I've seen A LOT of posts about making HP with a 318-So why is it so ???
- Thread starter RAMM
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Whats your combo ?
PRH
Well-Known Member
113mph@3250 shows 360hp.
That’s 360hp uncorrected, as it sits on the starting line, in whatever the air/weather was when you made those runs.
That’s 360hp uncorrected, as it sits on the starting line, in whatever the air/weather was when you made those runs.
ValiantRacing
Well-Known Member
You don't see that combo at least making 400 hp ? I wouldn't be surprised if your more like 425-450 hp.
My 380hp crete engine dyno over 400 hp that just a stock truck long block with a cam and intake.
PRH
Well-Known Member
318+.030, 9.9cr, unported 308 heads, 1.88/1.50 11/32” stem valves, solid cam, RPM intake, 2bbl adapter, 650cfm annular discharge Holley 2bbl carb(#6425), 1-3/4” headers.
This carb wasn’t legal to run in the car, but it was interesting to see what it did on the dyno.
The class rules mandated a Holley 4412 500cfm 2bbl, which was about 30hp less.
The 650 2bbl we used had the stacks to go with it.
This carb wasn’t legal to run in the car, but it was interesting to see what it did on the dyno.
The class rules mandated a Holley 4412 500cfm 2bbl, which was about 30hp less.
The 650 2bbl we used had the stacks to go with it.
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That thing made good power all around.
If you could remember or look up that cam spec, I’d appreciate it a bunch.
If you could remember or look up that cam spec, I’d appreciate it a bunch.
It should, don't forget 2bbl are rate different, a 650 2bbl flows a lot less then a 650 4 bbl never mind a 750 4 bbl.
PRH
Well-Known Member
Well.......That was 25 years ago.
We did a lot cam testing in those things....... and I didn’t keep any notes from the particular builds.
I did them for a few years, and the basics are kind of ingrained in my head since the rules remained mostly unchanged for the whole run.
The stuff I tried was high-240’s to low-250’s, .875 lobes for all but one(the .904 cam did nothing for us in the 318) sometimes tight lash, sometimes not........ 106-109lsa.
I think for this test it got one of the bigger & wider cams(mid-250’s, 108 or 109)....... which did real good on the dyno, but didn’t race all that well on the track.
It was a little soft coming off the corners at the shortest track, and for trying to fit the car into a hole in line that might open up.
The best driving/racing cams in those things were right around 246-250@.050.
When the rules changed to allow 360’s, we only used cams about 4-5deg bigger.
PRH
Well-Known Member
Possibly a little.
The 30hp from the 650-2bbl was actually more of an improvement than we expected.
That’s the only motor we tried it on.
Several years later, when the 360’s/350’s/351’s were what was being run in that class, and the Chevies were running the Vortec heads........
a really good 355 Chevy Vortec combo would pick up 40-50hp from the 4412 to a good 4bbl.
One that didn’t use all the good stuff...... which could be down close to 20hp with the 2bbl....... would only gain about 30-35hp with the 4bbl swap.
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PRH
Well-Known Member
Here it is with the 4412 on it:
2bbls are rated at a higher pressure than a 4bbl.
The “500cfm” Holley 4412 is really the same physical size(venturi and throttle bore) as half of a 4779 Holley 750 DP.
2bbls are rated at a higher pressure than a 4bbl.
The “500cfm” Holley 4412 is really the same physical size(venturi and throttle bore) as half of a 4779 Holley 750 DP.
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ir3333
Well-Known Member
circle track?
replicaracer43
Grumpy Old Man
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The last oval track 360 I built, gained 59 HP from a 350 2barrel to a 500 "HP" 2 barrel in a back to back test, quite a eye opener.
RAMM
Well-Known Member
That's strange I find that low, EVERY single time I have gone from a 4412 to a 650,750 etc... It was 60-70 hp change. The first time ever it was a 383 SBC--430hp with a legal 4412--stuck a 650 dbl on and 503hp. I also tested a W2 headed 360 I built---447 hp with a 4412---650dbl= 527hp. I've done numerous other SBC's and when troubleshooting have switched from a 4412 to a 4150 and have never seen less than a 60hp gain. Usually 70hp. Thanks for sharing Dwayne. J.Rob
PRH
Well-Known Member
Jesse, it looks like the examples you’re using are motors that are making more power with the 4412 to start with...... so a “better” combo to start with, where the 4412 is an even bigger restriction.
So, removing the restriction yields a bigger gain.
On the Busch North motors we used to service(358”, 18* heads, roller, Jesel, dry sump, etc), that had to run a 390cfm 4bbl........ swapping to a hp950 picked up almost 100hp.
So, removing the restriction yields a bigger gain.
On the Busch North motors we used to service(358”, 18* heads, roller, Jesel, dry sump, etc), that had to run a 390cfm 4bbl........ swapping to a hp950 picked up almost 100hp.
