Gen2 Hemi experts. Review my refresh plan?

[INTMD8]

I have a 69 Charger with 426, TKO600 and 4.10's which I got on the road earlier this year. I bought it as an incomplete project and didn't get any real information on the engine, other than it made 520hp on an engine dyno (with headers).

I think it's a "crate" engine that's been freshened up (I was told it was as it was burning oil initially) and a larger hyd flat tappet cam. Very choppy idle, 8in vacuum at idle with 23deg initial at 950rpm.

Has exhaust manifolds, dual AVS2's on an edelbrock single plane intake. 150psi cranking compression.

Made 405rwhp on a Dynojet and noses over/breaks up just over 6k rpm so I'm assuming it's light on valve spring.


My thoughts are this- Remove engine, rebuild with a bit more stroke (4.0-4.25?) and 7.1 rods. 11 to 11.5-1 compression pistons that aren't 800+ grams, port the iron heads and replace the manifolds with headers.

Would like it to rev to 7k and make 500 at the wheels. Prefer rpm and horsepower over off idle torque, plus I want to keep the trans in one piece.

Undecided on type of cam. I'm reading hydraulic roller is problematic on these, unless something has changed with what is available parts wise.

Any thoughts on solid flat tappet or solid roller? Not going for crazy power so not sure if solid roller is worth the extra cash.

Or if there is a very high quality hydraulic roller lifter that is known to survive I would go that route.

Any suggestions appreciated. Thanks!!!

 

[Fran Blacker]

Didn't say if it's a street car. 11+ compression on street? 7000rpm needs a oil system upgrade over stock.

 

[wyrmrider]

as fran says you need oiling with 7k and more expensive to make reliable
you probably do not need 7K with the stroker
depending on the heads big time
if you port your stock heads get flow (from .050 up) B4 thinking cam
(or compression as better flow fills better)
I would PM AJ over on the ABBO forum and have him run the numbers 4 U as far as desired compression
Usually a little lower as CU in rises
flow trumps compression

if you go roller tip rockers contact rocker arm specialists in Redding CA on geometry fix - depending on lift

 

[Challenger340]

I have a 69 Charger with 426, TKO600 and 4.10's which I got on the road earlier this year. I bought it as an incomplete project and didn't get any real information on the engine, other than it made 520hp on an engine dyno (with headers).

I think it's a "crate" engine that's been freshened up (I was told it was as it was burning oil initially) and a larger hyd flat tappet cam. Very choppy idle, 8in vacuum at idle with 23deg initial at 950rpm.

Has exhaust manifolds, dual AVS2's on an edelbrock single plane intake. 150psi cranking compression.

Made 405rwhp on a Dynojet and noses over/breaks up just over 6k rpm so I'm assuming it's light on valve spring.


My thoughts are this- Remove engine, rebuild with a bit more stroke (4.0-4.25?) and 7.1 rods. 11 to 11.5-1 compression pistons that aren't 800+ grams, port the iron heads and replace the manifolds with headers.

Would like it to rev to 7k and make 500 at the wheels. Prefer rpm and horsepower over off idle torque, plus I want to keep the trans in one piece.

Undecided on type of cam. I'm reading hydraulic roller is problematic on these, unless something has changed with what is available parts wise.

Any thoughts on solid flat tappet or solid roller? Not going for crazy power so not sure if solid roller is worth the extra cash.

Or if there is a very high quality hydraulic roller lifter that is known to survive I would go that route.

Any suggestions appreciated. Thanks!!!

The crates were a cheap starting point "Box of Parts" for the money back in the day.... then depending how much/far a guy wanted to go substitute accordingly.
That said,
it's amazing how many guys just installed "as is", and then after many attempts at upgrade in/out of the Car just eventually GAVE UP and reworked complete ?
Surprised you even saw 405 rwhp out of yours ?

Doesn't look like you are seeking much more than 650-700hp flywheel ?
Which is doable even just on the stock 426, 91 Octane, Flat Tappet Cam, better Intake & Heads on because by the time a guy farts around with the Irons better to just buy the Eddy's.
We typically see about 670-680 hp Flywheel out of the 426 Crate Engines reworked with new Pistons @ .030" over, Eddy Heads gone thru/cleaned up, Ray has some nice Flat Tappet Cams for that application, Good Intake & Carb, some Oiling/Pan Mods but still internal, never had a problem or return sub 7,000.

If a guy does want to spend more ?
Then yes... the 4.15/4.25 Cranks Rotating Assemblies in conjunction with again the Eddy's as a cost effective entry Head, Flat Tappet Cam/Intake, Oiling, etc., and same-same still up to about 700hp but at lower well sub 6,500 rpm.

TIP: HR Cams are NOT efficient higher rpm sticks.... pretty much useless(IMO), we won't even waste our time with them in Hemi's above 6K on the Dyno anymore.

