273 302 318 340 build

[4spdragtop]

Hi all, looking for some guidance here. May be a little long winded here, with lots of questions lol. Like the title states Im looking at a budget build involving(possibly) above components.
This is going in dads 67 cuda, factory S fastback with factory 904 3:23 SG and 8 3/4.

For engine right now it has a 66 date code 273. Originally a 2bl engine, so pistons are low compression. Factory adjustable valve train.
When dad bought the car we installed a comp cams kit #CL20-246-4 and upgraded to the double roller timing chain set. New cam bearings. We also topped it with Eddy 1406, then added an elec choke. It has MP elec ignition.
Factory 273 exhaust manifolds.
Sounds and idles great, oil psi good(approx 45-50 at idle) but did not have the power low end I thought it would.
Unsure of what stall the torque converter is. I know I had to grind a weight off of it as per recommendations. 360 converter maybe?
Last year I removed factory heads with comp springs and retainers. I stripped them down, sandblasted, relapped valves and did a diy "port" job.
Reinstalled heads and added an LD4B.
Still not much in low end power, but its been a reliable motor since dad n I put it together in 2012. Probably around 10-12,000 miles since then.
Im unsure of where timing is at and rods and jets in carb are orig Eddy spec.
I believe that I have over cammed the 273 due to the low comp pistons

My plan is to drop in a budget build respectable small block using as much as what I have and still have the swap done in the course of a weekend. Hoping to add maybe 50 HP??


What I bought was an 87(I think) 318, I was hoping for the 302 casting heads, but came with heads #4027163. But it did come with LD340 and Eddy 1405 and brand new oil pan. Compression test was over 120(using a lousy battery, and engine was out of vehicle, so we stopped at 120). All plugs removed and WOT. No disassembly has begun yet so unsure of pistons, bottom end.

I continued my search for heads and have located 2 sets of 302 heads. 1 is bare and 3 are loaded. Machine shop magnafluxed bare one and came back no cracks.
3 loaded ones I brought home to disassemble and then have them magnafluxed.

I am hoping to be able to strip down the 87 318, use 302 heads, which will bump compression a little bit. Then there is the option of intake. I have an LD4B unmodded currently on 273. I also have the LD340 that came on the 87 318. LD340 can wait for my 340 build for my 69 ragtop(whenever I get to it lol)

Heres list of parts on hand and hope to use most of these to keep costs down(if 302's need machining it gets pricey!)
On hand
-runnning 66 273 2bl pistons, Eddy 1406, LD4B, factory manifolds, adjustable valve train
Comp cams 270-s cam and lifters(10-12,000 miles)
-LD340
-complete 340 x heads
-factory iron 273 4bl intake
-factory iron 70 340 intake
-68-70 HP 340 exhaust manifolds.
-302 heads
-complete 87 318
-set of 4027163 318/360 heads

Would stock 273 adjustable valve train work on 302 heads? Also whats the opinion of using the complete Comp Cams kit from the 273 and installing in 318? Is that cam an overkill even for the 318 with 302 heads?
If 302 heads come back good, Im open to do the DIY cleanup/port job as well.
Combinations/advice?

Thanks all
Steve

 

[66fs]

First that cam is nasty for a 340 or a 360 with 3.23 gears. I think I'd run the 318 with the heads it has and slap that 340 intake and Edelbrock carb on top. Get a 340 cam, lifters and valve springs or an updated cam close to it. Use the 340 exhaust manifolds. Replace the seals, gaskets, except the head gaskets, and brass freeze plugs. Maybe a windage tray. About as cheap and easy as it gets. Once I take one apart I can't stop till it is completely done. You will also need an adapter to mate the torque converter to the larger pilot on the 318 crank. Then, if you want you can take your time with the 302 heads.

 

[mvh]

You aren't going to get any low end on a low-compression 273. There isn't a lot of low end on a 273 Commando -- it's all about revs. I agree you will be better off starting with the 318.

