Critique this combo - 318!

[rmchrgr]

I've been trying to zero in on an engine build for a while now using Desktop Dyno as a guide. I put in as much info as I can, especially published flow numbers for heads to make it as accurate as possible.

I've come up with what I perceive to be a nasty street/strip combo but naturally wanted to hear what others think. Goals for the car are to putt it around for ice cream and cruise nights but also drive it to the track, run it to low 12's and drive it home. Guess I'm willing to put up with whatever inherent drivability issues there are with a 'big' cam, loose converter and steep gears.

Car is a '71 Dart, lightened, but will be installing frame connectors. Hoping to get it down to 3,050-3,100 without me.

Here's the specs on the engine:

318 bored .040" over, 3.950" bore. '67 casting. (thick!)
Stock stroke, 3.31" (318-3 steel truck crank)
RHS heads, 1.92" intake valves
Hughes 1.6 rockers
Smith Bros. pushrods
KB 167 Hypers, 5 cc piston volume. C.R. works out to be approx. 10.2:1 with M.P. thin head gasket (.025") KB's web calculator says 8.8 dynamic compression if that matters to you. These come w. 2 5/64 and 1 3/16 rings and a 984 pin. No coating that I'm aware of.
Holley Strip Dominator intake
6139 TQ, (small primaries, 800CFM).
TTi headers, 1 5/8" primaries, full dual exhaust.
Mopar elec. dist., MSD 6
Mech fuel pump
Comp. 282s - 282 adv, duration, .495" lift, .528" w. 1.6 rockers. LCA 110, Intake CL is 106. Not sure what it would be installed at, probably between 2-4 degrees advanced.

Machine work planned: square deck block, index crank, line hone mains, bore and hone .040" over w. torque plate, recondition stock rods w. new bolts, deburr block, intall new bearings (possibly coated). Possibly may bush the lifter bores, just trying to get everything square and equal.

Plan to CC heads and ensure chambers are correct @ 62, check I.H. on springs, not sure if I will need longer valves, undecided on valve springs. Cam requires Comp. 995-16 which are 115 lbs @ 1.7".

Car will have a 4.10 rear, low gear 904 w. shift kit. DD shows torque peak for this combo @ 5,000 rpm, converter might end up around 4K+ unfortunately, not so great for the street. Oh yeah, 27" tires.

May consider picking up an Air Gap and a Holley Ultra Series 750 rather than the TQ and Strip. Dom. which i already have.

Basically just want to hear what people think about this combo for my intended goals.

Whew!

Thanks,

- Greg

 

[dodgetkboy78]

I've been trying to zero in on an engine build for a while now using Desktop Dyno as a guide. I put in as much info as I can, especially published flow numbers for heads to make it as accurate as possible.

I've come up with what I perceive to be a nasty street/strip combo but naturally wanted to hear what others think. Goals for the car are to putt it around for ice cream and cruise nights but also drive it to the track, run it to low 12's and drive it home. Guess I'm willing to put up with whatever inherent drivability issues there are with a 'big' cam, loose converter and steep gears.

Car is a '71 Dart, lightened, but will be installing frame connectors. Hoping to get it down to 3,050-3,100 without me.

Here's the specs on the engine:

318 bored .040" over, 3.950" bore. '67 casting. (thick!)
Stock stroke, 3.31" (318-3 steel truck crank)
RHS heads, 1.92" intake valves
Hughes 1.6 rockers
Smith Bros. pushrods
KB 167 Hypers, 5 cc piston volume. C.R. works out to be approx. 10.2:1 with M.P. thin head gasket (.025") KB's web calculator says 8.8 dynamic compression if that matters to you. These come w. 2 5/64 and 1 3/16 rings and a 984 pin. No coating that I'm aware of.
Holley Strip Dominator intake
6139 TQ, (small primaries, 800CFM).
TTi headers, 1 5/8" primaries, full dual exhaust.
Mopar elec. dist., MSD 6
Mech fuel pump
Comp. 282s - 282 adv, duration, .495" lift, .528" w. 1.6 rockers. LCA 110, Intake CL is 106. Not sure what it would be installed at, probably between 2-4 degrees advanced.

