318 Roller Build - Thoughts?

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KingofSwing

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Hello all,

I am not completely new to reading this forum, but this is the first time posting here. First, a little back story. I purchased a '73 Dart Swinger about a year ago that is all original with only 63,000 miles. Problem is, it is a slant six, there is nothing wrong with a slant six i just need a slight power boost. Jump forward to about 2 months ago, I purchased a 318 which at the time was believed to be a 77 out of a 77 roadrunner. I know a 318 is not the greatest choice for power but it was $75 for the complete motor and I am still looking for MPG. Well, once we got the motor back, come to find out it was an 87 with a roller cam.

The car is going to be used for daily driving, mostly.. As a drag racer at heart (pontiac's.. sorry) I still need some power. But, I really like the roller cam aspect of this engine for valvetrain reliability. So here is the plan:

Engine Build:
1987 318
#302 Casting heads (mild port work)
Edelbrock Performer/RPM Intake
600cfm carb
Lunati Hyd. Roller 60711 Cam:
213int/219exh duration @.050 -- .485/.485 lift -- 112 LSA
Comp 901-16 springs
Stock roller lifters
1 5/8 headers to dual exhaust
904 trans with 2500 stall
8 1/4 (at least) with 3.23+ gears

Thoughts, Concerns?
Potential HP/TQ estimates?

This motor is in really good shape internally so it is getting a freshen besides this, with bearings, gaskets, etc. I am keeping the stock pistons as much as they suck. This project is on a serious budget.
 
Sounds OK, being a 318 guy, heres what I would change.

Performer manifold, Holley street dominator. The Performer RPM is a big port manifold.
Use the springs lunati recommends.
Thin as hell head gasket, adjustable rockers. (never used a hyd cam and adj rockers, not sure what pushrod you would use......)

Power?

340TQ at sayyyy........ 3K
275HP at sayyy......... 5K

Thats coming from Bobby's Headtop dyno, LOL.
 
If your keeping the RPM (AKA allready have it) Port match the head to the intake. Although I'd prefur a smaller runner intake than a RPM for such a mild build. (Like Bobby said above) Also measure how far down the hole the slugs are and cc the head. A little bit of a mill could help. IIRC, the comp. raio will be low. Not as bad as my 7.8-1, '79 - 318, but low.

I have a simlar combo with a;
Hyd. Crane split @ 216 - 228-.454/.480 on a 112.
LD4B,
Carter 625,
Hooker headers into,
Jegs dual 2-1/2 exhaust and 3.21's on a 225-70-14
8-1/4 can have 3.21's, They don't have 3.23's for this rear. OK, hair splitter of a note. Just a FYI.

I'd like to get a 2200 - 2500 stall verter for my ride. That would be cool. And a shift kit done someday. My 904 is a lock up trans.

Anyway, I did manage to take it down to ATCO on there MoPar gathering day and ran an untuned carb and distributor to a 15.14 @ 89 w/2.2's for a 60 footer. Not bad for bolt on's and a baby Crane cam w/3.21 gears.

Some fiddling around with timing and carb tune chores and I'm sure I can weasle into the 14's.

OH, 1 quick note, the /6 trans will not bolt up to the small block. Don't know if you know that, but the one cave eat I hate is tranny's are for the engine family. /6 needs a /6 trans as does a small block needs a small block trans and a ig block needs a big block trans. Hate it hate it hate it.

I like Bobby's head dyno.
 
adjustable rockers and hydraulic cam/lifters use a Comp Cams pushrod, I THINK the number is 7821-16 I just installed a set, if you do things like mill the heads and run tiny head gaskets this length may not work for you and custom ones may be in order.

Speaking of those thin head gaskets who makes em now?? the mopar part number I have doesn't come up with anything like it's discontinued.
 
Am I thinking too small of a cam? I was thinking in a 318 that would be starting to get on the less streetable side. Although, I do want to remind everyone that this is a Hydraulic Roller cam, not a regular Hydraulic.