 

[Lelo Dart]

I vote 318 with 302 heads and LD4B intake. I have that combo with XE268 cam and KB167 pistons. Still soft on the low end but pulls very hard. Does the 87 318 have a roller cam now? If so I would try it and see how it does. Maybe some stronger valve springs.

 

[69conv]

Hey Steve have you thought about working on the other end? Talkin about swapping in 3.55 or 3.91 gears. Your 273 will rev to the moon and it may be an even swap for your 3.23. You'll get into the power band much sooner to.

 

[65Val]

Subscribed....Steve...yes your stock 273 adjustable valve train will work fine on 302 heads...thats what I have on my '67 273 right now.

 

[4spdragtop]

Got 1st head stripped. From a visual with magnifying glass looks good.
Valves are really clean. Hopefully if head checks out I can re-use valves. Measured 1 set of valves.
Intake
Valve dia 1.75"
Stem dia. 0.373"
Overall length 4.9695"
Exhaust
Valve dia 1.4630"
Stem dia 0.374
Overall length 4.9820"

66fs when you say 340 intake are you talking factory iron or LD340?
Im thinking a bit.much for 318?
I dont wanna do the same to the 318 that I did to the 273.

69conv. I was hoping to keep the 323 gears for highway tours. Fuel mileage?
Will the 318 not gimme a bit more bottom end to help make up for the 323?

Lelo thats the exact.combo I was thinking of. But I was hoping to be able to reuse cam/lifters from 273. Sounds like it might still be too much for the 318?

I hope.to.finish stripping the other 2 heads so will know more once.they are.checked.
Hope.to get checking into the 318 by the weekend.
Porting recommendations on heads or.exhaust manifolds?

Thanks.for the replies and advice. As I said the 273 runs good but im looking forward to this budget build with a little more grunt.

 

[66fs]

I did mean the 340 factory intake. It is a nice dual plane that in the end will only breath through the 318 ports. I was thinking just a quick easy hop up to get you by without tearing the 273 apart or taking the good 318 down too far. If you want to take everything apart and take the best parts and do some quality machine work, I'd have a different answer... lap the valves, if nothing else to check the seal. Definitely keep the 3.23 gears for the street.

 

[318willrun]

Had a '85 318 that had factory 302 heads in a older B-body. stock converter and gears. Weiand Action plus intake. 273 exhaust manifolds. It would lay rubber like a 440. I could roll 10 mph and floor it and it would break loose. low end was it's sweet spot. Didn't pull all that great in the rpm's.
Point is, when you add bigger cams and flow to heads, you move the power band up. That is ok if you give it a little converter help. I agree with the 340 (or that size) cam.

 

[4spdragtop]

Well got the other 2 heads stripped, they were a ***** to say the least.
So one of the 3 I brought home came apart good, nothing seized/rusted. Hope it checks out so that makes a pair (bare one at shop crack free)
In the meantime I'll try to start stripping the 318 and see what I have there.
Apparently I need an adapter/ring for the factory 904 to mate up with 318? The cuda isnt here so the current torque converter is unknown but 273 is 67
Thanks all

 

[nm9stheham]

Steve, if you are moving from the 273 920 heads to the 302 heads, and keeping the same 273 2 BBL pistons, then you are not changing the compression ratio if using the same pistons in the 273, and the same low torque problems at low RPM's will still be there.

So, I am assuming that you are moving on to the 318; is that right? You have the opportunity to improve things... a LOT. With the best flat top cast pistons that you have, you will still not have a great compression engine for low end torque. The Sealed Power 526P flat topped cast pistons are still going to end up .080" or so in the hole, and with a 1121G head gasket (the thinnest out there now), your SCR will be in the 8.6 range, and your DCR in the 7.1 range.

