cam timing?

 

[TommyShameless1978]

I just did a little reading...seems that I can boost cylinder pressure by running a cam with a tighter lobe separation angle. This will increase the maximum torque, and move it down lower. However, it also narrows the power band, and has a negative effect on vacuum (I'll be running power brakes). Hmmmm...

Maybe I should just install the damn thing with the cam it's got in it and go from there?

I am also still very curious about advancing the cam a touch. Even the stock cam. Anyone want to weigh in on that? Think I should try it? Has anyone toyed around with cam timing on a smog-era big block with the stock cam? I know I could just do it, and then undo it if it sucks, but I figured it can't hurt to hear from someone who has already.

Tommy

 

[69 Runner]

SMOG HEADS HAVE SMALL VALVES???

Don't even believe that. A 452 is almost as good as a 906. Actually a tad better on the exhaust side due to more short side radius. They also have the exact same size valves as a 906.

 

[YY1]

Also, don't sell 250 net HP too short. That's what my 2000 Dak R/T 5.9 has and with the 3:91 SG rear, it will smoke the 255/55/17 stickies until I let off the throttle, and knock you back in the seat from 55 to when ever I decide to let off.

Doesn't have the best 1/4 mile times, but not bad for a full frame extended cab truck.

...and on 87 octane.

I have another motor/trans just like it for my 74 Charger. Might do a little better in that

Dusrer, anyone???

With a cam, exhaust and tuning, etc, you should be able to push 300-325 with a modest amount of expendature and labor.

 

[2quick]

Comp cams has a great new line of cams, the extreme energy. Very fast ramp design and tight lobe separation great street cam good vacuum. get something with a advertised duration around 270 deg and no more than .500 lift. Port the heads yourself with the MP template kit, 1 7/8 headers, and use the 750 carb you have. should make decent power. If your real tight on money gasket match the stock intake and run it for awhile till you get some extra cash to buy something else. I recommend the performer RPM but the performer will work too.

 

[q-ship]

Tommy: Your initial plan sounds like a good one.

As for the late BB cams, yes they were ground 4 degrees retarded for emissions reasons, and compression was dropped substantially for the same reason.

Because the cam was ground with the modified timing, just replacing the timing chain/gear set won't change the cam-installed centerline.

As a teenager, we used to advance the cam gear 1 tooth as a no cost, "hack" method of substantially increasing overall performance of the 70's engines. --- Don't try this as your stock nylon coated cam gear definitely needs to be replaced as it will fail on you for sure due to the brittleness of the nylon after so many years, regardless of mileage, and a new gear/chain set will not have any "stretch" in it yet, and installing it one tooth advanced will over advance the cam.

A new timing chain/gear set (which is a required item no matter what you decide to do) with a 4 degree cam advance bushing installed would help performance, but would be a major mistake in my opinion as now would be the time to install a cam designed for the low compression since the engine is out of the car, and will be the most substantial improvement you can make.

Your 452 heads are the best stock head ever made for street performance and will out perform any of the others from a low RPM torque standpoint, plus they have hardened exhaust seats. Don't be swayed by opinion, magazine articles, flow bench tests, etc; They work better for what you are looking for than even the aluminum aftermarket heads. They are called "smog heads", but have nothing to do with emissions, they were designed for maximum torque on the low compression engines ... It would have been far cheaper to just install hardened exhaust seats into the already existing 906 castings, but the factory went the extra mile and redesigned the ports to improve performance in the exact situation that your O.P. is requesting info on.

If you can get an Edelbrock performer for reasonable, use it, otherwise the stock manifold is a better choice than any other. Don't use a single plain or RPM type manifold as they will be counter productive to your goals. The bigger the ports, the worse for velocity and turbulence which provide the ultra low RPM torque (punch) your looking for, and fuel mileage.

If your engine has the stock Thermoquad on it, and it's in good condition, use it. Otherwise I'm sure your Holly will be just fine -- keep in mind the stock TQ is rated at 850 cfm, and works amazingly well with its small, 2 stage primaries.

