|
By Richard - 11 Years Ago
|
I called Comp Cam to see what they offer for the Y Block. They have two, but recommended to me the smaller one for the street. They call it a Thumper Cam P/N 37-600-5 $196.00 Lifters P/N 2931-16 $169.00 Free shipping no tax outside Tenn.@ .050 intake .231 duration .479 lift Exhaust: .245 duration .470 lift. I will be using 1.60 ratio rockers Has anyone had any experience with this cam or thoughts on the specs.
Thanks
|
|
By Oldmics - 11 Years Ago
|
Using 1.6 rockers ?And those lifts are correct at the 1.6 ratio?
Oldmics (just curious) |
|
By Richard - 11 Years Ago
|
|
No, the specs are for 1.5 ratio, sorry I did not note that, I am using 1.6 which the tech guy said would increase lift, however I did not request the change. So good point, before or if I buy I will clarify.
|
|
By RB - 11 Years Ago
|
|
I am not a fan of Thumper series of cams from Comp.. In my opinion they are poser cams, designed to make the engine sound tough idling, but far from optimum for making power or mileage. Notice the huge difference between exhaust and intake duration.. That is how they get the racy idle sound, by opening the exhaust valve very early. Great for cruising the drive-in but not great for anything else. However, Comp will grind any lobe in their catalog on a Y Block blank if you ask them. I did not see or search as to what your intended use might be for the engine. If it is a full size car with an automatic I would dial back the intake duration 5-10 degrees. Something like the Comp 270S.. Or you could go with one of Mummert's cams that have been well developed for specific applications... You can do a lot better than a Thumper cam unless you want the hot rod idle and don't care about power or economy
|
|
By Richard - 11 Years Ago
|
|
Thanks that what I thought, I don't need the rump rump just thought I would see.
|
|
By NoShortcuts - 11 Years Ago
|
|
I'm not sure we've got enough application information to give you suitable camshaft advice, Richard...
In an earlier posting you said...I have a modified 312...Mummert pocket ported heads, B Manifold modified with matched ports, Holly 600 cfm dbl pumper, 57 exhaust manifolds with matched ports
Clay Smith C-284-8b Duration at .050 234* lift .450 Dove rockers 1.6 ( may increase lift ) Engine balanced. Manual Trans T85 w/od. I have a vintage mallory and a stock 57 dizzy's with points for now.
Questions:
1) stock cylinder bores? (3.800 inch diameter)
2) flattop pistons? 3) what cylinder heads? (need to understand static compression ratio and intake valve size) 4) 'B' intake manifold modification? Did you write in an earlier thread that you connected the primary and secondary throttle bores on each side? 5) carburetor to manifold spacer type, construction material and thickness
6) Holley 600 cfm double pumper with mechanical secondaries? 7) rear end gear ratio? 8) wheel and tire size
9) primary intended use of your '54 station wagon... street and highway?
IF you share the above info, I'm sure there are Forum members who will be able to share their cam selection experiences...  |
|
By miker - 11 Years Ago
|
Having a flat lobe on #1 exhaust, I just went thru the process of selecting a cam. The motor is fairly high compression and modified. Ted Eaton, John Mummert, and my local engine builder worked with me till I was able to make a choice.
I found a couple Dynamic Compression Ratio calculators on the net, although neither exactly duplicated Ted's analysis. It took a lot of head scratching, and I never felt I understood all. I ordered a standard grind on custom lobe centers from John.
Links I was sent, and found useful:
http://www.popularhotrodding.com/tech/0607phr_camshaft_basics/photo_11.html?__federated=1
http://www.popularhotrodding.com/enginemasters/articles/hardcore/0606em_camshaft_specs/viewall.html
https://www.uempistons.com/index.php?main_page=calculators&type=comp2&zenid=8e9027fc60bbc5227c417444b739f709
Given what it take to change the cam and lifters on a Y block, I hope I got it right.
You can apply this info to your application. All the comments above still apply, especially Charlie's about the engine/drivetrain spec's
|
|
By Richard - 11 Years Ago
|
|
I talked to John Mummert and going with the same cam as before. Clay Smith 284. I pulled the motor yesterday and doing the teardown to see if I caused any other damage. The advice to disconnect the bell housing from the engine was great advice. I put a transmission jack with wheels under the trans for support.
Richard
|
|
By NoShortcuts - 11 Years Ago
|
With 68 degrees of overlap, that's quite a cam, Richard!  It would be interesting to figure out the dynamic compression ratio for your engine combination with the intake valve closing so late with this grind.
Y-284-S 284° 236°@.050" 108° Lobe Separation Valve Lift .465" Valve Lash .018" IO 34 BTDC IC 70 ABDC SPRING PRESSURE 105# SEAT 240# OPEN EO 70 BBDC EC 34 ATDC Let us know how things go as you dig into the engine internals after having the cam lobe failures. Best Wishes,
|
|
By PF Arcand - 11 Years Ago
|
Did you discuss with Mummert, his Y-280-1 (107 or 111 LSA) cams? He has had terrific results with that grind in Y-Blks & apparently the 111 LSA has a liveable idle too. The results are available on his site & are impressive..
|
|
By miker - 11 Years Ago
|
|
What I ordered was the Y-284-S, ground on 113* lobe centers which we're going to install 4* advanced. When done, we'll do a couple dyno pulls (sorry, chassis dyno) to recurve the EFI and advance curves, and I'll either be a proud poppa, or a "don't do this" when I post the results. And it's a Clay Smith cam.
|