I am at the point of buying new headers, but I don't know which to buy. Right now I have a set of long tubes on there. Don't know what brand. Do know 1 5/8" primaries. This is a street car. Currently< 350cid, TKO 600, 4.10 12 bolt posi. Very soon< 385cid, TKO 600, 4.10 12 bolt posi. I don't know if I should get a tri y header or long tubes again. The longs are for mid-top end. Tri y's for idle-4500rpm. The 385 will have AFR 195cc heads, hyd roller cam, same tranny and rear. Basically I will be taking this freshly .040" bored, 4 bolt block and filling it with flat top Speed Pro pistons. The current intake(Performer RPM Q-Jet manifold and heavily modified Q-Jet, Crane roller rockers from current motor). The only new things will be the block, pistons, rods, crank, oil pan, heads, cam and harmonic damper. Valve covers, rockers, intake, carb, dizzy, windage tray, rear pan baffle, and oil pump will be coming off old motor. Maybe some other things I may have over looked. I need new headers, but what should I get? Do you think the 385 will have enough torque to make the tri y's mute? I can't see a motor making over 400ftlbs needing a header that makes power from idle, but maybe it will. This is where the primary diameter comes in. If I get a long tube, should the tube be 1.75" or 1.625"? I don't race this car, but I would like it to be able to run on the highway and the occassional strip run. The AFR's will most likely have a 64cc chamber to give me right around 10.2:1. I don't want to go much lower than 10:1 and I don't want to go higher than 11:1. Here is what I came up with:

CID: 385
Cylinder Head Volume: 64cc
Piston Head Volume: -5cc
Gasket Thickness: .015
Gasket Bore: 4.125
Cylinder Bore: 4.040
Deck Clearance: .010
Stroke: 3.75
Rod Length: 5.7
Intake Closing Point + 15*: ???

The static compression ratio would be 13.241 and the dynamic ratio would be ? because I don't know what the intake closing point is at .050 with this cam. It gives me the .006 closing point, but I don't know how to find it at .050. Does anyone know how to do this?

I believe I got it. Going by the following chart:
http://www.compcams.com/Base/Images/Technical/800-615-ValveTimingIllustration-002.gif

It appears that the intake closing point @.050" is around 45*ABDC. If you add the 15* to that you get 60*ABDC. Plugging that into the calculator gives me a static compression of 10.953:1. This may be high or low a bit depending on the actual closing of the intake valve, but I think I am pretty darn close.

If I increase the gasket thickness to .025", it will lower both the dynamic and the static. The dynamic will drop to a more streetable 12.837 and the static will be 10.624. I think this will do a little better on 93 octane. Of course, I will be running the Octane Supreme 130 TetraEthylLead substitute. If I bump the gasket thickness to .039, the dynamic will drop to 12.316 and the static to 10.201. I don't think .4 of a point will make a difference.

Charlie,, been down the road with Tri Y on a 383 with AFR heads, they are good, fit well but tend to limit the motor some. I just went from Tri Y to Dougs D368. There is lots of differance.
I decked to 0 and got my quench to .039 using the Felpro 1010 gasket, I am at 10.3

So you're saying machine the block to where the pistons sit flat with the top of the cylinder bores, then use a .039" head gasket? What type piston did you use? Flat top is presume? If I do what you suggest and keep everything the same except the gasket thickness and the deck clearance, it says I will be at 12.66 and 10.48. This is with the Comp 280HR, but I am not sure I want this cam. I may do what you did and have Harolds suggest one. So when people say quench, they mean deck clearance?

Didn't know your motor was out or apart but , this is what I did after 2008 Powertour. I already had my stroker together, SRP flats with dish -16cc pistons on Compstar 6.0 rods, Old style AFR 195 heads with big valve stems. I pulled motor apart and decked block to 0. Beacuse I wanted the newer Street Eliminator heads, I ordered a new set thru Mike Lewis Racing. I told him I wanted to bump my 9.9 compression up to 10.5 range . We determined to flat mill new head at AFR to 60cc chambers. Using the Felpro that brought me up to static 10.3 , dynamic about 8.
I was alreadying running Harold's cam so basically with this combo, just made it run better. I feel the tight quench did a lot for me but I had to go thru all this extra work. I made to 09 Tour and all is well. Still burn pump prem. Have not tested to run reg. I probably could at my altitude 3500' but when I go south to 0 elevation, I would need the prem fuel.
That 280 cam could still be in your ball park, I am 282/290 advertised with 112 LSA.