I'd need to work a bit more to figure up the 273 SCR and DCR that you had, but you really need to be heading to the range of mid 9's for SCR and upper 7's to low 8's for DCR if you want to cure that low RPM torque problem. Since you want to keep the 3.23 rear gear (for reasons I would agree with), then it is even more critical to move up in SCR/DCR. Low RPM torque is where you need to focus; you will gain HP for mid and high RPM range but CR is what extends your torque band down as low as it can be.

BTW, know that if your 318 comes with the 4 valve relief pistons, then you are even further down in the CR toilet. Don't go there LOL Check how far the pistons are down in the hole with the heads off; the best you are gonna find is in the .075" to .080" range. Some piston pix would be appreciated.

Ways to get this SCR/DCR up are :
1. Block decking to reduce in-block (See RAMM's Cheepy 360 thread)
2. Head milling to reduce chamber volume
3. Raising piston compression height to reduce in-block volume
4. Going to a smaller cam to maintain higher DCR
You CAN keep that cam and get where you want to go; you just need to implement 1. or 2. or 3. above. You just need to decide which is the cheapest: some combination of 1. and/or 2., or 3.

- Head milling with the small 302 head chambers is going to take .100" off the heads to get up to around 7.9 DCR with the 526P cast pistons, and I would serious expect problems trying that.
- Decking .050" will get you there with the 526P pistons. Now you probably have to change the pushrods.
- Pistons for getting close to zero deck: The KB's are the most easily found and least expensive that I know of. (Try Campbell enterprises.) The KB167's will put the piston tops just .012" in the hole, and with the 1121G head gaskets, your DCR will be around 7.9 with no other machining. Easy..... And the nice part is you will have some quench effect with those 302 heads with the gap around .040". You can advance the cam and ignition timing more and get away with it; so some more torque can be 'tuned' in.

Now just one issue for you to deal with on the KB167's; they weigh around 85 grams lighter than the stock 318 pistons, so that is a balance issue. BUT, use those 273 2 BBL piston pins (around 220 grams each.. .heavy!) and you are within 20 grams of the stock piston+pin weight and bobweight will be approximately just 26 grams light. A machine shop can make that level of bobweight change on the crank with a few small holes in the 2 large counterweights; it is not a big change.

And of course, changing cams will be the other way to get that DCR back up. But it is never going to be very high at all with a stock 318 LA bottom end, and even with the 526P flat top cast pistons. (Those 120 psi compression readings tell the story there...) I don't want to blow your budget, but really I want to see you get out of your low torque hole.

 

[4spdragtop]

So while heads are getting checked I started to tear down the 318.
Both the chrome valve covers and LD340 came off very easy. Not sure if either has been run on this engine.
Turns out center divider on intake was cut down. Rocker shafts were oriented correctly. Drive side notch down and front. Pass side down and rear.
Got one head off. Rounded head bolt is holding me up from getting passenger head off.
Front cover off. Original nylon tooth cam gear. TONS of slop in timing chain. Timing set will be replaced if I continue with this engine.
Flat top pistons. Best I could measure with verniers was the dirty piston down in the hole 0.0770". Thats a sloppy measurement.
Removed dist drive gear and tried to remove cam...no go. Looks like its spun the rear cam bearing? And the bearing is now stuck on end of.cam. Cam rotates fine but only pulls out about 1/4". So it looks like new cam bearings are on the list as well. I set the tools down once I couldnt get cam out. Lol
I'll inspect everything tomorrow.
To buy list so far
Timing set
Cam bearings and installed
Cam n lifters
Gasket set
302 heads and machine work.

