70sgeek

Apparently you never stop at one...


So 2 months ago when I scored my '72 Cutlass ragtop the summer plan was relatively simple. Swap out the 14" rally/white walls for 15" mags/RWL's, new driveshaft, dual exh, full rebuild/upgrade of the steering and suspension with a CPP 500 series steering kit, good front/rear sway bars, and Bilstien shocks, upgrade the motor to a 4bbl with HEI, new water pump, t-chain, cam and tune up.


This was supposed to carry me at least through Spring '17, after which I could assess the need for other upgrades/maintenance.


Well ok so much for that - after practically being handed a complete-super clean '72 cutlass 8.5 rear which had been replaced by a 12 bolt, I decided to go ahead earlier than planned and build a new 3.08 posi to go back in with my intended suspension upgrades.


I figured, budget still good, I could do this and still have a little left from the prior car I had just sold to buy this one.


UNTIL... and there's always an 'UNTIL'.... I started on the motor projects whilst awaiting some of the other new parts to arrive. Pulled the intake and found the top side of my motor (the #s matching SBO 2 bbl) had pretty significant sludge buildup within the valley.


But wait, wasn't this supposed to have been a 54k mile vehicle (oh, did I forget that detail).. ? Well maybe it still really was and the sludge resulted from the car actually not having been driven enough in its 40+ year life... UNTIL (again...?) I noticed the t-chain had been replaced (and had pretty substantive slack)... So much for the original low-mileage claims.... Perhaps my first clue should have been the non-matching TH-350?


Ok, greatly humbled and with scraps of a budget left, I now find myself @$$ deep in a complete motor rebuild. So here are the highlights of basic plan 2.0 ...


Edelbrock 2711 intake with fully rebuilt Qjet 750 carb p/n 17056523; Howards 510011-12 cam/lifter set; New pistons still to be determined, with goal to reach 9.5 or so compression; new stock rockers set; heads will be fully rebuilt with new valves, springs, etc.; crank will be turned as needed; adding new Pertronix Ignitor III HEI distributor w/MSD coil and wires; new balancer; new Mellings standard oil pump; Milodon water pump, new aluminum radiator; I'll be adding a 1700 stall converter to the transmission as well.


I guess the bright side is it should be almost twice the car it was before when it's done .

Fun71

Here are my thoughts:

Pistons: Use either Speed Pro L2321F (6cc dish) or L2320F (flat top) depending upon your combustion chamber volume and piston-to-deck clearance to get ~9.5:1 compression.

Camshaft: The Howards cam you listed has the specs below:

Valve Lift: 0.448 int./0.475 exh.
Advertised Duration: 259 int./269 exh.
Duration at 050 inch Lift: 205 int./215 exh.

I think that is too small of a cam (too short duration) for 9.5:1 compression ratio. Either adjust the compression ratio or the cam.


Converter: If you go a bit larger on the cam, go higher than 1700 RPM stall. Back when I had a .435 lift/204 duration cam with ~8.5:1 compression I used a 2100 RPM stall and it worked very well. When I went to a larger cam, I increased the stall to 2400 RPM, then again when I went with the current cam I increased to 2500 RPM stall.

oldcutlass

Unless you cleaned the sludge out already, I don't call that sludged up. However you did have a head issue. Another MAW afflicted owner, it will pass as you run out of projects. But... then you'll have to start on something else.

70sgeek

Those actually are the 2 piston choices I thought of after doing some research. Had been leaning towards the flat tops since that's what my former car ('72 Skylark with a '70 GS 350 factory 10.25:1 comp) had and it ran strong on pump gas with similar intake and ignition mods. It had a Comp 260H cam and I'm sure the actual comp was in the 9's for that motor though, so was hoping for similar results this time around.


Still giving thought to the converter, 1700 was what my transmission shop suggested based on the cam specs but I recall installing a 2200-2500 Hughes converter in the Buick which worked well for that combo - I chose the cam largely on basis of threads I've read here and other places - not wanting to go hotter on the cam than the engine would work well with (also wanting to retain stock valve train geometry, decent idle and good p/b vacuum to keep things simple where possible).


I'm waiting on the machine shop to give me an update on the heads and their thoughts as to pistons.. They're working to evaluate my options now based on the current cam


And yes, for sure there will definitely be more projects as budget recovers - factory bucket seats to replace the bench, some real gauges to supplement the dash lights, and a stereo install.

coppercutlass

i would go with the 2500 stall. With 9.5 to 1 i would go with a bigger cam . I have a pretty big lunati cam and still have power brake. The 3.08 will hold it back a bit but with a short tire like a 26 in. tall will be closer to 3.23 .

Fun71

About cams, the current one in my engine (UD 217/221) pulls a steady 16" vacuum with the HEI initial set to ~18º and the power brakes work great. Nice smooth idle even with the AC on. Starts sounding a bit choppy when I drop the initial to 10º and disconnect the vacuum advance for emissions testing (which it passes easily even with the larger than factory cam). I used Comp Cams roller tip rockers just because someone had a set for sale cheap.

