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Keane165's 1970 LeMans

2022 June
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Getting ready for My engine rebuild (400)


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Good day everyone. Been awhile since I have logged on. 

I am currently getting ready for the rebuild of my 1971 400 out of my LeMans sport. This is my first engine rebuild, I have some knowledge gained from reading some articles and watching videos of you tube ect. 

I'll tell you a little about my engine. It's a matching numbers 400ci it has 96 heads and a  edelbrock aluminum intake. My plan is to keep it as a 400 and not bore or stroke it. If needed I will go .030 over but I would like to keep it stock bore and stroke.  I ordered a holley sniper efi, and ram air exhaust manifolds already. 

My plan is to do 

Roller rockers (1.6 ratio?)

New springs

new cam and lifters (flat tappet?)

Forged rods

Forged  pistons (cc?)

New bearings ( clevite?)

New main bolts (arp)

I'm curios what cam to use, I don't want to go to far from stock as it's mainly a cruiser that i want to have decent fuel economy, But I still want to have a bit of power for when the new sports cars to pass me.  Can I use a ram air cam on a non ram air motor? 

Also what rocker ratio I need? 1.5?, 1.6? Does this depend on my cam?

Am I dumb staying flat tappet? I don't really want to drop $1000 for roller cam and lifters and I've also seen a few roller lifters break on people and that scares me.

 

What compression ratio should I be aiming for? I want to use pump gas lf course . I believe its 8.4:1 stock should I be aiming for 10:1? 

 

Any help and recommendations is appreciated. Here is a pic of my beauty.

DSC_1809.jpg

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Hey fella, I recently completed my own 389 rebuild. Get How To Rebuild Pontiac V8s by Rocky Rotella. Read it like a novel from start to finish - it's full of good advice and is comprehensively illustrated with teardown & rebuild pics. If you're handy with wrenches, it's not easy per se, but certainly do-able. Give yourself plenty of time and do a good careful rebuild. If you check out Fitzy's GP Is Back! you'll see all the gruesome details of what I discovered on my own rebuild journey.

All things considered, it was enormously satisfying and I'm quite proud of myself for actually carrying out the entire procedure from start to finish, with of course the exception of all the machining. I used a Pontiac 068 cam which is actually a Tri Power grind, just to give it a little more pep in the mid range without sacrificing any drivability in an auto 2 tonne land yacht with a 2.73 diff.

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  • 1 month later...

Nice job.  Take your time.  Don't wanna get hurt, esp workin by yourself.  Started the new motor for my Sunbird today.  Dug it out, got it on a stand and started the teardown.  Long story, but this engine has all my high performance Blower parts. Was installed and ran for 5 min and started a knock. Pulled it and threw together a junk motor to get the car on the road.  That motor lasted 25yrs!!!  Thankz for the update on your project, look forward to the next one.

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Clearcrow - nice job on pushing through getting the motor out yourself.

Here are my thoughts on your motor.

I have a 455 in my '72 Lemans Sport convertible, we call her Lucy.

Lucy is bored .030 over - making it a 462

She has stock rods and new JRE oversized pistons. She has a new Eagle crank - stock throw

I run a hydraulic flat tappet cam from Melling. It is close to a Ram Air II or III grind. Matching Melling springs. I am running a roller tip stamped steel 1.6 rocker for durability. It is matched to my cam, so talk to your cam maker or a reputable engine builder to see what they recommend. There is nothing wrong with a flat tappet cam. Rollers are nice, but unless you are going to take advantage of that technology for some sort of high performance application, why waste the money?

Melling high volume, high pressure oil pump.

Edelbrock Performer intake - although a stock factory 4-bbl will work equally as good unless you are trying to save weight. Stock Rochester Qjet carb.

Ram Air Restoration reproduction HO/Ram Air exhaust manifolds

ARP stud bolts 

Cleveland bearings

Heads are a stock 7K3 head with 2.11 intake, and 1.77 exhaust. They have been ported matched to the intake, polished, hardened valve seats installed, and a triple angle valve job. Nothing elaborate but requires a good machine shop.

Compression should be around 9.5-10:1 to keep it pump gas friendly. 

