valve job for flat deck head.

[cboggs]

Darin, larry, .. anyone,

Do you guys have some ideas for this little project???

It's a round intake port, .. nice long short turn, no chamber, .. flat deck head with the chamber in the piston. Low cam lift, .350" max lift at valve.

OK, Ideas for the valve job, .. what would you try????

I've tried varius things, .. currently have, ..
.010" wide 30º top,
.051" wide 45º
.040" wide 60º
.120" wide 70º all sharp edge.
1.55" valve.

I'm at 90% at the 60 for my throat, .. but the 70º deeper in the bowl is around ( I gotta measure, forgot it ) 80% or so. It seems the sharp edge 70º help to get the flow turned as it does seem to help numbers on the bench at .250 up to .350"

I was thinking of trying a wider 60º, .. like .060" or so, reducing my throat to around 85% ????

Thanks,

Curtis

[Guest]

What diesel are you working with?

[cboggs]

What diesel are you working with?

It's not a diesel, it's a 4 cylinder gas engine. Raod race.

Curtis

[shawn]

i would think that a valve seat angle of about 35* would be a better choice with the lift being limited to .350.Have you tried different valves and back angles?
shawn

[cboggs]

i would think that a valve seat angle of about 35* would be a better choice with the lift being limited to .350.Have you tried different valves and back angles?
shawn

Well, I guess I should have given all the info, ..

it's a restricted class engine, .. have to use a 45º seat and the stock valve with no back cut. Sooooo, .. I'm stuck playing with the top & bottom cuts, ..

I haven't tried it on the dyno, .. but I was thinking if I sunk the crap outa the valve to get some top angles, maybe a .040" wide 30º then a .020" wide 12º to the deck, would it help hp or even wet flow??
I know that combo doesn't look real good on the bench, .. but what does IT KNOW.

Curtis

[maxracesoftware]

it's a restricted class engine, .. have to use a 45º seat and the stock valve with no back cut. Sooooo, .. I'm stuck playing with the top & bottom cuts, ..

I haven't tried it on the dyno, .. but I was thinking if I sunk the crap outa the valve to get some top angles, maybe a .040" wide 30º then a .020" wide 12º to the deck, would it help hp or even wet flow??

with only .350" Valve Lift to work with..i don't think sinking the valve to get more top angle will help you ?...i think a .060 to .080" wide top angle will be all the Head will like ???

at .350" or lower Lifts...curtain area velocity fps is sky high...it just wants metal out the way, as Flow is shot off almost sideways at lower Lifts

at Higher Lifts...it wants the large top angle widths and gentle transisition to chamber from bowl/seat to maintain flow velocity fps and keep flow cone attached closer to valve head as valve head moves further from seat, thats why heads like 50/55/58/60 seat angles at higher lifts and with usually one very large 45 top angle transitioned into chamber

maybe trying out different Manufacturer's valve head shapes if that is Legal might pickup Flow gains ??
look for valve that has only .080 to .100" 45 angle width at most with "as made" sort of backcut or lower valve-head angle


.350" and less Lift is going to have all the Flow controlled by the
valve job and valve head shape , with the Short Turn just starting to effect Flow near .350" Lift and upwards

[tk]

Darin, larry, .. anyone,

Do you guys have some ideas for this little project???

It's a round intake port, .. nice long short turn, no chamber, .. flat deck head with the chamber in the piston. Low cam lift, .350" max lift at valve.

OK, Ideas for the valve job, .. what would you try????

I've tried varius things, .. currently have, ..
.010" wide 30º top,
.051" wide 45º
.040" wide 60º
.120" wide 70º all sharp edge.
1.55" valve.

I'm at 90% at the 60 for my throat, .. but the 70º deeper in the bowl is around ( I gotta measure, forgot it ) 80% or so. It seems the sharp edge 70º help to get the flow turned as it does seem to help numbers on the bench at .250 up to .350"

I was thinking of trying a wider 60º, .. like .060" or so, reducing my throat to around 85% ????

Thanks,

Curtis

It almost sounds like a F1600 ( Cortina Ford) head

I have done a few and found lots of gains but when bolting on the intake and carb you loose most of the gains so I started all over again but this time i bolt on the intake and carb for each flow test...Its important to always use the same carb and intake because bolting on another changes everything again.

If you think that head is challenging try porting a VR6 VW head

[SWB]

You need a smaller throat area (like 85%). I've found that smaller throat areas result in more flow at lower lifts. So I think you are on the right track.

I would not bother with any more top angle than you are already using.

SWB

[cboggs]

I'll try the smaller throat, . . makes sence to me too, ..

thanks for tossing this around guys. Nice thing about the net, .. can bounce things around, ..

Curtis

[STOCK 1090]

If your rules allow, coat the back side of the intake valve. In some quick testing it showed a little gain in the very low lifts on a SBC. After about .4 lift the advantage was gone. Give it a shot.

3.2 % gain at .2 lift 118.3 to 122.1
1.8% gain at .3 lift 161.8 to 164.8
@ 28"

[cboggs]

Rich,

Interesting, .. didn't think of that.

The rules don't allow coatings, .. but there are stealth coatings around.

Curtis