need a new cam

[v8ranger]

Ok, after thinking I was all set with going with the trick flow cam, a friend of mine came over and I was showing him the cam. Then we got looking at more cams. He thought, why not go with this one http://www.summitracing.com/parts/CCA-35-440-8/ It says carb only, so Im thinking it might work better for my carb setup since it says "carb only" If this one is better, should I still NOT use the 1.7 and go back to the 1.6's?? I hate this part of building.... I cant make up my mind what I should do.... lol....

[cgrey8]

LOL. That cam is Comp's version of the E303. It is ALMOST a replica of the E303. Check it out:

Code: Select all

              FMS E303         Comp FW 281H-R10     TFS S1
Adv Dur:      282/282          281/281              275/279
Dur@.050:     220/220          220/220              221/225
Lift w/1.6:   .498"/.498"      .512"/.512"          .499"/.510"
Int Ctr:      110              106                  108
LSA:          110              110                  112

The specs are almost identical between these two cams. Yeah the Comp has slightly higher lift and one degree less off-the-seat duration, but those differences are not enough for you to ever tell the difference with GT40 heads. The ONLY significant difference between these cams is the Intake Center Angle...110 vs 106. Just like with the TFS S1, Comp thought it was valuable to grind 4° advance into the cam without you having to do it with a timing set. You could theoretically advance an E303 using your timing set and get the same performance this Comp Cam would offer. I honestly have NO clue why this is listed as a carb-only cam. BTW, notice that TFS is also advanced 4° compared to the E303, except they split the 4° between the Intake center and the LSA.

Now you might be asking yourself why would someone actually buy this cam instead of just buying an E303. A couple of reasons:

1. The 4° advance is built-in. So on a budget-build, you could reuse the stock timing set or get away with a cheap timing set that doesn't allow you to advance/retard the cam.
2. It's made by Comp Cams which means this cam is probably ground with more accuracy than the FMS cams are. Even if that's not true, you are buying the assurance that Comp did a good job making their cam. Comp is a reputable company with good quality control. Every cam is tested on every lobe to assure it is ground to spec.
3. People may not recognize the similarity and buy this cam purely based off description.

Bottom line...IMO the TFS S1 is still a better pick than this cam because it is cheaper, has a faster ramp rate, slightly wider LSA (better low end torque) and is a tad more aggressive on the .050" duration which I suspect is more meaningful to you. It's also the safer direction to go given there's a supercharger involved. With more info about what's going on inside your engine OR a change in your intentions for this build could easily change my opinion on which cam is best. But given the info so far, I still believe the TFS S1 is all-around the best option of all the cams we've discussed here.

But you are doing the right thing by asking around, verifying the advice you are getting here, getting other people's ideas/opinions, and verifying their advice. I certainly don't want to discourage you from doing further research or discourage you from bringing any info/findings/opinions you come across back to this discussion. But most importantly, I want you to better understand the information you are being given so you aren't blindly taking people's advice. Instead, you are making a more informed decision about what makes the most technical and financial sense for you and your build. After all, you are the one that has to pay for it all and live with the results.

[v8ranger]

Ok, so why are these number the same on two of the cams Lift w/1.6: .498"/.498" .512"/.512" .499"/.510"
, but on the TFS there is a .001 differance?? Should I NOT use the 1.7 with the TFS? Or go ahead and use them?

[cgrey8]

The TFS is a "split" profile camshaft. Traditional cams have the same lobe shape and height for both intake and exhaust. However through experimentation, cam mfgs found that it is often beneficial to have the intake and exhaust lobes different. When the lobes are different, the most common condition is for the exhaust to have a wider duration and higher lift than the intake lobe. This is one of the "upgrades" the TFS has that the E303. I completely missed mentioning that detail all along. Back 10 years ago, people thought only the highest of the high performance engines needed this. Today, it's not common place, but it is a little more common to see cams doing this. Also keep in mind the TFS S1 cam is optimized to be used on TFS Twisted Wedge street heads. That doesn't mean it can't be used elsewhere, but evidently the TFS TW heads benefited from a little more time and lift on the exhaust side. It's quite likely other heads will too hence why I don't consider the split a bad thing. Cam mfgs sometimes have a split and non-split version of their cams since the split potentially requires you have two different spring packages, one for the intake, and one for the exhaust. For example, Comp XE266HR-12 is a split profile, but the XE264HR-12 is not although when the XE264HR-12 is used with 1.7RRs, it is VERY similar in spec to the XE266HR-12 with 1.6s. In fact, Comp even advertises that the XE264HR-12 is designed to be used with 1.7RRs.