Machine work planned: square deck block, index crank, line hone mains, bore and hone .040" over w. torque plate, recondition stock rods w. new bolts, deburr block, intall new bearings (possibly coated). Possibly may bush the lifter bores, just trying to get everything square and equal.

Plan to CC heads and ensure chambers are correct @ 62, check I.H. on springs, not sure if I will need longer valves, undecided on valve springs. Cam requires Comp. 995-16 which are 115 lbs @ 1.7".

Car will have a 4.10 rear, low gear 904 w. shift kit. DD shows torque peak for this combo @ 5,000 rpm, converter might end up around 4K+ unfortunately, not so great for the street. Oh yeah, 27" tires.

May consider picking up an Air Gap and a Holley Ultra Series 750 rather than the TQ and Strip. Dom. which i already have.

Basically just want to hear what people think about this combo for my intended goals.

Whew!

Thanks,

- Greg

Beware, the 67 casting usually isn't thick, the 68 up to about 72 are tho....

Look carefully at the crank, -3 trusk engines past about 70 usually had dish pistons and cast cranks..

Please get Forged pistons, no use spending all kindsa dough and using hyper pistons. Yeah yeah, I know, so and so has ran them 2400 runs at 9200 RPM, with no issues....... but when the bore wears, the skirts like to migrate to your pan, and face it, good exhaust and flat to the floor, it's hard to hear it ping, and I have seen pistons become see through in one pass.

With the cam, and the small cubes, I would go Performer RPM, or a worked over street dominator. For a 318, your cam is in the dual plane range. IMO

TQ??? Really? Nothing like leaving HP on the table. (thinking maybe one of those cool holley ofshoot carbs, or even a 750EB, before a big ol thermobog) Good carb for the street, but, squareish bore feeds the cylinders fuel more equally. Anyone who has pulled the four corner plugs while tuning knows thiis.

I'm thinking a voodoo can about the same size....... But, Just like the hyper pistons, I don't trust comps in my motors, not even a stock motor. The ol 260/260 I used to use tons in my stock rebuilds, but after a few lobes dissapearing..... Nahh.

With that cam, if you really get a stall speed of 4K, your probably about 1K under your peak torque, and take it from someone who ran a 318 with a 3500, drop her in gear and the car wont move, 4.88 car. 3500 stall in a short stroke SB equals HOT trany temps, and slippery times in the rain, hehe. (and 5MPG) *4K in say, a 440, almost will feel stock at low throttle settings, because of the greater torque of the motor)

Make sure the rods are the old floaters, the old 318 rods were pretty strong, and lighter than the HD 318 rod. (*Stock 360 rods were called the HD 318 rod in about 72, I am guessing to save money)

And, again, all my opinions are exactly that, opinions from a 318 guy, who has built many many many of them.

 

[rmchrgr]

Beware, the 67 casting usually isn't thick, the 68 up to about 72 are tho....

We'll see when I get it machined how thick it is. Plan is for .040" over, I would think most LA blocks should be able to handle that without issue. I've read that some of the earlier blocks can go over 4". Obviously sonic checking is the only way to verify.

Look carefully at the crank, -3 trusk engines past about 70 usually had dish pistons and cast cranks..

Pretty sure this is a '68 model year short block. Didn't think the truck cranks went past 1970.

Please get Forged pistons, no use spending all kindsa dough and using hyper pistons. Yeah yeah, I know, so and so has ran them 2400 runs at 9200 RPM, with no issues....... but when the bore wears, the skirts like to migrate to your pan, and face it, good exhaust and flat to the floor, it's hard to hear it ping, and I have seen pistons become see through in one pass.

