318 problems? • The Dodge Challenger Message Board

by **Linka** » 05 Jun 2009 19:46

Hi!

I´ve got a big problem which I can´t figure out how to fix. I have a 318 with a Crower cam (in: 292, ,534 exh: 310, ,552) with a holley 750 vaccum carb, msd 6AL ignition, edelbrock perf intake. I have changed the holley "mouthpieces" ( don´t know if that is correct word for it ) from "68" to "63" and it run very well. But after driving for awhile it started to go bad, like it cuffed like "host host". Just like it didin´t get enough power amps. We measured the charging and it was up to 13,9V. Anyone got an idea what it might be? :s001:

by **dave-r** » 06 Jun 2009 9:05

The word you were looking for is "jets". You changed the jets to a smaller size.

Well really it could be anything from just bad fuel to a fuel leak in the carb.

Or electrical. But as you have around 14 volts I would concentrate on the fuel side of things.

by **Goldenblack440** » 06 Jun 2009 18:01

i'd say for a start, the carb is too big for the engine, even with that largish cam. A 600 Holley would be more suitable, or even better, a well tuned Thermoquad.

by **Linka** » 07 Jun 2009 7:51

I might think that too, that the carb is too big no matter what jets I put in. I have a Holley 650 DP laying in the garage but I need to restore it a bit first. But will it be suitable when I put on the NOS system?

by **Goldenblack440** » 07 Jun 2009 14:25

You're probably better talking to Eddie Airfuel about NOS. But i'd still say that the 650 DP is too big. Lots of fuel there. But if you're engine is quite worked with large ports, big flow heads and high compression, big cam etc AND you are thinking of NOS, then a 650DP would be quite enough. But that's only my opinion with reasonably limited experience. There are other fellows here who have a broader experience base than me.

by **Linka** » 07 Jun 2009 14:47

Ok, lite off topic here talking about fuel and NOS... but some ideas and thinking of that would be nice. Thanx for the answers though.

by **Eddie** » 07 Jun 2009 18:14

I dont have any Nitrous Oxide experience. Never used it. Never will. Linka- does the 'problem' go away at RPM's above say 2500? If so it's the reversion from that huge cam and the reversion at low speeds is causing the hiccup at take off. What you need is a bit more fuel. Those big cams cause the eyes to water at idle, a rich condition is necessary at idle because of this. I would replace the Jets with the ones you had or maybe try a 1 step increase. What do the sparkplugs look like and what type of plug are you using??

by **Linka** » 07 Jun 2009 18:52

Yes Eddie, when I rev it up to lets say 4000 rpm when the cam starting to work, the car goes very well. The plugs looks great, but when I am out cruising the plugs is totally black, not wet though. And I did a test and reved it up on first gear to 4-5000 rpm and turned the engine off and the plug looked as it should. I use AC Delco plugs 44xls I think. But I´ve tried the Accel plugs too and it was the same result.

by **Eddie** » 07 Jun 2009 21:03

Yep, it sounds like it needs more fuel at the lower RPM scale,,you're 'rev' test confirms this. I would replace those Jets back at least 1 step up and see how it does. But it's never going to be perfect with that large camshaft at lower RPM's Linka... Can I ask why you are using such a large camshaft with the small port 318? I like NGK plugs myself but others have had good luck with AutoLite's.. I have never used Accel plugs as I cant find anyone who likes them. AC Delco,(GM), plugs might be acceptable but it's personal preference really. You also might try a hotter plug than the one you have now.(1 step hotter for street driving,, 1 step colder if racing it hard). If the heat range is too cold it will gas foul and carbon up in short time. The plug never gets hot enough to burn itself clean. These are all little things that help the driveability and have worked for me because I too like big cams!!! :mrgreen:

by **Linka** » 09 Jun 2009 15:27

I´ve changed the carb to a Holley 650 DP and changed the jets to 63. Now it runs pretty good I think. But as you said Eddie, when I go to the track I probably change the plugs to harder ones, especially when I put on the NOS. I had the cam just laying in the garage and I thougt, what the heck, I put it in the 318 and see what happens. It runs really great on high rpm and I love it.

by **Eddie** » 09 Jun 2009 15:37

Linka wrote:I´ve changed the carb to a Holley 650 DP and changed the jets to 63. Now it runs pretty good I think. But as you said Eddie, when I go to the track I probably change the plugs to harder ones, especially when I put on the NOS. I had the cam just laying in the garage and I thougt, what the heck, I put it in the 318 and see what happens. It runs really great on high rpm and I love it.