I planned on running the thin head gasket (wigsplitter you can find them at mancini racing that I know of). What type of adjustable rockers should I run, remember I am on a very tight budget though. The build Is not complete, the only thing in my possession at the moment is the complete 318, this was just the plan. I am looking for at least 300HP+ 350TQ+, more is perfectly fine, but I want this thing streetable and try to get at least 20mpg. That might be a tall order, but I think it is possible.
 
wigsplitter74 said:
adjustable rockers and hydraulic cam/lifters use a Comp Cams pushrod, I THINK the number is 7821-16 I just installed a set, if you do things like mill the heads and run tiny head gaskets this length may not work for you and custom ones may be in order.

Speaking of those thin head gaskets who makes em now?? the mopar part number I have doesn't come up with anything like it's discontinued.
Click to expand...

thin head gasket is mr gasket 1121...
same one mopar sells...p4120094
they are the same head gasket.


http://www.monicattichrysler.com/comersus/store/comersus_viewItem.asp?idProduct=247
 
KingofSwing said:
Hello all,

I am not completely new to reading this forum, but this is the first time posting here. First, a little back story. I purchased a '73 Dart Swinger about a year ago that is all original with only 63,000 miles. Problem is, it is a slant six, there is nothing wrong with a slant six i just need a slight power boost. Jump forward to about 2 months ago, I purchased a 318 which at the time was believed to be a 77 out of a 77 roadrunner. I know a 318 is not the greatest choice for power but it was $75 for the complete motor and I am still looking for MPG. Well, once we got the motor back, come to find out it was an 87 with a roller cam.

The car is going to be used for daily driving, mostly.. As a drag racer at heart (pontiac's.. sorry) I still need some power. But, I really like the roller cam aspect of this engine for valvetrain reliability. So here is the plan:

Engine Build:
1987 318
#302 Casting heads (mild port work)
Edelbrock Performer/RPM Intake
600cfm carb
Lunati Hyd. Roller 60711 Cam:
213int/219exh duration @.050 -- .485/.485 lift -- 112 LSA
Comp 901-16 springs
Stock roller lifters
1 5/8 headers to dual exhaust
904 trans with 2500 stall
8 1/4 (at least) with 3.23+ gears

Thoughts, Concerns?
Potential HP/TQ estimates?

This motor is in really good shape internally so it is getting a freshen besides this, with bearings, gaskets, etc. I am keeping the stock pistons as much as they suck. This project is on a serious budget.
Click to expand...

Be sure to do the bowl work on those 302's and open the ports some,as they are small. Dont go so far as to kill the velocity.

Maybe go with 3:55 gears,depending how much highway it will see.

If you can find the cash,square deck the block..Mopar engines are better designed than most,but factory machining was poor. There's some compression to be had doing this as it will bring the pistons up in the hole. Thats one area where the "teen" falls down is low compression,small cam,small ports.

Kb167 pistons are readily available and very reasonable. You could have about 10:1 with them,otherwise I think you'l be stuck around 8:1,8.5 at best. Even with the small chamber 302 casting.

The cam is fine. You could even push for more duration,but I'd stick with it unless you raise the compression.
 
IMO, I'd skip the adjustable rocker arms and reuse the OE rockers and pushrods. The Lifter has .100 of travel and the first and last .010 are not good to use in actual use/calculations.

20mpg's may be a strech. I'm getting 17 on the Hwy. A MSD is being sought to help a tad. An overdrive would do it and add performance in it's deeper first gear and .69 overdriven gear.

3.55 X .69 = 2.4495 final drive gear ratio feel.
3.91 X .69 = 2.6979
4.10 X .69 = 2.829

Remember, the final drive ratio should work with your cam at hwy. speeds. Cam for this!

The 500 is the 904 with a overdrive
A 518 is the 727 with a over drive.

Though expensive for a on the cheap project, it is food for thought.
You'll also need to shorten your drive shaft and re-work the tranny mount. I know theres someone out there making a trans mount that bolts up and has a proper mount for it as well. A torque converter may be needed for this as well.

Again, not cheap, but IMO, a worth wile expense if your keeping the car and making lots of use with it.

I also do not think your cam to small. I'd rather see a slight increase to the duration, more like mine or a slight larger.
 
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