Thanks all.for advice/opinions

 

[4spdragtop]

Thanks a LOT for the explanation and options! Im not making it easy, but I was hoping with the variety of parts/engines and minimal new stuff and machining I would end up with something healthier than the 273
Its hard to judge whats going to happen when using used stuff and with the 302s still getting checked.
But initially my plan was to put 302s on 318, swap 273 mechanical rockers, swap cam lifters timing chain and gears from 273 into the 318 and put the LD4b with Eddy 1405 on top. Leave the bottom ends on both the 273 and 318 as is
So the only unexpected changes so far
1. current 270-s cam in 273 is too big for 318 with the stock bottom end. So now to check on new cam n lifters
2. Cam bearings in 318, rear one has spun.
3. Adapter for Torque Converter is apparently needed?
4. Machining $$ ??

Tomorrow Ill try again on the stripped head bolt, try to get cam out and drop the oil pan.

Thanks again for advice/recommendations

Steve, if you are moving from the 273 920 heads to the 302 heads, and keeping the same 273 2 BBL pistons, then you are not changing the compression ratio if using the same pistons in the 273, and the same low torque problems at low RPM's will still be there.

So, I am assuming that you are moving on to the 318; is that right? You have the opportunity to improve things... a LOT. With the best flat top cast pistons that you have, you will still not have a great compression engine for low end torque. The Sealed Power 526P flat topped cast pistons are still going to end up .080" or so in the hole, and with a 1121G head gasket (the thinnest out there now), your SCR will be in the 8.6 range, and your DCR in the 7.1 range.

I'd need to work a bit more to figure up the 273 SCR and DCR that you had, but you really need to be heading to the range of mid 9's for SCR and upper 7's to low 8's for DCR if you want to cure that low RPM torque problem. Since you want to keep the 3.23 rear gear (for reasons I would agree with), then it is even more critical to move up in SCR/DCR. Low RPM torque is where you need to focus; you will gain HP for mid and high RPM range but CR is what extends your torque band down as low as it can be.

BTW, know that if your 318 comes with the 4 valve relief pistons, then you are even further down in the CR toilet. Don't go there LOL Check how far the pistons are down in the hole with the heads off; the best you are gonna find is in the .075" to .080" range. Some piston pix would be appreciated.

Ways to get this SCR/DCR up are :
1. Block decking to reduce in-block (See RAMM's Cheepy 360 thread)
2. Head milling to reduce chamber volume
3. Raising piston compression height to reduce in-block volume
4. Going to a smaller cam to maintain higher DCR
You CAN keep that cam and get where you want to go; you just need to implement 1. or 2. or 3. above. You just need to decide which is the cheapest: some combination of 1. and/or 2., or 3.

- Head milling with the small 302 head chambers is going to take .100" off the heads to get up to around 7.9 DCR with the 526P cast pistons, and I would serious expect problems trying that.
- Decking .050" will get you there with the 526P pistons. Now you probably have to change the pushrods.
- Pistons for getting close to zero deck: The KB's are the most easily found and least expensive that I know of. (Try Campbell enterprises.) The KB167's will put the piston tops just .012" in the hole, and with the 1121G head gaskets, your DCR will be around 7.9 with no other machining. Easy..... And the nice part is you will have some quench effect with those 302 heads with the gap around .040". You can advance the cam and ignition timing more and get away with it; so some more torque can be 'tuned' in.

Now just one issue for you to deal with on the KB167's; they weigh around 85 grams lighter than the stock 318 pistons, so that is a balance issue. BUT, use those 273 2 BBL piston pins (around 220 grams each.. .heavy!) and you are within 20 grams of the stock piston+pin weight and bobweight will be approximately just 26 grams light. A machine shop can make that level of bobweight change on the crank with a few small holes in the 2 large counterweights; it is not a big change.

And of course, changing cams will be the other way to get that DCR back up. But it is never going to be very high at all with a stock 318 LA bottom end, and even with the 526P flat top cast pistons. (Those 120 psi compression readings tell the story there...) I don't want to blow your budget, but really I want to see you get out of your low torque hole.

 

[4spdragtop]

Anyone got ideas how to remove stuck camshaft?