Cool,, a 'Hot' 318 is a great thing man! :lol:

Be careful Linka,,usually the Racetrack calls for a COLDER plug heat range not a hotter plug! :thumbsup:

You will probably have to experiement with what the engine likes as far as heat range of the sparkplugs. Good Luck and any pics?? :lol:

by **Linka** » 09 Jun 2009 15:39

[/quote] Cool,, a 'Hot' 318 is a great thing man! :lol:

Be careful Linka,,usually the Racetrack calls for a COLDER plug heat range not a hotter plug! :thumbsup:

[/quote]

Yes that was what I meant Eddie... colder ones that is!
Yepp I like the small blocks and a fast 318 is the way to go hahahaha.... :s024:

by **Eddie** » 09 Jun 2009 15:40

by **Jon** » 10 Jun 2009 2:01

Hey Linka, I am no expert by any means but the 63 jets seem a little lean. For instance my 340 with a 650 DP is using a 67. Secondaries are 80 I think. :s022:

Milder cam but the air/fuel (Eddie? :lol:

) mix shouldn't be that far off.

As I said just my opinion. Good luck bud.

by **dave-r** » 10 Jun 2009 8:02

I am using #63 jets in my center carb on my six pack but in 4bbl terms that is only a 250cfm carb. Like Jon I think that must be quite lean in your carb with your cam.

Don't forget you will need LOTS of initial spark timing with this cam to reduce the unburnt fuel in the exhaust (which means it smells rich) and to make the engine run cooler.

At least 18 degrees initial is needed. But only 34-36 total (depending of fuel).

by **Jimiboy** » 10 Jun 2009 17:50

I can agree with the guys, it sounds a bit lean Linka... I have a mechanical 650 double pumper that i use 69- 83 on, i also have stepped up the main "increment?" (Tillskottsventil) to 10,5 And acceleration "injector?" (spridare) 0,040...

It wants fuel, but it runs very good with this setup... :thumbsup:

by **Linka** » 10 Jun 2009 18:44

Ok, so you guys think I should increase the jets to lets say 67 or 68? I have 68 on the secondaries now. Now it runs pretty good but it´s very hard to start when it´s cold. Like it don´t get fuel or something but it smells alot of fuel as I have to put the pedal like 1/4. But that maybe has to do with that I have too small jets? I spoked to my "mechanic guy" and he said that cam will work great with NOS... I can´t wait to try it.... :mrgreen:

by **Jon** » 10 Jun 2009 21:53

The drill with mine on cold startup is; No choke, "feather" pump a little to richen the mix while cranking then hold an even 1500 or so til it warms up. Too much will flood the engine so try experimenting a little at a time.

I'm interested to hear your results using NOS. Sounds like a real kick in the pants. :s004:

by **Linka** » 11 Jun 2009 6:10

Jon wrote:The drill with mine on cold startup is; No choke, "feather" pump a little to richen the mix while cranking then hold an even 1500 or so til it warms up. Too much will flood the engine so try experimenting a little at a time.

I'm interested to hear your results using NOS. Sounds like a real kick in the pants.

I will let you know the result when I got some ET:s. But a wild guess I think I would be driving on let´s low 13... I would be very glad if I could get like middle 12:s. But I will let you know. :s002:

by **Eddie** » 11 Jun 2009 15:26

I would increase it 1 jet number at a time Linka. It takes a little more time but the results are sometimes better, jumping around is too chaotic and sometimes you forget what your 'baseline' was. If you're gonna hit that 318 with Nox do you have forged pistons? Stock rods/rod bolts? Stock ringlands? How much of a 'hit' are you going to use? That stuff stresses these components bigtime! Nox is addictive thats why I wont use it. :thumbsup:

Post some pics if you can,,would love to see it!

by **Linka** » 11 Jun 2009 17:53

airfuelEddie wrote:I would increase it 1 jet number at a time Linka. It takes a little more time but the results are sometimes better, jumping around is too chaotic and sometimes you forget what your 'baseline' was. If you're gonna hit that 318 with Nox do you have forged pistons? Stock rods/rod bolts? Stock ringlands? How much of a 'hit' are you going to use? That stuff stresses these components bigtime! Nox is addictive thats why I wont use it. Post some pics if you can,,would love to see it!

Yes, the "short block" is all stock, but I´m just gonna use 100 hp, maybe 150 hp NOS so I think it will go allright?! Yes I´m gonna take some pictures as I am going forward with this. I have pretty much all I need to install the NOS, just some minor things that I may have forgot. Yes I will only increase the jets 2 at a time and I will put on the tacometer and the "vaccum clock" so I see that it will be done right this time.