Think I'll stick with the KBs. Can't beat the price and despite your opinion, I think they are proven parts. If I'm at the point of bore wear, I think
I will have gotten my dollar's worth out of them and will probably be in for a rebuild anyway. Let's hope I can put that many miles on the car! Like everything else, if they're set up correctly they should work OK. Might even get them coated! Probably not though.

With the cam, and the small cubes, I would go Performer RPM, or a worked over street dominator. For a 318, your cam is in the dual plane range. IMO

Strip Dom. is a 'small' single plane and it's got a TQ flange. IMO, the Air Gap is essentially a dual plane Strip Dominator. Something is telling me to use an Air Gap though.

TQ??? Really? Nothing like leaving HP on the table. (thinking maybe one of those cool holley ofshoot carbs, or even a 750EB, before a big ol thermobog) Good carb for the street, but, squareish bore feeds the cylinders fuel more equally. Anyone who has pulled the four corner plugs while tuning knows thiis.

I won't get into a disagreement about the merit of TQs. Ma Mopar seemed to think they were OK enough to use them for what, 15 years? I have a 6139 which is the small primary one, so part throttle cruisng will benefit. But when the secondaries open, it's 800 CFM. Plus mine's NOS so the phenolic body is good. Keeps the fuel cooler, can't argue with that. I am considering a Holley though because of parts availability. Ever try finding a Strip Kit for a 6139?

I'm thinking a voodoo can about the same size....... But, Just like the hyper pistons, I don't trust comps in my motors, not even a stock motor. The ol 260/260 I used to use tons in my stock rebuilds, but after a few lobes dissapearing..... Nahh.

Took a long time to arrive at the 282s. Don't want a hydraulic like the Voodoo. As I said above, as long as I set it up correctly, i.e. ensure the lifters are rotating, use the right additives and adjust the lash correctly it should be fine.

With that cam, if you really get a stall speed of 4K, your probably about 1K under your peak torque, and take it from someone who ran a 318 with a 3500, drop her in gear and the car wont move, 4.88 car. 3500 stall in a short stroke SB equals HOT trany temps, and slippery times in the rain, hehe. (and 5MPG) *4K in say, a 440, almost will feel stock at low throttle settings, because of the greater torque of the motor)

I understand that the converter will likely be inefficient under 3K. What am
I going to do? That's the street car trade off - want to go fast? You need a good converter to take advantage of the combo but don't expect it to be street friendly. A custom conveter is part of the budget.

Make sure the rods are the old floaters, the old 318 rods were pretty strong, and lighter than the HD 318 rod. (*Stock 360 rods were called the HD 318 rod in about 72, I am guessing to save money)

Floating rods, yes. Plan to polish the beams, re-size, shot peen, ARP bolts, yada yada.

And, again, all my opinions are exactly that, opinions from a 318 guy, who has built many many many of them.

Thanks for the input. So I'm guessing that you think it will 'run the number'?

 

[PanGasket]

Forged will obtain you a loner lifetime than those hypers by far too. And I'd avoid hypers, they have some bad habits such as the ones he listed and then them fusing to cylinder walls is pretty unattractive. I wish I still had the article about it, but it was real real nasty.

 

[dodgetkboy78]

Yes, it will run great, IMO, it could be better, for me..... As far as wearing out the bore, with a 4K converter, your looking at 10K miles, with a 160 thermostat.

Just a thought.

 

[dodgetkboy78]

Oh, I was talking the mech voodoo, 2800-7k range. Big diff between should be fine, and wil be fine.

 

[RustyRatRod]