 

[nm9stheham]

If the same pistons are staying in the 318 block then I can suggest:
- Use a Comp XE or Lunati Voodoo or Crane cam of shorter duration; you will get some higher lift than stock lift to help the mid range and top end, with the best lift to duration ratios you can get.

With the existing flat tops and the 64 cc 302 chambers, your SCR will be at 8.6 with the 1121G head gasket. Mill the heads .040"-.050" and get the chambers down to around 59 cc's, and now you are at 9.1 SCR.

All of the following assumes you milled the heads to get to the above SCR. Some cams to consider:
- Put in a Crane H-260-2 hydraulic as the largest duration cam to use with 6 degrees advance (1 degree more than the 5 degrees of ground-in advance), and you'll be a 7.7 DCR... considerably better than you were. (I like the Cranes for their less aggressive ramps that put less peak pressure on the lifter/cam contact.)
- Put in a Voodoo 10200701 (installed straight up with 4 degrees ground-in advance ) and you'll be at the same point with a hair more lift.
- Both cams have 'little brothers'; the Crane H-248-2 (installed straight up at its 5 degrees of ground-in advance) would push up the DCR to 7.95.... now you are closing in on 'as far as you should go with iron heads' without and still keep the tuning relatively easy and run pump gas. This cam's lift is only .400" on the intake; easy on the valvetrain but I would bet it will cut your usable top end RPM's by 800-1200 RPM's over what you have now. I am not sure if that is what you would like or not.
- The Lunati Voodoo 10200700 will give you back some lift and take away a bit of DCR versus the Crane H-248-2. So it will move the RPM range back up some. The ramps are more aggressive so more care with the valvetrain is needed.

Since these are hydraulic lifter cams, I would expect different pushrods for the 273 rockers. (And I have not run numbers with your present cam with more advance and maybe a bit more lash. But I don't think that's gonna get you all that far.)

FYI, I have run a low duration cam like the H-248-2 with higher rocker ratios with a good breathing heads/intake/headers, with 10+ SCR, and had a solid 1500-6000+ RPM engine with great torque, over a ft-lb per cubic inch. So a wide torque range on the street is not all that hard to get if you focus on a high SCR to start with, and then work on the breathing components, and get the valve's lift to duration ratio as high as you can. Others have done the same so this is all known. You won't be in 400-500 HP that way in a small block, so it is not the formula if you are into lowest ET's....but it has superb driveability on the street, and is a versatile type of engine combination.

And yes on the adapter for a pre-'68 TC and a '68 or later crank. (I have never run into this but everyone says it is needed!) You can throw the calipers on both parts to be sure.

 

[krazykuda]

Anyone got ideas how to remove stuck camshaft?

Remove the rear "cup plug" in the block and bang it out from the rear....

Put the front bolt in and use a dent puller....

See if you can get it to rotate first, then it won't be so hard to bang out....

 

[nm9stheham]

Anyone got ideas how to remove stuck camshaft?

Pop out the rear plug to see if it is cam bearing that has pulled out. Then just tap on it. I see varnish rings on the bottom's of the lifters and it may just have a varnish ring on the back s of some cam journals that is hanging it in there. (You would not believe how hard /6 lifters can be to get out of their bores due to varnish rings; it often is hammer time....)

If the rear bearing really has pulled out, I'd go from underneath with a grinder and grind a slot in the bearing to release it from the rear cam journal. But you'd have to pull the crank and rear pistons. And then you have to see if that rear cam bearing spun in the bearing bore; it might not be fixable.

Are you sure it is hanging on a bearing, or just has dropped down and is hanging up on a lobe?

 

[krazykuda]

Steve, why not use the heads from the 67 273, they should be the 920 head with the small chambers... The book says that they are 57 cc, but mine measure 63... They are the smallest combustion chambers that you can use on an la head as they are closed chamber... We're putting a set of them on our 72 318 for the kid's challenger... They raise the compression from 7.6 with 360 heads to 8.6 with the thinner .040" fel pro gasket....

