With the 5 speed conversion (finally) more or less completed, on to the next project.

I've been collecting parts for a long rod build for quite a long time now. The currently worn out six is just there to test out the 5 speed conversion. While it keeps on trucking, I intend to build a more interesting motor.

I'm planning on the following:

• Ported, polished heads with oversize valves (enginebuilder)
  Wiseco 2.2 pistons, .084 over
  Molnar 7.005 rods
  4 barrel holley 390 on a clifford intake
  headers
  '73 forged crank, '73 block, to be prepped per Doc's instructions
  Cam TBD. I'm thinking the Erson ERSE470302 (280/280) if I can get it, but open to suggestion
  Mike Jeffries windage tray/crank scraper

My intended usage is hot street - I'm ok with some bad manners and a rough idle, but I would like good drivability (ie, good for more than just WOT drag runs). It's a street car, so pump gas is a must. 93 octane is readily available here. It will be in front of a 5 speed. The car is a 73 dart, so not a super lightweight - no a/c, manual steering and brakes. The current gearing is 2.90 with a sure grip, and soon to be upgraded. I'm thinking 3.55, but I'm open to higher or lower, depending upon what makes sense. I would like to be able to comfortably drive 70 or so on the freeway.

I'm thinking I should aim for around 10:1 static CR, and a cam that puts the DCR into pump gas range. I have large bore gaskets, and am hoping that the overbore will unshroud the valves, and the gaskets will give me enough extra to further unshroud if required. I'd like to get 200+hp out of it, without the spray

I'm expecting this combo to rev between 5k - 6k, so I am slightly concerned about using the stock flywheel. Since I'm using a forged crank, the reduction in rotating mass could be fun.

So now, pictures! Because they're fun.

Headers


Crank


Cylinder head. Already hogged out by the machine shop for 1.70/1.44 valves, awaiting a port/polish job


Bronze valve guides installed


Gaskets


Windage tray


Nitrous, maybe?


Valve gear


Pistons, rings, pins, etc. With friction coating.


Fancy rods.


Holley


Valves and retainers


Manifold adapter


Clifford. Somebody previously machined holes for injectors. I'm probably going to thread them to seal them off. I can always ream them back out and press in inserts if I go injection on this manifold, I suppose. It's also got plugs in its water passages, which i assume I'll want to hook back up for drivability.


Next steps are taking the block, crank and pistons to the machine shop and doing the port/polish on the head.

Hopefully I can finish this one faster than 5 years.

Looks like a fun project and a sensible combination of parts.

Do not get too aggressive when porting the walls directly between an intake port and its companion exhaust port. If you try to "make a line" for the air in that area, you will very likely hit water.

I would suggest just putting rubber stoppers in the injector holes. I did this for years and never had a problem (not a boosted engine). Or, if you want to trade, I would be happy to swap you for an undrilled Clifford or Offy.

Happy building!

Lou

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Home of Slant6-powered fun machines since 1988

Sounds like you know what you want... just some thoughts and things to think about:

Check the molnar Rods, they usually don't come with the oil holes to sling oil on the cam, so you can have the machinist drill them, or you may need to set up some other oiling means (having him score the lifter bores can dribble some oil from the lifter bay onto the lobes).

Depending on the 5 speed you use, and the size of the car you might go with deeper gears (a 1973-1976 A-body slant six would be nice with 3.91's and a .7 OD gear for a final ratio of 2.7...which is about the same as the A904 and 2.76 rear gears...), the only down side is most T-5 boxes have a granny 1st gear and a set of 3.91's would be a bit 'granny' to start in. Keep on the look out for a set of Dart Lite hoods and bumpers to drop a little weight out of the car later....)

You will get the most mileage out of the 390 cfm, but with the compression ratio, porting/OS valves/ headers it will take more (I dropped 1/2 second in the 1/4 going from the 390 up to a prepped 600 cfm for racing, if you have both setup right, you can drive to the track swap, run your races, then swap back for mileage).... That cam would be fine for the street, the 280/270 would be a better bet so you keep the useable torque band a bit lower for 'street' use... but if you don't mind sacrificing a little mileage look for a cam that gets you in the .500 lift range (OCG 549, ERson AM if they still grind it), that will give you better breathing since you are going to the trouble of porting and O/S valves...

It would have been better to get the head hot tanked and magnafluxed, then do your port job, that way if you slip with the die grinder they can mill the mistake out or install new seats if needed. If they can get the block bored and ready first before the head, you can get the head mounted to the block and see how the bores line up so you can massage the chamber wall near the valves to unshroud them a bit without going too far outside the bore/fire ring...and you can check for core shift of the bores/chamber.

Make sure that they cut the top of the valve guides down so the retainers don't tag the top of the guide at high lift.... looking at the pic, those valve guide bosses in the bowl have to be ground down to the roof of the port if you want the best flow. You will need custom push rods.

