[70f400]

I received this custom ground cam and need some advise on what to do with it. Looking for installed ICL and rocker arm ratio input. 468 ci, 10.67:1 cr, KRE 290 D port heads, 0 decked block, HO aluminum intake, Q jet, RARE 2-1/2" manifolds, 1970 TA 3500#, 3.42 rear, 700R4 10" continental. should this tolerate 91 octane with 10% ethanol? I will run 91 with no ethanol when I am around home(best I can get in my area), but road trips may make the ethanol the only choice. This car is a weekend cruiser with occasional track time.

duration @.006 286/296
duration @.050 236/244
lsa 114
lobe lift .363/362
valve timing @ .05 with cam installed @ 114 ICL
intake open 4 BTDC close 52 ABDC
exhaust open 56 BBDC close 8 ABDC

[Steve C.]

Curious. Brand of cam ? hyd roller or hyd flat tappet ?


If it's ground with a 114 lobe separation and the timing events are given at 114 ICL then I'll presume the cam has no advance ground into it.

[70f400]

Comp cam hyd roller. was supposed to be close to the old faithful grind with some newer lobes the supplier suggested I try. A little shorter seat timing. I will degree the cam, but cam card suggest no advance.

[AG]

110 degree ICL

[Steve C.]

Although less seat timing the wider lobe separation reduces the overlap quite a bit compared to the 'Old Faitfull' cam. Also has quite a bit less lobe lift than the OF.


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[70f400]

Yes it's not quite what I had in mind I should of been more patient. I wanted the 114 lsa as it was recommended due to the ra manifolds. I can make up for the lift with some 1.65 rockers. I no the old faithful was recommended installed @ 108 icl just looking for suggestions on we're to install this and what rocker arm ratio would be best. 1.65 gives me almost .600 of lift. The 290 d ports probably won't flow much past that lift?

[Steve C.]

My thought, the improved combustion chamber design in conjunction with the wide lobe separation there should not be a issue with the static combusion ratio. Your heads ported or not will thrive on valve lift above .600" lift. Use a higher rocker arm ratio. Presuming it's mechanicaly achievable. And DO NOT skimp on the valve spring package !

What is the duration at 0.200" lift ?


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[Lee]

I have a somewhat similar engine combo saved for my engine simulation software, which I use to design cams. I tweaked it to match your motor a bit more closely, and put in your cam specs, and ran some simulations.

I would advance it 3 to 5 degrees. If you go smaller than 109 ICL you'll start losing top end without gaining enough down low. So 109 to 111 ICL.

[70f400]

Thanks Lee.

Steve. The cam card from Comp does not list the duration @.200 but I may call them with the part # and find out. I assume your wondering about side loading on the lifter bores and the need for a brace.

[steve25]

You received the Cam, you mean you bought it right? Not to be mean, but it sounds off that bat like a disclaimer that if it runs bad it's not your fault?

[grandville455]

The lobes they used will be on your cam card.

[70f400]

Originally Posted by steve25

You received the Cam, you mean you bought it right? Not to be mean, but it sounds off that bat like a disclaimer that if it runs bad it's not your fault?

I wanted the old faithful cam and 295 d ports, but was impatient waiting for a response from Dave at SD I know he is very busy as I've have owned my own manufacturing facility for 22 years. I asked KRE who is porting my heads if they could get me the same cam and this is what I got. I am not bashing or putting the blame on anyone. My reason for posting is this cam is different then what I expected. I spoke with KRE about it and they thought it would work well at 110 icl with my current 1.5 ratio rockers but 1.65 would give a little more hp. I was just wanting another opinion, and if this was a bad choice of cam then I would look into reply it. Thanks for the help.

[grandville455]

Originally Posted by 70f400

Thanks Lee.

Steve. The cam card from Comp does not list the duration @.200 but I may call them with the part # and find out. I assume your wondering about side loading on the lifter bores and the need for a brace.

Steve was probably wondering on the .200 numbers to see how close they are to the Old Faithful ones, which i believe are 160/164

[70f400]

51-000-11
Grind # P8 3017B/13143B HR114.0

I not sure were to look up the specs of these lobes.

[Singleton]

.200 dur - .159/.165

Lobe Lift - .362/.361

XFI Lobes

http://www.compcams.com/Technical/Ca...terCatalog.pdf

[Steve C.]

I had no concern about lifter bore bracing. As Darby suggested I was just curious as to the .200" duration compared to the Old Faithful lobes. The "B" suffix code after the lobe numbers often alter the lobe lift. Example the .3630" lobe lift on the intake compared to the catalog listed .3620".


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