I don't know about GT40 valves, but GT40p valves require different springs and/or retainers anyway due to valve lock location differences. Check it out:


Notice how much further down the valve the locks are on the left (exhaust) valve as compared to the right valve. So if you want to run the same spring, the retainer has to locate the locks lower on the exhaust valves. The other option is to run the same retainers and use different springs between the intake and exhaust valves. Also notice, Ford uses different retainers on the valves as a result of this. But why Ford uses 2-piece retainers on some valves is still something nobody has been able to answer for me. Perhaps it has something to do with the added lift pressure of opening an exhaust valve with the cylinder under pressure? I don't know. My aftermarket retainers are 1-piece and significantly lighter than either stock retainer.

As for whether to use the 1.7s or not, that's more a question of IF you can use them. What I would recommend is when you reassemble the engine, try the 1.7s on cylinder 1. When you get ready to degree the cam, you'll know if the springs are binding or if the valves are interfering with the piston. I don't expect you to have any issues, but I can't say that with any degree of confidence since I have no clue what springs you are using. If they do bind the springs, you either need to drop down to 1.6s or change the spring package. But I wouldn't make that decision now. Until you know it is an issue, I wouldn't worry about it...but I would budget for it just-in-case.

I'm more curious/concerned about whether the TFS S1 has a smaller base circle. A smaller base circle would require you get longer pushrods. My Crane Powermax 2020 has a smaller base circle than my stock Explorer cam. From what I've been told (not confirmed) is that the base circle doesn't usually change until the cam's lift goes above .512" w/1.6 rockers. The Crane I have is .530" w/1.6s. Unfortunately base circle diameter is not something cam mfgs publish...but should IMO.

[cgrey8]

BTW, the stock Mustang GT camshaft and the Explorer camshaft are split profile cams. So even the factory found it beneficial to do this. The odd thing is the stock Mustang GT cam had the intake lobe setup with a wider duration than the exhaust lobe. Although both have the same lift.

The Explorer cam is more traditional with the exhaust lobe having both more lift and duration than the intake lobe. Perhaps the split profile of the Explorer cam has something to do with why the valves have different lock heights??? I don't know if those are related or not.

[Dave]

Lots of site having the same kind of discussions on the good, bad and ugly in cams. Most seem to follow right along with what Chris has mentioned. Did notice that the XE264HR-12 has the same duration, same lift and the XE264HR-14 but with a two degree tighter LSA. Each cam has the same lift for intake/exhaust but the split duration. The exhaust side of the SBF has been a known problem for a long time. Think some have even used the 1.7 ratio just for the exhaust.
Dave
http://www.stangnet.com/mustang-forums/ ... ation.html
Edit: Chris, measured the Explorer cam and the "E" that I sold to Mark, still sitting here in the computer room. Had to measure the lift to make sure I sent him the right one. Base circle measures 1.439.

[v8ranger]

Well its all back in.... I havnt taken it for a test drive yet.. To much salt on the roads... Hear are some pics of the rebuild...

[plowboy34]

Looks real good, only problem I see is your white headers are giving away your age..... Looks old skool to me....I like it....

[Dave]

Looks real good, only problem I see is your white headers are giving away your age..... Looks old skool to me....I like it....

Looks good with these old eyes also, white just dirty too quick. Forgotten how long them water pumps snouts are, been looking at the Explorer ones too long.
Dave

[v8ranger]

I liked the looks of the white. We will see how long they stay that way. Its header paint, so hopefully it last longer than the first run up the road... lol... They say we have some pretty good snow fall coming in over the next couple days, so It wont get run up the road any time soon.....

[fordmike]

[quote="v8ranger"]Well its all back in.... I havnt taken it for a test drive yet.. To much salt on the roads... Hear are some pics of the rebuild...


quote]

If the heads on the engine in this pic are supposed to be GT40's then I am sure that some one lied to you. The heads look like just plane ole windsor heads. The GT40's and GTP's have three and four lines cast into the front and back of the heads and are marked with GT or GTP in one corner of the head next to one of the bottom head bolt holes. I just thought that you would like to know.

[v8ranger]

They are GT-40 heads. They do have the 3 lines on them. You just cant see them in the pic....

[fordmike]

They are GT-40 heads. They do have the 3 lines on them. You just cant see them in the pic....

Ok great then you are all good then.