Doing it right -need some advice

-
plumkrazee70

plumkrazee70

Well-Known Member
Joined
May 5, 2013
Messages
3,742
Reaction score
1,437
Location
Medford, Oregon
I have a 70 Dart with a '68 340 4.10 and soon to be 4 speed with Passon OD gearset.

I rebuilt the engine about 10 years ago and admittedly just wanted to get it running. (I didn't really follow any build, other than following the machinist recommend needs for the block.) Plus I was pretty young back then. Now I am wondering if I have parts that aren't complimentary to each other. After reading and learning from here.

Here is what I know on about the engine.
68 340 .040 over
KB hypers
Forged crank stock
Stock rods
CRS 268H-10 cam (specs attached)
Air Gap
Stock heads 2.02 intake
273 adj rockers
MSD ign without vac advance
Fitech EFI

I am going to take the engine out to mate the 4 speed and motor together, so while it's out I was going to do a true compression check and see how far out the hole or in the hole the pistons are. That will give me some ideas on where to go.

I saw the Edelbrock Performance package (heads, intake and cam) yielding 417HP.

The goal for the car is a torquey street car. The OD will override the 4.10 on the freeway, but I want something that is really fun to drive, but not have to be a high winder to make power. Few pics of when I was putting it together.

Screenshot_20220116-085936.png


IMG_20130204_193552_132.jpg


IMG_20130202_202921_512.jpg


IMG_20130204_193559_950.jpg


IMG_20130423_200627_241.jpg


IMG_20130423_211252_476.jpg
 
Last edited:
That's a pretty good build you have there. Looks like those pistons are close to zero deck. Verify the combustion chamber volume to calculate the static CR. The stock 4 speed cam is 276/284 duration .444/.453 lift so I like the cam you already have. Should be exactly the build you want. 65'
 
Looks good! Like above, if you can, find out how deep the pistons are in the cylinder. The cc the head. And let us know what head gasket your using. These numbers will be the compression static ratio.

The Edelbrock RPM package is fine IMO except the camshaft. I find it wrong for a hot street package like there selling. Edelbrock says “Matched” which is a buzz word some can’t get passed and others know it for what it really is, a gimmick. My old uncle couldn’t get passed that. He hated the Performer package a lot. It made him very angry. So he came to me for advice. He just kept saying over and over, “But it’s matched, but it’s matched…”

In your case, I would not go big on the cam since your looking to do an overdrive. In all honesty I’d use the cam you have now and see how it performs. That’s if you like the rpm range it performs in now. 218@050 is pretty small and will work basically in the 1800 - 5500 range in your car. With the OD, it should be Hwy friendly.
I would t go to much larger but I would seek more lift. As to take advantage of the heads air flow abilities. Perhaps? If it is within your wallet, Adding 1.6 rockers will help.
 
Plymouth 65 said:
That's a pretty good build you have there. Looks like those pistons are close to zero deck. Verify the combustion chamber volume to calculate the static CR. The stock 4 speed cam is 276/284 duration .444/.453 lift so I like the cam you already have. Should be exactly the build you want. 65'
Click to expand...

Appreciate that! I think I'll know more once I cc the heads and find the compression ratio. I'm also going to make sure the cam is degreed. I got a wheel coming.
 
rumblefish360 said:
Looks good! Like above, if you can, find out how deep the pistons are in the cylinder. The cc the head. And let us know what head gasket your using. These numbers will be the compression static ratio.

The Edelbrock RPM package is fine IMO except the camshaft. I find it wrong for a hot street package like there selling. Edelbrock says “Matched” which is a buzz word some can’t get passed and others know it for what it really is, a gimmick. My old uncle couldn’t get passed that. He hated the Performer package a lot. It made him very angry. So he came to me for advice. He just kept saying over and over, “But it’s matched, but it’s matched…”

In your case, I would not go big on the cam since your looking to do an overdrive. In all honesty I’d use the cam you have now and see how it performs. That’s if you like the rpm range it performs in now. 218@050 is pretty small and will work basically in the 1800 - 5500 range in your car. With the OD, it should be Hwy friendly.
I would t go to much larger but I would seek more lift. As to take advantage of the heads air flow abilities. Perhaps? If it is within your wallet, Adding 1.6 rockers will help.
Click to expand...

Thank you. I was planning on cc'ing the heads, seeing how deep the pistons are in the bore and was also going to follow Krazykuda way if measuring the compression ratio.

I've read that about th Edelbrock package also. So maybe depending on my compression ratio, should I focus on a higher lift cam and maybe 1.6 rockers?
 
