valve to block notch clearance

[stage3]

whats the minimum exhaust valve to block notch clearance 1 can run? i know valve to piston "exhaust" is .100 minimum which i have more than enough but because i'm running a 426 wedge block bored .010 over with 1.88 exhaust valves,,with my .650 roller,,i'm averaging .060-.070 clearnace before hitting the block now above max lift,,,with deep reliefs in block almost to the ring line,,cant really go anymore...milodon full cover gear drive.

the max extent of the block apparantly...a google search came back all over the place on this from .005 to much more.....any thoughts on this....thanks..the last hurdle on the short block..

 

[PRHeads]

As long as you’re not lofting the valve more than the clearance you have, I’d say you’re fine.

The other clearance for the ex valve to bore notch you’d like to know is the radial clearance.

I’m thinking something like .040 is as little as I’d want to see, but if it only had .030, I’d probably still run it, then look for signs of contact next time it was apart.

 

[stage3]

As long as you’re not lofting the valve more than the clearance you have, I’d say you’re fine.

The other clearance for the ex valve to bore notch you’d like to know is the radial clearance.

I’m thinking something like .040 is as little as I’d want to see, but if it only had .030, I’d probably still run it, then look for signs of contact next time it was apart.

thanks for the response,,,now,this is with NO valve lash factered in,cam card calls for .028 lash,just mic on top of valve,,press down and count the lift..the radial side of it is tapered to that point of contact using machinist blueing..0 at contact,then opens way up right away..still the same with 0 lash? should be better right...thanks.

 

[IQ52]

Direct result of lack of valve to block clearance.

 

[stage3]

ordered a tool that goes in the head thru valve guide with a 2.00 cutter on it...lindy tools sells it.carbide cutter ran by a drill,,same as isky sells but better,,.will finish the job end of week when it arrives..the right way to do it...060 minimum clearance plus the lash,,will finish at .080 plus the lash...should be good to go..

 

[66Satellite47]

Not an expert but, seems like you're good. Just make sure you have GOOD valve springs.

 

[stage3]

Not an expert but, seems like you're good. Just make sure you have GOOD valve springs.

wont work with std bore block with .670 lift cam....block has been bored .062 to std 440..thick block at appx .342 cylinders..now with a bore of 4.320(stock 440) max heads should work without any valve notches?............

 

[66Satellite47]

wont work with std bore block with .670 lift cam....block has been bored .062 to std 440..thick block at appx .342 cylinders..now with a bore of 4.320(stock 440) max heads should work without any valve notches?............

At 4.32 you should be good. But for flow I'd still put notches in the bores to match the head gasket. Just my opinion.

 

[stage3]

At 4.32 you should be good. But for flow I'd still put notches in the bores to match the head gasket. Just my opinion.

i agree,,just a small radious of the edge,,,bought some trw l2295 std bore pistons off ebay,,,175.00! speedpro still makes these in + .030 and .060 over..but not std bore..old trw book lists them as press fit and full floating..anyone want a set of diamond 426 wedge pistons at +.013? will list them soon as i get back from wai ki ki........

 

[66Satellite47]

I ground the notch to match the head gasket shape & deep enough to be well above the ring. More flow is always good.

 

[4spphil]

If this motor is not a stock/super stock build there is another solution to consider. Cut the 1.88" down to 1.81". I've never heard a good explanation for the 1.88 valve in that head...should have been engineered with a 2.14 intake/1.81 exhaust.
Most all the aftermarket performance head manufacturers use the 1.81. It's not until you get into the heads designed for big bore mega cube motors you see the exhaust valve size increase for wedge engines.
1.81s with the cylinder notch may improve flow even with the smaller valve. By not having to cut the notch so deep in the block the top ring groove on the piston can also be moved up.

 

[stage3]

thanks for the replys,,these #518 stage 3 heads r like new..i believe they r NHRA approved(non modified in any way) units that came from a well known max wedge racer who now races brand X...thats why i have come to the decision not to try and modify them to use on this application. the stage 3 intake, the same thing from the same guy and carbs...

SO i have decided to get a set of trickflow 270's..and use them with a minimum 4.320 bore.no more problems...they look like a great deal..and all my stock style rocker gear just bolts right on with 350 cfm! without the xtra cost of cnc $$$$.$$ porting.

anybody know of anyone who needs nhra approved cherry stage 3 top end?

 

[4spphil]

I've heard good things about the Trickflows. Are you also using their intake? Not needing any special valve train components is a definite plus also.

 

[stage3]

I've heard good things about the Trickflows. Are you also using their intake? Not needing any special valve train components is a definite plus also.

heads showed up yesterday from summit! santa was driving a fed ex truck!..i'm going to use my indy tunnel ram,which both r max wedge port, along with my RAS roller rockers..other than these heads , all the expensive parts were already here for the 426 block, now to find a std bore 440 block..

 

[4spphil]

Should be a good combination. I believe the 270s have the max wedge intake port dimensions. As another option your crossram should also work.