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Chryco's Tech Shop => Engine & Go Fast Goodies => Topic started by: Flatdad on February 01, 2017 - 12:57:11 PM

Title: Grassroots 400, think it will crack 350hp?
Post by: Flatdad on February 01, 2017 - 12:57:11 PM
Winter boredom has set in, so thought I'd upgrade the 400 a bit for the fun of it.

The engine that's in my challenger when I bought it is a mystery 400 that ran and idled well enough to drive the car on a trailer but sounded one cylinder off. Found one of the header pipes smashed shut almost. I have some old wedge parts lying around that I couldn't sell last year so here's the plan:

Swap the 452's for a fresh set of 915's with .020 gaskets, port match an Edelbrock tm7, swap in an old Summit cam and lifters, and replace the smashed header with an old flowtech. Not sure which carb to run though, I've got a 600afb and a 600 vac holley both need rebuilt.

Cam specs: 298/303 224/234 @.050, .466/.488 lift and a 114LSA.

Think it can make 350? Think it can put a stock E-body into the 13's?
Title: Re: Grassroots 400, think it will crack 350hp?
Post by: 1 Wild R/T on February 01, 2017 - 01:38:04 PM
The TM-7 & the cam both are a little hotter than a low compression 400 likely will want... Swapping to the 915's certainly helps but your likely going from 7.8-1 up to 8.2-1....  Personally I'd consider milling the 915's .050-.060.... That would take you close to 9-1....   Another .5 would be nice but not worth the cost.... A true 9-1 should make that cam allot happier...

What gear are you running? 4 spd? Auto? Convertor?
Title: Re: Grassroots 400, think it will crack 350hp?
Post by: Flatdad on February 01, 2017 - 02:36:10 PM
Don't know the current rear gears, probably still an open diff, have a 4.57 suregrip lying around and a 3.23 sg in a Road Runner, also a spare set of 28.5" tall slicks that barely fit the Road Runner. I bet the torque converter is whatever came with the 400 since its still externally balanced. Figured the head swap would bring it from maybe 7.2 to 8.0:1. Originally ran that cam in a 440 with a whopping 7.0:1 compression, seemed pretty mild.

If I had the heads milled, would need new pushrods. So far the only costs involved for this project are the various gaskets, seals, motor oil, etc. Open to suggestions like that though, like I said this build is just for fun.

Which carb should I try on this turd?
Title: Re: Grassroots 400, think it will crack 350hp?
Post by: RCCDrew on February 01, 2017 - 05:32:44 PM
Mild hand porting is free and can help. Anything else you can do to help the compression will help too. Milling deck or heads. A matched cam for your application would be worth it as well.

Or just run all your stock parts and find some take off Cummins turbos lying around. Problem solved!
Title: Re: Grassroots 400, think it will crack 350hp?
Post by: 734406pk on February 01, 2017 - 07:30:51 PM
The 400 is very strong block but the stock piston compression height is very low.  IMO i would replace the pistons with something taller to achieve near zero deck height and go from there. Use a .040" + - compressed thickness head gasket for some quench and you will be happy!
Title: Re: Grassroots 400, think it will crack 350hp?
Post by: Road_Runner on February 02, 2017 - 05:13:33 PM
I ran an old Edelbrock DP4B dual plane intake on my mostly stock 383 before I built it and was very happy with how it ran. That intake or its modern equivalent the Performer RPM would be my choice for intakes.  I ran both 3.91 & 4.10 gears with the original 10.5" converter and the car was very strong off the line, even more so after I rebuilt it with new 'pop up' pistons, cam, etc.  The 383 loved to rev like a small block so your 400 should like the same kind of mods.

Later, Jim
Title: Re: Grassroots 400, think it will crack 350hp?
Post by: 1 Wild R/T on February 02, 2017 - 07:16:26 PM
I ran an old Edelbrock DP4B dual plane intake on my mostly stock 383 before I built it and was very happy with how it ran. That intake or its modern equivalent the Performer RPM would be my choice for intakes.  I ran both 3.91 & 4.10 gears with the original 10.5" converter and the car was very strong off the line, even more so after I rebuilt it with new 'pop up' pistons, cam, etc.  The 383 loved to rev like a small block so your 400 should like the same kind of mods.