Stock distributor running a Petronix Ignitor II (Ignitor III is available now) to eliminate points

Stock oil pump with windage tray, stock replacement oil pan from Melling.

 

Other things I will ask you to consider:

Transmission - rebuild vs. replacement. I suspect you have a TH350 ot TH400. Great trannys. however, have you thought about an overdrive transmission? A TH200 4R will bolt up to your Pontiac engine. It is a couple of inches longer than the 350/400, which means shortening your driveshaft. However, you would now have an overdrive transmission. So do some homework and see what it would take to find a used 200 4R case and have that rebuilt in lieu of your original transmission. It will help save a few bucks on fuel on long distance drives. Or consider a Gear Vendors Overdrive add-on.

Rear end - is it a one-legger? If so, are you going to add positraction?

Rear sway bar - if you car was built without a rear sway bar - add it! This means replacing the rear lower control arms with boxed ones that have a couple of holes drilled in them to mount the rear sway bar. Well worth the money. Kits are available at all the catalog oneline stores.

Front Sway Bar - find a 1 1/4" sway bar from a WS6 2nd-gen Trans Am out of a wrecking yard. This is bigger than the factory Lemans/GTO sway bar. Get new bushing and end links for the Trans Am from your local auto parts store and bolt it onto your Lemans. 

Steering box - are you replacing it? If so look at a 3rd gen IROC Z28/Trans Am box, they are quick ratio boxes but are dimensionally the same as the Lemans/GTO box. You should be able to get a reman unit from O'Reillys or Autozone on the cheap. 

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4 hours ago, Frosty said:

Clearcrow - nice job on pushing through getting the motor out yourself.

Here are my thoughts on your motor.

I have a 455 in my '72 Lemans Sport convertible, we call her Lucy.

Lucy is bored .030 over - making it a 462

She has stock rods and new JRE oversized pistons. She has a new Eagle crank - stock throw

I run a hydraulic flat tappet cam from Melling. It is close to a Ram Air II or III grind. Matching Melling springs. I am running a roller tip stamped steel 1.6 rocker for durability. It is matched to my cam, so talk to your cam maker or a reputable engine builder to see what they recommend. There is nothing wrong with a flat tappet cam. Rollers are nice, but unless you are going to take advantage of that technology for some sort of high performance application, why waste the money?

Melling high volume, high pressure oil pump.

Edelbrock Performer intake - although a stock factory 4-bbl will work equally as good unless you are trying to save weight. Stock Rochester Qjet carb.

Ram Air Restoration reproduction HO/Ram Air exhaust manifolds

ARP stud bolts 

Cleveland bearings

Heads are a stock 7K3 head with 2.11 intake, and 1.77 exhaust. They have been ported matched to the intake, polished, hardened valve seats installed, and a triple angle valve job. Nothing elaborate but requires a good machine shop.

Compression should be around 9.5-10:1 to keep it pump gas friendly. 

Stock distributor running a Petronix Ignitor II (Ignitor III is available now) to eliminate points

Stock oil pump with windage tray, stock replacement oil pan from Melling.

 

Other things I will ask you to consider:

Transmission - rebuild vs. replacement. I suspect you have a TH350 ot TH400. Great trannys. however, have you thought about an overdrive transmission? A TH200 4R will bolt up to your Pontiac engine. It is a couple of inches longer than the 350/400, which means shortening your driveshaft. However, you would now have an overdrive transmission. So do some homework and see what it would take to find a used 200 4R case and have that rebuilt in lieu of your original transmission. It will help save a few bucks on fuel on long distance drives. Or consider a Gear Vendors Overdrive add-on.

Rear end - is it a one-legger? If so, are you going to add positraction?

Rear sway bar - if you car was built without a rear sway bar - add it! This means replacing the rear lower control arms with boxed ones that have a couple of holes drilled in them to mount the rear sway bar. Well worth the money. Kits are available at all the catalog oneline stores.

Front Sway Bar - find a 1 1/4" sway bar from a WS6 2nd-gen Trans Am out of a wrecking yard. This is bigger than the factory Lemans/GTO sway bar. Get new bushing and end links for the Trans Am from your local auto parts store and bolt it onto your Lemans. 