 

[wyrmrider]

Iron is expensive to port
several sources for heads
check them all out depending on where you want your heads to flow
street is much different than blown or top fuel
I used Stage V a lot- great people and easy to work with
They and others will tell you if their heads are not a fit
Power is in the heads-but you need it in the rpm (cam duration) and lift range which you need to lock down first- as "top end HP is seductive- and much more expensive
pick valve gear along with the heads
even stock needs rework
I trust the guys at rocker arms unlimited now in Northern California to give me the straight shot- but check them all out as YMMV not may- will
agree on the HR
My go to on custom FT or Roller cams is Mike Jones but not till after heads and flow
but I would ask his opinion on what head flow to look for
his brother Rick's controlled induction software could help- now sold through Pipe Max
Bottom end
Big thing to me is to lighten up the pistons
which leads to a longer Rod
as far as strokers go the bigger the better on the street- and this affects your head and cam so plan on re-iterating your search a few times
measure twice- cut once
cheers

 

[68 HEMI GTS]

Solid cam is the only way to go. I’d use a nitrided flat tappet. Add stroke if you can. More the better. Go with the Edelbrock heads on a stroker. If you stay 426 I would port the iron heads.

 

[INTMD8]

Thanks for all the info guys! Much appreciated.

I know hemi is a different beast but had to ask about HR as I've ran them in turbo LS engines to nearly 8k rpm. Of course the valvetrain is much lighter overall.

675 at the flywheel would put it around 600 at the wheels (give or take) and I would be perfectly happy with that.

If that can be done with solid flat tappet and 426ci I will probably go that route as I would prefer it to be making power up higher in the rev range rather than be a stump puller. (just my preference)

I was thinking some bowl work and a good valve job and the iron heads would flow well enough for my needs but if they are a pain to work with I have no problem going aluminum.

Thanks again.

 

[HEMI-ITIS]

If your giving the engine to a builder you want one with good hemi history.There quite a few out the and I like Vignogna Perfance,Porter racing heads and Marsh Performance.Never heard a bad word about any of them!

 

[68 HEMI GTS]

Thanks for all the info guys! Much appreciated.

I know hemi is a different beast but had to ask about HR as I've ran them in turbo LS engines to nearly 8k rpm. Of course the valvetrain is much lighter overall.

675 at the flywheel would put it around 600 at the wheels (give or take) and I would be perfectly happy with that.

If that can be done with solid flat tappet and 426ci I will probably go that route as I would prefer it to be making power up higher in the rev range rather than be a stump puller. (just my preference)

I was thinking some bowl work and a good valve job and the iron heads would flow well enough for my needs but if they are a pain to work with I have no problem going aluminum.

Thanks again.

even with a stroker crank they turn RPM’s. My iron headed 505 (4.15 stroke) wanted to go well over 7. I cut it off there just to keep it alive. A few times I bumped the shift point up to 7400 and it would instantly gain ET. I’m putting a 4.5” crank in mine in an attempt to make more power but also drag the rpm range down. Less RPM=better for longevity reasons. I think my new heads will counter that though ..

 

[wyrmrider]

4.5 crank good move
what's the rest of the combination
rod length and pin size
BBC crank pins?
I'd rather have the stroker with tuned up stock heads unless class racing
not have to over rev it before shifting with rpm drop unless the largest converters which are not really streetable

 

[68 HEMI GTS]

4.5 crank good move
what's the rest of the combination
rod length and pin size
BBC crank pins?
I'd rather have the stroker with tuned up stock heads unless class racing
not have to over rev it before shifting with rpm drop unless the largest converters which are not really streetable

7.1 rod, 2.2 pin, 548ci 11:1, solid roller .440 lobe lift, 270 @ .050, on 112, ported Vic jr’s flow 465 @ .700. Nice little street/strip package.

 

[wyrmrider]

NICE 68 Hemi gts

 

[INTMD8]

Finally got this out and started taking it down.

Pretty much as expected. 9-1 pistons but look like .050 in the hole (just guessing) Would be surprised if it's much better than 8.5-1 actual.

Cam is a Comp "Mutha thumpr" (not sure why that name annoys me so much) 235/249 107. Not a great match for single valvesprings. Well these at least. I'll test them tomorrow but I can open them with the palm of my hand. Feels like the guides are sloppy and the ports/bowls make me sad.

Have the time so I'm going to port them myself. Would go with edelbrocks but feel the port volume may be a bit big (or bigger than ideal) for the displacement.

 

[BSB67]

I have a 69 Charger with 426, TKO600 and 4.10's which I got on the road earlier this year. I bought it as an incomplete project and didn't get any real information on the engine, other than it made 520hp on an engine dyno (with headers).

I think it's a "crate" engine that's been freshened up (I was told it was as it was burning oil initially) and a larger hyd flat tappet cam. Very choppy idle, 8in vacuum at idle with 23deg initial at 950rpm.

Has exhaust manifolds, dual AVS2's on an edelbrock single plane intake. 150psi cranking compression.

Made 405rwhp on a Dynojet and noses over/breaks up just over 6k rpm so I'm assuming it's light on valve spring.


