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| Engine rattles https://www.slantsix.org/forum/viewtopic.php?t=66000 |
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| Author: | twister6 [ Sun May 30, 2021 3:01 pm ] |
| Post subject: | Engine rattles |
Fresh build slant 6 225 with molner rods and wisco pistons with 10.5/1 650 holley hurricane long intake. Question: Engine runs good, but when cruising at about 55 and nail it pass traffic, I get a rattle/valve/maybe detination. If i nail it out the hole it doesnt rattle until it reaches about 3500 rpms. I played with timing until i got tired and no results. blocked the vacuum advance and still no result. I dont think its an octane issue, running 93/non ethonal with a bottle of lucas octane boost. Could it be valve lash out..engine only has 100 miles on the build. It did this since day one. What are yall thoughts on this. |
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| Author: | Jase [ Sun May 30, 2021 5:47 pm ] |
| Post subject: | Re: Engine rattles |
Many here on the board much more knowledgeable than I am, but I would start with a cranking compression test, and report back..as cylinder pressure can suggest how to tune for a happy engine. also have a look at the spark plugs for proper coloration. If you are lean, it will rattle.. even if you are using good gas. |
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| Author: | DusterIdiot [ Sun May 30, 2021 6:05 pm ] |
| Post subject: | Re: Engine rattles |
Long ram manifold and 10.5 SCR.... time to break out the vacc gauge and tune the carb and timing.... I tuned the Hyperpak and a 600 cfm Holley using this ball park 65-68 primary jet, and a 73-78 secondary...PV should be about a 10 to fill the gap that occurs due to the longer runners than stock...I would install the pink cam in #1 to start and run it with the brown spring, changing to plain once you think everything else is dialed in ... this will be pretty close on a 650. Next on the list will be to recurve your distributor... at WOT I would not go past 28 deg total mech + base timing... cruise sounds like it's fine but pending gearing and transmission I would install a VC-185 vacc can on an EI mopar unit (limiting the full adv- static+mech+vacc to 47 total... if everything was in order, I would prefer the dizzy to be 13-14 static, 16 mechanical and 17 vacc). |
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| Author: | DusterIdiot [ Sun May 30, 2021 6:06 pm ] |
| Post subject: | Re: Engine rattles |
Quote: Long ram manifold and 10.5 SCR.... time to break out the vacc gauge and tune the carb and timing....
Hopefully the cam is at least 270-280 deg adv. duration.
I tuned the Hyperpak and a 600 cfm Holley using this ball park 65-68 primary jet, and a 73-78 secondary...PV should be about a 10 to fill the gap that occurs due to the longer runners than stock...I would install the pink cam in #1 to start and run it with the brown spring, changing to plain once you think everything else is dialed in ... this will be pretty close on a 650. Next on the list will be to recurve your distributor... at WOT I would not go past 28 deg total mech + base timing... cruise sounds like it's fine but pending gearing and transmission I would install a VC-185 vacc can on an EI mopar unit (limiting the full adv- static+mech+vacc to 47 total... if everything was in order, I would prefer the dizzy to be 13-14 static, 16 mechanical and 17 vacc). |
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| Author: | twister6 [ Sun May 30, 2021 8:27 pm ] |
| Post subject: | Re: Engine rattles |
I am running 78 primary jets, and I changed the vacuum secondary spring to a heavier spring, and put in a 2.5 PV, because I had a bad bog in the engine thinking it was getting to much fuel.. Maybe going back to the 6.5 PV may help some. It may be running to lean. What is the pink cam in #1 not sure what you mean..? Running 904 tranny with 3:23 gears. Running the 270/280 cam. |
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| Author: | DusterIdiot [ Mon May 31, 2021 12:19 am ] |
| Post subject: | D |
D |
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| Author: | Dart270 [ Mon May 31, 2021 5:59 am ] |
| Post subject: | Re: Engine rattles |
My guess is the total advance is too high and it is detonating. With factory advance springs, it will not hit max advance until over 3000. Lou |
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| Author: | twister6 [ Mon May 31, 2021 6:13 am ] |
| Post subject: | Re: Engine rattles |
thanks guys for your input. I will have to play with it more, at least I have some valuable info to get me started in the right direction. Thanks again.. will report back. |
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| Author: | twister6 [ Sat Jun 05, 2021 8:46 pm ] |
| Post subject: | Re: Engine rattles |
I did some home work on the slant. I installed the green and black springs on the dizzy and changed the vaccuum advance pod to a vc-185 played with the timing. Installed the 10.5 pv on the primary side and left the 78 jets in. Runs good till about 3800 rpms and then it starts to fall and sputter some, almost like its not getting fuel, however the rattleing stopped. Did not put in the secondary metering block. Maybe that will help?..Your thoughts. |
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| Author: | slantzilla [ Sat Jun 05, 2021 11:01 pm ] |
| Post subject: | Re: Engine rattles |
With 78 jets in it I would guess it's pig rich. I only run between 68 and 72 in my race junk. |
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| Author: | Dart270 [ Sun Jun 06, 2021 9:22 am ] |
| Post subject: | Re: Engine rattles |
Agreed. Lou |
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