Hypothetical cam question...how would it run?

General engine tech -- Drag Racing to Circle Track

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travis
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Re: Hypothetical cam question...how would it run?

Post by travis » Sun May 13, 2018 8:17 pm

jeff swisher wrote:
Sun May 13, 2018 8:49 am
Both were 102 ICL.
I liked the MPG increase so much that i almost want to try 117 LSA
I am sure doing it the way I had him do it the upper end power would be horrible.
And then in the back of my mind i think dual pattern grind may be an advantage here.

But I stop where i am at and enjoy driving the thing.

Here is a crappy video with the cam ground on a 106LSA watch the tachometer swing to 7000 rpm
I had to make that video to show naysayers that 305 heads do not quit flowing air at 4500rpm.
Where some people come up with that nonsense.

https://www.youtube.com/watch?v=hivG7qlPTZA I had 325 gears in it at that time.

When i switched to 456 gears and 4500 stall for giggles first time I got on it the engine swung to 7200rpm and floated the valves just a wee bit.
I have 80 psi seat pressure on that build.
I wonder if the big increase in mpg was from the 12* difference in overlap, or the earlier opening exhaust event cutting the pumping losses, or some combination of both? Did the top end fall on its face from the reduced overlap or from the earlier exhaust closing? What if you was to add 6-8 degrees on the exhaust side on the 112 lsa version?

How was the idle quality and off idle part throttle response between the 106 and 112?

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Re: Hypothetical cam question...how would it run?

Post by jeff swisher » Sun May 13, 2018 11:07 pm

This thing revs quick..with either cam you can't tell you changed cams until you got past 5700rpm then you notice it just did not pull as hard and you shift at 6000 rpm.
When at the track i could shift the 106LSA at 5500 or 6700rpm or anything in between and made only .2 difference in ET.
If I shift this one (the 112LSA) at 6500 rpm it will make over .5 seconds difference because power just falls off.

Now that was with exhaust manifolds.. just 5 days ago I installed full length headers and had to rejet because it was so lean.
I got a lot of that power back that i lost on the topend when going to the 112LSA.
Headers make my exhaust scavenge much better.. I knew that would or could possibly help out.

I think the loss of overlap killed topend as the heads are ported 601's which are just 305HO heads and small 1.84-1.50 valves.
The crappier the head the more overlap really helps them out.

To explain how responsive this thing is : I let people drive it and it takes them usually 6 times of touching the throttle before they quit jerking your head back.
You barely touch the throttle and the thing jumps out there.
Solid mounts help that a bit and Leaf springs set up like mopar super stocks so the ass end does not squat.. just rares up a tiny bit and lunges forward.
The converter is a 600-800 over stock stall and will flash to 2400.
little runners help it out also.

On the 351 van deal.
I installed ported 351W heads on a 302 but NOT the early 1969 small chamber.. that 302 was a putz.
had an earson 292 cam and like 214 @ .050 or something small like that.

Pulled those off after a month while buddy was porting his 302 heads and the 302 heads got installed and power came way up.
That was a buddies deal..I said that large 351W chamber was going to kill the power.

I always thought some worked over 289 head would be best for the 302.
That was before GT40 heads and the like.

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Re: Hypothetical cam question...how would it run?

Post by travis » Mon May 14, 2018 12:33 am

Any idea what that ‘47 weighs?

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Re: Hypothetical cam question...how would it run?

Post by jeff swisher » Mon May 14, 2018 9:10 am

The 47 dodge weighed in at 3176 lbs.
Currently the 350 engine with the 112LSA is in a 1957 4 door chevy car that weighed 3600 lbs. it was 1/2 second slower in the 1/4.

I had built a 385" stroker for the 47 with a 280H comp magnum flat tappet hydraulic on a 110 LSA with some 601 heads.
I have 6 sets of those heads i really like them.
That stroker was just ridiculous . I could at least get the 350" engine to hook up if I drove out of the hole correctly.
The 385" is a different story.. it just blows the tires off even at 45-50 mph in second it would haze the tires.

In a race i would be left behind by the 350.
Unless I fixed the traction issues.
I even ran a super tight 1500 stall converter.. that is all you could flash it to 1500 behind the 385". That did not stop it.

The compression was 11.3 on the 385"

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