Nuthin wrong with hypereutectics. Almost EVERY single time you hear of somebody havin a problem with um it was operator error. They have VERY strict top ring gap specs and as long as you adhere to them, you will be fine. I always run mine by adding the "towing" spec and the "nitrous" spec for their top ring gaps together. Usually end up over .040" top gap, but it works well. People who spew bad things about KB pistons have either not used them, not used them correctly or seen or heard of someone who has done some of both. They are great quality pieces, but like anything else, you have to follow the deestruckshuns. Now, the only other "problem" I see with your combo.......the carburetor. And guess what? That's comin from a TRIED and TRUE Thermoquad guy. As far as Im concerned, there's not a better carburetor on the planet.......BUT, it sounds to me like you're leaning more towards a race car than a street car. That said, I would do one of two things. Get the RPM with a good HP Holley of some sort....Demon....whatever......OR go with the 440 version of a TQ and trick it out some. You're only talkin about 50 more CFM.....AND you're talkin about a pretty hot 318. It'll take it just fine. the TQ is a really forgiving carburetor. Some may say it'll never handle the 850, but I got news......it will and then some. You're gonna be talkin about trap RMPs over 6K. That's a lotta RPM. It's gonna need a big carburetor. Now....one last bit of advice......and I HATE DETEST ans DEPLORE carburetor adapters.....BUT....that RPM intake is a real gem. You wanna try sumthin that I bet will REALLY work? Slap an 850 TQ on top of that RPM intake. The adapter in this case will act as an RPM extender and probably give you another couple hundred RPM on the top end. Yer gonna need it. Other than that, your combo sounds great. hell, it's great like it is......you just asked and those are "MY" opinions.

 

[1wild&crazyguy]

go with a med/tight convertor=3200 stall and 4.10-4.30@25-26'' tire gear to get into the 12's with this combo.jmo

As for pistons...poor tune/crap oils/and missfiring is what causes scuffing, not piston material..and besides, the stock pistons are softer than hypers and are they always scuffing and smearing themselves all over the cyl wall?
hypers are harder than stock cast, while forged are even harder though they grow more.
hypers are used though out production car engines today along with forged.

lets get over that part already..

now are those 167's domed? so you wanna use a domed piston with a closed chamber?

are we squeezing it over a hill for ???

are the 995 springs doubles with a dampener?
the same ones that I run on my 340 that are '135psi on the [email protected] and [email protected]?
your info is off.

The heads are good, the rest is preference-intake/header brand/ignition etc..
I like solid cams myself but in the range you're talkin or better is a good start.
BTW how it actually runs is a reflection of your tuning ablity or lack of.

 

[1wild&crazyguy]

btw run the engine too cold and the bore go's away too, not from piston choice.

constant higher rpm's is what wears bores/rings [amongst other things] out as well, thats the only reason newer car engines/jap engines last as long as they do-light foot & Overdrives.

if you could keep the rpm's down yer old mopar would go over 300k
my 1500 4x4 is an example where with the overdrive/lock up it has 215k on it and go's down the freeway at speeds of 70-90mpg @19-2100rpm.

 

[1wild&crazyguy]

as for the thermolog,thermobog,thermohog or what ever....lol

well...look at the secodary initiation...spray bars/piss tubes...and it go's from 280cfm to 600+ with that crap initiation...

the only reason they get any credit , in my book, is that on g stock cars they do prvide enough cfm to to run 10.80's, but they start out at 1500 rpm idle at the line and get hit with 5000+ stall so that the air is already moving like a freight train to band aid the lagging secondary into providing strong signal and /mix.......but put a holley on it of the same cfm and watch the et's drop!

if they could/had a similar rated holley as stock equip , they'd be using it. peroid

hence the reason why it is the '71 340 cars running those low g stock times...not any other non thermo equipt 340 car....

It's cfm over metering when the r's are sky high anyways.


the factory had to compete in the mpg/smog crowd as well as the 'hp sells cars' crowd.

 

[340 8BBL]

lose the carb and intake.rpm,ld340,rpm-airgap would be a better choice.along with an annular booster holley,or 650 dp.i also dont like "off the shelf"cams.not saying they suck though.i like custom grinds from independent hole in the wall places like schneider cams,crower, etc.

 

[rmchrgr]

go with a med/tight convertor=3200 stall and 4.10-4.30@25-26'' tire gear to get into the 12's with this combo.jmo

That's what I thought.

AFAIK, 27" tires fits in my stock Dart wheel well but deep down I think a 4.10 may not be right for it. 26" would likely be best.