Stock flywheel has no problems taking multiple 6000 rpm dusteridiot hyperpak clutch dumps... it's the clutch and housing that is tough... I have not found a good 10" clutch that will take repeated abuse at the track without withering or not clamping after the shift...

Rotating mass isn't a real problem, if this is a heavy car, a heavier flywheel from a 1980's truck actually helps since it stores more energy and helps launch the weight... but as you surmise the downside is it takes longer to spin up the RPMs between upshifts...

Lastly make sure you recurve your distributor once you settle in on your build/cam/compression, rear ratio and transmission gearing.


2 cents...

-D. Idiot

I have a very similar engine that was run for years in a '66 Valiant. I found the more cam I stuck in it the better it liked it.

It also LOVED nitrous.

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Official Cookie and Mater Tormentor.

Thanks for the tips so far!

I dropped everything off at the machine shop this morning, so things are officially moving forward.

Lou - I may take you up on the trade offer, still pondering a little bit on that one.

I'm not overly concerned about mileage on this one, that's interesting to hear that a 600cfm carb might not be too much for this motor.

For the head, I'd already had it checked out by a machine shop - they just did the inspection and roughed out the ports; the seats are not yet fully finished. I'm going to have it all finished up after the porting is complete.

The flywheel I'm using is in fact from a 1980's truck.

The distributor I will be using was already re-curved from another build I did some time ago. I don't remember how it ended up, but I followed the advice of several of the posts here.

The machine shop seems like they're willing to work with me on the build, so I should be able to get things done in a good order... we'll see how it goes.

You will have to redo it again... higher compression more cam, etc will require a whole new curve

Fixed image hosting.

Got the whole thing back from the machine shop a couple months ago - about 1k miles on it now. I've updated my T5 thread, also.

Initial impressions - way more power than the stock slant or my previous 2bbl/dutra duals build. Revs freely to 6k, afraid to spin it past that; I'm shifting at no more than 5800 rpm currently.

Manners are better than expected with a manual transmission. I'm in Georgia, so I'm not expecting it to run in 20 degree temps.

I love the sound; I used the largest Dynomax muffler I could fit in there - no drone, despite using 2.5 inch exhaust all the way back! It's quiet enough, but still has a rasp. The usual sounds you would expect on a car with headers are present. I used the nice gaskets for the exhaust and heads, so I don't hear any leaks, but headers are only so quiet.

Sorry I don't have more assembly pics; I'd originally intended to have the machine shop just do the head and bore; by the end I just had them do basically everything.

I'm still working on the carb tune and timing curve. I am coming to the same conclusion that I've read elsewhere on this site - the holley 465 is not a great match to this motor. I got it in the classifieds here with the clifford headers and intake for a great price a couple of years ago. Future plans will be either a 390 carb or a megasquirt efi setup.

I used an SFI approved flywheel from Romac, which didn't quite align with the water pump and alternator pulley. Some spacers were required to get it to stop tossing fan belts.

Cam is a custom grid from Comp (I know, I know...). 239 degrees at .050 on both sides, .534 lift.

of course, pictures...

Paint


Headers Paint


Port job


Single Port


Gasket matched manifold


Assembled


Plus Carb


In the car


Working on the downpipes


Looks perfect!


Final welding plus O2 bung


Getting closer with the exhaust


Over the axle


Pretty much put together...


Turns out the radiator (a v8 rad, this was originally a v8 car) above was plugged up... replaced with a nice aluminum unit - was on a time crunch and didn't have time to take the other rad to a shop to be flushed.


Added an electric fan, controller, and fixed pulley spacing.

Looking at what you took pictures of... the 390 Holley will now be the bottle neck even with the light yellow spring.... Anything 500 to 600 cfm 4 barrel will make the max power if the secondaries are
properly springed/staged... to make best power the distributor needs to be all out mechanically at 3000 rpm...

240 degrees at .050 performs best at high compression... FYI... if it's 10:1 you'll leave a lot on the the table...

Wow, that is a lot of nice work! Congrats on your successful build.

I suggest you resize the pics so they are 1/3 to 1/2 that size. Somehow my computer/browser is not resizing them and they appear very large.

That is weird your Romac did not line up with pulleys properly. I have seen maybe 1/16" of misalignment. If it sticks out more than that, I might suspect it (or the crank timing gear) is not driven onto the crank far enough (which might ruin your oil slinger) or that the crank is somehow a bit far fwd in your block.

One other suggestion: Use double nuts on the header flange bolts. You can lose those bolts, even with lock washers in place.

I guess I disagree with DI on the cam/comp. 240 @ 0.050" should be about perfect for 10:1 comp on pump premium gas. You could go a bit higher in compression, but I would stay below about 10.5:1 if you want to stick with pump gas. 10:1 is exactly where I would set it up for a street car. What is the installed centerline that you set up for your cam?

I hope we get to meet in person sometime, maybe at a Slant 6 race this year!

