what teh biggest cam that can be used with the stock valve springs.

 

First what is your engine and what is your stock valve springs. Each cam have there recommend valve springs. Usually when you change a cam you have to match the valve springs recommendation by the manufacturer. Also you don't want worn lifter on a new cam.

check this site : http://www.compperformancegroupstore...e=ClevelandCam

 

what ever came stock in a 79 400

 

The stock cam.

DO NOT install a higher lift cam or a cam that will run your motor past the stockers 3500 rpm limit with stock springs. Coil bind and valve float are not your friends. What Mustang 81 said.

 

generally a rule of thumb is that the stock springs and valves start to bind around the 0.500 lift mark. And as mustang above has stated ensure you put a set of matching lifters in there. Have a look at the stickies at the top of the forum and look up the Bubbas workshop stuff (one works, the other doesnt) torino website I think. It has the rough specs for all the cams, timing chains and heads etc. Worth a look.

 

geez, 3500rpm, is that all they were good for?

 

Grandpa's '77(?) LTDII 351M: WOT upshifts at 3500 rpm. I'm sure they might have been good for more, but using old stockers with a different cam is just asking for trouble.

 

When you select a cam, they grinder will have recommended spring part # or a spring rate.

 

I agree with everything, but with regards to Comp cams.....

FYI on Comp Cams.....

Comp has by appearance - seems to be a company that has experience more cam lobe failures than most and places the blame on the low ZDDP in the oils. Is it a factor yes, but I highly suspect that they are also using Chinese cam billets & they do not include Parkerizing their cams (Parkerizing is the final step and a crucial step to help break the cam in- a heated acid bath that microscopically etches the metal surface and adds a very thin layer of graphite coating which allows the cam lube to hang onto and penetrate into the cam surface during cam break in) unless you specifically request and pay additional money for it. Considering the cam has such critical importance to the engines performance and life, to me it makes sense to use a cam grinder who will talk with you directly- even modify the cam grind to fit your needs even better and to address the possibility of cam lobe failure with the new oils. With regards to price...the difference is nil- especially considering its cheap insurance to know exactly who is machining such a critical part for your engine. And remember, advertized lift/duration/lobe separation is just that- advertized and not the specific grind including ramp profile that is used on the cam.
That is why I highly recommend Ford Racing or Iskenderian & Crower & Chet Herbert & Lunati...all are family owned, been grinding cams for decades, and both will even re-grind your oem cam if possible- saving you even more $.

As you are probably aware, many of the cam mfgs in the past few years either sold, closed their operations to re-open elsewhere (typically with new staff) or .......In addition to Isky & Crower, I use to very highly recommend....
Sig Erson & Crane...Both became part of corporate entities, eventually leading to periodic quality issues and closing their doors- I think Crane re-opened, but with a different staff. Typically the staff is very, very young and well- requires a learning curve.

If you do a search on the net, Harvey Crane has posted a little summary of the history of the people who made the cams at Crane, his opinion of what happened and the eventual outcome of several of the staff.

While there are some cam failures cause by start-up/break-in error, cam lobes that are of a street type profile should not be completely worn out in 10,000-30,000 miles- and while just about every cam mfg recommends adding ZDDP (and sells) to the oil, I still highly suspect Parkerizing is not done by some and the billets are of Chinese origin with inferior properties, specifically low carbon- which would explain the proneness to lobe failure (lack of carbon reduces the harness of the steel)

Given the criticality of the component- IMHO, I don't like speaking to a catalog parts sale person- they really don't know any more about the cam than what they are reading- companies like Summit, while their bulk purchase agreements are great for price, when it comes to making an engine breathe, there are so many variable including elevation, humidity, fuel blends/available octane, most cam mfgs will vary a "core grind pattern" to match the external impactors in addition to the internal impactors- which today IMHO makes the different between and engine that runs well, to one that just seems to run a little bit better, smoother and gets better mileage than expected.

Comp has alot of rhetoric about its quality versus the family owned cam grinders, but here is what I believe is the reality of it all.....
By SAE standards, 1% failure rate is unacceptable in US production standards (this is also ISO, Sigma, TQM, TPM, I could go on).....the US standard is 1% internal (not external ie customer), Chinese standard for example is 15% failure rate (internal). This does not nor should be implied to say that this should mean there should be no failure at the customer level, that is just not realistic as everyone would agree. But let's assume that Comp's 1% failure rate in the marketplace is acceptable, by comparison this would mean every day 100,000 prescriptions would be incorrectly delivered to customers (statistics provided by FDA & Harvard).......would this be acceptable to anyone- of course not. Per both GM & Ford, if each production run of any single vehicle series was built 99% to standard (ie 1% failure rate @ market/consumer deliverable), no less than each vehicle would have on average 15 defect's (published data available). Now before anyone says it, I will- yeah, we all know of certain vehicles that everyone considered "lemons" and everyone has known more than one person who bought one of these that had at least 15 defects of more. In summary, consumer's simply do not accept 1% failure rate in any significance of large scale consumer population.

Therefor, if correctly stated by Comp as such, this validates at least from & of Comps product, their production quality risk management practices are shifted from manufacturing internal controls onto the consumer. Again, the family owned cam grinders do not function under this model & could not remain in business....I can personally attest that both Isky & Crower do not prescribe to this (Comp's) model- as fyi, Isky checks/inspects/test every single valve spring before it is shipped to the customer (whether its VascoJet or whomever).....that's simply a QA step that again does everything humanly possible to ensure customer satisfaction. High/mass production facilities count every single penny and in essence do a "risk assessment" of what the likely hood of failure is and who is to accept fault, this risk assessment includes "how many customers will get upset and leave", unfortunite but true and built in specifically (typically) in writing (in many cases, companies that are required to submit SEC filings are required by federal law/regs to produce such a document and it must be review annually and signed by the CEO/President).

The reference that you can find by comparative analysis, similar QA complaints on other Cam grinders, I searched......with Comp I found 2 full pages (threads), Crower 3 threads (one of which was a result of using oem valve springs with a new cam- that's just not real bright as I'm sure everyone will agree) the other 2 threads Crower took care of the customer and have had no problems, 1 on Isky- turned out not to be an Isky cam but a "Copy-cat" brand that was suppose to be the same as the Isky #####, they had spring bind and busted up their engine pretty bad- of course, that should always be checked for during assembly- I'm sure Comp has similar type reasons for claim failure, but the ratio of complaint is easily 300 to 1 from my simple google search (which of course has extreme variability)

Comp's statement, assuming it clearly represents the company's position on QA, has verified to myself why I have not, nor will ever recommend nor ever use their products in any of my vehicles- they have affirmed my thoughts & suspicions.

 

Bigger is not always better alot of people like to "over cam". I saw something about .500 lift limit. That may be true but your going to need to go through and check. If you have rotaters its going to be less. Check your retainer to guide clearance and that will give you a rough idea on how much lift your can support without machining the guides. Then when you get your cam find out what the reccomended pressures are from the cam manufactor for your springs.

IIRC you can swap in BBC single springs with dampers no problem. But whatever you do if you swap cams swap springs. Your only spending like 30 more bucks. It's better then dropping a valve and blowing the engine.

Also I believe anything more then 268 advertised duration doesn't really do anything on theses engines. Remember you have 8.4 to 1 compression, exhaust manifolds, 2 barrel, and a retarded timing set.