Engine combo advice

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Retnuh22

Retnuh22

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Hello,

I have been working on a 67 Dart and was hoping to get a couple of questions answered. This is a, "Budget" build, of course over budget already.

1. What do you all think about the set up?
2. Looking to get a radiator - possibly a 2 core 22" Champion. Would this be enough to cool the setup. I will be using a fan/clutch combo.

1975 360 Engine block was: magna-fluxed, Bored (+.030), honed, align bored
- Crank is stock cast. Cut .010 and polished
- Clevite main bearings/rod bearings
- Speed pro cam bearings
- Speed pro 405cp pistons +.030 (.046 down in hole)
- Stock connecting rods (weight adjusted as assemblies to +/- 0.2 grams) resized with ARP bolts
- Competition Cam 268 high energy kit
- Stock 273 adjustable rockers
- Competition cam pushrods
- Mopar Performance electronic distributor (aftermarket box)
- Melling high volume oil pump/pickup/mopar performance distributor gear/new bushing
- Edelbrock LD340 intake
- 596 heads: magna-fluxed (no cracks) cut to 68cc/plugged smog ports (Allen set screws) new seats/valves (1.88 and 1.60) guides/seals/3 angle job)
Competition Cams springs/retainers
Felpro 8553pt head gaskets
- B&M flex plate (external balance) with ARP bolts
- Hughes Convertor (2500 stall)
- 3310 vacuum 750cfm Holley carburetor (used)
- Headman headers (full length) exhaust into two chamber flow masters dropping at differential
- Factory harmonic balancer
- Dodge 904 transmission with 2.54 low gear (Bob Mazzolinni)
- New driveshaft/slip yoke and joints (7260)
- Rebuilt 8 3/4 rear with all new 10x2.5 brakes
Dr. Diff axles/green bearings (5x4.5)
741 with 3.55 gear set (non sure-grip)
- Front end has been disc swapped (CPP) (5x4.5)
- 70's a/c pulley setup and a Saginaw p/s pump

Thanks in advance for any input. This is my first go around with a mopar, and first engine I have built, (we've had a mopar friend helping us through the process.) It has been a father/son project and I have learned tons of info here on this site.

Garret
 
1. looks like you are basically duplicating the factory late 340/360 4Bbl package with a few slightly more modern parts. Should have good street manners and keep up with traffic just fine.

2. The factory used 2-row 22" radiators for similar power levels and thee cars weren't known for overheating if everything was in decent shape. The number of core rows isn't always what determines radiator capacity. Keep in mind that if you are using 70-up brackets and pulleys you'll need 70-up water pump and radiator.
 
Thank you for the reply! We are building it to be easy to drive for the wife and my almost 16 year old son. The water pump is the aluminum type and the radiator will match the configuration. Upgradied wiring mods will be done and hopefully be ready to go in early to mid-August. I know the community likes pictures so:
 

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Sounds like a fun project.That right rear tire will be begging for help with a limited slip unit.But then again not going sideways may keep a 16 year old out of the ditch!
 
Yeah, traction will be limited, but when the budget gets better, so will the parts. The car will be a weekend driver and not my son's primary transportation. I have told him, if he helps build it, he'll get to drive it. It has taught him to respect the car (he gets to know the amount of money going into it), and the labor spent. He has also been show graphic pictures and heard my stories of what young age, speed and alcohol mixed with a 3500 pound bullet can do. He's a good kid. Now, if I could get the wife to work on the car too...
 
