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#1
07-21-2020, 12:46 PM
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All Summit 2801 cam vacuum
If you have ever used a summit 2801 what kind of vacuum did you have?
I am sorting some things out and was curious what I could expect in the form of vacuum with this cam. Thanks for your reply Greg |
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#2
07-21-2020, 01:21 PM
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Depending on your engine and static compression you should have between 16 and 17 hg maybe even a tad more
__________________
Tim Corcoran |
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#3
07-21-2020, 01:35 PM
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Quote:
13 heads 9.5:1 pontiac 1965 tri power 2801 cam w adjustable rockers cam degreed by machine shop Summit ready to run dist. adj vacuum can 12-13 inches of vacuum Still sorting alot of things out Only running center carb for start up Greg |
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#4
07-25-2020, 03:44 PM
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The car idles well now?
Little more back ground on your deal with this engine>?? Fresh rings, bore, rering or valve job, etc.? Have you driven it under load to seat the rings yet? |
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#5
07-25-2020, 06:41 PM
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Quote:
Greg |
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#6
07-21-2020, 03:31 PM
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"2801 cam w adjustable rockers cam degreed by machine shop"
Where did they put it in at? Ignition Timing at idle? Deck/COmpression Ht of pistons? Valve relief CC? Gasket thickness? 13 are 72CC ...stock IIRC??? Calculating your CR. Last edited by STEELCITYFIREBIRD; 07-21-2020 at 03:50 PM. |
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#7
07-21-2020, 08:12 PM
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The Summit 2801 is very close the the original tri power cam (Melling 068). You should have plenty of vacuum to run power brakes. The only thing I see sketchy in your combo is the Summit distributor. Never had any luck with anything except an original Pontiac dist.
__________________
LEAD, FOLLOW, OR GET THE HE!! OUT OF THE WAY!!! HONEST JERRY'S SPEED AND EQUIPMENT
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#8
07-21-2020, 08:51 PM
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Quote:
Greg |
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#9
07-21-2020, 10:54 PM
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Quote:
__________________
1977 Black Trans Am 180 HP Auto, essentially base model T/A. I'm the original owner, purchased May 7, 1977. Shut it off Shut it off Buddy, I just shut your Prius down... 
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#10
07-22-2020, 09:44 AM
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I run the Summit 2801 in a 400 9.25:1 compression in an automatic with 3.08:1 gear. Heads had some work done and have headers with a stock intake. Vacuum is 17.5" and is a really good cam in a 400. Best band for your buck type of deal
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#11
07-22-2020, 12:50 PM
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Something's not right. I had 14+" vacuum in a 9.25:1 400 with a comp xe274. I would expect a minimum of 16" vacuum from that cam unless your compression is really low.
__________________
---------------------------- '72 Formula 400 Lucerne Blue, Blue Deluxe interior - My first car! '73 Firebird 350/4-speed Black on Black, mix & match. |
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#12
07-22-2020, 10:21 PM
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compression check
1 167 2 167 3 160 4 165 5 160 6 155 7 162 8 167 #13 heads ccd at 77 with 7cc relief Flattop pistons I don't know any more Greg Last edited by footjoy; 07-22-2020 at 10:26 PM. |
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#13
07-23-2020, 09:18 AM
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Following both threads.
Is you vacuum steady at idle? Off idle? ~ 2k RPM? |
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#14
07-23-2020, 04:22 PM
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Quote:
Idle 11 inches of vacuum 1400 rpm 14.5 inches 2000 rpm 16 |
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#15
07-23-2020, 04:51 PM
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If the needle is steady,I'd try advance the timing,
Current ignition timing? Idle RPM? Do you have vacuum advance connected? Some good diagnostic info: https://www.crankshaftcoalition.com/...gine_diagnosis Last edited by STEELCITYFIREBIRD; 07-23-2020 at 05:03 PM. |
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#16
07-24-2020, 08:20 PM
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Greg, My new 400 build has 9.94 to 1 compression, the 2801 cam, stock exhaust manifolds, 2.5" exhaust system, Q-jet carb on the stock iron intake.
It's a fresh build and still breaking in (maybe 10 miles on the engine since it was installed a few weeks ago). The heads are 1970 small valve #16's. Timing is 12 degrees initial; 36 degrees total (by 3000 rpm) and has a 10 degree vacuum advance cannister for 46 degrees total for cruise. Vacuum at 800 rpm idle (no vacuum advance) was 15.5 - 16.0 inches and we expect it to go up a couple pounds with more miles as it breaks in. The running temperature was 180 - 190 degrees on an 85 degree day. Cylinder pressure was consistent at 175 in each cylinder. The cam was installed straight up (I don't recall the intake centerline). Dennis |
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#17
07-24-2020, 09:46 PM
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Quote:
I just sent the carb to Dick Boeneske to go through, it was not idling at all. I was surprised I thought my compression test would ne higher. with almost 10:1 compression. I have been following your build and am quite impressed. I found out my small valve 15s ccd at 90 cc which gave me about 8.1:1 compression on the previous build. Good to hear from you. Greg Last edited by footjoy; 07-24-2020 at 09:57 PM. |
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#18
07-25-2020, 08:19 AM
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I'm running the 068 in my 70 400. 10.13:1 compression with the original 12 heads.
I run 14 initial timing with 34 degrees total all in by 2600 rpm. I run an additional 10 degrees of vacuum advance. I installed the cam on a 108 ICL. I have a solid 13 inches of idle vacuum at 5,000 feet elevation. At sea level it's a little over 16 inches. Very small cam for a 400, idles smooth, very docile. The engine has been perfect on 91 octane for a few years now. |
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#19
08-07-2020, 10:08 AM
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Good base line, note the ignition advance /rpm @ idle and compare after seating rings.
Good you made progress! 
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#20
07-24-2020, 08:46 PM
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Dennis I would try removing the vacuum advance and bringing up the initial to 18 or 20..... You will need a 160 thermostat to do this... I would try 89 gas too if your using 87..
The 2801 is an excellent cam for a powerful street Pontiac motor.. |
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