40-80 cam with F.I.?

IMO I don't think 40/80 would work as well in a stock FI in an X as it would in something you could finer tune like a msquirt FI system or well carbed engine.

I read somewhere (might have been Matt's site) 35/75 is about as long a duration as you want to go with the stock FI engine.
 
I used to

Hi Greg,

I ran one in my FI X, back in teh days.

SXlfside.jpg


While it ran ok, I wouldn't recommend it.
Especially not with everything else (CR, exhaust manifold) stock.
On a FI car, I would increase CR and change out the manifold long before I would touch the cam.
 
40/80

Hello, I am running this cam with 70 thou cut on the head and 3 angle valve job on the intake and it idles ok at about 1000 rpm.
.
Bob
 
i'm interested in this as well ... I've got a very stock x that's been sidelined for a number of years due to lack of money issues. and so, with that in "lack of money" in mind, any improvements in performance will come slow and at longer spaced intervals.
 
80/40 cam

Just the cam , compression increase and valve clean up from MAtt. I think it needs exhaust to be opened, so that is next. The next step milder cam would be better but it was not available at the time. Compared to stock the bottom end is noticeably weaker, the mid and top end is better.
I have an extra motor to build up with a stroker crank and 75/35 cam. Just gotta find the time for the project.
Bob
 
Thanks for the info Bob. I'd gotten a Delta A411 to install in my interim 1500 build (~10.5:1 compression, slightly bigger valves, polished head + intake, header and free flow exhaust) but I really don't want to cut the heat and/or cam box to compensate for the regrind since that would preclude installing a non-reground cam in the future. I have a couple of Alquati 40/80 cams, one of which I ran in my mostly stock 1300 with no problems, so I was thinking to just use one of those. I expected it'd idle okay, even with the stock AFM, but it's nice to have confirmation. If it'll idle at 1k RPM until I get around to upgrading the EFI that's cool with me.

As to your stroker build, I'd suggest using the 40/80 cam instead of the 35/75 unless you're going for a very mild engine. You're going to get more torque from the longer stroke anyway, and the extra piston travel allows you to take better advantage of the additional duration. Just spec the compression ratio accordingly. For an unported engine with only a mild compression bump I'd expect the 35/75 to be a better choice. But for a fully built engine the 40/80 is actually a pretty mild stick.

As to the OP's question, a 40/80 would likely reduce overall performance unless you also upgrade the rest of the engine (particularly the compression ratio) accordingly. Even in my own interim 1500 build I'd probably be better off with a 35/75-- I just don't want to be limited to a reground cam and I don't have a non-reground 35/75.

Cheers,

///Mike
 
REground vs non ground

Matt cuts the bottom of the cambox to fit the smaller base circle cam ( reground cam) . You need to use a 1300 idler pulley, but it makes it easy to go to a larger base circle cam later. Cutting the top of the head is not really a good way to go. Just change the cambox and idler pulley to go back to another cam.
Regarding the 40/80, it is borderline but workable. I now have a 75/35 with full size base circle that I will use on the rebuild. Torque is better than HP.
Bob
 
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