My thoughts are this- Remove engine, rebuild with a bit more stroke (4.0-4.25?) and 7.1 rods. 11 to 11.5-1 compression pistons that aren't 800+ grams, port the iron heads and replace the manifolds with headers.

Would like it to rev to 7k and make 500 at the wheels. Prefer rpm and horsepower over off idle torque, plus I want to keep the trans in one piece.

Undecided on type of cam. I'm reading hydraulic roller is problematic on these, unless something has changed with what is available parts wise.

Any thoughts on solid flat tappet or solid roller? Not going for crazy power so not sure if solid roller is worth the extra cash.

Or if there is a very high quality hydraulic roller lifter that is known to survive I would go that route.

Any suggestions appreciated. Thanks!!!

Do you have an et and mph goal for the car? With the suspension set up you're planning to have, what kind of 60 ft are you expecting? There are so many types of dynos and how the're set up usually results in everyone talking a different language and not even knowing it. I think your 500 RWHP comment verses Bob's 700 flywheel hp comment is a good example. Somewhere you guys are 100 hp apart. FWIW, my math says you'll need 625 flywheel hp to get about 500 RWHP on a Mustang Dyno. Some people say Dynojets are 12% happy (higher than Mustang) Others say 6% Others say "it depends". Same with drive train loss, and same with flywheel hp. Starting with car and track goal usually help to get everyone on the same page.

What type of driving characteristics are you looking for. You didn't say that the 8" of vacuum was an issue for you. Personally, I can tolerate a much bigger cam with a manual tranny and 4.10 like you have. But that just me.

So why does this all matter? IMO, if you build a 4.25 arm Hemi and you want it to be in a happy place at 7000 rpm, it will be more than 500 RWHP and probably pretty easily a 10 second street car. If you only want 500 RWHP it will be more of a lower torque build, but still be a low 11 sec street car. Like Bob said, you can get to your 500 RWHP goal with a std stroke 426, but the engine/cam combination will be pretty rowdy at idle, but be in a happy place at 7000 rpm.

 

[INTMD8]

I don't have an et/mph goal as I don't plan to really drag race it. Might take it once just to see what it does but will be usually street driven on regular radials.

Maybe low 120's trap speed would be good.

The dyno I ran it on I've used for nearly the past 20 years so I'm very familiar with it. It is a Dynojet 248.

I'm trying to get there without going crazy on cost as these things can escalate pretty quickly.

If I do a stroker, I'm doing rods, then why not aluminum heads, then roller rockers, roller cam/etc/etc and at some point I would have been better off selling what I have complete and buying a different engine entirely.

I'm kind of leaning towards keeping the 3.75 crank, solid flat tappet maybe around 250-260 @.050, better pushrods (the ones in it seem very thin wall), and of course valve springs. 11.5-1 along with the ported iron heads and just see what it does.

I prefer a higher rpm engine vs a lower rpm torque monster. Had no problems with drivability as it was so I'm fine with it being a bit rowdy since it's not a daily driver.

Thanks for the insight guys, much appreciated.

I'm making a bit of progress on the heads. About 10 hours in so far. Looking better to me but I've never ported heads before so I guess we will find out when I get them on a flow bench. I concentrated on bowl work but also raised the port .090 to match the Edelbrock intake.

 

[BSB67]

I personally like your approach. The fun factor of high rpm, manual tranny at the power level your looking at will be incredible. I think you can get there with the std stroke. I would consider a gentle lobe, roundy-round type solid roller.

 

[Challenger340]

We usually find it's better to install & rough size the new Valve Guides FIRST.... so we can also rough in our new Valve Seats concentricity as well before we do our Port work ?
That way we can Port down to the NEW Valve Seats ?

Just say'in....
no fun when now you go get the Guides and Seats redone only to find out your Porting is now off to one side vrs the new seat work ?
The whole purpose in Porting is to allow the Port to "present" the airflow to the seat angles ?

 

[INTMD8]

Sounds right but I removed a ton of material around the guide boss and bowl, and raised the port roof which was going to be done either way. Of course there will be more to do after the guides/valve job.

Can't imagine the valve seats are going to move a hundred thou in any direction and if they stay in the same general area I don't think it's going to be a problem.

Maybe I'm wrong, like I said, have never ported heads before. Thought it would save some money to rough them in rather than pay a machine shop the same amount of hours.

 

[INTMD8]

I personally like your approach. The fun factor of high rpm, manual tranny at the power level your looking at will be incredible. I think you can get there with the std stroke. I would consider a gentle lobe, roundy-round type solid roller.

I was just concerned about roller as I've read about lifter failures. Bushed rollers I think are $1000+ which I could do but is it worth it on this build? Maybe

 

[INTMD8]

Well I ended up spending 16 hours on the heads and they are done for now. (or until guides/valve job are completed).

Didn't do a ton on the exhaust side. Short turn radius is strange, almost hooked rather than a consistent radius but I didn't alter that shape.