Later, Jim

DP$B is closer in design to the Performer than the Performer RPM.. :2cents:
Title: Re: Grassroots 400, think it will crack 350hp?
Post by: Flatdad on February 03, 2017 - 09:46:57 AM
The tm7 is actually what came on the car so it stays, unless I see a low deck intake for stupid cheap. The 600 afb is taken apart, cleaned, and just needing gaskets now. Wanted to run the holley, but the afb is just sooo much easier to rebuild. Put a big order in @ Rockauto using the the discount code (thanks cuda-challenger!) a whopping 694 bucks in sheetmetal, parts, and gaskets!

Cost of engine parts so far:
$13.16 Intake gaskets
$1.89 PCV
$34.60 New set of exhaust valves 1.74"

Yet to purchase:
.020 Steel head gaskets
Exhaust gaskets
New fuel hose
Hose clamps
Oil filter
6qts motor oil
Push in breather
+other unknowns

Yet to pay for:
Clean and mag, cylinder heads (they're crack free, woohoo!)

Might just start a build thread for the whole car heap of rust soon...with pics of course!

Here's a pic to show the junk I'm dealing with, and why I'm not too keen on investing too much time and $ in the engine. (the carb in the pic has been repurposed elsewhere)
Title: Re: Grassroots 400, think it will crack 350hp?
Post by: Cazbah362 on February 05, 2017 - 01:03:22 AM
I think you are spot on to your approach, just a thought.  I would probably do a leak down test before starting on this just to check health.  Yes, there may be a cylinder head issue such a burnt valve, but at least it would be a good start before ANY money goes in.  Those 915's are worth a bit on the market, so you could just sell them and re purpose the funds to milling and the push rods the 452's.  I would suspect you'd be a little more overall compression in the end the just the .020 gasket with the closed chamber 915's plus some cash back. 

And rent a steam cleaner, wire brush and Krylon can fix the overall appearance of the bay.

A little more down time and work, but 452's milled or even sell them both and get 440 Source heads?  Personally - 915's, gaskets and port match will perform well. especially for the price. 
Title: Re: Grassroots 400, think it will crack 350hp?
Post by: Flatdad on February 07, 2017 - 04:26:50 PM
Updates: Had to order 4 more exhaust valves. They come in packs of 2, so I ordered 4 thinking 8 would show up...Nope! -$35.

The intake is actually a TM6, as TM7 is for RB's.

Committing to using the 600afb, unless I spot a cheap Holley 3310 on craigslist.

Just moved into a new place, and the Dodge can come out of storage hopefully in the next couple of days! I've got a pile of metal and engine parts waiting!

In response to Cazbah362, I actually tried selling the 915's back in the fall. Listed 'em on CL for a whole 200 bucks but nobody wanted 'em beyond a couple calls and texts. I figure even if the engine turns out to be junk, the 915s will be more sale-able with the bigger exhaust valves now anyway.

Ended up with a full 2.25" exhaust system off a '69 RR, I'm going to shorten it to fit the dodge. $100 with mufflers and hangers.
Title: Re: Grassroots 400, think it will crack 350hp?
Post by: Flatdad on February 13, 2017 - 10:56:37 AM
The Dodge is out of storage and in the garage! Exhaust valves went to the machine shop Friday afternoon too.

Visited my brother with my dad over the weekend, he was going to be cleaning and painting parts for his Belvedere project so I brought the Holley 600 along for something to do.

The local O'reilly's happened to have a kit in stock. Was expecting a grubby mess, but instead it was the easiest Holley rebuild I've ever done! Except for a couple small issues, I think this Holley would have almost ran the motor BEFORE the rebuild.

Specs: 1850-2 (probably mid '70s) 600cfm vacuum secondary. 66 primary jets, standard secondary plate is 69 jet size. 6.5" p-valve, standard white pump cam (installed in #1 position), .025 accel pump nozzle, and standard secondary spring.