RAMM
Well-Known Member
PRH
Well-Known Member
Looking at it from the other side...... it’s not how much you gain from the 4bbl....... it’s how much you loose from the 4412.
On a stock low CR roller cammed 318, the 4412 might only cost you 15hp from the factory TQ.
At 5k the stock motor probably isn’t even using 400cfm, so the 375cfm @1.5” carb isn’t much of a restriction.
(Edit- I looked at the sheet from my 30 year old test...... while making 293hp@5000rpm, with a 4777 carb..... the motor was only using 417cfm. So the stock 318 would be using even less.)
On a 900hp 572 that runs a 1250 carb....... and uses most of all of that........ it’ll probably cost you 200hp.....maybe more(probably noticeably more).
On a stock low CR roller cammed 318, the 4412 might only cost you 15hp from the factory TQ.
At 5k the stock motor probably isn’t even using 400cfm, so the 375cfm @1.5” carb isn’t much of a restriction.
(Edit- I looked at the sheet from my 30 year old test...... while making 293hp@5000rpm, with a 4777 carb..... the motor was only using 417cfm. So the stock 318 would be using even less.)
On a 900hp 572 that runs a 1250 carb....... and uses most of all of that........ it’ll probably cost you 200hp.....maybe more(probably noticeably more).
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J Brooks
New Member
I’m looking to do something similar to my 904. I have a slant 6. I’m calling a bunch of repair shops here in northern Cali and can’t find anyone with the knowledge or the know how to install what I want. The one guys that does have the knowledge is charging me 1400 for a bench rebuild. Does that sound like a decent price? That’s New bandz, clutch plates, steels. I want a mild or stronger shift kit installed if possible. Also looking for the stall converter to be 2000 rpms. 2.76 gear ratio or higher if possible. I’m just looking for a fair price, but I don’t really know what that looks like. And suggestions if any would be helpful. Thanks
Dartswinger70
Well-Known Member
I remember a time when 318s were given away between Mopar guys,true story, i had a big block friend call me with 'a 318 for $40" that ended up being a 318 with a 904 from car to oil pan,and linkage etc the whole thing 40 bucks,why? he wanted it gone, the 40 bucks was the gas money for him delivering it to my garage. Short version? Mopar stuff is drying up, 318s are the next logical low buck platform. Uncle Tony 's Bottle Rocket" is a low buck build to show folks what can be done on the cheap. Nicks Id liek to see him dyno UT's 318 out of bottle rocket. that would be cool.
You can get 300 horse out of a teen pretty easy and with good heads and some compression (and all the rest of the goodies) 400 horse isn't out of the question.
Dartswinger70
Well-Known Member
I ran a 318 in my dart temporarily with the Summit manual trans cam. Stock heads,with headers and 2 1/2 inch exhaust. It pulled nice for what it was. I had an old timer come up to me at a gas station and say it sounded good,and asked if it was a 340...( I had the 340 badges on the scoops) 
I keep the 318s around because they direct swap with 340,same internal balance etc. I think the only thing you need is the different motor mount brackets,everything else direct swaps.
I keep the 318s around because they direct swap with 340,same internal balance etc. I think the only thing you need is the different motor mount brackets,everything else direct swaps.
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ChargedDart75
Well-Known Member
My first 318 was given to me. It is an '88 roller cam block with 302 heads. The guy didn't want it anymore and it was in great shape. Still have it around, just don't know what to do with it.
roller cam 390 stroker. 367 horse and 407 lb/ft Mild teen Idles like grandma's 318
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James Clews
Well-Known Member
What sort of HP do you think my teener will make? I have a 1980 CM Chrysler Regal SE (the last of the Australian built Valiants) The 318 will be bored 30Thou with KB pistons (approx 9.7 to one comp) Summit 6901 cam 218/228 470 lift(1.6 roller rockers) 114 lobe centre, Procomp fully ported alloy heads flowing 285cfm on the inlet and have really good low lift numbers, Exctractors running into dual 2.5 inch system Wiehand alloy dual plane intake with 650 AVS2 carb , Factory cold air induction. You may ask why am I doing this with a teener? I have a 410 Charger that runs low elevens and am restoring this lovely Regal with the factory 318 and am using most of the left over parts discarded over the years from my 410 Charger. The car will probably never see a drag strip but will be just a cruiser as it only has 77 thousand kays on it(About 48 thousand miles) and was parked since 1995. Car is fully loaded with air, steer , elec windows etc. Has Factory 727 auto and 2.92 diff. What sort of HP would you think this should make? Why not put a 360 in it? 1 it is the numbers matching motor . 2 petrol in Australia is $1.60 @ litre ($6.50 a gallon)Yes costs nearly $120 to fill up now days but yes I believe our tradesman wages are a lot higher than the US wages.
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