What's the most power you've been able to achieve?

[kmathis]

Spoke to John at Delta again this morning and he is going to send over the specs for the cam later today...when I get them I will post them for our enjoyment...

He hasn't had a chance to check to see if there are any differences from the original specs on the cam itself...however he is going to grind a cam to be sure it is true to the original and let us know.

 

[kmathis]

See Below for the cam specs from Jon at Delta.

Subject: cam specs

int duration 252 x .478 lift
exh duration 245 x .454 lift


duration is at .050" lift
rpm band 2600-5800


above standard street use but not a race cam I'd call it Hot Street




Thank you,


Jon Bodwell

 

[260Alpine]

Hey Kelly, That duration @ .050 lift seems pretty high. The lift numbers I like. Anything over about 230 has a pretty rough idle. I've had some high duration cams and like others have used high initial timing up to 20 degrees. I still measured about 4-6 manifold vacuum at idle. The specs on the 350 Buick V8 stroker motor are 226 duration and .488 lift. It has 400 flywheel HP.

 

[MikeH]

RootesRacer: I did a search on the Jose cam grind and found the following on our forum from a 2009 posting by Jose himself:

Intake: 290* duration
Exhaust: 280* duration
Lift: as close to .500 as your billet will allow.

I hope this is useful. I am enjoying this discussion - there is always more to learn!

I found a copy of the spec that jimE sent me. It matches what kmathis posted in the thread. Here is the thread that has the duration you indicate.
http://www.sunbeamalpine.org/forum/archive/index.php?t-10314.html

jimE thought the grind was DEL-111

 

[260Alpine]

Here is a good article on the subject:

http://www.streetrodlife.com/tech/big-cam-street-improve-drivability-part-1/

 

[RootesRacer]

RootesRacer: I did a search on the Jose cam grind and found the following on our forum from a 2009 posting by Jose himself:

Intake: 290* duration
Exhaust: 280* duration
Lift: as close to .500 as your billet will allow.

I hope this is useful. I am enjoying this discussion - there is always more to learn!

Thats a pretty stout cam, I assume that the duration figures are at .05" lift.

Not a full race cam but perhaps 3/4 race if you will.

 

[kmathis]

Jose always called it an "almost 3/4 race cam" in using this cam before I did get some rough idle but the timing was at about 14 deg BTDC. So, the jury is still out as to why I have so much timing now.

Delta is going to grind one next week and check it to be sure it is true to the original specs. I have done other performance mods to my engine, so that probably adds to the issue. Overall I am happy with the way my engine runs, however if there is an issue with the cam, I will change it out.

Glad you guys like these specs...I know the fundamentals about lift and duration, but overlap, and degreeing and all of that is over my head.

 

[MikeH]

That's a big difference between the specs Kelly posted and Todd posted.
Kelly's at 252/245 and Todd's at 290/280. As I posted earlier Kelly's matches what Jim E's card shows.
Jim E's card also shows 110.1 cam degrees in lobe center separation. And valve overlap of 29.7 crank degrees.
Jim's old post no longer has the picture, but I have a copy. Kelly and Todd, what compression ratio are you running. if the longer duration increases overlap, then compression needs to be considered. This article answers some questions.
http://www.compcams.com/v002/Pages/404/camshaft-faq.aspx#compressionratio

 

[260Alpine]

Mike, the two different durations are equivilant. The smaller numbers are @.050 lift. the larger are advertised duration. I think you should have 9.5 to 10.5 compression with that cam.

 

[MikeH]

Mike, the two different durations are equivilant. The smaller numbers are @.050 lift. the larger are advertised duration. I think you should have 9.5 to 10.5 compression with that cam.

Thanks for clearing that up.
Here is Jim E's cam card.

 

[MikeH]

Good explanation of cam terms.

http://www.lunatipower.com/Tech/Cams/CamSpecTerms.aspx

 

[DanR]

Mike, the two different durations are equivilant. The smaller numbers are @.050 lift. the larger are advertised duration. I think you should have 9.5 to 10.5 compression with that cam.

And I built on jose recommendations of 8.5

 

[todd reid]

Dan,
I think Jose also recommends shaving the heads to raise compression. The article Jim attached states that raising compression is one way to overcome idle issues with a long overlap cam.

