Hey guys,
I am trying to understand cam specs so i can choose an upgrade for my 69 mach. I have #s matching stock engine with scorpion roller rockers and full length headers. my carb is 600cfm edelbrock. I don't intend to race it but I do want to play with it on the weekends on the back roads. Currenty I get 7s on 0-60 and I'd like to improve that. Does anyone know what the specs are for stock cam so i can compare the #s on the new ones?
i found this link but the 351w specs do not match what i see on other sites.
http://www.mustangbarn.com/Techinfoimages/camsb.jpg
The stock 351W cam is fairly mild. Really nothing performance about it. There is more to selecting a cam than picking one with more lift or more duration. Lobe separation angles, intake centerline, symmetric vs. asymmetric lobes, and lobe profiles have a significant impact on how a cam performs. Not to mention how the remainder of the motor is configured, trans type, rear axle gear ratio.
Rather than try to select something I suggest calling Comp Cams or Lunati Cams and get their recommendation. My preference of those two is Lunati cams. Comp cams quality has went down since they moved manufacturing overseas, I believe to China. Comp cams only manufactures custom grind cams here in the USA. Plus, Comp cams has a reputation of poor quality hydraulic flat tappet and hydraulic roller lifters.
Keep in mind, along with the typical cam and lifter change you will need to upgrade the valve springs, retainers and locks. A timing chain and gear set upgrade from stock is also recommended. The cam manufacturer will have the correct components for whatever cam you select. Valve spring change on the car is not difficult to do. Just takes more time compared to when the cylinder heads are off the motor.
I think your car had headers which is good. If you are still using a stock intake manifold. An upgrade to a Weiand Stealth or Edelbrock Performer RPM would be advisable. I have used both of those on 351W's. They both perform about the same. The Weiand Stealth physically fits better under the hood and seems to have a crisper throttle response. The basic Edelbrock Performer (not the Performer RPM) is a waste of money.
Lastly, if a carb change is in the future, something in the 650 to 700 CFM range is more suitable on a 351W with some performance upgrades.
Best Regards,
Mike
I cannot really add any professional opinion on your question in that have not dealt specifically or personally with the 351W.
I believe that Mike has given you some good general guidelines.
There are a few guys here who are running some healthy 351W's so here hoping they will jump in and add what they have found in their personal experience.
I expected that the springs would have to change. I already have guide plates, hardened push rods and screw in studs from when I installed the scorpion roller rockers. I read on compcam that I would have to get my heads machined for the new springs because of inner coil binding against the step cast that the springs fit into. Do you really think i have to do that?
http://www.compcams.com/Pages/411/ford-t...-info.aspx
I really hate to change the intake manifold. I want to keep my heads and intake. I know that it will restrict but I'm hoping that the cam alone will add performance without compromising on the intake manifold and heads.
I have been reading up on the different cams. I'll give Lunati Cams a try. For comp cams it looks like the XE268H or HE268H are more suited for what I want. I'm trying to compromise between something I can feel off the line and some long drives to car shows.
For valve springs on 351W heads it can be tough. Mine are setup with larger intake and exhaust valves and the springs have an installed height of 1.82 inches. Because of that, Comp, Lunati, and Ford Racing offered valve springs that the fit the cylinder head without machining that step you are referring to. I think the stock valve spring installed height is 1.760" in a 351W.
For reference that step diameter is 1". Most springs, single with a damper, that have a 1.460" to 1.5" outside diameter will fit over the step correctly. Then it is a matter of selecting one with the correct open and closed loads and installed height.
Comp's spring #972-16 fit the cylinder head but has a 1.8" installed height. It is suitable for hydraulic flat tappet cams. There are offset valve spring retainers and keepers to increase the installed height. So I think Comp's 972-16 spring is a viable solution for you. If you call Comp or Lunati I'm sure they can select the appropriate spring that fits your cylinder heads without machining them.
NOTE: It's best to invest in a valve spring micrometer height tool when setting up the valve springs. The tool is used to measured the installed height of the spring which is critical. Summit racing sells them and some are not very expensive. Maybe get one to measure an intake and exhaust valve on your current setup. Then you know exactly what you can work with.
http://www.summitracing.com/search?SortB...micrometer
Best Regards,
Mike
The reply from lunati based on my 351 4 barrel with original bore was the voodoo hydraulic flat tappet cam & lifter kit 256/262.
duration 256/262
duration @ .50 213/219
bross valve lift .483/.499
rpm range 1000-5500
part 10350701k
Will this cam be an improvement from my stock cam? note that i will keep original heads and intake. I dont want to touch a #s matching engine, just the internals.
That cam should perform better than the stock cam. I wouldn't think by much. The Voodoo series, like Comps Xtreme series use newer technology lobe profiles. When compared to older cams, the Voodoo and Xtreme cams open and close the valves much quicker and have much more valve lift. But I think I would pass on that Voodoo selection.