The cam is the key to your goals. Improvement in this area can be worth maybe 40 to 60 horsepower, and a similar improvement in torque. However it is the single thing that can hurt you the most.

Comp, Hughes, Lunati, and others make cams designed to increase cylinder pressure, but they are also designed to provide a lumpy idle. Though I like the lumpy idle as much as anyone, it is too much of a sacrifice for your stated goals and engine. They also have a narrow powerband, with poor vacuum at idle.

The "fast ramp" cams are great, but require heavier valve springs (additional cost, and much more potential for a flat cam), and are a compromise between higher RPM, and ultra low RPM power, and will only work "best" with a higher stall converter (another couple of hundred bucks at minimum).

The problem with the "old school" (standard) ramps and profiles is that they were either designed for RPM performance, or towing. Most of the "old school" cams that were designed for your goals have been discontinued decades ago, as there just isn't any demand for cams for stock low compression engines with stock springs anymore.

Lunati and Isky still have some good (old school) profiles, but they aren't catalog offerings. You will have to call them to see what the have for your requirements. Comp also has some "old school" profiles, but from my experience, they will spend more time arguing with you than helping you.

You will need to change out your valve seals, as well as your timing chain/gear set. Since you need to disassemble the valves to change out the seals, you should "lap" all the valves to make sure you have a good valve/seat seal. If your nylon cam gear is missing chunks, you will need to drop the oil pan and at minimum clean out all the pieces of nylon from the oil pick-up.

If you didn't damage the stock steel head gaskets when you took off the heads (and you know which way the gaskets/heads went on), you can clean them with steel wool and re-use them (spray them with either aluminum spray paint, or copper seal before installation). New valve cover gaskets will be necessary, and I would highly recommend a baffled oil pan (402 style), and a windage tray if the engine doesn't have them.

These are the minimum parts from a cost/performance standpoint that I would suggest.

If you take the time now to do it right, you will be more than pleased with the results as you can achieve world beating street performance from a stoplight/through an intersection, while maintaining 18 MPG on mid grade fuel, while producing startling punch in a street environment. Deviate from your goals and you will be unhappy (as far as your stated goals go).

 

[rumblefish360]

G-ship, great post! 4 stars!

 

[TommyShameless1978]

Tommy: Your initial plan sounds like a good one.

As for the late BB cams, yes they were ground 4 degrees retarded for emissions reasons, and compression was dropped substantially for the same reason.

Because the cam was ground with the modified timing, just replacing the timing chain/gear set won't change the cam-installed centerline.

As a teenager, we used to advance the cam gear 1 tooth as a no cost, "hack" method of substantially increasing overall performance of the 70's engines. --- Don't try this as your stock nylon coated cam gear definitely needs to be replaced as it will fail on you for sure due to the brittleness of the nylon after so many years, regardless of mileage, and a new gear/chain set will not have any "stretch" in it yet, and installing it one tooth advanced will over advance the cam.

A new timing chain/gear set (which is a required item no matter what you decide to do) with a 4 degree cam advance bushing installed would help performance, but would be a major mistake in my opinion as now would be the time to install a cam designed for the low compression since the engine is out of the car, and will be the most substantial improvement you can make.

Your 452 heads are the best stock head ever made for street performance and will out perform any of the others from a low RPM torque standpoint, plus they have hardened exhaust seats. Don't be swayed by opinion, magazine articles, flow bench tests, etc; They work better for what you are looking for than even the aluminum aftermarket heads. They are called "smog heads", but have nothing to do with emissions, they were designed for maximum torque on the low compression engines ... It would have been far cheaper to just install hardened exhaust seats into the already existing 906 castings, but the factory went the extra mile and redesigned the ports to improve performance in the exact situation that your O.P. is requesting info on.

If you can get an Edelbrock performer for reasonable, use it, otherwise the stock manifold is a better choice than any other. Don't use a single plain or RPM type manifold as they will be counter productive to your goals. The bigger the ports, the worse for velocity and turbulence which provide the ultra low RPM torque (punch) your looking for, and fuel mileage.

