Not Getting Full revs Chrylser 318

[twwmm]

Hi There<br /><br />I have a 32' Coronet with twin Chryler 318 V8 Petrol Vee Drives. I ve only had it about six months and bought it second hand. One motor Only goes to about 3000 rpm on load ok off load the other goes to 4200 on load. I checked timing throttle linkage etc all the obviuous. <br /><br />Theyare on seperate tanks and I am going to try swapping fuel lines over abd a compresion test etc. <br /><br />The interesting thing is that the motor is really really louder in the exhaust than the good one. <br /><br />Maybe a burnt exhaust vavle ??<br /><br />Any one have any ideas ?<br /><br /><br />Thanks<br />Terry<br />

 

[DJ]

Re: Not Getting Full revs Chrylser 318

Terry,<br /><br />Do you have the same size props-port and starboard?<br /><br />Are the gear ratios the same on both sides?<br /><br />Are the tachometers correct?

 

[twwmm]

Re: Not Getting Full revs Chrylser 318

Both are identical, apart from counter rotating. I have done a compression test two cylinders are 150 the rest are arond 180 ? The two that are down are on oposiste sides of the block - not related. I have been told that this should be ok ?????<br /><br />I have put in a crossfeed on the tanks and checked input up to fuel filters - all ok to that poitn.<br /><br />

 

[WSUDERMAN]

Re: Not Getting Full revs Chrylser 318

Terry, Good Start!<br />As for the compression test, a general number would be no more than 15% - 20% difference between the highest and lowest numbers. So 150 - 180 would be a 17% difference. Not bad but not great either. <br />You did not say what year, so i am going to assume that its carbed...<br /><br />In addtion to djohns19 suggestions...<br />You might want to look at the Fuel pump pressure @ the carb. I think it should be about 6-8 psi.<br />If the pressure is ok...<br />At 3000 is about when the carb's secondaries kick in. They might be plugged or stuck or something, so you might want to look into a carb rebuild.<br />You also, said that you checked the timing. Did you check the timing Advance? If the timing is not advancing than check the Distributors advancing mech. <br />Almost forgot the Points? How are they?<br />I don't know chrysler products specificaly, these are just some general troubleshooting ideas... Good luck<br /><br />Wes

 

[DJ]

Re: Not Getting Full revs Chrylser 318

Terry,<br /><br />I don't know what kind of distributors (ignition) these have, however I have seen some older Chryslers break the timing advance springs. This makes for a very sick engine. They will go to full mechanical advance when you open the throttle and will rarely reach top rpm under load. The springs are located under the breaker plate (points) in the distributors.<br /><br />You might also want to perform a cylinder balance test. This is done by removing one spark plug wire at a time and noting rpm drop. Make sure you use insulated pliers when removing the wires. Also check the condition of the wires, they may be cross firing. Same holds true for the distributor cap.

 

[twwmm]

Re: Not Getting Full revs Chrylser 318

Thanks Guys<br /><br />They are circa 1974<br />They have electronic dizzy's<br /><br />The Carbs and Dizzys have been rebuit and a new fuel pumps, not to say that they arnt the problem though. <br /><br />I will check all suggestions and get back to you with whats happens etc,<br /><br />Thanks again will be interesting to see the results.<br /><br />

 

[DJ]

Re: Not Getting Full revs Chrylser 318

twwmm,<br /><br />Even though the "dizzy's" are electronic, they still have mechanical advance devices. Seeing they are "rebuilt" really makes me think there might be a problem in that area. The "bad" one might have the wrong springs. The springs are in the same place, just below the plate that has the Hall Effect sensor.

 

[norman158]

Re: Not Getting Full revs Chrylser 318

take a good long look at your harmonic balancers (lower engine pulley)if these are the same as the cars used they are 2 piece I have seen the outer ring where the timing marks are slip

 

[crazyray]

Re: Not Getting Full revs Chrylser 318

well will start with the simple, 1st change all plugs in weak engine, gap correctly, check color of tip of plug.......all the same?....has carb. been rebuilt/cleaned, if a jet is stopped up will cause this, next checking timing, light should show about 4-8 degrees advance at idle and should have about 28-32 degrees at WOT under load at your 3000 rpms, finally if these don't produce fruit you can remove both valve covers, with ignition system disabled check each valve spring movement with a dial indicator, these motors are prone to washing a lobe off a camshaft, ie you will have a cyl that is not doing much, check condition of all springs, rocker arms and pushrods for excessive wear while you are here, if these don't help get back to us.

 

[twwmm]

Re: Not Getting Full revs Chrylser 318

Have checked timing and changed the electronics module, these look ok, engine starts and seems to run well. Interesting about the cam lobes, dial guage may produce something, I will be doing more checks on the weekend and will keep you posted thanks to all for responding. Dont think the timing mark has slipped because it starts easy.<br /><br />Terry

 

[DJ]

Re: Not Getting Full revs Chrylser 318

TWWMM,<br /><br />Did you look at the timing advance plates in the distributors? Make sure the springs are OK (the right ones) and the plates move freely.

 

[twwmm]

Re: Not Getting Full revs Chrylser 318

The adavanced seems to be advancing ok<br />The fuel pressure is interesting<br /> 3.5lb of the bad motor 1.5lb on the good ????<br />Swapped carbries between motors not a difference.<br />Hmmmm..... Grumble<br />Next I think will be the dial guage on the valves<br /><br />

 

[twwmm]

Re: Not Getting Full revs Chrylser 318

Think Ill swap dizzies over as well just for the heck of it.

 

[WSUDERMAN]

Re: Not Getting Full revs Chrylser 318

That fuel pressure thing is a real question? I would think they should be close to the same!<br />I know that GM's need the pressure to be 6 - 8 lbs. A quick call to your local Chrysler service dept or manual should give the correct pressure required.<br /><br />Depending on where you took the reading, it might be a restriction in the fuel line. This would cause a increase in pressure before the restriction and a reduction in volume after. Which would cause a fuel starvation at high rpm...<br /><br />Just another thought but maybe the sick motor has a High Pressure/Low Volume pump and the ok motor has Low Presure/High Volume Pump? Another swap would tell you. <br /><br />It must be nice to have two motors!!!

 

[oldboat1]

Re: Not Getting Full revs Chrylser 318

fuel line and filter OK? collapsing fuel line?

 

[twwmm]

Re: Not Getting Full revs Chrylser 318

Pressure was taken at carbs fuel lines ok might try a filter bypass, running out of ideas before heads and cam (yuk)