Slant on,

Lou

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Home of Slant6-powered fun machines since 1988

Noted! I'll take care of the pics soon, I just uploaded the full res snaps and linked them, I wasn't thinking about scaling issues.

On a two-pulley alternator, the Romac lines up perfectly with the outside (farthest from the engine) pulley... I spaced the single belt water pump pulley out that far and haven't had an issue. I'll reach out to my builder to double check, I know folks have had to hone theirs to get them to press on all the way. This shop has a good reputation for slants, but it's from the 90's, I doubt they'd seen a Romac balancer before I brought one in. Apparently there was a dirt track slant 6 class once upon a time they built engines for. They're the only shop I could find in Atlanta that had a bore plate for a /6. The owner and his help had a glitter in their eyes when I described what I was building and showed them the parts.

I'll add some double nuts on the headers... I was kinda wondering if the stock hardware and torque specs still applied with the uncoupled headers and intake...

I asked for a pump gas 10:1 - 10.5:1 build, and they seem to have delivered. I haven't gotten any ping yet. The cam specs they suggested were very close to what I had in mind for a pump gas DCR; I know that Jeffries and others suggest the dual pattern - I don't have the facilities to do back to back cam comparisons, though. Their notes say 10:1 static compression. I haven't taken it apart to validate.

If I did it again, I wish I'd used chevy valves - apparently they are taller and thinner, so better flow (marginally), and less work to keep geometry correct. I'd gotten the engine builder valves and guides years ago and had the rough in work done before I went to this shop. Keeping the spring retainers from hitting the guides with the specified lift was apparently a pill.

Cam is ground at a 104 centerline, I can't find my notes on the installed centerline right now. I'll try to dig that up.

I'm really not happy with the 465cfm Holley I have on it currently. I've gotten both mechanical and vacuum secondary holley's to run better on other engines than this one. I do have a vacuum secondary 600 on the shelf that I might try to see if it does better. By the numbers, the venturi aren't that different in size.

I'm really sad I missed out on the hyperpak manifold that was on sale here a couple weeks ago... I think I ultimately want megasquirt (with fuel and spark timing) on this engine, but it's hard to beat the hyperpak mojo.

I'll measure my timing curve to see where I'm at - I've run 12 degrees initial so far without ping. I've lost my notes on how far I shortened my distributor slots (and I'm pretty sure I've got springs from DusterIdiot in this distributor) in the last build, but I suspect I'm not dialing in enough timing. My kingdom for a distributor machine, or a shop near me that would let me use one...

Where's the next slant 6 race in the SouthEast?

I am going to agree with Lou actually and take back my statement... After reverse engineering this Comp Cam and this possible build, he can't go to far with
this cam grind as they picked a Ford Cam Lobe Profile... that is 239@.050...but is only 268 advertised duration... the lobe is typically selected for higher rpm small
blocks (typically Clevelands) with high ratio rockers or high rpm use...Comp advises that the lifter bores get extra oiling for high rpm and stiffer valve springs...

Sadly... this cam is not as pliable as some chrysler lobe grinds and if he's at 10:1 SCR with the 104 LSA and set to centerline, the DCR is already 8.88... if he rolls
it to 100 it goes up to 9.2-ish... (which is what I run in my 11 and 12:1 builds and will run on clear pump premium... but I have more cam at .050 to bleed things down)...
if they cheated and didn't give him the full 10:1 (say 9.5 SCR, it will run on pump midgrade)....

His estimated dyno number look like if the cam was set to centerline he will have peak hp about 3500-4000 rpm, with peak torque coming in 1000 rpm lower than that...
That carb is for Ford use and isn't really well suited as a medium carb... On my hipo builds the 600 functioned better and gave a good increase in power (breathing)... using annular boosters also was a plus over the stock boosters, and you will probably use the brown or plain spring in the secondaries anyway... I think the other issue on the 465 carb is the lack of a PVC fitting is not helpful to a streetable engine either...
I dont' understand this... when I told my machinist that I was using a .54-ish lift cam, he already had a guide tool that would properly reduce the height for the higher lift cam...
I got no complaint...unless your machinist isn't as chrysler savvy...mine was nice enough to compress the spring and do the wire test to make sure the coils wouldn't bind at that
lift either.

I would set timing for this engine to be 14 initial, 30 mechanical total.

72Polara,

See this thread for racing info. Looks like we might have June 16-17 race at my home track - Radford, VA...

http://slantsix.org/forum/viewtopic.php?f=10&t=62054

Wilkesboro, Knoxville, and Radford are not too far for you.

Best wishes and hope you can join us!

Lou

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Home of Slant6-powered fun machines since 1988

Where did you get your machine work done? I want to get a block bored, but the local machine shop (small mom & pop place with 1 employee) does not have torque plates for a slant. Also, they were excited because they had "never worked on a slant six before" They make their bread and butter on Chevrolets for dirt track racing in Woodstock.

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If it was easy, everybody would be doing it.