74 Challenger driver

[femtnmax]

I added a post describing scratch built subframe connectors in the body shop section.  Here's the results.
They are not grossly weak back at the leaf spring hanger like the weld-to-the-bottom-of-the-floor types.   This weak point is right where the hemi and 6-pack cars would buckle the unibody from high-torque starts (where the back of the door meets the rear quarter panel).

[femtnmax]

The car went to the paint shop today.  This was the first sunlight the car had seen in several years.   Replacing lots of metal, new includes:  R/T hood, trunk lid w/ spoiler holes, both rear quarters (full), and roof skin.  Expect 3-4 months, will pay in increments to cover work completed at each step (suggested by autobody101 website).  The body shop really liked the idea.
Sealed the seams with 3M ultrapro urethane seam sealer (not firm and fast) per suggestion of the website mentioned.  The body shop said they use it also, and liked the way it turned out on the Challenger.   I'm adding the headlite buckets to adapt 1970 grille to the 74.
Now for a drive train update.  I already rebuilt the rear axle/rear diff.  I did NOT use "green" wheel bearings, I stayed with the semi-floating tapered Timken bearings because they support side load (turning corners), and the green ones do not.  For the pumkin used 742 case with clutch type posi (sorry, I've always called them that).  I like the case because there is no crush sleeve, its all shims for bearing adjustment.  I liked the clutch posi because it is rebuildable.   I had originally picked up a cone-type posi.  Being the ex-ASE certified mechanic that I am, I have to tear everything apart.  Well.... the cone type unit was in usable shape true to what the seller said, but there were "hard areas" in the case casting, which were causing gaulling of the cones.  So I could see the unit would not last long term.   I cut 0.080 off the ends of each cone to extend the life of the unit as recommended in "Chrysler Performance Upgrades" by F. Adkins.   I then sold the pumkin. 
The 742 unit I have has a flat and true ring gear case, I replaced all bearings, and added NEW OEM ring and pinion 3.23 ratio.  Hard to find this ratio, but an outfit in Long Island had several.
The trany was another story.  Looked at the trany before buying, it turned over ok, but a little stiffness in spots.  I thought, ohh, I can fix whatever it is.  WELL..... the previous builder had left out one of the spacer/washers that supports the end of the double set of needle bearings at the end of the counter shaft .  So the needles were feeding into the groove in the case that retains the thrust washer.  The needles were being eaten alive by the case, and vice verse.  The case and countershaft gear were ruined.
So I bought a used case and bearings/rebuild kit from Brewer's Performance, he's a great guy to deal with.  I bought a complete set of gears from Zumbro Bearing and Gear (ZBAG) in MN, they were also very helpful.  The gear set was not OEM, and they said it would not hold up to 600 hp 6000 rpm clutch dumps with slicks, but I"m not going to race the car.
So in the end the used trany had a good input shaft bearing retainer, and the better shift cover assy (the good early style).  I replaced all the bearings, new countershaft and an OEM new output shaft and syncro assemblies.   Also new steel shift forks from Passion Performance.
The gear set I bought has the "older" lower first gear ratio (2.66:1) so when it's combined with a 3.23 axle ratio gives you 8.59:1, which is real close to the newer first gear ratio (2.47:1) combined with a 3.55 axle ratio (result = 8.77:1).  SO... I have the low first gear for good acceleration, and also have a highway type rear axle ratio.  Trying for the best of both worlds.  Should work well I think.
I had the bell housing opening enlarged to fit the large diameter front bearing retainer.
Does money grow on trees???  I wish it were true.   I'll be returning to working on the cylinder heads next; they are half done.  Port molds, pushrod restrictions, more lessons learned.
 

[wagesofsin]

 

lookin good!!

[70shaker6pk]

Your making some real fast progress,  great work!!

[The Cuda Guy]

Those frame connectors look awesome!   

Don

[femtnmax]

For my 360 engine build, I'm sorta copying an 340/414 stroker build, but doing a 360, and not doing the stroked crank.  The article I followed was in the spring 2008 Hot Rod do it yourself engine series, and included the 414 build done by School of Automotive Machinists in Houston, TX.
Their compression ratio was 10:1, mine will be about 10.5:1, so when allowance for aluminum head heat dissapation I'll have about 9.5:1;  which works well at my elevation above sea level 4800 feet.
Their piston tops were set at zero deck, top of block.  Mine will be a little above zero deck for quench clearance of about 0.035 using 0.040 head gasket.
They used Edel magnum cylinder heads, which they said had slightly better flow numbers, and improved combusiton chamber compared to Edel's LA heads.   They said the combustion chamber size was increase from 58cc to 65cc to obtain the correct compression ratio.  I found that the chamber size increased from 58cc to 64cc when both intake and exhaust valves were unshrouded: cut back to near the head gasket scribe line.  Remember, its the port/bowl work done within 1 inch each side of the valve seat that has the most effect for street type valve lifts where the lift divided by valve diameter equals about 0.25.  This is where the valve seat region controls most all the flow.
A mistake I made was first adding to the size of the valve reliefs on the piston tops to lower my compression ratio, then doing the work on the heads and finding the large increase in combustion chamber volume with the unshrouding cuts.  I had to mill the heads 0.010 to get the combustion chamber cc's back where they belonged.
The cam they used was a Comp 242/248 hyd roller with 0.594/0.581 lift using 1.65/1.6 rockers.  LSA was 110 deg.   I chose to use a Lunati Voodoo hyd flat tappet designed for Mopar's 0.904 lifter diameter.  Specs are lobes # VH44/VH45, LSA 110 + 4, 271/279 duration and 226/234 at 0.05, lift .559/.547 using 1.7/1.6 rocker ratio.
They used a single plane victor intake manifold modified to fit the magnum heads and a 1 inch tall open carb spacer; said they did not need the additional low end torque of a dual plane intake.    I'll be using a Edel RPM air gap dual plane intake with 0.875 4 hole spacer to adapt thermoquad carb to the intake.
Here's a photo of a mold for a stock intake port of the Edel magnum cylinder head.  Note the generous pushrod restriction.  SAM ported the port completely out and added bronze inserts in the pushrod holes in the heads to open up this restriction.  Their intake port volume went from 176cc to 190cc.  I'm working on the same idea.
Their TQ/HP on the dyno was  503 tq at 4300 rpm and 501 hp at 5700.  So if I reduce those numbers by 12 % for 366 cubic inches vs 414 cubes, then my TQ/HP could be 430-440 each.  I'd guessing maybe end up with 400 hp and 420 tq.
We have a chassis dyno in the area, but how do you tell if its accurate?