In response to question #1
Please dont hate me, but,I have to ask, is that cam already in there?
I think that cam has too little .050 for its advertised .006.That is to say, its rate of lift could be a lot better.It will not trap cylinder pressure as well as some of Comps other offerings.Its rate of lift is gentle on the parts, but,the Dcr will be a bit on the low side.
Your Scr will come in around 9.4, and the Dcr will come in about 7.8@sealevel.
Now couple that with the 3310, and the 2500TC. First gear will be ok with the 3.55s and the 2.54s, but second will lay down a bit, and in direct once the engine has to really work,it could be a lot better.
So if the cam is not yet purchased I would strongly recommend a cam with a shorter period advertised and a longer period .050.
For instance, they (Comp) have a 262Extreme Energy that offers the same 218* @050,but just 262*advertised.This cam wil increase your Dcr to 7.95, and make a little more power, and noticeably more torque.Not a big difference, to be sure, but it also offers 6* extra in the exhaust, and will/should, make better Mpgs.
There are also faster rate-of-lift cams from other manufacturers out there, that could bring the Dcr up closer to 8.2, with a torque and power gain as well.
The Dcr increments are somewhat deceiving A 0.15 to 0.2 change is a lot. I can be the equivalent of one cam size.
So again, If the cam is not yet purchased, at least consider bumping the Dcr up with a drop in advertised duration, but not giving up any .050 duration. There is no downside to it.
But if you already own that 268, and its already installed,well, it will still be a fun engine.
 
Wouldn't have posted and asked questions in a forum if I didn't want to hear opinions and facts. No apologies needed. The cam is bought and installed. I still need to break it in and get the tune up to par. I asked around when researching cams, but never did the acutal math for this particular one, (as I don't have the knowledge.) I was thinking I would end up high 7's to low 8's for dynamic. Was you resultant based on a computer program or based on experience? I wanted to be able to run 87 octane, to try to avoid the eye rolls at the pumps when the wife is with me. I also won't be using it on the track. Is a smaller carburetor warranted? The one thing stated that bothers me though, is the dcr at sea level. I live at 5200 feet... If you guys have a good cam idea for my combo, and I hope I have given enough information, please fire away. I won't be able to change it right now, but will give me options down the road when, "More" is wanted.
 
With the 268H being a hydraulic cam, why the 273 rocker arms? Applying the K.I.S.S. principle, it may be less hassle in the long run to go with the non-adjustable stock rocker arms.
 
Opinions on cams are like butt holes. You can sniff 'em all day and they all stink. Which stink you like is another story.
I like split duration cams myself. Choose the duration @ .050 RPM band for your driving.

IMO, the single pattern 268 isn't a bad cam at all and given it's soon to be duty chore, it'll be fine.
 
Regarding the rockers: I got the block and heads separate. (I sent five heads to the shop before I found two that weren't cracked). I Found the rockers cheap and, as I didn't have any, I figured if later down the road if I wanted to upgrade, I'd have something adjustable.

I will admit, I may have mismatched some of my combo, and done so prior to getting on this forum. I have since read post after post about subjects I've had questions about, and found most are answered right here. You guys are an awesome wealth of knowledge, and to that I say, thank you!! I'm hoping my project will go well, and again, any input is welcome.
 
The Comp 268H is a great street grind,have had great luck with multiple installs. Drive, & enjoy.
 
I think that combo should be fun and do what you want it to. There are better cams out there, that will give you what you want and a few more hp but these cams are somewhat harder on valvetrain parts.
 
