I know this has been asked multiple times and I have done a couple of searches but there is a lot of info to process. I have a stock ’69 302 that is getting rebuilt and I have recently picked up some GT40 heads--I want to stick with the stock exhaust manifolds for now. I want to get the car back on the road with minimum mods but plan ahead for future upgrades. Car has a C4 with pretty low rear end (2.8 something ?). I was planning on using an RPM air gap intake and 650 carb but the question is cam and valvetrain.

Thoughts? I have seen some recommendations on COMP Cams XE266 or the ford e303 (although this gets some negative comments). I am probably going to call COMP Cams and tell them what I have and let them recommend something.

 

Hi,
Sorry, I can't offer specific off-the-shelf cam advice as I run custom designed cam shafts. But in choosing a cam, you might consider a couple of thoughts.
1. If this is a street warrior, choose for low end torque (better for street performance).
2. Since you're running a C4, you might consider a 3.25 as your ratio of choice, depending on your tire dia. A 3.55 (ideal) will have you cruising the hwy at 3K.
3. You might re-consider the carb size to a 600 CFM, at least for now. (I ran a 600 Edelbrock, on a Performer RPM and with Windsor JRs., TRI-Ys and made 348 RWTQ on a 331. It wasn't until I added bigger heads (2.02/1.60), and a bigger cam, that I went to a 680 Holly.)
4. Most likely, you should consider bumping up the converter to, perhaps, a 2500 stall, dependent on the cams events.
5. Consider a CR of about 9-9.5

Regarding the cam, be sure the grinders provides the approximate engine vac it's capable of making.

Ideally, to make you feel like you are accomplishing something, add the heads, cam, intake, carb, and headers. Next, definitely bump the rear lower, as the car's performance is going to feel sluggish until you do.
Hope this provides some insight.
Happy Motoring!

 

I know the low gear ratio is going to hamper things....but wanted to hold off on replacing everything right away.

I agree a 600 cfm carb would be a better choice.

Thanks for the input.

 

Hi,
I'm very familiar with your approach, as I've been there, just as many others have been here.
Just stay focus on what parts make for the best street application and performance.
Good Luck!

 

do yourself a huge favor and contact Ed at http://www.flowtechinduction.com/

he will build you a custom cam to fit your exact setup for almost the same price as an off the shelf cam. If someone does not reccomend this its because they have not done it themselves. probably one of the best bang for buck mods I have done. I switched from an xe282hr to an FTI cam. =)

 

you should really know or do all the mods you plan on doing. If you buy a cam for your set up now and change anything later such as gears or intake, you cam will no longer match.

Thins would be the reason i collect cams,intakes,blowers,gears etc. Becasue my end result changed.

 

I’ll give Ed a call…I’ve heard and read multiple times that a custom grind is not much more than an off the shelf cam.

I got this car when it wasn’t running so I don’t have any history of performance/driveability/gas mileage, etc. My thought was to warm the engine up a little while its down but still keep the rear end gears, c4, etc. I agree that it makes the most sense to change everything now while the car is being put together. What I don’t want to do is throw in higher gears when what I have now may be acceptable.

At what point will the lower geared rear axle become a noticeable problem? I’m not looking to smoke anyone at the stop light but would like to pin my 6 year old into her seat every once in a while. The ratio of me driving the car on the highway to trying to smoke the tires at the light is probably 1,000:1.

 

Hi
On Ed's site is a questionnaire of your present setup and is typical and quite detailed when pursuing a custom cam.
Rear gears ratio.. can be confusing as when a particular gear-set is mentioned and referenced as one being lower than another, the numerical reference actually increases as an example: 3.25, 3.5, 3.89 or 4.11, the 4.11 is the lowest in this grouping. Typical mustang rear gears are either 2.80 or 3.00, and considered to be higher ratios.

As far as designing a cam, my advice would be to research what you might think will be your mid level or high level performance engine build will be. As you'll see from the questionnaire, you will want to have in place or already on your shelf, the main components of your proposed final build. For example:
Building for spirited street, street/track, or strictly track
Block Cu In., (roller/non roller, hydraulic/non-hydr., head (mfg, type etc), induction, header type, exhaust system, transmission
(auto/manual-4 sp/5/6 sp)
As was mentioned, the more you have in place, the better job ED can do at designing your cam.
Good Luck!