If your engine has the stock Thermoquad on it, and it's in good condition, use it. Otherwise I'm sure your Holly will be just fine -- keep in mind the stock TQ is rated at 850 cfm, and works amazingly well with its small, 2 stage primaries.

The cam is the key to your goals. Improvement in this area can be worth maybe 40 to 60 horsepower, and a similar improvement in torque. However it is the single thing that can hurt you the most.

Comp, Hughes, Lunati, and others make cams designed to increase cylinder pressure, but they are also designed to provide a lumpy idle. Though I like the lumpy idle as much as anyone, it is too much of a sacrifice for your stated goals and engine. They also have a narrow powerband, with poor vacuum at idle.

The "fast ramp" cams are great, but require heavier valve springs (additional cost, and much more potential for a flat cam), and are a compromise between higher RPM, and ultra low RPM power, and will only work "best" with a higher stall converter (another couple of hundred bucks at minimum).

The problem with the "old school" (standard) ramps and profiles is that they were either designed for RPM performance, or towing. Most of the "old school" cams that were designed for your goals have been discontinued decades ago, as there just isn't any demand for cams for stock low compression engines with stock springs anymore.

Lunati and Isky still have some good (old school) profiles, but they aren't catalog offerings. You will have to call them to see what the have for your requirements. Comp also has some "old school" profiles, but from my experience, they will spend more time arguing with you than helping you.

You will need to change out your valve seals, as well as your timing chain/gear set. Since you need to disassemble the valves to change out the seals, you should "lap" all the valves to make sure you have a good valve/seat seal. If your nylon cam gear is missing chunks, you will need to drop the oil pan and at minimum clean out all the pieces of nylon from the oil pick-up.

If you didn't damage the stock steel head gaskets when you took off the heads (and you know which way the gaskets/heads went on), you can clean them with steel wool and re-use them (spray them with either aluminum spray paint, or copper seal before installation). New valve cover gaskets will be necessary, and I would highly recommend a baffled oil pan (402 style), and a windage tray if the engine doesn't have them.

These are the minimum parts from a cost/performance standpoint that I would suggest.

If you take the time now to do it right, you will be more than pleased with the results as you can achieve world beating street performance from a stoplight/through an intersection, while maintaining 18 MPG on mid grade fuel, while producing startling punch in a street environment. Deviate from your goals and you will be unhappy (as far as your stated goals go).

Wow! Thank you so much!!! You are so right about Comp Cams...I asked them for their cam suggestion, and told them what I was willing to do and what I was unwilling to do. They recommended a cam that seemed way too big and required special machining on my heads. Thanks for nothing, Comp Cams.

I will call Lunati and Isky personally, and get suggestions from both of them. Hopefully, they are both similar.

 

[Meep-Meep]

Hey Meep Meep, I already had to pull the heads off. It rained on the way home, the kind of torrential rain we get here in Southwest Florida. Enough to get some water in the heads. I pulled them off the second I got home, of course. I was pleased by how clean and tight the cylinders were. This thing is like a brand new engine inside.

You're probably right about what the cylinder pressure was/is. How do you suggest boosting it? Cam selection? Cam timing?

Yes, cam selection will affect cylinder pressure. As an example, I had a 72 Porsche 911 T and those came stock with 7.5:1 CR. When I put a compression gauge on it it blew 150 PSI. I rebuilt the engine and had Wiseco make some custom 8.0:1 pistons for it and with the same cams my cranking pressure went to about 160 PSI. The car was responsive and fast even with 7.5:1 CR!

Since the heads are off measure how far in the hole your piston is then do some calculations to get your chamber volume and cylinder volume. From there you can figure CR.

Since you don't plan to change pistons your octane requirement is already decided and the low CR decides your cam. Make sure whoever you talk to about cams knows your CR. The single most important valve timing event is when the intake valve closes and not how much lift you have. This is when you start building cylinder pressure and cam grinders know this.

