Alrighty, the build is slowly coming along, but I've come to a few more questions.

First off, any recommendations for an economical hyper piston to play nicely with some 7" rods? (Hey, it was a good price...) The deck has been shaved .030, and a head chamber of 57cc. More can be shaved off the deck if need be, but I'd prefer not to cut the head a whole lot (theoretical purposes) I plan on running a Victor-Reinz gasket (3.5 bore .038 compressed) I'm shooting for the 10:1 ballpark and would prefer a floating piston. I've found what I thought were some decent ones, but they were press fit and my machinist wants to run floaters.

I have an OCG 346 ground on a 109LSA, with an ICA of 105. The car this is going in is a ~3500lb Dart Sport, 904 w/ 2300-2500 rated converter, and planning on 3.23 gears w/ a 25.5-26" tire. Most likely Hurricane intake with some form of large-ish 2v, but have a Offy and 500AFB as well to experiment with. This car will mainly be street, looking for a wide power band (Ken guessed this cam to be ~2k-5500, but I know this can vary. Like Sandy's Poor Man's stroker), but I'd also like to get it on a chassis dyno and put close to 165 at the wheels. And I don't see any plans in the near future to spin it much past 6k. All that being said, how much advance should this cam be installed with? 2*, 4*?

And I've got a head and a set of o/s valves, plan on porting it myself (may try my hand at the ol' vacuum cleaner flow bench) Any measurement recommendations for port size or bowl diameter? I'm looking for as much velocity as I can get, and just letting cfm fall where it may. Vizard tells how to get this type of bench calibrated to figure cfm, but I most likely won't go through that work.

That's all I can think of at the moment, looking forward to the responses!

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1976 Dart Sport
Currently under revision

I would install that cam at 100 deg centerline (4-6 deg advanced from where it is ground). I am not sure why you wanted 109 LSA, since 106 is close to optimal for a 225, but it will not make a big difference.

Best idea with pistons is to look through the KB catalog or other off-shelf piston catalogs to find pistons with dimensions to match. To me, it will be hard to beat the Wiseco kit for <$500 with everything. Stock cast pistons (of suitable dimensions) should be fine up to where your engine will run out of steam (around 5500).

Get your rotating assembly balanced and use new high quality rod bolts and resize the rods.

Have fun!

Lou

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Home of Slant6-powered fun machines since 1988

Just remember the Wiesco pistons no longer come with the rings. You must order them seperately

Rick

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2 Mopars come with Spark plug tubes. One is a world class, racing machine. The other is a 426 CI. boat anchor!

12.70 @ 104.6

The cam was widened to a 109 for the reason that I was worried about intake reversion and the such. That and I wondered if that much overlap might give some driveability problems. Did you run the 106lsa with your hurricane? The rods I have are k1s with the arp bolts, and the crank is a cast one that seems lighter than another one I have. I plan on having it balanced. I just have a hard time dropping $550 on the wiseco pistons (this is just what cambell lists them for, dunno about elsewhere) when I don't feel like I need a forged piston.

When you say run out of steam, do you mean this is where it will peak and it won't pull as strong after this? Or are we talking hitting a brick wall and falling on its face because the cam and intake both stop being efficient at 5500?

Thanks!

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1976 Dart Sport
Currently under revision

Yes, hitting a peak and dropping off in power. The dimensions and head specs on a 225 mean that it tolerates much more overlap (smaller LSA) than most other engines. 105 LSA and 106 LSA cams (ranging from 234@ to 255 0.050") with Hurricane intakes have worked fine, although the Clifford 4V beats everything in the HP race (possible exception of 3X2 Webers).

If you believe everything the V8 guys tell you about a 225, you are doomed to repeat their mistakes...

Lou

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Home of Slant6-powered fun machines since 1988

Ah. See, I hadn't ever read any of this before. The changing to a 109 lsa was not influenced in any way shape or form by v8s. Couldn't tell you much at all about a v8.

On porting the head, I see you mentioned in another thread that you can go bigger on ports and valves because they are so undersized for the displacement... So, does this mean I need to not be so worried about the porting yielding to big cc of a port? What about valve seat angles? David Vizard talks of using a 30° seat on engines that need more flow at low lifts. Does the slant have any benefit here? From what I understand the only problem with a 30 degree seat is a) getting it to seal at higher rpms, and b) they tend to flow worse at higher lifts. I think on the flowing worse at higher lifts part it wouldn't be that big of deal, since the intake is the main one I am worried about and it only has .476 of lift at best (assuming the stock rockers are a true 1.5) but he doesn't quite elaborate what he means by 'higher rpms', I don't know if 6k counts for this or not.

Thoughts?

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1976 Dart Sport
Currently under revision

You should note that the drop off in power won't be highly noticed a big bunch if you haven't driven a hi-po slant before, at that rpm range it will just feel like you need more distance to accelerate more...being a street driven car your concerns will be at normal rpm ranges, and there won't be a place outside an isolated country road that you can reach 5500 rpm in 3rd...and being an automatic without a lot of mods your up shifts will be in the 1500-2000 range (and race guys 904's that aren't manually shifted will program the upshift at 4000 rpm and run a higher stall...which may not help much on the street).

My perspective would be that LSA isn't much of a concern at streetable levels, if the hurricane does it's job in adding a little low end torque...the slant will tolerate more overlap, but you have to consider the wave reflection in the manifold, and how that can cause a bounce in the vacuum reading and power valve if he runs say a Holley... I agree the loss of performance going from a 105 LSA to a 109 LSA is minimal but for a novice tuner this can mean the difference in not so lumpy idle and easier carb tuning and dialing in the distributor recurve....

I have 2 versions of the OCG 549 cam (250@.050) and on an all out race build I found no difference in ET or performance on the track going from a 111 LSA to 107 LSA with the same build...the difference was that the 111 LSA idled fine with a little lump/bounce in the gauge and was happy at 16" of vacc. at a 900 rpm idle....the 107 LSA had a .5" "lump" at 1000 rpm idle and was only at 14"....I'm not sure that an LSA at 104/5 would've made anything better if I had gone that direction...

I would also be concerned with DCR when setting the cam advance and making sure he can run a lower pump grade for daily driving if desired...

2 cents...

Alright, this is kinda what I was wondering, how long it would stay hanging on after peak. You are correct, I really should be worried about midrange since I'm wanting to run this thing on the street mainly. No straight country roads around here, just twisty lake roads along the Ozark 'mountains'.

My machinist and I had a talk today and we decided on the KB239 for a piston. Jeg's did some price matching for me and I ended up getting them for 260ish for 6. I think this means I'll have to use my uncut block (the block decked .030 may be cutting it close) I think if I use an uncut block I can get around 9.7:1 (give or take the variances the factory had in machining) would it be better for me to advance the cam a lot and run less compression or run less advance and more compression? 89 octane is the most readily available in these parts, so I don't want to build something that has to have timing retarded way back to drive.

Lou, you've had a bit of experience with the hurricane, does it actually ram tune? Runner length calculations lead me to believe if it did it would be somewhere north of 4k, but I don't know if there is something preventing it from doing so. Does it have any distribution problems? I wouldn't think so, other than the rear running richer from unheated intake, but again, I haven't got to play with mine as much. And is there any intake manifold modifications that would be beneficial to me? I know the h-pak guys split the plenum, if I had a 4v intake I'd do that in a heartbeat, but the 2v would be a little trickier...

Anyone care to weigh in on my previous head questions? Thanks for the help! I dunno what I'd do without this forum!

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1976 Dart Sport
Currently under revision