Thinking of upping the primaries to 69 or 70 jets and a .028 pump nozzle. Have to wait and see what it wants for a p-valve, but I think the 6.5 should be darn close.

Trailer rental+light adapter: $77
Holley 4160 rebuild kit+2 cans carb cleaner: $37
Title: Re: Grassroots 400, think it will crack 350hp?
Post by: Flatdad on February 24, 2017 - 11:44:28 AM
Not much to update: Waiting on my heads (and the bill) from the machine shop. Pulled a valve cover and verified the old heads were 452's as suspected. Discovered the gas tank had a leak at the top. My cousin and I dropped it down so I could redo the trunk and I managed to spill the smelliest gas ever on the floor.

After these next couple swap meets, the plan is to order the rest of my gaskets and more sheet metal including a fuel tank. My brother has an old digital camera to donate to the project so hopefully you guys should have some pics soon!
Title: Re: Grassroots 400, think it will crack 350hp?
Post by: joes74challenger on February 24, 2017 - 03:55:56 PM
 :popcorn:
Title: Re: Grassroots 400, think it will crack 350hp?
Post by: Chryco Psycho on February 24, 2017 - 08:20:16 PM
The cam is actually a decent choice the 114* l will help a lot with the low compression .
 The package should work OK .
I would never use an AFB over a Holley , both are too small but the Holley will be more responsive
Title: Re: Grassroots 400, think it will crack 350hp?
Post by: Flatdad on March 02, 2017 - 04:33:05 PM
MMMH! Tasty Crow, my favorite! I had the heads redone with new exhaust valves, claiming it would still be worth it over aluminum heads or keeping the questionable 452's...NOPE!

$687 which included: clean & mag, 8 new oversize exhaust seats, 8 new guides, and all machining associated with installing guides, grinding seats and valves, making them all the same height installed, freeze plugs, etc...

I have a long list of the work they did. I would have been perfectly happy if it had been less than $600, but gee wizz it was almost 7!

To total the cost of the heads, for all to see (and ridicule):

200 initial purchase in 2014
  70 for new exhaust valves
687 in machining
_____
=$957 still needing stem seals!

Cost of new 440source heads: $998 pair + shipping + having them gone through.

Downside is I just barely beat the cost of new aluminum heads, they weigh more, and flow less. The few upsides are: I know everything on them is "right", none of it is made in china, and the money spent stayed in my local economy.

I can usually admit mistakes pretty easily, but this one hurts my pride a bit, lol. Think I'm going to run these heads for a loooong time to get my money's worth. What kind of beer goes well with crow?

Next time: CC'ing and port work! stay tuned...
Title: Re: Grassroots 400, think it will crack 350hp?
Post by: rUNCHARGER on March 02, 2017 - 05:24:30 PM
We've all been there, that's why we recommend what we do. i did a set of 915's about 10 years ago, put 2.14 and 1.81 in them, ported them myself but you still need the machine shop to surface them and cut the seats. the investment was exactly what the new Edelbrocks cost, however I knew that going in and didn't want that goofy Edelbrock look.

Sheldon
Title: Re: Grassroots 400, think it will crack 350hp?
Post by: 1 Wild R/T on March 02, 2017 - 10:56:49 PM
We've all been there, that's why we recommend what we do. i did a set of 915's about 10 years ago, put 2.14 and 1.81 in them, ported them myself but you still need the machine shop to surface them and cut the seats. the investment was exactly what the new Edelbrocks cost, however I knew that going in and didn't want that goofy Edelbrock look.

Sheldon

I did 915's last year for my Challenger, but I bought valves, seats, springs, retainers, keepers & guides all throughout Summit & traded labor so it wasn't to bad & on a car like my Challenger where I want it to look stock Eddies weren't an option....

