[Skippy597]

Hey guys, so I'm piecing together my 66 lemans and trying to plan out my engine to slap together. I've gone all over on the planning stages from high dollar to true budget but I've settled on doing a budget'ish stroker build. I could go high dollar but I feel that in the likely event that I'll eventually have to rebuild or replace the engine I would feel better not having a mountain of money in it.

The plan so far
400 block (I've got a couple), eagle cast 4.25 crank, scat 6.8 I beam rods, DSS 18cc dish pistons (about 10.5 CR I think), Speedmaster rd port heads lightly cleaned up (already have them), HS 1.65 rockers (have them), SFT cam, solid vintage HLJ lifters (have a set already) port matched performer rpm intake, and last but not least THERMOQUAD!

The car
1966 lemans full weight car
8.2 rebuilt with posi and 3.36 gears
Muncie m20

What I want
Street car that can get into the 12s and haul the family around so looking for mid to high 400 hp mark.

Curious if you guys think the cast crank will hold up just fine for my purposes. I also have a stock 400 crank that was dropped so its possible I could use it but would have to be checked first and obviously not be a stroker anymore. But if I went that route I have a luanti 703 cam and hlj hydraulic lifters I could use. DECISIONS DECISIONS... I'm trying to use what I have just to make a fun car to get it going and things can be upgraded or swapped down the road. Also would love some input on what cam you guys would recommend, I've been looking at the crower catalog and the 60310 looks pretty close to me.

Always love reading this forum and looking forward to your thoughts and advice.

[Verdoro 68]

When I was shopping for my setup, I went in looking at a forged crank. Butler talked me out of it and told me that a cast crank would be just fine if I'm not running any power adders. If you chose to go with a stroker, you may be reaching the limits of that 8.2 rear. It's a slippery slope.

[RocktimusPryme]

Just about every reputable builder Ive spoken to about cast cranks across multiple engine families says that the cast cranks are stronger than given credit for. Same with two bolt main setups. I wouldn't hesitate with a cast crank well north of 400 HP. I wouldn't give up the cubic inches with your goals.

With the parts you have listed you are going to easily be 400+.

[JLMounce]

I think you're plan sounds pretty good. I also think that you'd have to put a pretty small cam in that thing to be near 400 hp. With an as cast SM head and a SFT of any respectable size, you're going to probably even be north of 450 at the crank.

I can't comment on the cast crank. I've never run a non-factory cast crank. The times I've read on here about failures tended to be in cars with a lot more power than you'd be making in fairly severe racing situations.

[Skippy597]

Thanks guys
Yeah I know I'll be on the edge of the 8.2 but since I have it, I'll run it till I need a trailer to get home lol. Also I plan on adding a T/A girdle cover to help it.

That's good to hear that butler told ya a cast crank is good enough versus trying to upsell you. I think I'll be fine from what I've read so far.

[PunchT37]

That cast crank will outlast that 8.2 rear.

[RocktimusPryme]

Originally Posted by Skippy597

Thanks guys
Yeah I know I'll be on the edge of the 8.2 but since I have it, I'll run it till I need a trailer to get home lol. Also I plan on adding a T/A girdle cover to help it.

That's good to hear that butler told ya a cast crank is good enough versus trying to upsell you. I think I'll be fine from what I've read so far.

Make sure you have a rev limiting device. You don't want to unload the engine and lose it to an over-rev if the axle gives up at the wrong time.

[hurryinhoosier62]

Originally Posted by PunchT37

That cast crank will outlast that 8.2 rear.

Definitely!

[Skippy597]

I do have a rev limiter that will be on the car and thinking about it now since I'm not going high dollar or high rpm maybe I'll be better set wih a hydraulic cam like the comp 51-116-3? Seems like it would probably have a better bottom end and help with the 336 gears I have currently.

And yeah I know the 8.2 will be the first grenade probably followed by the Muncie but what happens happens. Also have been reading on here about the 8.5 vs 8.2. Is it really worth the upgrade. I can't see doing a 12 bolt at the current cost but have also been looking at a quick performance 9" for down the road

[Skippy597]

Ok so I've decided the cast stroker crank is the way to go so I'll get that on order and start piecing together the parts. But I also decided to use my hydraulic HLJ lifters instead of my solids and use the comp 51-116-3 (pretty much a RAIV cam but more lift). I think with the 1.65 rockers and everything else it should have a good bottom end and pair decently with the 336 gears.

[b-man]

The 8.5 is head and shoulders above the 8.2 in strength, pretty much equal to a 12-bolt in actuality.

You’re going to break the M20 and the 8.2 trying to run in the 12s, it’s just a question of which one breaks first.