Steering box - are you replacing it? If so look at a 3rd gen IROC Z28/Trans Am box, they are quick ratio boxes but are dimensionally the same as the Lemans/GTO box. You should be able to get a reman unit from O'Reillys or Autozone on the cheap. 

That's for the input. 

Originally was going to go flat tappet  but a few people talked me into a roller set up. Money spent. The cam came matched with springs and timing set. And I will be using 1.5 roller rockers with it. 

 

I was planning to do new forged I beam rods but will wait to see the condition of the stock rods. 

I plan to go .030 over and +10 cc hypereutectic pistons. 

Holley sniper efi, and holley hyperspark ignition and distributor. 

I would love OD but not sure I want to swap trannys at the moment. 

It's a th400 and a positraction rear end. Not sure abourt the gear ratio but I think k it's in the 3's

 

I am definitely getting a high ratio steering pump. 

 

 

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Do some homework. Check out the cost of repairing the TH400 vs. the cost of a TH200-4R. They may be close to the same amount of moeny, then consider the TH200. If the repair/refresh is a lot cheaper, then there is your answer.

You can determine the rear ratio real easily. Jack up the rear end and turn one of the tires one turn. Count the number of revolutions of the yoke. If it spins 3 1/4 turns, it is a 3.23, 3.5 its a 3.55, and so one. 

Stock rods are good for about 350-450 HP. Not clear from your post what your desired horsepower/torque goals are but a stock rod can handle this amount of horsepower. 

A new timing chain set is just cheap insurance. I assume it is a double-chain set.

What is the condition of your radiator? Lucy came with a factory 4-core radiator since she has factory A/C so she handles parade duty and highway speeds without overheating with the stock clutch fan and a Mr Gasket wide-mouth thermostat. I did install a catch can/overflow bottle though that I got from Speedway Motors for about $35 back in the 90s and I mounted to the core support next to the radiator.

What about brakes, does this have factory front discs or drums. Any significant upgrade in "go" should be met with a similar investment in "whoa"! So if there are front drums, consider a front disc conversion. IF you have front discs, consider either rear discs or upgrading the fronts with better rotors, brake lines, pads, calipers, etc.

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On 3/21/2022 at 9:34 PM, Frosty said:

Do some homework. Check out the cost of repairing the TH400 vs. the cost of a TH200-4R. They may be close to the same amount of moeny, then consider the TH200. If the repair/refresh is a lot cheaper, then there is your answer.

You can determine the rear ratio real easily. Jack up the rear end and turn one of the tires one turn. Count the number of revolutions of the yoke. If it spins 3 1/4 turns, it is a 3.23, 3.5 its a 3.55, and so one. 

Stock rods are good for about 350-450 HP. Not clear from your post what your desired horsepower/torque goals are but a stock rod can handle this amount of horsepower. 

A new timing chain set is just cheap insurance. I assume it is a double-chain set.

What is the condition of your radiator? Lucy came with a factory 4-core radiator since she has factory A/C so she handles parade duty and highway speeds without overheating with the stock clutch fan and a Mr Gasket wide-mouth thermostat. I did install a catch can/overflow bottle though that I got from Speedway Motors for about $35 back in the 90s and I mounted to the core support next to the radiator.

What about brakes, does this have factory front discs or drums. Any significant upgrade in "go" should be met with a similar investment in "whoa"! So if there are front drums, consider a front disc conversion. IF you have front discs, consider either rear discs or upgrading the fronts with better rotors, brake lines, pads, calipers, etc.

Hey Frosty. My horse power goals are to creep into the 400s. Depending on price to recondition rods I may just grab some forged ones from Butler. 

New doubled roller timing chain csme with my  cam kit, 

My car came stock with disc on front and drums on rear. I'll be upgrading the front to bigger disc's on front with better calipers. I'll keep drums on the rear for now. But maybe one day do disc's. Been told rear disc's are less important. 

My rad seems in good shape but I might up grade to aluminum Rad. Not sure if mine is 2 or 4 core. It has a aftermarket over flow alread. Here is some pics of the progress.