[71_340Challenger]

Great start to your project. Keep up the great work and updates. 

Once question though, do you have the name of  the place you got your 3.23 gears? My 71 Challenger orignally came with 3.23 and they were damaged. I would like to replace them, but I have not found any yet. Thanks.

[femtnmax]

Great start to your project. Keep up the great work and updates. 

Once question though, do you have the name of  the place you got your 3.23 gears? My 71 Challenger orignally came with 3.23 and they were damaged. I would like to replace them, but I have not found any yet. Thanks.

It's been over a year since I bought them, boy you are lucky so far.  I usually clean house.
I bought a NOS OEM ring and pinion set, still in the factory box, from S-K speed racing equipment of Lindenhurst, NY.  Talk to Brian.  Phone # 631-957-9525.  Ring/pinion set part #2070817, for 1 3/4 pinion, 742 case, 10 spline yoke.
I went thru an ordeal to find a good ring gear housing for clutch type posi unit.  Good ones are getting hard to find.  I think I saw replacement ring gear cases being made by someone.   
I bought the bearing kits, shim kits, seals, etc from NorthWest Differential of Seattle.  All timken parts... good stuff.   They rebuild them too, which in the end might have been easier to do.  Took me awhile to get the tooth pattern "perfect".  I didn't have the factory tools, and had not done one in over a quarter century.
Mopar still offers the ring gear bolt sets.
Hope this helps.

[71_340Challenger]

Phil
Thanks for  the information. I will have to check them out. I luckily have a get set of cases. My original 741 case, a 742 case with 2.76 gears that I have in my car right now ( purchase that was supposed to be 3.23) and a 489 case I bought locally just in case I wanted/needed it at some point.

Keep up the good work.

[SilverChally]

Looking good!  I use 3m pads that go on grinders for removing paint.  They are the coated spongey looking pads.  I can't recalls the name.  But they strip paint great and long as your careful won't warp the panels.  Work alot faster than a da sanded and cleans them much better. 

[femtnmax]

Finally a progress update.   Been busy with work, taxes, helping my mother, etc.
Body shop stripped off the roof and rear quarters.  I then cleaned and primed the substructure.
I started back on the engine build.   The ARP  main cap bolts are strong enough that they distort the main caps.  The cap ends under the bolts are "low" and the center "high".  The ARP washers are larger in diameter than the bolt head "pattern" that had formed on the caps, so I had the main caps spot faced at each bolt location so the washers would havve full contact on the caps.  Then I hand fitted the caps to the block within 0.0005 of the minimun spec, so the machine shop would not have to remove much metal with the hone.  If the caps are cut too much, the hone can end up working the diameter parallel to the main bearing parting line, then the holes are no longer round within spec.    Next I'll check the align hone of the block main bearing bores, bearing shell thickness, and crank main journal diameters to verify main bearing clearance.  I expect the crank to spin freely when done.
The pistons have already been fit to the bores, with about 0.002 clearance.   I'll double check the rod big end diameters, bearing shells, and crank journals for rod bearing clearance.  Then install the pistons on the rods.   With that I can install one piston in all 4 corners of the block to check piston/block deck height.   I'm looking for locating the pistons 0.004 above the block deck.
Felpro 1008 head gaskets have 0.039 compressed thickness, which means the quench clearance between piston top and cylinder head will be 0.039-0.004=0.035 inch.  An acceptable quench clearance is 0.040, but a little tighter just means that detonation is prevented even more.   

[wagesofsin]

well, now i dont feel so alone seeing my car without a roof everyday! hahah. looks like you guys are chipping away at it.
thanks for the heads up phil, lookin good.   

[femtnmax]

well, now i dont feel so alone seeing my car without a roof everyday! hahah. looks like you guys are chipping away at it.
thanks for the heads up phil, lookin good.   

Yeah the roof was an unexpected cost increase.   It's good there's been a bunch of those already so it justs melts in with the rest of them

[71ChallengerSE]

What did you do with the roof skin? I could sure use some sections of it if you could cut some pieces off. I need to fix a hack job on mine and I could help take the sting off the cost to replace the new one. Just a thought.

[femtnmax]

What did you do with the roof skin? I could sure use some sections of it if you could cut some pieces off. I need to fix a hack job on mine and I could help take the sting off the cost to replace the new one. Just a thought.
[/quote
No problem, I sent you a pm.