Too big of cam?

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mitch67

mitch67

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I have a 67 Valiant, 225 aluminum block slant six, Holley single barrel, 904, 83/4. I bought it from an older guy near me that owned it for years and years. He did a lot of work to it but kept it pretty mild although he did install a bigger cam so it idles pretty rough. It runs fine when going down the road but at lights it stumbles and bumbles like it's going to die, but doesn't. I have the end of the box that the cam came in and the specs are on it, they say...

Delta Camshaft Inc, 270, Perf. 264 S Mech. Grind.
Duration Deg (Int 264) (exh 264) ~
Valve lift (Int .440) (Exh .440) ~
Valve Lash (Int .010) (Exh .012)

None of this means much to me but I was wondering if it is too big to run well or is there anything I can add on to make it run smoother, maybe a super six set up? A local carburetor mechanic said it won't help to add a 2 bbl because you can only get so much out of a six cyl (whatever that means).
I love this car and plan on continuing to drive it every day BUT would love to have more 'get up and go', it's not fast at all and rufuses to spin the tires unless it's pouring down rain! I'm a kid and want to show off every once in awhile when one of those Honda jerk offs are next to me revving their engine. I don't have a ton of money and would love to keep the six but need more out of it. Help??

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Either add some forced induction (blower or turbo) or swap in a V8 if you want any real power. Slant 6's need quite a bit of work to make fast, chief among them being a ported head. Headers, a Hyper-Pac intake, and a good-sized 2-bbl. carb would wake it up though for now.
 
i put a 2bbl set up on my 66,it made a very noticeable difference.as for the cam,i dont think its too big.
 
Sonds like a carb issue not cam.Sounds like the accelerator pump going bad.My slant 6 was doing the same thing I rebuilt it and it was fine after that.Buy a kit and rebuild it yourself it is very easy no much to it.
Jim
 
Hey, great looking Valiant.
You should be very proud of your car.
 
Whatever he means? He means that the /6 only gets so big and itis now about as big as they get as far as Chrysler 6's go. They allready have a 4 inch stroke crank and are limited in bore size.

Theres a bit you can do to it for more performance but just how far you want to go is up to you and how far from stock do you mind going?

Headers OK? 4bbl carb and intake? Newer better cam?

Without getting into the engine part, theres other ways you can help it. The forced induction is a nice idea but may require a rebuild all togther with fordged pistons ($$$)

Not much more expensive would be a overdrive tranny and change the gear ratio. What ever your rear gear is or will be, the overdrive ratio multiplied by the rear ratio will be the new ratio as a final drive. Heres an example;

3.91 rear gears times the O.D. ratio (.69) of an A-500 Chrysler trans equals

3.91 X .69 = 2.69
4.10 X .69 = 2.82
4.30 X .60 = 2.96

Dont sweat the ricer crowd. Your engine is very old in it's orgins. So old, it may be older than some of your school mates dad's. No joke. Old iron is much more difficult to get going fast much less faster than some new cars stock engines.
 
The cam is just fine, your poor slant just can't breathe and you probably have 2 something rear gears. You need to open up the exhaust, (headers or split manifolds with 2 1/4" pipes and duals) give it some lungs, (4 barrel or twin 2 barrel intake) and add a set of rear gears 3.55 or higher numerically. I go Mustang hunting in my slant powered '66 Valiant with Comp Cam's version of your camshaft with duals, an Offy twin carb intake with Holley/Weber progressive 2 barrels, and 3.55 gears. Just bear in mind that it will cost more to hop up the slant than it will to swap in a V8. It really rubs their nose in it when you spank them with a 6 though.
 
How about starting with the basics. Timing is set at what?
 
agreed, check all your tuneup type adjustments and make sure everything is where it is supposed to be (timing, points plugs, wires, vacuum lines, etc), check for vacuum leaks where the intake manifold bolts to the head, and the base of the carb. the cam you have is going to have a noticeable lope to it but it should run ok and perform decent. I have a 4bbl intake I would sell if you think you want to keep the 6, I'm in the process of changing to a 318 as we speak.
report back after you tune her up a bit and let us know how it's going.
 