Cast aftermarket crank ?

No thanks, they’re not worth buying in my opinion. I’d use a cast factory crank any day over an aftermarket one, but of course a factory 4.21” crank doesn’t drop right into a 400 block.

Get a forged crank and sleep better, it’s well-worth the extra money.

[RocktimusPryme]

I make more power than you are intending and I have a Nova 8.5 with a Moser 30 spline axle upgrade. I dance right around the high 11 second mark with no problems. And that's even with a solid 1310 U joint, which is definitely my weak link. The 8.5 is a worthy budget upgrade if there is a bolt in option for your car.

If I were spending real money on rear end I would jump right to the 9 inch. I don't understand why someone pays out the nose for a 12 bolt just to have c clip axles still.

[Skippy597]

I know the forged crank would be better but I feel for my goals the eagle cast will be fine. It's too easy to get carried away with planning, you go forged here, roller there, etc and next thing you know in over 10k and if you ever have catastrophic failure your at the bottom of the wall to start climbing again. I realize that the more premium you go the less chance you are of a failure but I also have terrible luck.

Anyone swap a 8.5 into the earlier a bodies? I know they bolt in but they are wider by an inch per side I think. Just wondering if anyone has had one shortened and custom axles? But at that point you probably in the same for a 9" swap.

[b-man]

The 8.5 from a ‘71-‘72 Buick/Olds is only 1” wider overall so 1/2” per side. Should be a pretty simple swap as long as your wheel/tire combo isn’t at the edge clearance wise. Only the earliest 1966 cars had the narrower rear ends so more than likely the rear end width won’t change at all with the swap to the 8.5 rear.

Back around 1993 I talked a friend out of using his brand-new M20, clutch, flywheel and scatter shield when we were both building cars to bracket race in the mid to low 12s. He had a 455 with stock #16 heads and a RAIV cam in a ‘69 GTO with a stripped interior.

He sold that manual trans setup for some good money instead of blowing it up and went with a tried and true TH400, he thanked me later.

We raced with an older guy who had a Tri-Power ‘65 GTO with a Muncie and a 3.55 8.2 running in the mid-14s. He was always worried about breaking the trans, plenty of stock 389 GTOs were blowing up 4-speeds and 8.2s back in the day.

I guess I’m trying to say stay off the drag strip if you are keeping the M20 and 8.2 rear unless you’re ready with a trailer or towing service to get it home after it breaks. I’m sure it will be fun on the street even without an actual 12-second time slip in your wallet.

[tom s]

If using a cast crank I would feel better with a factory than a orient crank.Tom

[Skippy597]

So yes, I could probably sell the m20 for a fair price it's a professionally rebuilt one with zero miles and that would probably pay for half the cost of a tkx swap which Is what I plan to go to down the road... but I have the m20 already and it's even the same hydraulic clutch kit as the tkx and to quote Freidburger "don't get it right, just get it running". I feel like once it's one the road and fun I can justify the upmost later, but I'll plan on staying off the track for now.

Man people are split on the eagle cast cranks. It seems either people run em and no.issues as long as they realize the limits and then there are people who whip out the cross when they even hear about them. Lol. If I can find a 428 crank I suppose I could get it turned to 400 journals but at that point with the cost of the crank and machining I might as well go forged.

Sigh.... no easy decisions

[b-man]

Get the forged crank and don’t look back.

Cast Eagle cranks are always a question mark.

[Skippy597]

So yes, I could probably sell the m20 for a fair price it's a professionally rebuilt one with zero miles and that would probably pay for half the cost of a tkx swap which Is what I plan to go to down the road... but I have the m20 already and it's even the same hydraulic clutch kit as the tkx and to quote Freidburger "don't get it right, just get it running". I feel like once it's one the road and fun I can justify the upmost later, but I'll plan on staying off the track for now.

Man people are split on the eagle cast cranks. It seems either people run em and no.issues as long as they realize the limits and then there are people who whip out the cross when they even hear about them. Lol. If I can find a 428 crank I suppose I could get it turned to 400 journals but at that point with the cost of the crank and machining I might as well go forged.

Sigh.... no easy decisions

[tom s]

If you turn down a 3 1/4 main crank you will have to deal with the thrust bearing spacer.Dont mess around,get a forged crrank.Most people dont have the time or money to do thing right but seem to find the time and money to do it over!Tom

[PDC]

Not wanting to argue - but genuinely curious about how many documented failures there are of the Eagle cast 4.25 crank in a build that did not see boost or spray. Particularly a street oriented build in the +/- 550 hp/tq range…