JimM has basically same motor but larger 64 cc heads and -5 cc pistons I think and same cam. Far as I know, he has no issues other that motor comes up fast with the 3.27 first gear TKO. He bought my first TKO 500 as it was just too steep for me.

Charlie, Your DCR should always be less than your SCR. Use the seat measurement to calc the DCR. The .050 plus 15 is a rough guess to get to seat, may work for a soild lifter, but I was advised not to use for hydraulic.

Running your numbers I have 10.1 SCR and 8.25 SCR, I used quench of .040. I entered the 5cc valve relief as a positive value, and used the closing value of 61 for the cc270H

Charlie, Your DCR should always be less than your SCR. Use the seat measurement to calc the DCR. The .050 plus 15 is a rough guess to get to seat, may work for a soild lifter, but I was advised not to use for hydraulic.

Running your numbers I have 10.1 SCR and 8.25 SCR, I used quench of .040. I entered the 5cc valve relief as a positive value, and used the closing value of 61 for the cc270H

Hope I got my dcr / scr numbers in the right place , but thats what my final comes out to.

Did you meam 10.1 scr /8.25 dcr?

Charlie, The only problem that I can see is, Dougs D368 are 1 3/4 tubes. They will hit your idler arm if it is not the small stock unit. Yes, even with the Moog arm, they will hit. I am not sure on the Doug's D308's. These are 1 5/8 tube.

The (2451) Hooker Competition headers fit well, but again they are 1 5/8 tubes. The Hooker Super Comps are 1 3/4 and usually require a hammer to install.

These are for a 1969 with 350 frame mounts (stands or brackets) and Engine mounts.

Charlie, The only problem that I can see is, Dougs D368 are 1 3/4 tubes. They will hit your idler arm if it is not the small stock unit. Yes, even with the Moog arm, they will hit. I am not sure on the Doug's D308's. These are 1 5/8 tube.

The (2451) Hooker Competition headers fit well, but again they are 1 5/8 tubes. The Hooker Super Comps are 1 3/4 and usually require a hammer to install.

These are for a 1969 with 350 frame mounts (stands or brackets) and Engine mounts.

TOM , has a point, some D368 do, some don't .. I have no issue on clearances. They do need to be installed , from almost a vertical position up into engine, recommend leaving wrapping on while doing this.
They are also a close fit on the 621 ball housing that requires me to use the AC PF 454 oil filter.

Hope I got my dcr / scr numbers in the right place , but thats what my final comes out to.

Did you meam 10.1 scr /8.25 dcr?

Yes, your right, I flipped the SCR/DCR values. Should be 10.1 SCR & 8.25 DCR, sorry for the confusion

Hope I got my dcr / scr numbers in the right place , but thats what my final comes out to.

Did you meam 10.1 scr /8.25 dcr?

***Yes, your right, should be 10.1 SCR & 8.25 DCR, sorry for the confusion

double post

Charlie, Your DCR should always be less than your SCR. Use the seat measurement to calc the DCR. The .050 plus 15 is a rough guess to get to seat, may work for a soild lifter, but I was advised not to use for hydraulic.

Running your numbers I have 10.1 SCR and 8.25 SCR, I used quench of .040. I entered the 5cc valve relief as a positive value, and used the closing value of 61 for the cc270H

The reliefs in the piston head have to be entered as a negative number. If I go to the Ferderal Mogul website and look up the part number for a .040" over 383 stroker piston(H669CP40), it gives me a head volume of -5cc. When I go to the Keith Black calculator and plug in the following numbers:

Cylinder Head Volume: 64cc
Piston Head Volume: -5cc
Gasket Thickness: .025
Gasket Bore: 4.125
Cylinder Bore: 4.040
Deck Clearance: .020
Stroke: 3.75

It gives me a static compression of 12.476 and a dynamic ratio of 10.331, which is a little too high. If I change the gasket thickness to .039, it lowers the static to 11.985 and the dynamic to 9.932. The static is still too high by about 1.5 points. If I change the gasket bore to 4.200 and the gasket thickness to .071, it gives me a static of 10.934 and a dynamic of 9.077. Running 93 octane and a true lead additive, this should be good. So the final specs would be:

Cylinder Head Volume: 64cc
Piston Head Volume: -5cc
Gasket Thickness: .071"
Gasket Bore: 4.200"
Cylinder Bore: 4.040"
Deck Clearance: .020"
Stroke: 3.75"
-----------------
Static: 10.934
Dynamic: 9.077