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Clearcow - thanks for the update / info.

Butler is top notch builder and parts supplier. You won't be disappointed with them.

400 HP is a reasonable goal for a street cruiser. 400 HP (at the crank) then stock rods can hold that with ease. So if you need to pinch pennies, you are safe there. If you can afford better, then go for it.

I agree that upgrading the front discs are more important than the rear drums at this point, so long as you've thought about it. A lot og guys think horespower but not brakes.

Sounds like you are well on your way.

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  • 1 month later...

Clearcrow - she's looking real good.

So what did you finally end up with for the engine combination as a whole?

The engine bay looks real pretty!

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Nice job!  Betcha can't wait to get out there cruisin.

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4 hours ago, JUSTA6 said:

Nice job!  Betcha can't wait to get out there cruisin.

I'm hoping I'll be on the road end of May beginning of June. Weather is just starting to get nice where I am. So I'm starting to see all the other cars on the road. 

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6 hours ago, Frosty said:

Clearcrow - she's looking real good.

So what did you finally end up with for the engine combination as a whole?

The engine bay looks real pretty!

Thanks Frosty.

The engine specs are. 

Bored .030 over.  405ci

10cc dome Keith Black hypereutectic pistons

Stock rods reconditioned with arp bolts

Stock crank, 

Butler ram air 041 hydrollic roller cam

Morell hydrollic roller lifters.

1.5 roller rocker arms 

#96 heads, multi angle valve job, new springs, guides, etc.

Ram air 3 exhaust manifolds

Holley sniper stealth efi, either hyper spark distributor, holley ignition box

Speed master mid rise ram air 4 style aluminum air intake. 

Compression is around 9.5 :1 

 

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Just now, 64 kiwi boni said:

Ah you wont regret using these Clearcrow !! i have them on my 389 and i am super happy with how quiet they make the engine bay and heaps of room around them for everything else!!!

Figure they should flow alot better than my logs. And easier to install that headers. I think I got the last pair for sale. Got lucky and got a very good condition set hardly used off a Facebook group  since then everyone's been asking for them but none seem to be for sale anywhere 

Screenshot_20220407-123023_Messenger.jpg

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2 minutes ago, CLEARCROW said:

Figure they should flow alot better than my logs. And easier to install that headers. I think I got the last pair for sale. Got lucky and got a very good condition set hardly used off a Facebook group  since then everyone's been asking for them but none seem to be for sale anywhere 

Screenshot_20220407-123023_Messenger.jpg

yes they are super hard to get, i waited months to get my ones !!! certainly worth it 👍

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I've had mine on Lucy since the 2004-05 engine rebuild. I purchased mine directly from Ram Air Restoration booth at the Trans Am Nationals in Dayton Ohio in 2004. I love 'em and I've never considered going to headers ever since.

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4 hours ago, Frosty said:

I've had mine on Lucy since the 2004-05 engine rebuild. I purchased mine directly from Ram Air Restoration booth at the Trans Am Nationals in Dayton Ohio in 2004. I love 'em and I've never considered going to headers ever since.

yeah and they flow justA as good as headers do !!, 2 1/2 inch outlets :dancingpontiac:

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  • 4 weeks later...

Hey everyone. Went to the engine builder today becuse they ate Making progress in the assembly room. Should be painted tomorrow. 

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Looks good!

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I like what I see so far!

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So we ran into a small issue. The new intake I got doesn't seem to fit well.

Last fall I installed a edelbrock performer intake, but with the new cam i figured a bigger intake was needed. So I ordered a speed master mid rise which is designed after the ram air 4 intake  sell the bolt holes lines up poorly and there was a large gap between the intake and timing cover at the water port.  This probably would have been solved by cutting the water cross over off but I didn't really like the look of that. So I sent it back and ordered a edelbrock performer rpm.

Here's a picture of the gap we were left with and a sneak peek of the colour  

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20220603_171218.jpg

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Simply WRONG...... Bummer.   You'll find the right parts N get er on da road.  Good Luck.

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Yeah - that's a fail. You would have been fighting an ongoing water leak for sure. Good call about sending it back.

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