Once I take the plunge and start getting ready to build this thing, i'll start asking around about converters.

As for pistons...poor tune/crap oils/and missfiring is what causes scuffing, not piston material..lets get over that part already..

I'm not Austin Coil but hopefully this thing will be tuned to a razor's edge.:thumrigh:

now are those 167's domed? so you wanna use a domed piston with a closed chamber?

167's are flat tops with two valve reliefs. See them here.

are the 995 springs doubles with a dampener?

They are indeed double springs with a damper. See them here.

 

[stroked 340]

Hey,why not build the 340 i sold ya' ??...

 

[1wild&crazyguy]

comp better fix their site info cause those #'s they show r bs.

I've tested these on the rimak to know..

 

[rmchrgr]

Hey,why not build the 340 i sold ya' ??...

Couple reasons. First, the 340 pretty much needs 2.02 valves which unfortunately is not in the budget at the moment, due to the extra machine work. If and when I upgrade the heads to larger valves I'll build the 340.

The 318 has already been hot tanked, has new freeze plugs and bearings.

Piston choice for the 340 is also a little bit more difficult since most everything is out of the hole and the cams that are good for my goals are a little less streetable than what they are for the 318. The 340 generally RPMs higher too, making street driving all the less fun.

Also, just wanted to see how it goes with this level of build. Can't say I've ever completed something like this from start to finish. Thought it would be best to start with the 'expendable' 'teen.

Vague reasons maybe, but oh well.

 

[turbodart68]

Couple reasons. First, the 340 pretty much needs 2.02 valves which unfortunately is not in the budget at the moment, due to the extra machine work. If and when I upgrade the heads to larger valves I'll build the 340.

The 318 has already been hot tanked, has new freeze plugs and bearings.

Piston choice for the 340 is also a little bit more difficult since most everything is out of the hole and the cams that are good for my goals are a little less streetable than what they are for the 318. The 340 generally RPMs higher too, making street driving all the less fun.

Also, just wanted to see how it goes with this level of build. Can't say I've ever completed something like this from start to finish. Thought it would be best to start with the 'expendable' 'teen.

Vague reasons maybe, but oh well.

I am not sure what you are referring to as to the cams being less streetable in a 340. I realize you have the 318 and I am okay with that. But a 340 is 22 cubic inches bigger and that will mellow out the idle and streetability a bit as well as making more power due to it being bigger. Okay enough on that.

The 318 in question sounds like it will be a fun little motor for sure. The reason that Thermoquads are slower than Holleys is due to the way that Carter rates the CFM. See there is no industry standard on rating carbs. Holley flows theirs at 3.5 inches. Carter flows theirs at 5 inches. For this reason two 850 carbs tested side by side will have very different results. Not to mention the lack of a secondary pump shot of fuel. I think you may have some trouble getting the stall speed you need since you have a short stroke engine with low compression and a lot of camshaft. Obviously 5k would be ideal for a stall speed, but the converter would have to be so loose that it will be very inefficient. I think by over gearing it you can minimize the lack of converter. The intake is another area I think you could pick up some hp with. The RPM Air Gap is an excellent intake and I think it would be very close to ideal. A single plane would make more power hands down with a slight trade on driveability. If you are going all out, which you will need to make your goal, a single plane would be best. A 750 Holley DP should be what to park on top of that intake. Good luck, I look forward to hearing how it runs.

 

[rmchrgr]

I am not sure what you are referring to as to the cams being less streetable in a 340. I realize you have the 318 and I am okay with that. But a 340 is 22 cubic inches bigger and that will mellow out the idle and streetability a bit as well as making more power due to it being bigger. Okay enough on that.

That's probably right, didn't think my statement all the way through, thanks.

 

[1wild&crazyguy]

when it comes to intake design 'single plane vs dual plane' sometimes 'rule of thumb' is more like 'rule of dumb'

on occasion 'ultimate' cfm go's to the way side for velocity/air speed/better mixed fuel with a longer runner.