408,Stage11 Ed head,XE294, Need advice on cam, valvesprings,combo

[604B1duster]

I need some advice. I bought a nice used 408 short block with flat tops. Bought a stock set of eddy heads and comp xe294 cam and lifters. I put it together with .100 cometics to get the compression down. It has 1.5 crane rollers. Its almost ready to go in the car. Then later, got a deal on a set of stage 11 ported eddy heads done by Hughes. I am going to swap the heads and want to keep the cam. The springs comp recommends for the xe294 have a seat load of [email protected] and an open load of [email protected] (.550). The springs on the hughes heads are [email protected] and [email protected]. What I need to know is can I leave this cam in the motor, run the ported hughes heads and use a 1.6 rocker to get the lift up to around .550. With the .100 gasket I come up with about 10.9 comp. T ram with two 500 eddy carbs, 3000 stall dynamic and 4.10 gears. Street car . I really want to use what I have, if possible. What do you think ?

 

[moper]

Not sure I agree with your numbers... What pistons are in the shortblock? Where are they in relation to the deck? Do you have the 1.6 rockers?

 

[604B1duster]

Not sure I agree with your numbers... What pistons are in the shortblock? Where are they in relation to the deck? Do you have the 1.6 rockers?

Thanks Moper
I dont remember but they are forged flat tops with deep pockets and close to, or zero deck. I have 1.5 and 1.6 crane gold. I also have a new set of H sharps but dont know ratio, (ebay). I am pretty sure I am in the ballpark on the compression, and I know this cam makes pwr. My real concern is the springs on the heads I have. 140seat pressure compared to 115 recommended for cam, and 315 open compared to 336 recommended foe cam. The springs are Hughes 1111 and I believe coil bind is @ .700, so its not an issue with the 1.6 and this cam.

This is the cam in the motor. This is the same cam Muscle Motors uses in there Street Killer Krate and the Killer Krate.

http://www.compcams.com/Company/CC/cam-specs/Details.aspx?csid=630&sb=2

http://www.musclemotorsracing.com/engines/small-block-street-killer-krate.html?fontstyle=f-larger

http://www.musclemotorsracing.com/engines/sb-killer-krate.html

 

[moper]

Ok. I'm coming up with about 10.2:1 for a static ratio and that was using 6ccs for the valve pockets. I don't have the info for the dynamic but I think I'm close at around 7.8:1 with the 1.5s. However, you gave away all the quench with the thick gasket. Not sure I'd call that a wise compromise but it is what it is and you're using what you have. In any event, it's not close to 10.9:1.
My thoughts - If it were in my garage I'd have the chambers enlarged slightly and shaped better, mostly to gain volume but some flow and detonation resistance can be found by doing this. I'd run the Felpro 1008 gasket to get quench back. That brings the static down to around 11.4:1. Then I'd get a larger cam. That XE294 kicks ***. It's an 11s cam in a 340 so it will make good numbers in the 408 but IMO you need more duration and lift, and a hydraulic isn't the way to go so it isn't really the right cam to run. Get something like the Comp XTQ281S-6 that will help bleed down the pressure to get the dynamic down to around 8.3:1. That wil give you a pump premium small block that will make some killer street numbers.
Regardless of your ultimate choices, definately run the valve spring the cam manufacturer specs for it.

 

[604B1duster]

Ok. I'm coming up with about 10.2:1 for a static ratio and that was using 6ccs for the valve pockets. I don't have the info for the dynamic but I think I'm close at around 7.8:1 with the 1.5s. However, you gave away all the quench with the thick gasket. Not sure I'd call that a wise compromise but it is what it is and you're using what you have. In any event, it's not close to 10.9:1.
My thoughts - If it were in my garage I'd have the chambers enlarged slightly and shaped better, mostly to gain volume but some flow and detonation resistance can be found by doing this. I'd run the Felpro 1008 gasket to get quench back. That brings the static down to around 11.4:1. Then I'd get a larger cam. That XE294 kicks ***. It's an 11s cam in a 340 so it will make good numbers in the 408 but IMO you need more duration and lift, and a hydraulic isn't the way to go so it isn't really the right cam to run. Get something like the Comp XTQ281S-6 that will help bleed down the pressure to get the dynamic down to around 8.3:1. That wil give you a pump premium small block that will make some killer street numbers.
Regardless of your ultimate choices, definately run the valve spring the cam manufacturer specs for it.

WoW you know your shtt, huh. Ok how do you get 10.2 ? I went over this with a well know builder and he sold me the cam and gaskets, but that was with stock eddies. I dont plan to touch the heads, if I have to I would swap out the comp cam and get another that matches the springs. I see hughes has hyd cams that use these springs. What problem can the extra 25lbs seat pressure cause ? These are the springs. Thanks
http://www.hughesengines.com/Index/products.php?browse=search&search=1111&partid=22039

this is the smallest hyd they recommend with these springs and 1.5, so I figured with the cam I have and 1.6 I would be close enough ???
http://www.hughesengines.com/Index/...ZW5naW5lcw==&level1=Q2Ftc2hhZnQ=&partid=21859

 

[moper]

lol... nah. Online calculator. I used 63cc chamber, .100 gasket, 4.10 gasket bore, 6cc valve relief, 4.03 cyl bore, zero deck. Comes to 10.2:1. If your machinist actually measured everything his numbers would be more accurate. That XE294H will work with 10.2 in a 4" stroke engine. Additional pressure isn't much of a big deal. Not enough is a big deal. Especially with a hydraulic cam. As I said, I'd buy the right springs. There's no need to use Hughes parts and the RPMs as delivered don't have enough pressure. Just buy the Comp 995-16s.

 

[604B1duster]

lol... nah. Online calculator. I used 63cc chamber, .100 gasket, 4.10 gasket bore, 6cc valve relief, 4.03 cyl bore, zero deck. Comes to 10.2:1. If your machinist actually measured everything his numbers would be more accurate. That XE294H will work with 10.2 in a 4" stroke engine. Additional pressure isn't much of a big deal. Not enough is a big deal. Especially with a hydraulic cam. As I said, I'd buy the right springs. There's no need to use Hughes parts and the RPMs as delivered don't have enough pressure. Just buy the Comp 995-16s.

Ok, The hughes heads have thier 1111 springs installed at 1.8 and the comp 995s are to be installed at 1.7. The paper work I have for the heads says the heads were milled back to original cc's to compensate for special valve job. Does this mean the valves are sunk into the head to allow for more installed hieght ? Or are the spring seats cut down ? It doesn't say how much they are milled.

 

[moper]

My apologies I missed that part about them prepping the RPMs. I'd say give Hughes a call and ask what they did. I'd hope they would not sink them just for spring height but there are flow reasons they might reshape the chamber and sink them, or they may be running a longer valve. If the chamber shape was altered enough the milling would be to return the chamber to whatever size they want it.