Kelly,
Jim's article would imply your current engine's thirst for timing means that it has lower compression than your first one, but you are pretty sure that is not the case - right?

Another possible explanation is that Delta has somehow unintentionally altered the spec's to the "Jose grind".

TR

 

[kmathis]

I am positive that is not the case. My first engine had .060 deck clearance, as I had shaved the block.030 to raise the compression to 8.5. My current deck clearance is .000 My stock deck clearance was .090.

That first engine ran great, with no idling issues...meaning it had a definite lope to it, but it idled at 7 - 900 rpms no problem. Now mine idles at 1100 - 1200 rpms with a heavy lope, and I'm ok with that.

I'm not positive what my compression is now, as I have lost the original cc measurement of the combustion chamber.

 

[DanR]

Todd, Your comments: Another possible explanation is that Delta has somehow unintentionally altered the spec's to the "Jose grind".

TR"

IS a possibility I raised awhile back. When I pull this cam I will probably send it to Delta for their evaluation.

DanR

P.S. Had a two hour drive yesterday, running thru all the gears and trying to figure where it did best....As usual in the higher RPM range above 25K.

It acts as if it has my Camper hooked to the rear at 2k in third, 4th & 5th. Raise the rpm to 3K it begins to climb based upon the easing (slowly mashing) of the accelerator, which allows some vacuum. If a hard press of the pedal regardless of RPM it has zero vacuum on up thru 5-6RPM.

 

[260Alpine]

Guys, Dynamic compression is most important. With a hot cam it usually needs the cam advanced 4 degrees to lower the RPM range. For example the Buick cam in the MGB wasn't big enough for what Chris wanted. initially it was advanced 4 degrees and it had 200HP at 2000RPM and max power at 4500RPM. We retarded it 4 degrees and the power curve moved up to 200HP at 3000RPM and max power at 5500RPM. For 4 degrees cam timing the power band usually moves about 500RPM. We moved 8 from 4 advanced to 4 retarded. If running over 10 to 1 you should check piston to valve clearance also. You would do just the opposite with this cam to lower the power band. Dynamic compression number should be between 7-8 to run pump gas. Initially we had 9 now it is at 8. There is a formula for figuring Dynamic compression. I use a desktop Dyno program. I can run this cam at different compression ratios to see. I would need intake open @ BTDC, close @ ABDC. Exhaust open @ BBDC, close @ BTDC. I see it is in the cam card. I'll get right on it. Kelly, at zero deck you probably have over 10 maybe even 11 to 1 compression.

 

[MikeH]

The card I posted shows
I opens @ 14.9 BTDC. closes @ 58.1 ABDC
E opens @ 50.6 BBDC closes @ 14.9 ATDC

 

[260Alpine]

Guys, Here is what the program shows: Cam straight up 8 to 1=5.5, 9 to 1=6, 10 to 1=6.9, 11 to 1=7.5. 4 degrees cam advance 8 to 1=5.8, 9 to 1= 6.5, 10 to 1=7.2, 11 to 1=7.9. 8 degrees cam advance 8 to 1=6, 9 to 1=6.8, 10 to 1=7.5, 11 to 1=8.2. This tells me ideally you should have 10 to 11 to 1 for straight up. 9.5 to 10.5 to 1 for 4 degrees advance. 8 degrees advance 9 to 10 to 1. all graphs in the 7 range show 190 to 200HP. I'll do a chart with a lower duration cam next.

 

[260Alpine]

Milder cam, INT 230 @ .050, EX 220 @ .050 duration. Still makes 185-195hp @ 6000RPM. Straight up 8 to 1=6.3, 9 to 1=7.1, 10 to 1=7.8. 4 degrees cam advance 8 to 1=6.5, 9 to 1=7.3, 10 to 1=8.1. Straight up 9 - 10 to 1. 4 degrees advance 8.5 - 9.5 to 1. Remember you want 7-8 dynamic compression. Octane of gas required, 87 to 93 correlate to Dynamic compression, 7 for 87 and 8 for 93.

 

[Charles Johns]

Maximum HP

I raced for several years with a 1940 Ford coupe and much modified 283 SB Chevy. There is an old saying among race engine builders..."I want it to win the race then blow up just as it crosses the finish line. That way I know I got all I could out of that engine!" DO NOT build an engine to-the-max for the street!