Am I wanting too much from the 60919 cam?
 

Finally did 2 test runs yesterday. Car did not pull in the last 1/8 mile of the run like the old cam I was using.

I have 1.65 Scorpion rockers, but with spring pressure applied they are 1.62 ratio. So the 60919 has .507 lift and the old cam had .532 lift with different duration-246/252 flat solid cam.

I realize the 60919 is a mismatch for my engine, but I had the cam so I thought I would use it.

1965 GTO 3800 lbs car and driver
t-400, 3.73 gears, 28 inch tires
428 .030 over , 9.7 compression
9380 Holley, 850 annular
RPM intake
670 heads, ported
1 5/8 headers, full exhaust

1st run 2nd run
1.693 1.689
7.781 7.769
87.35 mph 87.95 mph
12.335 12.289
107.40 mph 108.20 mph

With the old cam, those 60 foots would give high 11's for 1/4 mile times at 113 mph. I was thinking the 60919 would be at most 12.20.

Since we were rained out, I did not get a chance to tune/change anything.

Anyone have similar numbers for the 60919 or think something might be off, say carburetor, etc?

I did the same thing but in reverse. Swapped a RAIV for a 247/252 112 Crower SFT in a .030” over 455 and gained nothing. It ran identical times and drove on the street the same. In my case it acted like a solid flat version of the RAIV.

I think Cliff has done lots of dyno & drag strip testing, with the 60919 cam, 1.65 rockers, & Rhoads lifters. He can post his results, and has.

You are giving up lift and duration compared to your other cam and apparently your combo didn't respond well to those changes. Also looks like the 60919 may be done by 5000 rpm in your 428. Where are your shift points? On a different note, I noticed you are running 1&5/8 headers; I think you would benefit from 1&3/4" headers, and 2&1/2 inch exhaust pipes if not already that size. We have had good luck with 3" collectors from the header to an x-pipe and then 2&1/2 inch pipes out of the x back to the mufflers, then 2&1/2" tail pipes.

Shift points, I did 5700 rpm first run, 6000 rpm 2nd run, and was going to try 5500 on a third run but the rain started and did not stop. So as of now I don't know what is best. If you are correct and 5000 rpm is the limit, I will need to lower the rpm. Those headers were on the engine when I purchased the car many years ago, still in good shape. I welded a 3 inch exhaust system with homemade x pipe. I'd like to redo it (moving the mufflers and tailpipes ) with something similar to what you have, prostreet.

tc, I am curious why you switched cams; did the old cam get wiped or are you just experimenting with the 60919 since you had it on hand?

I noticed many broken inner valve springs ( they were on the engine many years ). Disassembled the engine and noticed a worn lobe on the SFT cam. I had the 60919 and had never used it. I did not want to purchase a new cam for this 428 as I have another 428 that will get a new cam, ( hopefully ) better heads, for my '68 Firebird. I was expecting slower et's, but after having such good 60 foots I was wondering if I had something not right.

If forum members think the car runs what it should with the 60919 cam, I'll get back to working on the bird, when I have the time for that. I'd like to get the GTO running good for the BOP day at Cordova.

Made the switch from a ram air 4 cam solid lifter to a Crower 60311 solid 48 52 duration picked up very little

Obvious. When going from a hydraulic cam to a solid cam you should increase the amount of intake duration for similar results. Opposite when going from a solid to a hydraulic. How much difference is often open to a spirited debate and or opinions... and it depends on the lobes involved be it Comp Cams, UltraDyne, Crower, etc. No set rule.


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Did you degree the cam???
ICL???
Total timing???

Yes, the cam is in at 109
total timing at 34 degrees

Like Steve C said, when going back and forth between a hydraulic flat tappet and a solid flat tappet, You generally have to add about 15 degrees of duration on the solid to produce similar results to the hydraulic. As most solid flat tappet cams will loose about 15 degrees of duration with lash.

So it's no surprise that many have tried this and find the car runs very similar when they are moving from a 230 @ .050 hydraulic to a 247 @ .050 solid. They will act nearly the same.

If you switch to a solid flat tappet and want to see improvements over the hydraulic you're running, you'll have to increase the duration more than ~15 degrees. Otherwise it's a wash.

as expected you would lose some bottom end switching to a hyd from a solid cam. the solid cam has a true 532 lift. the hyd lift due to the lifters you lose about .30 lift or more . so that 470 lift cam ends up being a 440 lift cam. less lift =less power for those ported heads....