It's a great engine to learn on. If you can port and polish the cylinder head including short radius improvement, and get the cam degreed properly, and get the intake and exhaust right, you'll be surprised how much torque and power you'll get. Then if you get a V8, you can apply everything you learn to build a tire shredder. If you mess up, you can usually get another /6 without spending a bundle (aluminum blocks in good shape are rare, though).
 
You need a minimum of 2.93 gear to not be a dog off the line, as for the cam size...it's fine, not too big at all I used to run a MP .460 268* grind, pretty much the same cam.

If automatic, get yourself a 2200 stall torque convertor, 3.55's work nice with that size of a cam while 3.90's would be excellent.
 
If you want to stay with the six, the best thing to do right now is to check the basics. That cam should not be a problem. If you do not have much experiance with engines, I would stay away from "power adders" at this time. Go over to www.slantsix.org for good advice on the slant, without the comments about swapping to a V-8. There are several slanters from your home state over there, and one might be close enough for some "hands on" help.
 
The local mechanic doesn't know jack.

I second the dot org experience. A bunch of the guys out here on the left coast are punching out some very respectable times down at the strip with drivers.

Mine's kinda lame. It still get's right at 20 mpg towing a trailer, and cuts 15.6's on a carter AFB. :lol:

Maybe if I keep at it. :grin:

CJ
 
All, very good advice and thank you for taking the time!
I'm new at engines but willing to learn. Although it is a dream to someday fly down the track, right now I just drive to school and back. I do want a quicker faster car, but I'm not going to be doing any racing any time soon. I would be happy with a good launch at the light when next to a ricer and then let him go ahead to get the ticket. (Just kidding if you're reading this Pops.) I also want to be able to drive down the freeway every now and then and keep up with traffic.
I totally understand and agree with making sure that the car is tuned before spending much money on anything else. I have been doing a tune up around every 3000-5000(ish) miles, oil, filter, plugs, wires, cap, rotor, points, condenser, air filter, pcv (which by the way sounds like a shaking paint rattle can at idle). I'm going by memory but I think I gap the plugs at .035, points at .023, all pretty much what Haynes says. Haynes says to set timing at 5 degrees btdc but I don't think I can use that spec due to the larger cam. I use the dwell on the gun, set at (aprox~between) 15 and 16 tdc,( not sure why, other than the car runs best set there, no dieseling, pinging etc). I've replaced the vacuum hoses and I do want to check for leaks (intake/carb) but I'm not really sure how, I think I've heard something about spraying with starter fluid or something but I would find out how before tryng.
I am still in high school and don't have much of a job but I'm willing to spend some on my car. I'm trying to figure out what would be the best bang for my buck to achieve what I'm after. I'm sure my dad would pitch in if I like paint the barn again or something. I just worked off a rebuild on the tranny! I have an extra Holley1920 (in pieces) and I plan on trying a kit rebuild BUT I want 4 bbl ooomph.

Also on a different note, my trunk leaks like a *****. Not sure where the water comes from and have even gotten inside with a buddy spraying a hose around lid, window etc, but never saw a leak. My trunk lid does have a rotten inside corner but don't think water is coming in there.
 
One thing I do suggest, in your case, is DO NOT remove the head, unless you absolutley have to. The aluminum engine takes a special head gasket. These are getting hard to find, and are not cheap. Usually I would reccomend milling the head, for more compression, but not in your case. I would suggest looking around for a head gasket, or engine gasket set (make sure it is for the aluminum engine), so you have one on hand if/when you need it. I would highly suggest converting from the point ignition system to electronic.
 