At 5200ft with your current combo,your Dcr will be about 6.74

-If that was my combo, I would be bumping the Scr up to in the range of 11 to 11.5.
I would be trying to reduce the total chamber volume to 72.5cc +/- .5cc. I would use a fast-rate cam with an ICA of 60*. This may run on 87, most of the time. That could be the XE268H (PN20-223-3).Reducing the total chamber volume with those heads as is will be a challenge.It will take some pop-up pistons for sure.This will get you; 11.32Scr/9.32sealevel/[email protected] leaves a bit of room to go to a smaller cam, but might be a hair low, to upsize. To combat that I would work the numbers using the .039 headgasket. Then if in the future the bug bites for a bigger cam, you can swap in the .028 gasket, and maintain some Dcr.
The cheapest,easiest way to get the Dcr up, is to go to a much earlier ICA.For instance, with a ICA of 42*, the total chamber volume would be 84cc for a Dcr of 8.0. That would be 68head+9.6deck+6.3thin gasket+0 eyebrows. That ICA normally comes on a pretty small cam,(stock type), so you would want a custom grind.
Decisions, decisions. So many decisions.
If you are willing to give up some cam, it will be easier to get the Dcr up. However, IMO, going to an ICA of less than 60*in the Comp line-up, doesnt get you much cam.Furthermore,since you already have the 268H, with the correct 60*ICA, I guess you could give that a chance.But then again since it hasnt been run, Id shelf it.
I also think that with the current combo, that 750 will be lazy. Again, if it was me Id try a 650DP. But since you already have the 3310, I guess you should give it a chance.
If you bump up the Scr as above, the 750 will work much better.
So to recap;I would urge you to install some hi-comp pistons,custom fit into the chambers.Then you can give the 268H, and the 3310, a chance. See if you are happy.
-I realize that everyone is cheering you on with the current combo.And I may be swimming upstream here. I just hate to see you bolt this altogether with the low Dcr, and find out the laziness is unbearable.Then again with an open diff. it could peg-leg its way down the road pretty good.At least until the cross-pin leaves home.
Wishing you all the best
 
I would not use a comp ratio so high. IMO, it would be insane. The closest I would get to a high compression mill would be 10-1 with the Hyper slugs from Speed Pro, the 116's or KB's.

Your on the right track.

Sorry A/J. While you can science out and reason your thoughts with a good argument, it is not needed to go there. Custom fitted slugs to iron heads is overkill. It ignores possible trips to lower land levels. The limit of the states octane and driving the cost will make the car difficult to fuel.

The build is for......
We are building it to be easy to drive for the wife and my almost 16 year old son.
Click to expand...
Considering it is his first engine build with a MoPar buddy at his side, IMO he need not push the engine build. He needs to just get a good combo together. Not a ton of science. In this effort the K.I.S.S. method will work excellent on many fronts and for the overall package and target.
 
Rumble
Youre right. I lost sight of the intent. And also of long distance trekking. Thanks for the reality check.

Sorry 22.I got a little focused there.
So I guess its TurboTime!
Heh-heh.
Kidding

I still wouldnt use that cam,tho.
 
I'd run what you have and tune it well. Are there parts people would prefer to use over what you have, sure. Get it together and drive it. Cars aren't any fun sitting in the garage because you are constantly building it or can't find fuel.

At that altitude, you can likely get away with a lot of total timing. Down in SB/Riv you'd need to dial it back a little.
 
Thank you again for the input, facts and opinions!! I do live at 5200 ft, but it only takes about 10-15 minutes to get to lower land, so my tune will have to either suffer at altitude, or maybe have a happy medium. If any of you are ever in So. Cal, the Rim of the World scenic highway is not to be passed up.

Regarding the higher compression slugs and cam, the engine is built, so that isn't going to change right now, though I took good notes for down the road. I could go with the thinner head gaskets, and shave the heads some more, but not sure if that will be worth the effort for the little increase I'd see.

I'm going to get her running and drive her before changes are made internally. I may be disappointed, or I may get what the bulld was intended for, a nice weekend cruiser. I want to be able to sit shotgun, look over at my boy driving, and feel proud we had great times together putting her on the road. I lost my father too early, and have cherished memories of time spent with him in the garage. The car has a great back story and will be kept for a long time. Upgrades may be done when the time comes. Now about the turbo.... ;)
 
Retnuh22 said:
Thank you again for the input, facts and opinions!! I do live at 5200 ft, but it only takes about 10-15 minutes to get to lower land, so my tune will have to either suffer at altitude, or maybe have a happy medium. If any of you are ever in So. Cal, the Rim of the World scenic highway is not to be passed up.
Click to expand...

That's one of my favorite ways to get up to Lake Arrowhead or Big Bear. From home I take the 605, to 210, and then get off Waterman and take that up all the way. It's super beautiful on a clear day (which doesn't happen too often). Even on a not so clear day, it's pretty nice!

After I get my Duster on the road, that will be one of my destinations.
 
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