It will depend on the cam profile. This is a SBF cam (lobe lift data from a Cam DR file) that was to use 1.65:1 rocker arm ratio and 0.021" lash. 0.021" lash is 0.12727" lifter raise.I rounded to 0.013"

► 267.84 - 258.27 = 9.57 degrees less

Stan


CAM_______Lift______Opens___Closes__Duration
_________________Deg_BTDC__Deg_ABDC_____________Ar ea

_________0.00600____56.01_|__92.95_|_328.96_|__39. 04
_________0.01000____50.50_|__87.43_|_317.93_|__39. 00
_________0.02000____41.86_|__77.65_|_299.51_|__38. 83
_________0.04000____30.98_|__65.35_|_276.33_|__38. 48
_________0.05000____26.89_|__60.95_|_267.84_|__38. 29__<<<<<<
_________0.06300____22.24_|__56.03_|_258.27_|__38. 00__<<<<<<
_________0.10000____11.47_|__44.82_|_236.29_|__37. 07
_________0.15000____-0.70_|__32.36_|_211.67_|__35.53
_________0.20000___-12.08_|__20.95_|_188.87_|__33.37
_________0.25000___-23.72_|___9.23_|_165.51_|__30.83
_________0.30000___-36.39_|__-3.48_|_140.13_|__27.21
_________0.35000___-51.53_|_-18.59_|_109.88_|__22.27
_________0.40000___-72.76_|_-39.65_|__67.59_|__14.31

That was my impression, it is cam specific, but in general, @ 10 degrees diff between HYD & solid. Or should one say 'performs as if it's 10 degrees difference'?

The 919 does give up earlier than one would expect though, you may just be seeing typical results. With your setup, you can easily go bigger.

My understanding is that with iron heads, depending on the porting, you generally don't see much flow gain over around .500-.525 lift. So duration is your friend with iron heads. In stock form, iron heads' flow rounds out @ .470-.490 lift. At least that's my understanding.

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34 degrees total is low for the closed chamber in the 670 heads.

I would have liked to have seen you try 38 had it not rained on you!

The 60919 cam is a bit too much for a 428 build with only 9.7 to 1 compression, but should be OK. The 428's are considerably more efficient that the undersquare 455's so I like to tighten up the LSA some and put more cam in them. They will easily make the power numbers of a 455 without a lot of additional RPM's.

The last one I did here was 10.6 to 1 compression, unported KRE aluminum heads (74cc chambers), exactly zero decked, Oliver rods and Ross flat top pistons. I used a customer ground HR cam from Comp with XFI lobes, 236/242 on a 110LSA. ICL at 108 degrees. It made 497hp/540tq and 12" vacuum at 800rpm's. Peak HP at 5800rpm's so you can clearly see how efficient they are as most similar 10 to 1 455 builds make similar power but down at 5500-5600rpm's. It also made those numbers with an iron intake, and swapping on the RPM right on the dyno lowered it to 491hp.

We didn't test a T-II with a 1" spacer but I'll bet it would have picked power up about 10-15 over the iron intake just from what I've seen with 400's and 428's on the dyno, they seem to respond very well to single plane intakes being more efficient at higher RPM's.

I can see that a RAIV size cam would produce a "flat" power curve in a 428 and not surprised it doesn't really work quite as well as expected. 12.20's still isn't bad for the combination....IMHO......Cliff

With a somewhat similar UD 288/296 cam in my old 455, I lost e.t. rapidly if I shifted past 5300.

IMHO start low on shift points, and work your way up. No sense in exposing your engine to unnecessary RPM.

Of course depending on the lobe profile goes without saying. That's why I used words like "most" and symbols like "~" in my post. I simply explained it in a very simple manor that everyone could understand. I enjoy the details and appreciate them being posted, but as we know, there are many people here that can't even degree a camshaft, let alone understand the lobe profiles, lol.

Above is from a thread on another forum. -- Tight lash camshaft questions
https://www.speed-talk.com/forum/vie...101ec2e72ce4be

When I get sometime I will see if I can find the numbers from that Engle cam.

Stan