Stock cylinder heads will limit what valve lift you can use. Not too bad of a limiting factor for your needs. A stock intake will work with most cams but will significantly reduce the performance potential of them. A bigger limiting factor is the stock torque convertor. Many performance cams require higher idle speeds which cannot be obtained with the stock torque convertor.
Even though I prefer Lunati I have used Comp cams in the past in my 351W. Comp's tech have always directed me to their Magnum series of camshafts. Even though the Magnum series are older designs, several of Comp's techs told me they are better suited for higher compression engines. If your original 4 barrel 351W has flat op pistons with valve notches it should have 10.7:1 compression ratio. The same Comp's techs told me the Xtreme series cams are more suited for 9:1 compression ratio motors.
I don't know exactly what you are seeking in a cam? I realize better performance. But do you still desire a stock smooth idle? Also, what gear ratio is in your rear axle?
This cam comes to mind but I don't know if suits your needs and wants, or it's too aggressive for your liking.
http://www.compperformancegroupstores.co...=FTCAMSMAG
This is the one you already looked at. It's a little more mild but might actually be a good choice for your needs.
http://www.compperformancegroupstores.co...e=FTCAMSHE
Those both list a mild rough idle. I'd expect the first cam to idle only slightly mild rough and the second cam to idle just about stock smooth in a 351W. Also, both of them list required valve springs that should fit your cylinder heads.
Comp also has their online Camquest utility to assist in cam selection.
Best Regards,
Mike
I just wanted to add this information to be certain you are aware. Any time a performance camshaft is installed the engine vacuum at idle with be reduced from stock. More aggressive cams develop less vacuum at idle. Vacuum assisted power brakes won't work as well and require a little more pedal effort. If the car has vacuum operated heater and air conditioning controls, they will sometimes also be adversely affected. For your situation, the cams you are considering shouldn't create noticeable issues in these areas.
Regards,
Mike
Mike, I don't mind a ruff idle since I will drive it for weekend fun. I use my other car for family drives and going to work but on the weekend I like to drive the back road and take it off the line a few times. So mostly looking for improvements in 0-60 and 1/4 mile if both are possible (mostly 0-60 though). With the Magnum 270 series I assume valve springs, lifters and push rods would have to change. I recently bought new sized push rods because of the scorpion rockers I put on so i assume the size will change again.
I don't mind changing the torque converter but would prefer to not do everything all at once unless i have too. You mentioned my my rear gear ration but I don't know what I have. How can I tell? Previous owner did not mention that he changed it but I was wondering myself what size it is. Keep in mind I don't mind changing that as well. I'll change whatever I have to, to improve performance but within reason to keep the car mostly stock. I dont think its concurs perfect but does have # matching fmx trans, engine, and original upholstery. I also heard that I may need a trans go it for the fmx but hoping i could wait.
Mike, very rough estimate, how much HP do you think I would gain from Magnums 270 and HE 268 ?
I would think 20-25 hp. gain with only a cam change. I'd run it through Comp's Camquest utility but it won't load right now.
Yeah, the cam change would involve cam, lifters, valve springs and retainers and locks, and maybe a slightly longer pushrod. The required pushrod length cannot be determined until after it is assembled. I would upgrade the timing chain and gear set if you are still using a stock type. Ford Racing offers a True Roller Double Roller type timing chain and gear set made by Cloyes for a good price compared to a Cloyes labeled assembly.
Both of those Comp cams, the Magnum 270 and the Hi Energy 268 will need new valve springs. Actually, Comp specifies the same valve spring for both.
If you don't mind the idle being a little rough I would lean toward the Magnum 270 or something equivalent. I think with something more aggressive than that you will notice reduced power assist with the brakes and also need a different torque convertor in the trans.
If you are curious, Comp has a sound clip of the Magnum 280 on their website. The Magnum 270 will obviously idle smoother than that. For my taste the Magnum 280 doesn't sound too rough but it might cause issues with the power brakes and stock torque convertor.
If you want to keep a stock intake manifold I would keep tabs on EBay. Ford use to sell aluminum performance intakes manifolds back when these cars were new. They pop up on EBay occasionally.
As far as rear axle gear ratio. First look for the tag attached to the center section (third member). Second, if it is not any type of Posi-Traction then, with the back tires off the ground and trans in neutral, hold one back tire from rotating, then rotate the driveline and count how many driveline rotations are needed to rotate the other wheel 2 revolutions. If it is some type of Posi-Traction simply count the driveline revolutions needed to rotate the wheels one revolution. To get any closer you will need to remove the third member and count teeth on the ring and pinion gears.
For a street driver, ratios in the 3.50:1 to 3.70:1 are good. Unless you like to cruise on the freeway for long distances. Your car likely still has the common 3.00:1 ratio. If so, a gear change will make a huge difference in how it feels.
Regards,
Mike