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Re: ADVANCING CAM TIMING 2-4*
[Re: Labratt]
#814517
09/28/10 03:02 AM
09/28/10 03:02 AM
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Joined: Jun 2005
Posts: 793
Utah
topbrent
super stock
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super stock
Joined: Jun 2005
Posts: 793
Utah
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Quote:
In your opinion..with doing nothing else but CNCing the heads and getting a GOOD valve job..what gains in MPH..and ET could I expect? Gary Jacob thinks I should pick up 75-80 hp with porting alone!????  What's your opinion??? Thanks again!   RandyB 
Bear with me, as I have posted this chart before, but here is a test that was done by Dulcich directly comparing the out of the box Edelbrock RPM heads to Modern Cylinder Head CNC Edelbrock RPM heads.
Granted, this is one mans test, but I think this test data directly applies to your question, as the specs of this engine are extremely close to yours.
Same CI, same compression, similar intake, same stock heads, ect.
Given the similarities, I would think your larger , 260°/266°(SQ lobes) 108°lsa cam should make more power than the smaller 243°/247° (MM lobes) 110°lsa cam used in this test.
Horsepower gains from MCH-CNC RPM Heads: see attachment
4800rpm + 17hp
5000rpm + 20hp.
5200rpm + 28hp
5400rpm + 36hp
5600rpm + 38hp
5800rpm + 39hp
6000rpm + 45hp
6200rpm + 41hp
Given these kind of gains, CNC porting your heads would probably net you the .20'ish ET needed to obtain your 10 second timeslip.
Test engine 448" combo:
- Speed-Pro-2355 pistons, 10.2 compression
- Comp MM Flat tappet cam, 243°/247° @.050, .586/.597 lift, 110°LSA, 106° installed
- Comp 1.6 Roller rockers
- Victor Intake
- TTI 2-2/18 headers
(click the attachment for a larger view)
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Re: ADVANCING CAM TIMING 2-4*
[Re: Labratt]
#814520
09/28/10 10:28 AM
09/28/10 10:28 AM
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Joined: Dec 2005
Posts: 1,495
Shelby mi.
JAKE68
pro stock
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pro stock
Joined: Dec 2005
Posts: 1,495
Shelby mi.
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Look at the torque no.s thats a nice improvment. That would move that car. We had some ported 915 heads with 500 in. .590 cam motor that went 10.90's put on a set of Jeffs 440 sorce heads on and the car now goes 10.30's
JAKES AUTOMOTIVE
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Re: ADVANCING CAM TIMING 2-4*
[Re: Labratt]
#814523
09/28/10 03:58 PM
09/28/10 03:58 PM
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Joined: Dec 2005
Posts: 1,495
Shelby mi.
JAKE68
pro stock
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pro stock
Joined: Dec 2005
Posts: 1,495
Shelby mi.
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Randy, I am sitting here thinking of your question If I had to guess you would pick up et and loose some mph? Maybe. Or pick up some et and no gain on mph. I look forward to doing some tuning.!!!!!!!!!!!!!!!!!!!!!!!!
JAKES AUTOMOTIVE
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Re: ADVANCING CAM TIMING 2-4*
[Re: Labratt]
#814525
09/28/10 07:20 PM
09/28/10 07:20 PM
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Joined: Jun 2005
Posts: 793
Utah
topbrent
super stock
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super stock
Joined: Jun 2005
Posts: 793
Utah
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Quote:
..just by porting the heads and getting a GOOD valve job,I should be running 10's in good weather conditions?
Randy, you keep referring porting the heads and getting a GOOD valve job as separate things.
Is there something you feel is wrong or lacking with the valve job that Jeff @ MCH gives the heads when he CNC ports them?
His list of clients is pretty impressive and most seem very satisfied with his work and the results of his labor. I have heard nothing buck good about his work. Just curious if you know or have heard something otherwise.
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Re: ADVANCING CAM TIMING 2-4*
[Re: topbrent]
#814526
09/28/10 08:00 PM
09/28/10 08:00 PM
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Joined: Jan 2003
Posts: 17,914
S.E. Michigan
ZIPPY
I Live Here
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I Live Here
Joined: Jan 2003
Posts: 17,914
S.E. Michigan
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There's no doubt ported and milled heads would, most likely, get it where Randy wants it to go. Simple one stop shopping.
But I'm wondering if all the low buck tricks haven't been used up yet?
Randy I noticed you had some sort of cutouts in the exhaust? Being that the car is trailered, why not take the pipes off completely to save a few lbs and put collector extensions on?
Open headers was worth 40 ft lbs in mine, back when it used to have 3" exhaust, St Dominator intake, 850, smaller headers etc. If I hadn't limited myself to no trailer/being too broke to buy one anyway/must run through the exhaust, I would have made alot less work for myself......
Another thing, the car has both a clutch fan AND an electric fan on it. Why not take the clutch fan off completely at the track? It might make a difference.
