Installing cam. Advance or not to advance?

Posted By: VITC_GTX

Installing cam. Advance or not to advance? - 03/14/11 01:27 AM

Putting a '70 383 together with the parts I have (read: not buying any additional parts).

Measured compression of 8.3:1 with stock pistons and 906's. Going with a 3.23 or 3.91 and an auto. I plan on using the Summit cam (224/234 @ .050 with .465/.488 lift and 114 centerline).

I've have been told by some here to advance it 4-6 degrees and others have warned me not to advance at all because of the split pattern. Anyway, this is over my head...HELP

Posted By: 602heavy

Re: Installing cam. Advance or not to advance? - 03/14/11 01:37 AM

Low compression along with long duration will kill power , that cam is around 284/294 @ .004" , in other words advancing that cam too far will open exhaust valve to early bleeding off power , this is the reason i don't like split pattern grinds on low comp motors ,the 114 lobe sep just adds to the problem (early ex opening) plenty better cams out there as was posted in you're previous thread.

Posted By: Pacnorthcuda

Re: Installing cam. Advance or not to advance? - 03/14/11 01:44 AM

First off you need to find out if that cam has and advance already 'ground in'. Many do. THat means the manufacture already advance the cam when installed in its 'straight up' keyways. If is already advanced 4 degrees I would not advance it further. If no built in advance then consider advancing it. Compare Intake Center line number against Installed center line.

....and.......degree your cam install

Posted By: HYPER8oSoNic

Re: Installing cam. Advance or not to advance? - 03/14/11 01:55 AM

8:3 to 1 comp ratio? Something around the 383/440 Magnum cam would be good. Strong midrange power would be best, your choice with the 3.23 or 3.91 gears. With the 3.91's, you could spend a little more money to raise the compression
(heads, pistons) in the motor for more torque/power with the present cam you have. Degreeing ALWAYS helps.

Posted By: RapidRobert

Re: Installing cam. Advance or not to advance? - 03/14/11 01:57 AM

Quote:

Compare Intake Center line number against Installed center line.

Is one of these the LSA (lobe seperation angle)? Trying to edumacate myself on cam theory

Posted By: Pacnorthcuda

Re: Installing cam. Advance or not to advance? - 03/14/11 02:13 AM

No LSA is different. Try calling Summit Tech support, if you can't get an answer you will find out when you degree the cam. What is the ICL?
108? 110?

Posted By: VITC_GTX

Re: Installing cam. Advance or not to advance? - 03/14/11 02:40 AM

Quote:

First off you need to find out if that cam has and advance already 'ground in'. Many do. THat means the manufacture already advance the cam when installed in its 'straight up' keyways. If is already advanced 4 degrees I would not advance it further. If no built in advance then consider advancing it. Compare Intake Center line number against Installed center line.

....and.......degree your cam install

Does this help?

http://static.summitracing.com/global/images/instructions/sum-6401%20cam%20card.pdf

Posted By: RapidRobert

Re: Installing cam. Advance or not to advance? - 03/14/11 02:46 AM

Quote:

No LSA is different.

Thanks Pac. By coincidence I have that cam in the Summitt link for my upcoming 451

Posted By: 602heavy

Re: Installing cam. Advance or not to advance? - 03/14/11 02:50 AM

The card states an intake centreline of 109 , this puts the intake/exhaust lobes 5 degrees advanced.

Posted By: goldmember

Re: Installing cam. Advance or not to advance? - 03/14/11 03:38 AM

Install the cam,check the ICL. Adjust as needed to get 109ICL(+/- 1 degree) and run it.

Posted By: VITC_GTX

Re: Installing cam. Advance or not to advance? - 03/14/11 04:34 AM

Quote:

The card states an intake centreline of 109 , this puts the intake/exhaust lobes 5 degrees advanced.

It appears that you subtracted the intake center line (109) from the lobe separation (114) to get the 5 degrees advance. Is that correct? Sorry, but I am very ignorant when it comes to cams.

Posted By: goldmember

Re: Installing cam. Advance or not to advance? - 03/14/11 04:43 AM

Yes. A 114ICL is straight up,109 ICL is 5 advanced.

Posted By: 68Barracuda

Re: Installing cam. Advance or not to advance? - 03/14/11 04:50 AM

I put this exact cam in my 70 road runner. Original hp engine never rebuilt, It was put back together just as you are doing yours. We did degree the cam but my mechanic friend did the work and I'm no expert so I don't have much detail for you. I read several post on here that talked about this cam so you may want to do a search. I can tell you I'm happy with it, very streetable and it pulls hard. I do have a bit more stall which is recommended for this cam. Good luck with it, I don't think you will be disappointed.

Rob

Posted By: VITC_GTX

Re: Installing cam. Advance or not to advance? - 03/15/11 01:55 AM

Quote:

I put this exact cam in my 70 road runner. Original hp engine never rebuilt, It was put back together just as you are doing yours. We did degree the cam but my mechanic friend did the work and I'm no expert so I don't have much detail for you. I read several post on here that talked about this cam so you may want to do a search. I can tell you I'm happy with it, very streetable and it pulls hard. I do have a bit more stall which is recommended for this cam. Good luck with it, I don't think you will be disappointed.

Rob

Thanks for the info Rob. I believe you may have more compression than I do. I think HP engines were about .5 to .8 higher CR but this is still good news. I think I have a 340 converter that I can through in the car that will help me a little.

Thanks again for the personal experience.