As stated by Charrlie. If the engine is really a Aluminum engine then you need to be careful. On an aluminum engine I would just upgrade to EI or HEI ignition, Super six (2bbl carb, manifold and 2 1/4 inch exhaust) and recurve the distributor. When that is done then lets see where you are at. If its an iron engine then we will talk.
Frank
 
66aCUDA said:
As stated by Charrlie. If the engine is really a Aluminum engine then you need to be careful. On an aluminum engine I would just upgrade to EI or HEI ignition, Super six (2bbl carb, manifold and 2 1/4 inch exhaust) and recurve the distributor. When that is done then lets see where you are at. If its an iron engine then we will talk.
Frank
Click to expand...

That's a good point, forgot about your aluminum block. If it really is aluminum then you run the risk of blowing it up with a little too much power.
 
mitch67 said:
I have a 67 Valiant, 225 aluminum block slant six, Holley single barrel, 904, 83/4. I bought it from an older guy near me that owned it for years and years. He did a lot of work to it but kept it pretty mild although he did install a bigger cam so it idles pretty rough. It runs fine when going down the road but at lights it stumbles and bumbles like it's going to die, but doesn't. I have the end of the box that the cam came in and the specs are on it, they say...

Delta Camshaft Inc, 270, Perf. 264 S Mech. Grind.
Duration Deg (Int 264) (exh 264) ~
Valve lift (Int .440) (Exh .440) ~
Valve Lash (Int .010) (Exh .012)

None of this means much to me but I was wondering if it is too big to run well or is there anything I can add on to make it run smoother, maybe a super six set up? A local carburetor mechanic said it won't help to add a 2 bbl because you can only get so much out of a six cyl (whatever that means).
I love this car and plan on continuing to drive it every day BUT would love to have more 'get up and go', it's not fast at all and rufuses to spin the tires unless it's pouring down rain! I'm a kid and want to show off every once in awhile when one of those Honda jerk offs are next to me revving their engine. I don't have a ton of money and would love to keep the six but need more out of it. Help??
Click to expand...

Slants make a GREAT all-around engine for a guy in school with a limited budget. It won't outrun truly "fast" cars, but if properly tuned, it will perform a LOT better than you (and most V-8 guys) expect. I used to be a V-8 guy myself, and every slant car I drove as a kid were DOGS, so I assumed ALL slants sucked. I bought my current slant six Swinger specifically for a V-8 swap. But now that I've learned a few things and how to tweak a slant to make it run the way it can, I LOVE it. All I suggest is to give it a chance. But if you lack the patience and understanding to to get all you can out of a slant, then a V-8 swap is the "easy way" to make more power (at the sacrifice of mileage and uniqueness).

To address your questions, the cam is not "too big". It's similar in size to the cam in MY engine, and it idles fine. You may want to go with a higher stall torque convertor. Too bad you just had your transmission rebuilt - that would've been the easiest time to upgrade it. I have a 2600 stall convertor in my Swinger, and with the valves adjusted, it idles fine (you HAVE adjusted the valves, haven't you? If not, time to learn!).

A mechanic who says a slant six is "too small" to run a 2bbl is, flat out, talking out of his behind. There are probably hundreds (if not thousands) of slants around the world running 2 AND 4 bbls, along with multiple Webers, and fuel injection. The common 2bbl upgrade for the slant is the Super Six, which was a FACTORY OPTION for several years. Too big? Whatever.

The easiest way to get the "off the line" quickness and tire spin you're looking for is to go with a lower differential gear set The gearing has to be balanced with how much highway driving you do, however. If you do a fair amount of driving at or above 50 mph, you probably don't want gearing more than 3.23. If you drive the car mainly BELOW 50, you could go with 3.55s, 3.73s, or even 3.91s out back. These WILL allow you to spin the tires, even with a lowly little stock slant, as long as it's TUNED properly. What I suspect you have is a mismatched combo, and that can be a problem even with V-8's.

You need to sort out exactly what you have. Understanding that will help prepare you to work on ANY engine, be it a slant, a V-8, or a W-16. Come here are visit www.slantsix.org and ask lots and lots of questions. Good luck!
 