Rich H.
Esse Quam Videri
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Re: ADVANCING CAM TIMING 2-4*
[Re: Labratt]
#814528
09/29/10 01:05 AM
09/29/10 01:05 AM
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Joined: Jan 2003
Posts: 931
dulcich
super stock
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super stock
Joined: Jan 2003
Posts: 931
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I would advance it to 102, and run it there. You will likely pick up low end, and I would be willing to bet you will not notice any loss in top-end power. Many times the cam timing thing is not a direct "take from here and give to there" trade-off. Usually with a fairly long cam and less than optimal compression, you will gain torque at the bottom advancing far more than you will lose top-end.
The change will be moderate, so don't expect a night and day difference, especially with a good amount of stall and the cam already in at 105. The ported heads and higher compression would be much more dramatic, but of course a cam timing change doesn't cost anything.
Not wanting to be a master of the obvious here, but if you want to go for the big step up, Jeff's porting works very well on the E-heads, and you can increase the compression at the same time with milling. Jeff is the real deal from the work I've seen. Frankly, at the risk of sounding like a jerk, I have also seen plenty of work by various internet board "heros", here and elsewhere that is average at best. Only a select few are really accomplished at port work.
I would have no hesitation to run it at 11:1 or even 11.5:1 on pump gas with good quench and aluminum heads in street/strip application with a 260+ cam.
-dulcich
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Re: ADVANCING CAM TIMING 2-4*
[Re: dulcich]
#814531
09/29/10 01:40 AM
09/29/10 01:40 AM
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Joined: Oct 2006
Posts: 4,765
quick77rt
Parts Problem
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Parts Problem
Joined: Oct 2006
Posts: 4,765
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I love your car by the way, that year and color, I painted a KZ900 that color as well. Anyway... I like this reply, it seems im on the right track. Maybe as far as advance goes. My cam is a solid in the 270s intake 280s in the ex, at approx 8k ft actual altitude im about 45 plus pounds down on cranking comp so my cam is advanced 4 degrees to bring the powerband down a bit and with a 4 inch crank and .033 quench, al heads, almost 11.1 its one of my better running combos. The cam advanced 4 degrees sets mine at 102 as well and produces enough tq to launch the car just as the cam comes on hard, (Foot brake to 3800)Can go 4300 on the brake. It says it likes 4000-7400 but with the longer stroke it likes 7200 vs 7400 and falls hard off at 7600. And it pulls hard to the 7-7200 area....I think I got lucky. I guess im using the low end tq to launch and drive into the cam and I think if setup is semi right it makes a great street strip car. Quote:
I would advance it to 102, and run it there. You will likely pick up low end, and I would be willing to bet you will not notice any loss in top-end power. Many times the cam timing thing is not a direct "take from here and give to there" trade-off. Usually with a fairly long cam and less than optimal compression, you will gain torque at the bottom advancing far more than you will lose top-end.
The change will be moderate, so don't expect a night and day difference, especially with a good amount of stall and the cam already in at 105. The ported heads and higher compression would be much more dramatic, but of course a cam timing change doesn't cost anything.
Not wanting to be a master of the obvious here, but if you want to go for the big step up, Jeff's porting works very well on the E-heads, and you can increase the compression at the same time with milling. Jeff is the real deal from the work I've seen. Frankly, at the risk of sounding like a jerk, I have also seen plenty of work by various internet board "heros", here and elsewhere that is average at best. Only a select few are really accomplished at port work.
I would have no hesitation to run it at 11:1 or even 11.5:1 on pump gas with good quench and aluminum heads in street/strip application with a 260+ cam.
-dulcich
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Re: ADVANCING CAM TIMING 2-4*
[Re: quick77rt ]
#814532
09/29/10 11:18 AM
09/29/10 11:18 AM
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Joined: Sep 2009
Posts: 2,325
Clinton Twp... north of Deetro...
Labratt
OP
Good Ol Randy B!
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OP
Good Ol Randy B!
Joined: Sep 2009
Posts: 2,325
Clinton Twp... north of Deetro...
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Mark,Ron,Steve...For me, there are only 2 head porters that I would use..not that there's not a LOT of good ones out there,but Jeff at Modern is only 30 minutes from my house,and I do know him from past help he and his brother,Bob,have given me, when I installed my Comp SQ lobe cam 2 yrs. ago! They're BOTH GOOD GUYS! The other,who actually picked out my cam,is Dwayne Porter..another GREAT GUY! Can't go wrong with either one of them!  What Steve said on advancing only 2* makes sense. Might not make a big difference,but should help torque some..without giving up any top-end power! Sooo..2* advance..CNC'd heads..mill heads for 11-11.5 CR,if I have the clearance..collector extension..remove clutch fan..sounds like a solid recipe for a 10 second time slip..in good air! 
Last edited by Labratt; 09/29/10 11:21 AM.
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As long as I get a 10 second time slip in my grubby little hands! 