Then pop in a set of Rhoades lifters with your cam, and you should have some good low end grunt...

Here's some pictures of our set that we had our head guy go through and port, install hardened seats, and install 360 valves 1.88" intake and 1.6" exhaust...

 

[krazykuda]

Pop out the rear plug to see if it is cam bearing that has pulled out. Then just tap on it. I see varnish rings on the bottom's of the lifters and it may just have a varnish ring on the back s of some cam journals that is hanging it in there. (You would not believe how hard /6 lifters can be to get out of their bores due to varnish rings; it often is hammer time....)

Hammer time....

 

[4spdragtop]

Thanks guys. I'll pop the plug out. Knock it out from inside the engine or knock it "in" from outside?
If knocking it out from inside can I use the camshaft as a punch?
It sure looks like bearing is spun but we will see. Not sure what best case scenario is lol
Cam turns nice n smooth. Just hits a "stop" when trying to remove from front.
Lifters were nice n smooth. Took few "in n outs" to get a few of them out.
Pan coming off after I remove rounded head bolt.
Thanks again guys much appreciated!

Remove the rear "cup plug" in the block and bang it out from the rear....

Put the front bolt in and use a dent puller....

See if you can get it to rotate first, then it won't be so hard to bang out....

Pop out the rear plug to see if it is cam bearing that has pulled out. Then just tap on it. I see varnish rings on the bottom's of the lifters and it may just have a varnish ring on the back s of some cam journals that is hanging it in there. (You would not believe how hard /6 lifters can be to get out of their bores due to varnish rings; it often is hammer time....)

If the rear bearing really has pulled out, I'd go from underneath with a grinder and grind a slot in the bearing to release it from the rear cam journal. But you'd have to pull the crank and rear pistons. And then you have to see if that rear cam bearing spun in the bearing bore; it might not be fixable.

Are you sure it is hanging on a bearing, or just has dropped down and is hanging up on a lobe?

 

[krazykuda]

Thanks guys. I'll poop the plug out.

Sorry, I had to fix that....

LOL!

 

[nm9stheham]

Steve, why not use the heads from the 67 273, they should be the 920 head with the small chambers... The book says that they are 57 cc, but mine measure 63...

Then pop in a set of Rhoades lifters with your cam, and you should have some good low end grunt...

IIRC, he has a solid lifter cam now. I always thought Rhoads were only for hydraulic cams....??

The 302 chambers are the same size, I do believe: 63-64 cc's typical.

FWIW, the 57 cc is from the IHRA or NHRA specs as to how small you are allowed to legally reduce the chamber size.

 

[nm9stheham]

Thanks guys. I'll pop the plug out. Knock it out from inside the engine or knock it "in" from outside?
If knocking it out from inside can I use the camshaft as a punch?

I'd start by drilling a hole in it, inserting a lag bolt, and try to pry it out. You might even use the lag as a pusher on the cam if the plug is really in there. Or just insert a drift pin through the hole and tap on the cam.

I am sure the cam has been used as a 'punch' before! My last resort... LOL

Yeah, your lifters had varnish rings on the bottom ends....

Edit to add: No don't knock the plug IN from the outside; there is a ledge there and you won't get it past that.... well, not without some real destruction.

 

[krazykuda]

IIRC, he has a solid lifter cam now. I always thought Rhoads were only for hydraulic cams....??

The 302 chambers are the same size, I do believe: 63-64 cc's typical.

FWIW, the 57 cc is from the IHRA or NHRA specs as to how small you are allowed to legally reduce the chamber size.

Oh, I didn't realize that was a solid lifter cam - Cancel the Rhoades lifter recommendation....

 

[krazykuda]

The 302 chambers are the same size, I do believe: 63-64 cc's typical..

What size valves are in them?

It may be worth bumping them up to 360 1.88/1.60 inch if they are smaller... Then open up the ports a bit and gasket match them...