340 Build

[CUDA ROLAND]

well i am starter my moter build tell me what you think anny ideas fell free to chime in.. first i have a 340 punched .040 over running forged pitons...speed pro molly rings...eagle steel crank...h beam rods...speed pro 3/4 groved maines to incres oil to the rods...77 hp rod bearings...did some oil passag mods to incres oil flow to the bearings ...millins hv oil pump...hardend oil pump drive...running 10 in. deep pan with marroso high volum tube pick up...hp cam bearings... the cam is a hughes solid lift flat tapit cam...running the cool face solid lifters with the extra oil hole.... cam spec 610 lift in. 614 on the exh...dur at .050 is 256... center line 106... victor intake ported magnum heads... headers are 1 3/4 prim. to 3in. slip on col.. headmens race headers... 750 hp carb ... msd dist and 6al box..anny other ideas out ther...

[MRL Performance]

Do you have flow numbers on the heads?

I think its a solid combo, good for 500hp

[CUDA ROLAND]

had some more port work dun intak 251 cfm exh 209 cfm thats with the small intake valve magnum head, i never thought a small valve head would flow that good. 466 casting magnum head...

[Cheapstreet_duster]

should make some strong torque numbers....
take it easy breakin in the cam...
soundsl like a health combo ....Roland.
cheapst

[CUDA ROLAND]

thanks ,,, just trying to git a good set up to run at the southen nats in may...

[79410aspenrt]

good combo. the Hughes solid cams are good cams. they will make power. 480-500 hp.

[MRL Performance]

I hate to be the one to put a Bad spin on this, but those numbers look good, but not together. you have 83% exhaust flow compaired to the intake. Thats to much and will rob power. You need to have 70-75% to have a good balance between the intake and exhaust.

Im surprised Cheap didnt catch this.

What happens is the exhaust flows to much. And if it flows that good, it will flow good the reverse direction cause a ton of reversion. this is why NASCAR heads have a big intake valve, 2.10" or bigger and a small exhaust valve, 1.50" in most cases. they have to balance it out or you run into trouble.

there is nothing you can do about it with these heads, so i hope it all turns out well, but you are going to leave a bit on the table

[CUDA ROLAND]

i was thinking that the header primery tube can help controll that,like the small 1 5/8 tubes will incres exh runner back presur and incres reversion at high rpm.. the 1 7/8 will cause exhust to flow out of the exh runner at a difrent rate and speed. that will help stop reversion. iwas going with the 1 3/4 to see how it works as a comperamise on exhust cylender scavenging. and reversion. what do you think??? also on the magnum head the exhust port is relativley small and by using a header with a larger tube than the port it will help to stop reversion also ther is (ar) header that can be used (ar) anti reversion headers.. i git what you are saying and agrey,but ther is ways around it...also i can go with the 2.02 valve report the heads and work of that but i am going to try the header thing first, also corect me if i am wrong but i thought that exhust reversion was a mid to low rpm thing...

[CUDA ROLAND]

have it built to a short block so far every thing whent well next step it to deg. the cam and ck for valve clearenc... have new magnum valve covers and hardend pump shaft on the way from indy heads. will have to redrill the head intake bolts with my drilling jig so i can fit and match port the intake to the heads,i use the intake gasket to git the port shap and size then i scrib marks on the heads with a strate edge acros the bottom of the ports the the ends of the head the run lines up all the ports to the top of the head after that i bolt the intake on with the gasket thin i transfer the marks from the head to the intake pull the intake and scrib lines down and a cdros using the transferd marks on the intake to math the intake runners to your heads this works better than gust using the gasket on the head and then puting the gasket on the intake without the alignment marks...

[CUDA ROLAND]

well back to the drowing bored my valve springs ar not going to cut it that bined at .600 lift,,,i need to git to .614 my with the 8 mm valve stock lenth and my pockets to go with 1.750 spring hight anny one know if i can cut the pocket down th git the hight i need??? i think i will need to cut it anuff to git a sprig hight of 1.800 in there...

[MYBD318]

Will Comp Cams Beehive springs help

[catfish]

Does someone offer +.050" or +.100" positive retainers for the 8mm valves to gain the install height? I know they make these for other valves.

catfish

[catfish]

Here's way's I see you correcting the reversion issue: (probably most you won't want to do)
run a single pattern cam
run 1.6:1 on intake and 1.5 on exhaust
upsize intake valves and port intake more
run large diameter headers and exhaust

The exhaust is probably your easiest solution, but most compromised. I'd personally have someone reflow the heads to confirm flow difference between intake and exhaust and if correct , upsize intake. Don't forget your cam is a split pattern that favors exhaust duration and lift to compensate for poor flowing exhaust ports. You're taking a very good exhaust port and making it better with that cam, biasing more toward reversion.

my $.02,
catfish

[Tubbed440]

Originally Posted by catfish

Here's way's I see you correcting the reversion issue: (probably most you won't want to do)
run a single pattern cam
run 1.6:1 on intake and 1.5 on exhaust
upsize intake valves and port intake more
run large diameter headers and exhaust

The exhaust is probably your easiest solution, but most compromised. I'd personally have someone reflow the heads to confirm flow difference between intake and exhaust and if correct , upsize intake. Don't forget your cam is a split pattern that favors exhaust duration and lift to compensate for poor flowing exhaust ports. You're taking a very good exhaust port and making it better with that cam, biasing more toward reversion.

my $.02,
catfish

I was just about to type the same thing..... I second this one for a quick fix.

[Canuk74Charger]

Why run a larger ratio rocker on the intake and less on the exhaust? I noticed racer Brown rockers come in sets like this, not sure the advantage of 1.6 & 1.5 to just all 1.6

[CUDA ROLAND]

i am looking at removing the 194 valves and going with the 202 intake also i am going to have to lower the valve pocits .080 to make the new valve springs work...

[MRL Performance]

If these are STOCK Magnum heads, I would not go to a 2.02" intake. 2.00" max. They are already prone to cracking between the valves and cutting it out that much will only make it worse.

[CUDA ROLAND]

well super mike from mrl performace save the day once more just got of the phone with him and he found a set of springs for my heads that will work with my cam and not have to cut the pockets thank mike

[CUDA ROLAND]

well the new springs are hear thay install at 1.700 coil bined at 1.028 so i shoud be go to go with .600 lift after taking away my valve lash...thanks againe mike for the help on the springs

[CUDA ROLAND]

just came in from the shop clayed the piton and did a valve clearance ck got .115 on exh. .109 intake looks good one thing i noteced is that the 340 pistons come out above the deck i am running closed chamber heads i clayed the pisto to ck head clearance i had about .045 from the head to the piston top is this ok????

[MrN2OBelvedere]

.045 should be fine.

[challenger500]

Perfect !!!! At that clearance, your piston will quench. I would be a bit more concerned with valve to piston clearance....Your's seems a bit close to me, but, I'm not the sb expert...lol Ask Mike on that to be sure. My bb is .125" on exhaust, and .155" on intake... I have been told .125 is minimum. My 2 cents tho....

[CUDA ROLAND]

i misread my dial gauge did not reset it my piston to head clearance is a lot closer it is .020,,, On my valve i pulled up the spec from hughes it is .100 on exh and .080 on in.

[challenger500]

Call Mike.... Seems to me .040" is minimum clearance piston to head.

[RacerHog]

How Far up out of the hole are the pistons?