340 is known for torque. These were high rpm motors, torque like stroke.
Strokers are very popular because of how cheap they are to build today.
How much was the 340 over bored ? Crank undersize ?
You may want to keep the 340 as-is and build another motor from a 360/5.9
 
MoparLeo said:
340 is known for torque. These were high rpm motors, torque like stroke.
Strokers are very popular because of how cheap they are to build today.
How much was the 340 over bored ? Crank undersize ?
You may want to keep the 340 as-is and build another motor from a 360/5.9
Click to expand...

Whoops forgot that part. 340 was bored out .040 the crank was undercut, but I can't remember how much. To be clear, I don't mind if it can high rev, I just don't want to have to be in the 5k plus range before the motor wakes up. Because it's a street car.

I don't really want to build another motor.
 
You already have one of the best street engines ever made. Stop second guessing yourself. That engine will be a blast to drive just like it is.
 
Hellrats said:
You already have one of the best street engines ever made. Stop second guessing yourself. That engine will be a blast to drive just like it is.
Click to expand...

I don't doubt that. Just want to be sure everything inside is working together. I'll update my numbers on what I find, in the coming weeks. Thanks again all.
 
plumkrazee70 said:
I don't doubt that. Just want to be sure everything inside is working together. I'll update my numbers on what I find, in the coming weeks. Thanks again all.
Click to expand...

Sounds like your already at about 400hp. True the heads and degree the cam an run it.
 
plumkrazee70 said:
I've read that about th Edelbrock package also. So maybe depending on my compression ratio, should I focus on a higher lift cam and maybe 1.6 rockers?
Click to expand...
Maybe 1.6 rockers. A lot depends on the camshaft you get. You may not “Need” the 1.6 ratio. But do look for a higher lift cam.

I don’t know if or how well the below cams will work with your Fi-Tec. I use carbs and such is the examples below are based on, the use of a carb.

If I myself was looking for a cam with your drivetrain set up, this is an example of what I might use, w/1.6 rockers.
https://www.hughesengines.com/Index...RmxhdCBUYXBwZXQsIEh5ZHJhdWxpYw==&partid=30241

The cam below, I would use the 1.5 rockers since there is plenty of valve lift for the street, (though IMO the 1.6 wouldn’t hurt anything) with your intended purpose via the description you wrote. I looked for this specifically because it is close in the duration @050 to the Edelbrock cam and will perform in a very similar rpm range.

The LSA is a good bit tighter, 112. Vs 108 which equals more torque. The idle will be rougher though.

https://www.hughesengines.com/Index...RmxhdCBUYXBwZXQsIEh5ZHJhdWxpYw==&partid=30243
 
rumblefish360 said:
I think he will like the cam he has in there with the rpm package above it.
Click to expand...

I would be open to that as well. I just want to do it right and not have to worry about it. The Fitech needs a decent amount of vacuum. Well at least 10" or more.

The package is on backorder anyway. But the heads aren't and I already have the intake and theoretically the cam,. It would the cam I have, be enough lift to utilize the heads? Or make up for it with 1.6 rockers?
 
Dang guys! Maybe my cam just needs degreed. Lol. We'll either way. I'm gonna measure th compression and cc the heads so I know what I got and report back.

Appreciate everyone taking the time to reply.
 
plumkrazee70 said:
Dang guys! Maybe my cam just needs degreed. Lol. We'll either way. I'm gonna measure th compression and cc the heads so I know what I got and report back.

Appreciate everyone taking the time to reply.
Click to expand...

While you have it out as mentioned get the actual compression ratio calculated, get the cam degreed, do a leakdown test on the cylinders to make sure you have good ring and valve seal. Other than that if you are not a tuning expert take the car to a chassis dyno tuner to set up the carb and distributor, or ask for help here if you are willing to learn. You have the basics of a kick *** little street build already.
 
As I said, you’ll probably like how it works with your cam now. Try it first. If you want more power, then revisit a cam choice.
 
What comp ratio? If over 10:1, I would be worried about detonation with that cam & today's fuel.
 
Bewy said:
What comp ratio? If over 10:1, I would be worried about detonation with that cam & today's fuel.
Click to expand...
I’m running better than 11-1 on (USA) 93 and a 224@050.
The rest is a 904/3.55-‘67 Cuda, stock everything except aluminum head and intake. Heads are TF’s zero deck 030-360. .028 head gasket.

Not that I recommend this. Just saying I’m doing it.
 
I like the build. Freshen it up if you think it needs it and let it ride!
 
You must log in or register to reply here.
-

Back
Top