4-7 Cam swap?

[Camaros79_83]

I was wondering if anybody has done this yet,and would it be worth doing on a street motor? I am building a 395 small block for my 79 and was woundering if this would be worth the $125.00 extra on the cam.I am going to do this with my race motor,but I was wanting to see if anybody has done it in a street motor.

Thanks
Junior

 

[warped]

This has been discussed here in the past a few times. If I remember correctly, there is little benefit to a street motor. The mags and TV buildups show HP gains that don’t seem to be attainable for the average motor build. If you are a serious racer and looking for that last little bit of HP gain, it might be worth while, but probably not for a street motor. Good luck.

 

[Marv D]

Here's the unoffricial word from some very experienced builders and designers I know. The 7/4 swap helps smooth out some harmonics in the small block. When Jay Allen did a cam change in a big inch SBC they found something like 4HP (running in the 750-800HP n/a gas motor). That's it,,, 4hp, and the only documented comparison that I know of.
Chris U had a lot of thought put into the matter when he was running the 352" small block The hopes was it would help eliminate some wierd sonic pulses in the intake flow or something like that (they suspected was causing some fuel distribution issue the motor was seeing at ultra high rpm's,, like crossing at 9200rpm). He abandonded the project, and I don't know if he ever got to a point that he could say one way or another what issue was, or if the swap cam helped or not. All I can say is I bought the heads, ran with a standard FO and have no big issue with fuel distribution. But I have a way different animal than Chris had.

My thoughts are,,, Furd has been using that FO for a long time, and the new LS FO is following suit. There has to be something to it. Outfits like GM do millions and miillions of $'s in research and for them to change the FO, there is good reason.

In that light, I'm building a hi-tec little 327 for a Elcamino project. Holley MPFI, Hydraulic roller, roller valve train, converting to serpentine drive, and an overdrive trans. I'm having Jay Allen design the cam with efficiency and fuel mileage on top of the list, without giving up performance. A lot of thought and discussion went onto the choice,, but it is going to be a 7/4 swap cam. If it's worth 1/4 of a MPG or 4HP,, in a couple of hundred thousand miles it will pay for it's self

 

[GetMore]

I don't think the swap is worth the extra money. Now, if you could do it for the same amount of money then I figure "why not?"

 

[J.Wright]

I don't know about justifying the cost per HP gain but I like the puzzled look on peoples faces when they hear to my car at the track.

Jim

 

[1981z28owner]

just curious, does the car sound any different?


also on a sidenote. Woohoo 2,000 lol

 

[rustbucket79]

Mine sounds no different with the F/O swap.

 

[Camaros79_83]

Thank's for the replies.
The guy at the machine shop is pushing these cam's real bad,and I wanted to find out from some that have done it and see if it is worth it.And it sounds like it's only worth 4hp,I think I can find something else to do with that $125.00.
I am not really worried about 4hp,I think it should do just fine the way it will be set up.10.5-1, 588 solid roller cam,World Motown 220 heads,Victor Jr intake and 850 carb set up for E-85. It's not gonna be a my everyday driver,just a weekend cruiser and a few trip's down the track.

 

[Marv D]

I think what I and everyone else was saying is that no one has done back to back, real world testing to prove what the FO swap is really worth, if anything. The one real world test I know of / mentioned was in an all-out-effort motor and they found a few HP. At that level they were happy I guess. What it does at lower levels of self destruction is yet to be seen IMO. It's one of those things that is a cool toy, and a gamble if it's worth anything other than causing the wallet to be lighter by the weight of a hundred dollar bill.

I agree with J.Wright,, the few FO swap cam cars I know of at the track sound like a Pontiac motor. Very distinctive crackle to the exhaust

 

[Camaros79_83]

So it's 6 of one and half dozen of the other.