Since every one has you covered on the engine, here is my $0.02 that I have learned. First, before you do anything other than fix known issues with the drive train is go over the suspension and brakes and modify them first. Decide what you intend to do with the car and upgrade from there. Add disc brakes (all thought you do have a disc brake master cylinder) or larger disc brakes, rebuild the suspension with quality parts, get good tires, and learn to drive the car. More power does you no good is you don't have a chassis to handle it and the ability to stop.

I do agree, basic tune up, convert to electronic ignition, maybe do a compression test for fun to learn how, Learn to read spark plugs (reading the spark plug can tell you a lot about what is going on in your engine from rich to lean and excessive oil consumption) hook up a vacuum gauge and watch it when you drive, this can help you diagnose issues.

Don't let the ricer fan boys get to you. It's called jealousy, I see it in their eyes when I drive by them in my WRX, they hate the fact I have a turbo and they don't. Their cars will be rotting in a you-pull-it when yours will be in a garage.
 
mitch67 said:
Haynes says to set timing at 5 degrees btdc but I don't think I can use that spec due to the larger cam.
Click to expand...

That would be correct. The stock spec was arrived at including a number of factors which likely don't apply here..

Since you don't have any smog issues, set it where the engine wants using a vacuum gauge. You'll probably have to limit mechanical advance when you are done. The engine will be a bunch more responsive down low, run cleaner, etc., when you get the initial timing where the engine wants it.
 
I'm soaking all of this in, learning, and loving it, thanks again! You all have great things to say and I feel like I should respond to everyone but can't of course so I will add what I can.
This is my daily driver and I need it daily, so unless something bad happens I don't plan on taking off the head or anything that radical at this time. The guy that I bought it from said it was an aluminum block engine and he would like to buy it back if I ever upgraded to a V8, (he kept saying that it was 'ready for a big block'). I have no reason to not believe him about the aluminum, everything else he told me has been true. When I was done paying for the car and backing out of his driveway the last words he said was "Don't punch it or you will blow a head gasket". He must have known how hard they are to find? I hope. Other than trying to stick a magnet to the side I'm not sure I know how to tell the difference, any special tricks to tell aluminum or not? Personally I don't see what the advantage would be to have the aluminum if you have to be careful with them and risk blowing them up with too much power. The weight difference must be better than I thought. But it came with the car (not originally), I like it, and don't plan on changing it out, just want to coax out a little more giddyup.
The previous owner is a retired railroad mechanic, did all of the work to the car himself and it all seems to be quality work (except for the paint job, it sucks). He passed to me stacks of receipts, he kept almost everything thank God. He installed 10" disk brakes on the front (drums still in back) and installed sway bars on both front and rear. The rear end is 83/4 open with 323 gears. Front end needs a little tweaking according to Les Scwab and the tires are around half life. He has redone the steering box too but I haven't looked hard enough for that receipt yet so don't know much about it except it steers sweet as long as I'm moving, no power steering.
I think I'll start with the easiest cheapest things first, (right after a trip to Schwab), like valve adjust, check for leaks, rebuild the carb, then look for 2 bbl intake, 2 bbl carb, HEI, bigger exhaust, stall converter.................HOLY CRAP, WHAT HAVE I GOTTEN MYSELF INTO?? :rolleyes:
 
mitch67 said:
HOLY CRAP, WHAT HAVE I GOTTEN MYSELF INTO?? :rolleyes:
Click to expand...

Hours and hours of hard, rewarding work, if it doesn't drive you crazy or broke first... Be patient – it'll take a while to fully absorb all the little quirks about slants, just like any other engine. It seems like I still learn something new about them every day, and I've been fooling around with mine for 10 years.

Best of luck, and let us know if we can help. Slanters tend to be a passionate and loyal bunch, so if you ever feel frustrated or overwhelmed, post here or over on .org and we'll help you through it.

But above all, Resist the Honda... Resist the Honda... :) :) :) :) :)
 
If you have any "you pull it" type yards, you can likely find a lot of extra parts such as electronic ignition, 2bbl cabs, manifolds etc. They put the Slant in cars and truck for many years, so parts are plentiful.
 
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