For most engine builds these days putting together iron heads makes no sense....
Title: Re: Grassroots 400, think it will crack 350hp?
Post by: Cazbah362 on March 02, 2017 - 11:56:11 PM
We have all done it. I agree, you have a set of heads you know are right!  Just a thought, spruced up 915's should pull pretty good money on EBay?
Title: Re: Grassroots 400, think it will crack 350hp?
Post by: RCCDrew on March 03, 2017 - 05:28:12 AM
Thanks for the honesty. Now time to get out the carbide burrs!
Title: Re: Grassroots 400, think it will crack 350hp?
Post by: Flatdad on March 30, 2017 - 01:58:56 PM
Feeling a lot better about these cylinder heads now. Engine and head work have been on hold, while I repair the rear structure on the Challenger. Found some time this last weekend to paint up one of the heads. I liked the duplicolor engine primer, but not a fan of their Hemi orange paint. Its too thin and runny.
Title: Re: Grassroots 400, think it will crack 350hp?
Post by: Cazbah362 on April 01, 2017 - 10:40:30 AM
Those look nice, what head gasket are you going to run?
Title: Re: Grassroots 400, think it will crack 350hp?
Post by: Flatdad on April 03, 2017 - 04:07:40 PM
Those look nice, what head gasket are you going to run?

Steel .020 gaskets to gain as much compression as possible on the 400. Haven't messed with ports yet, but was worried the heads would rust up without throwing some paint on 'em.

We had some nice weather over the weekend. The Challenger is going to take way longer than anticipated, so I dragged my old Road Runner out of hibernation once again...

The plan was to make the challenger a daily driver for this summer and fix up the Runner, but looks like the opposite is going to happen.
Title: Re: Grassroots 400, think it will crack 350hp?
Post by: Cazbah362 on April 04, 2017 - 11:17:07 PM
Cool RR, good luck on the port work, assuming you are looking to match port to exhaust and intake?  I get the change in direction, some times its best to put the toys away and take a break, drive around and enjoy the weather from the front seat of an old Mopar.  When life was much simpler...
Title: Re: Grassroots 400, think it will crack 350hp?
Post by: Chryco Psycho on April 08, 2017 - 07:58:21 PM
Cool 70 RR  :2thumbs:
Title: Re: Grassroots 400, think it will crack 350hp?
Post by: Flatdad on April 20, 2017 - 10:23:10 AM
Cool RR, good luck on the port work, assuming you are looking to match port to exhaust and intake?  I get the change in direction, some times its best to put the toys away and take a break, drive around and enjoy the weather from the front seat of an old Mopar.  When life was much simpler...

Got all fired up to work on the challenger again last night. I hadn't thought about port matching the exhaust side before. Funny thing is, I think the passenger side is going to end up with a nice painted up Flowtech to replace the smashed up hooker header while the driver's side will have to keep the old rusty hooker because of power steering clearance issues with the Flowtech. Lol

To throw a wrench into things, I spotted this on Craigslist today. Its just a ten minute drive, the piston compression height looks decent from the picture and I spy a forged crank. If the walls are decent, with it being a short block it would be easy to give a quick hone, re-ring it along with new bearings, and swap the other bits from the 400. A spare forged crank torque converter is in the shed.

https://fortwayne.craigslist.org/pts/6089928807.html (https://fortwayne.craigslist.org/pts/6089928807.html)

Waddaya think? Stick to my plan or take a short drive? I've got perfectly good calipers with the depth gauge doohickey and steel straight edge...
Title: Re: Grassroots 400, think it will crack 350hp?
Post by: 1 Wild R/T on April 20, 2017 - 11:27:01 AM
Those dished pistons are the kiss of death for making power... :2cents:
Title: Re: Grassroots 400, think it will crack 350hp?
Post by: 734406pk on April 20, 2017 - 10:01:43 PM
Those dished pistons are the kiss of death for making power... :2cents:

 :iagree:
Title: Re: Grassroots 400, think it will crack 350hp?
Post by: Flatdad on April 21, 2017 - 07:19:54 AM
I didn't go look at it. Did some calculation assuming the dish volume @ 15cc and maybe .040 in the hole, the CR would end up no better than the current flat tops in the 400. Thanks for the advice guys. Sticking with the original "cheap" hop up plans.