Don't let anyone talk you into to much cam! The goal is to build the most usable power for what you want to do with the car. Broad driving conditions will be better with taller gears and a cam that has a longer lobe center. 112-114 will tend to spread the torque over a broader RPM range as opposed to tightening it up and putting it up high like a 108 LC. My own 440 in my 66 Belvedere has an honest 10.1:1 CR and I'm running a .455" / 272 MoPar cam on a 112 LC. I'm blowing 190 PSI of cylinder pressure and as a result I can't run it hard on pump gas. However, this last weekend that 3700 lb as raced car went 109 MPH in the 1/4 with street tires and 3.55 gears and without exotic engine parts.

 

[rumblefish360]

Yet another excellent post and advice. Keep up the good work!

The problem I have found with low compresion engines is there octane requirements can still be high. In an example of my '78 - 400 may run on 87 octane, but when the summer heat is on, the engine like 89 alittle better. Everything is set to spec.

Poor performance qualities exsist in the engine considering the year and what tests it had to pass. This in itself is a problem.

Know this, it is a tired engine of 1/2 a million miles on it. I know this is haveing a impact on things. While I'd love to change a cam myself, The engine will be rebuilt first before doing just a cam swap.

 

[q-ship]

"I'm blowing 190 PSI of cylinder pressure and as a result I can't run it hard on pump gas."

I'm amazed that it is even drivable on pump gas. Your cam specs will only increase cylinder pressure as RPM increases.

The big problem with high cylinder pressure on non race gas is that you have to limit timing, otherwise pre-ignition dramatically reduces power, but then again so does reduced timing.

A street engine needs a good balance of stable cylinder pressure. In my experience, the biggest mistakes made by most people is to much compression, and/or to big a cam. I learned this the hard way over several decades.

This limits the satisfying and fun, bottom end punch (off idle through about 4,500 RPM), that a street car needs. Granted, this will not equal blistering 1/4 mile times, but the street engine will win everytime in a stoplight through intersection type contest.

It's a rare occurrence that a "street" car built for best 1/4 mile times will perform well on the street. The loose converters, RPM dependant power, slicks, etc. just don't couple well to municipal asphalt. They will "train length" a true street car at higher speeds/RPM, but if the (properly built) true street car has quit racing while the race car is still 2 lengths back, you get the fun of ignoring their protests of whatever excuse they have.

The most fun you can have for cheap in my opinion.

I live in a hot, low humidity climate, and after decades of experimentation, I find that about 160 PSI cylinder pressure is all I can achieve with iron heads without sacrificing off idle performance. I try to shoot for just over 150 PSI for a safety margin (91 octane).

This allows you to achieve max timing advance (about 37 degrees mechanical) without getting into pre-ignition, yet allows max vacuum advance for great fuel millage.

I can't tell you how many cars get 9 MPG nowdays while providing unacceptable (in my opinion) street performance. Stock 440's from the 60's could get 16 MPG on the highway. With the proper cam (cylinder pressure/compression) balance, you can easily get 18 or 19 highway nowdays while being able to embarrass the hemi car through the intersection, with a 9.0-1 motor.

Sorry to the OP for getting this off topic.

As a note to Tommy, since you plan on running headers (excellent idea), take the time while your heads are off to set/lean them so that the exhaust ports are level, and spray the studs with PB blaster, or some other rust penatrant, as you will need to remove the studs in order to use headers. Trying to do this on the car is a nightmare, and a broken stud requires a trip to the machine shop with the head.

Let the studs soak for a day or so, then you should be able to remove them with a couple of nuts.

Also, I think (99% sure) I have an old, unused Mopar Performance or Direct Connection cam designed just for what you are wanting. I'll give it to you for free if you are willing to wait till the weekend so I can dig it out (you will have to pay for shipping though).

I used one in a 68 truck I had that I put a 77 440 engine in. It made such a power and mileage difference that I bought another one for some future engine project in my 69 Chrysler 300 vert. Years later I learned that it would increase cylinder pressure too much in my 69 engine (I didn't know the the cylinder pressure/compression ratio balance in my younger days), so it never got used.

Let me know if you want it - I don't remember the specs, I'll have to dig it out to see what they are, but it sure worked wonders for my truck.