Previous cam was a Crower .461 lift and 210/221 duration, idle and driveability seemed the same as the .435 lift/204 cam. Idle was silky smooth and vacuum was in the 18" range. I used the factory rockers with that cam.

Hughes 2500 RPM stall feels like the original factory setup when driving around town. Same amount of slippage at light throttle as I remember when the car was in factory form (~200 RPM by my calculations).

I guess what I'm trying to say is don't be afraid to go larger than 205º with the cam if you are really shooting for 9.5:1 compression ratio.

70sgeek

So the interim update is machine shop cleaned the block and bored it .030 over, fit it with new flat top pistons and reportedly set everything up for 9.5 comp rating using the Howards cam I picked out.


Heads were completely rebuilt - new stainless valves, springs, rocker components, pushrods, guides and head bolts. Required minimal surfacing and it's anticipated I will have no problem retaining the stock valve train height.


The rest of my build will go as pretty much as noted before - the E-brock intake, Qjet 750, Pertronix Ignitor III dist, a Cloyes 2x roller timing set, etc.. Last minute MAW's will be a new stock oil pan, balancer, ATI flexplate and Powermaster hi-torque starter, just for some added peace o' mind .


Also recently stumbled onto a cheaply priced set of oem'74-5 350 valve covers with the Oldsmobile script embossments, so will strip and paint those up for install as well (much of the right side letters will be hidden by the AC bracket but still kinda cool to have these).


Really hoping all this work will return a healthy power bump. I don't know if it's funny or sad to see this car essentially completely apart right now - at this point the entire suspension and drivetrain are off the car - but it will be totally cool to put all the new upgrade parts back in and (hopefully) have them playing nicely together...

olds 307 and 403

I thought I replied to this thread. You should have went oversize on the valves, used the Ultradyne cam mentioned above or similar and the dished LF2321 pistons. I have the Edelbrock Performer cam with 9.5 to 1 compression, it pinged on 91 octane, needed a lot tuning to eliminate. I am switching to a custom similar to that Ultradyne. If the flat top pistons were used with that cam, it will be a nightmare, your compression will be more like to 10 to 1, not good. As said, you also want a 2000+ stall.

marcar1993

^Agreed. Not to belittle your machinist, but make sure the measurements come out to 9.5:1, and not with the piston .030 down in the block, that'll give you horrendous quench and it'll ping.
So what cc are the heads? how thick are the head gaskets? how far do the pistons sit in the hole?

Also, I think that cam is a bit small for that compression, and will only add to higher cylinder pressures leading to pinging (especially if compounded by poor quench.)

70sgeek

More info to follow as I speak further with the machine shop - haven't had time to talk in depth with them over the last week.


He's a 30+ year performance builder of all brand motors and I was clear on my goals - stronger street power but with priority towards still retaining good drivability, vacuum and idle - nothing exotic, just relatively simple, solid improvements where available.


I was concerned with engine detonation as well but I'm hoping the good experience I had with my prior Skylark GS motor will be relatively duplicated in this build.


That GS 350 motor was factory-rated at 10.25 comp but I'm fairly sure mine was actually 9-9.5 by the time I obtained it after it had been freshened up by the original owner. It had strong power + all the qualities noted above, but didn't ping even on 89 octane though I typically used 91 or above.


great info for discussion with my builder - many thanks - will post further updates as they develop.

70sgeek

350 motor build coming along slowly but sure - went with the Speed-pro L2320F30 pistons, crank was cut .010. All new Clevite and Hastings bearings installed.


Also, new ARP head bolts, Comp stock rockers and pushrod sets, Cloyes 2x roller timing set, Milodon water pump, Powerbond balancer, Powermaster starter, ATI flexplate.


So far everything has come together nicely with no surprises. Block was surfaced .007 basically for cleanup and the heads if I recall .003 or less. Exhaust manifolds blasted and painted. Block fitted with new freeze plugs and painted in factory gold.


Going to forego reinstalling the ported vacuum switch and reroute the vacuum lines to intake and carb instead. Will however be installing new idle air solenoid.


Still debating over torque converters for the TH350 but my trans builder still suggesting 1700-1900 range based on the motor build - will be installing 3.08 posi as well and running 245-60-15 on all corners.


Sure hope tax season is good to me this year - after all this + the new roof I had to put on the house, mac n cheese may be my new diet!

Fun71

Do you know what the head combustion chamber volumes measured? And how far down the pistons are? Without that info, you really can't know the compression ratio. Not knowing the compression ratio leaves you in a guessing game as to what cam and converter are optimal for your build. That also means your trans builder really has no idea what RPM converter should be used.

distributorguy

.010" off the deck and heads with those pistons should result in roughly 9.8:1 compression if you have 68-69 cc combustion chambers. Your pistons should be about .015" down the block. Not sure where the .030" number comes from that gets thrown around, because I have 2 stock blocks here at .025 - .028".

I don't see any issue with using a torque cam (low duration) at that compression level. It will moderately raise your cylinder pressures, but it will make great vacuum and give you decent fuel economy - if it matters.
I like a mild torque converter at 2000-2400 stall so there's no drag residual heat issues at idle. Anything lower than that is essentially stock.

