440 Rebuild - Advice Please

[VTMopar]

Hello    I've been a member here for a few years and have learned a lot and tried to share what I've learned with others.     I'm not a "gear head" (I wish) and I spend a lot of time researching things and am not bashful about tackling different projects as I've restored my challengers over the past several years.   I've swapped dashes, tore apart and restored the interior and will tackle other things (sway bars, etc.) ... but I know my limitations and taking a motor apart and getting into the intimate details about re-building one... well ... despite a lot of reading and research - as I grow older I've learned to know my limitations! 

So - I'm looking for some advice for rebuilding my '70 Challenger Vert.   This is originally a 318 car, but was converted to a 440 6 pack with a 727 transmission about 6 years ago when I bought her.    I've put about  15,000 miles on her, including a trip to Florida and back from Vermont.   She's always run great and I haven't touched the motor (or carbs) over the past 5 years (my philosphy is if it ain't broken, don't fix it).   She always ran great..... but this summer she started to spit, sputter and so I took her to my local garage (who are MOPAR guys and I inherently trust) for a tune up (about time, huh!).    After some work, my mechanics got her to run better but a compression check indicates 2 bad cylinders so they recommend that I consider a rebuild.   

Now I trust these guys - they've done a lot of work on my '74 (and some tranny work and other mainenance on the '70).   They drag race MOPARS and have an excellent reputation.   But - as I'm about to sink a fair amount of change into this re-build, I'd like to be more than a casual bystander and would appreciate any thoughts or advice as this project starts moving forward.    My mechanics and I agree that we can't decide anything until we tear it down.....  but basically here's what we have going into this project:

-   a 440 motor from a '67 Imperial with a Mopar Performance 6 pack set up.    The motor was installed about 5 years ago when the car was restored (originally a 318) and this is what the seller told me what he had done:   "  The bottom end ( pistons, rings, rods, crank) are low mileage originals (49k miles) they were checked for condition and clearances and were excellent and re-used. the heads were completely rebuilt, hardened exhaust seats for no lead fuel, new guides, new valves exhaust and intake, new valve springs. The cam is a mopar restoration cam 440-6 it is new, as well as the lifters.the push rods and rocker arm assy is original. the timing chain and gears are new, the fuel pump is new, distributor is a mopar electronic."

-   As a '67 block, it is only rated at 350 hp and -- from what I've read here and elsewhere, it should have the 915 heads (which some folks think are pretty good....).... but not sure what shape they are in until we get into the motor....       

-   I would like to keep a stock look.....  so I don't want to go with headers, etc.....   BUT I would like to kick up the hp to as strong as I can, so long as she remains streetable and not too tempermental.  Again - I've driven this for 5 years without incident and stepped on her pretty hard on occasion ... and drove her long distances....   That's the kind of driving I do and would like to have a motor that is reliable and has as much power as is reasonable -- given my driving habits and my mechanical abilities (which are limited

So - will be taking her into the shop in a week or so.... any advice or things I should consider before this project gets going?   

Perhaps I can also update as the motor is taken down and we can continue the "discussion" here on the forum... ? 

Thanks....   

VT Mopar

[brads70]

Did they say which cylinders were low? I was just thinking it might be something in the heads or head? If so it might be just a simple valve job, worn guide? Maybe not requiring a compleate teardown ? I would think a 440 should last more than 65K?
Does it blow smoke out the tailpipe? Does it use oil?
I understand you don't want an all out drag engine power wise but I'd be careful building to much motor being a Vert?

[VTMopar]

She does blow smoke when first starts up and later if you stomp on her .....  Never used to....but does now since  the tuneup when they went through the carbs.    They did the compression test with the tuneup ..... i think it was the 1st and 3rd cylinders that were low.    They also had fouled plugs in these cylinders (I checked this out myself....they definitely were fouled)   All this was about six weeks ago and they got it to run ok...despite the issues.... so i could drive her the rest of the season.   They may have tinkered with the carb settings to give me what they could until we tore her apart..... might this be causing the smoke if she is set too rich?     

As you say, it may be something with the valves ( although those were supposedly done when I bought her).   Will see when we tear her down, I hope!

You seem to suggest I should be careful with too much power since she's a convertible.....  While I understand she isn't as stiff as my 74 coupe.... What should I be considering in this regard?

Thanks for your thoughts...

Vt Mopar

[dutch]

I`d pull the driver side head before doing anything drastic. Could very well be a cracked head or maybe even just the gasket between 1 & 3...  Blue smoke is caused by burning oil, it it runs too rich it will smoke black. 

[HP_Cuda]

Could be worn rings since the guy re-used a good deal of components from the original build.

[PlumCraZRT]

I understand you don't want an all out drag engine power wise but I'd be careful building to much motor being a Vert?

I agree with Brad.  You should heavily consider installing subframe connectors.  I'm doing that on my hardtop challenger that will be receiving a 500hp 451-stroker.

[Perry]

I would agree about a thorough diagnosis first. If the compression doesn't raise after a few squirts of oil in a cylinder it may be guides and seals. Exhaust all possibilities before cracking it open.
On a side note I am about a week away from my first attempted startup on my 440. Had RPM Racing engines in Georgia VT do the machine work. Assembled it myself as a bucket list item.
Let us know as you find out more.
Perry

[Chryco Psycho]

A bad intake leak could cause the oil fouling but not low compression

[VTMopar]

Will start taking a good hard look .....and tear down in a week or so......  I'll post updates as we go forward.   Thanks for the ideas and suggestions.     Assuming will need to go through the motor and depending on what we find, I would appreciate suggestions on what we might do to kick it up some.....  But as I said in my original post, I would also like to keep her stock looking and not too temperamental to drive......

vt Mopar

[Chryco Psycho]

add cubes will keep it looking stock & not make it difficult to drive

[Jesus H Chrysler]

I've seen rebuilds in the past where someone had a low mileage short block and redid the heads, only to blow the rings and lose compression.  On the original motor, the heads and rings wear together and each develop a certain amount of leakage.  When you freshen the heads only, you then put more stress on the rings that now have to seal more pressure than they did before.  This sometimes causes them to fail, and you lose compression.  If your heads were rebuilt correctly and are not at fault, you may be into the motor for at least a ring job.  If the pistons, bores and bearings are good then no need for a full rebuild.  If you want to up the power, there are higher compression pistons as well as stroker kits that can increase your power with little to no external changes to give it away.  As a fellow convertible owner I must caution you.  I put a rebuilt 440 in my Challenger and now my door gap edge and front of my quarter panel are chipped from them contacting each other.  This is with 2" box channel frame connectors welded in.  Convertibles do not like a lot of torque and that's what a 440 is all about.  It hurts my heart but I am actually de tuning my 440 for less power just to save the car.

[VTMopar]

I appreciate your comment about torque with a Vert...... I've parked her on an incline and had a time getting the door open on occassion.....     I think we'll just have to see if you're right about the rings.... and what shape other components are.... and then kick her up as we can while mindful of the torque issue....   

Thanks
VT Mopar   

[Perry]

Any luck or progress?

Perry

[VTMopar]

A slight delay....... taking her into the shop middle of next week.    I'll keep you posted.   

thanks
VT Mopar

[VTMopar]

Well, she's finally done.    Will put her on the Dyno later this week, but she hit 440 hp at 5300 and a little over 500 lbs of torque on the engine dyno.    This was a 350 block - out of a '67 Imperial with 915 heads (that we kept)...and I wanted her to maintain her stock look, so I'm pretty pleased with these results.     

Now my guys are suggesting REV-N-NATOR.....  to protect the motor.   Anybody have any experience with these?     

VT Mopar