70sgeek

The block was bored .030 to clean up the cylinders and to make getting new pistons easier (most commonly available oversize).


I still haven't had time to follow back around with my builder yet for more specifics as to actual measurements but hopefully next week as time allows - I recall a brief conversation wherein a number right around the 70cc mark or so was discussed - he was pretty specific that he was trying to get me as close to 9.5 comp as possible to keep the motor pump friendly.


I agree as to the 2000 range converter being a better call over stock but can't seem to get my transmission guy on board with that (yet) - more discussion on that topic to hopefully follow as all gets closer to completion.

70sgeek

still moving slowly but surely forward. Final specs for the drivetrain are 72cc head chambers for a calculated 9.5 comp rating, going with the Hughes 2500 HD sprag stall converter connecting to an ATI flexplate (SFI-approved overkill I know, but figured it would compliment the new Powermaster starter).


Suspension, new fuel tank and send unit are in, CPP power steering kit and new power disc brake installs coming along, the rear will be built with new Yukon 3.08 Posi and Timken bearings - stock axles looked good so retaining those with new wheel studs and all new rear drum brake assemblies to be installed.


Will also be installing a new engine harness, idle solenoid and maybe a new forward lamp harness with relays for a new set of E-code headlamps I bought years ago for a former '68 Charger but never used.


Hoping to finish all before Thanksgiving so I can possibly make the huge annual Daytona Beach show that comes up around then.

oldcutlass

Ooooh you are afflicted... Very nice work.

olds 307 and 403

Looks good, nice and clean. Hope the motor runs great.

70sgeek

so do I - it went together well - all head and mechanical parts except for the rods and crank are new top name brands (no part-store off-brand crap). Hopefully with some fine super-tuning it'll all come together for a stout street package.


Coming into some cooler top-down crusing weather here now so really looking forward to finishing things up soon.


Some 'before' motor pics - it's the numbers matching engine for this car - a prior owner apparently swapped another stock-type t-chain (or at least a non-nylon gear) in at some point in the car's life and it was pretty stretched - water pump was still original (now a Milodon)

Joffroi

Sorry for the completely unrelated post... but I just had to with the title.

70sgeek

Everything finally completed but for some last dial-in adjustments. Motor running strong on the initial tank of 93 octane. Got on it somewhat hard during a post-cam break in test run today and no detonation issues were experienced. The idle has a hint of lope, overall power increase is obvious and the Flowmasters definitely enhance the motor's character without being obnoxious. New front disc brakes are awesome! Still to do: slightly firm up the trans shifts in character with the performance, add 1" wheel spacers in back to push the rear wheels out a just bit more for stance improvement and then drive it like I stole it

olds 307 and 403

With 93 and a slower timing curve, you should have no problems. I only have 91 here.

70sgeek

91 thru 93 are common octanes available in FL and much of the southeast - I'm going to drop down to 91 for the next tank, due to about a $.20/gal price difference and then hopefully I'll know for sure where I am on performance.

Pfiffle

WOw. Looking great. I'm jealous. Ha. I wish I had your budget. That ride is going to run strong. I have to do mine piece by piece and need months the in between to save the money. LOL. Keep posting for inspiration. I have a smallblock too and your giving me some great information.
I would like to hear more about the suspension upgrades, size of sway bars and brand, shocks, bushings etc. If you have time.
Thanks
Tom

70sgeek

My budget wasn't huge by any stretch - I spent endless hours comparing prices all across the internet on everything I wanted, searched out coupon codes, shipping deals, holiday sales, etc... Ultimately saved huge where I had the patience to wait for a deal... Of all places, JC Whitney saved me a TON on all the Moog parts.


Front suspension largely a stock rebuild with all new Moog parts, adding a Summit Racing 1-5/16" sway bar and some Energy Suspension end links. Rear springs were Moog 5415, rear control arms are UMI Performance tubular w/urethane bushings and a Summit 1" sway bar. Bilstien shocks all around. Also installed a CPP 500 series power steering box and pump.


What also saved me a ton was finding a fully blasted and rebuilt set of OEM front control arms that somebody put all the $$ in before deciding to go tubular.. About $150 shipped for all....


Right now the carb needs some dialing in - trying to find time to put some miles on the car to break it in a bit more before going back to the carb for more tuning. Trans shop is going to work on firming up the shifts a bit more.


Today I swapped in a set of OEM sport mirrors that I had painted to match the body - l/h remote, r/h is the later 80's convex glass head. Next up is to swap out the column for a rebuilt tilt, new locks all around and then onto the stereo upgrades (tax refund permitting) .


if you want, PM me your email and I'll send you some chassis and suspension pics - I've completely documented the overhaul so have hundreds of pics from start to finish (as if ever finished....)

RetroResto

I will have to check out JC W on the Moog parts. I plan on doing a full front end rebuild on my 71.

70sgeek

search the net for their coupon codes - usually 20% off + their free shipping makes for a great deal on most parts.