drfranky Posted November 4, 2014 Share Posted November 4, 2014 Built is cross bolted 4.0 block with 4.6 pistons and rods. 4.0 intake. Fully rebuilt. This is in a RRC LWB with a R380/LT230 What do you guys think of this spark map? Is it too conservative? Quote Link to comment Share on other sites More sharing options...
Hybrid_From_Hell Posted November 4, 2014 Share Posted November 4, 2014 As a rover v8 tick over is circa 50 map at +/- 8 degrees I would say you map is was a waaaasay off . Do a search in this forum for 3.9 spark maps Quote Link to comment Share on other sites More sharing options...
Bowie69 Posted November 4, 2014 Share Posted November 4, 2014 Totally wrong, never seen anything like it! As above, have alooksie on here for a 3.9/4.0 map, they are much the same being the same bore/stroke! I take it is still a 4.0, and you haven't done anything with the crank? I only ask as a 4.0 rebuilt with 4.6 rods and pistons.... doesn't that make them poke out the top of the engine? Quote Link to comment Share on other sites More sharing options...
drfranky Posted November 4, 2014 Author Share Posted November 4, 2014 Yes, I used the 4.6 crank, wouldn't have worked otherwise.. Ok will look for a map.. but most map on the forum are for MS1, does it matter? Mine is set up for TPS (Alpha-N). Thanks for your help guys! Quote Link to comment Share on other sites More sharing options...
garrycol Posted November 4, 2014 Share Posted November 4, 2014 You should have used the 4.0 pistons - you would have ended up with a higher compression ratio. Quote Link to comment Share on other sites More sharing options...
drfranky Posted November 5, 2014 Author Share Posted November 5, 2014 Ok, so I reduced the advance at tickover to about 10.. but the truck had no problem with 25 degree.. I have a max advance of 29 at WOT and 100 % tps. Milder accelerations tps 65 - 80 have a bit less advance I don't think that map is THAT off.. As for the 4.0 pistons, wouldn't a higher compression engine aggravate the liner slipping issue on 4.6? I cheaped on the t-top liners.. Quote Link to comment Share on other sites More sharing options...
Quagmire Posted November 5, 2014 Share Posted November 5, 2014 Any reason you are using tps and not map for load sensing? Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted November 5, 2014 Share Posted November 5, 2014 I thought you had to have a pretty good reason to run Alpha-N rather than Speed-Density, and given the reliability of Rover TPS I'd be very wary Quote Link to comment Share on other sites More sharing options...
drfranky Posted November 5, 2014 Author Share Posted November 5, 2014 Totally agree on that FridgeFreezer. That's why I switch the 4.2 plenum that has the round TPS [these are absolutely totally unreliable] to a 4.0 plenum that has a bosch TPS and the new GM style flat connector idle valve. I just feel that the truck is more responsive on TPS rather than manifold vacuum.. As for the idle valve, I would say that PWM is probably the way to go... the stepper is nerver quite right.. some idle is at 900 sometime at 1000.. all in all, I think you guys are right, if I had to do it again, I'd go MS1 extra... Quote Link to comment Share on other sites More sharing options...
Hybrid_From_Hell Posted November 5, 2014 Share Posted November 5, 2014 Ok, so I reduced the advance at tickover to about 10.. but the truck had no problem with 25 degree.. I have a max advance of 29 at WOT and 100 % tps. Milder accelerations tps 65 - 80 have a bit less advance I don't think that map is THAT off.. As for the 4.0 pistons, wouldn't a higher compression engine aggravate the liner slipping issue on 4.6? I cheaped on the t-top liners.. Er "Nope" your 10 is a 0 KPA - thats falling off a cliff engine braking.... 10 at 40-50 KPS is where tickover is TOO much spark generates heat / damage as much as too lean. That spark table has nowhere enough definition, look on the A-Z thread on tuining MS and take a look at those tables and then make yours up, MS1 has less cells as MS2 so its just streych everything a bit I would post up stuff, but getting ready for 5 day event to france 100 rivers !! Nige Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted November 5, 2014 Share Posted November 5, 2014 I just feel that the truck is more responsive on TPS rather than manifold vacuum.. That is likely just a matter of tuning it properly - MS still uses the TPS in speed-density for accel-enrichment but you can also use MAP-Dot either instead of or as-well-as TPS-Dot, "Dot" standing for rate-of-change in these cases, so how fast you push the pedal down / how fast MAP changes rather than the absolute position of the pedal / amount of load. Quote Link to comment Share on other sites More sharing options...
drfranky Posted November 5, 2014 Author Share Posted November 5, 2014 Er "Nope" your 10 is a 0 KPA - thats falling off a cliff engine braking.... 10 at 40-50 KPS is where tickover is TOO much spark generates heat / damage as much as too lean. That spark table has nowhere enough definition, look on the A-Z thread on tuining MS and take a look at those tables and then make yours up, MS1 has less cells as MS2 so its just streych everything a bit I would post up stuff, but getting ready for 5 day event to france 100 rivers !! Nige Hey Nige, these are %TPS value not KPA!! sorry I should have mentioned that! Have a good trip! Quote Link to comment Share on other sites More sharing options...
Bowie69 Posted November 5, 2014 Share Posted November 5, 2014 Still so wrong, get a base 4.6 map by searching, and adjust the bins, they are way off as well. Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted November 5, 2014 Share Posted November 5, 2014 Bear in mind his map has throttle position up the side, not MAP, so that will presumably skew things somewhat as most other maps are MAP/RPM rather than TPS/RPM. Quote Link to comment Share on other sites More sharing options...
garrycol Posted November 6, 2014 Share Posted November 6, 2014 As for the 4.0 pistons, wouldn't a higher compression engine aggravate the liner slipping issue on 4.6? I cheaped on the t-top liners.. Slipped liners are not compression ratio related - heat related. Using low compression 4.0 pistons in a 4.6 gives you a compression ratio of about 9.2:1 - about halfway between a low comp 4.6 and a hi comp 4.6 - a good compromise between increased compression ratio (power) and the need to use higher octane fuel. Quote Link to comment Share on other sites More sharing options...
drfranky Posted November 6, 2014 Author Share Posted November 6, 2014 Slipped liners are not compression ratio related - heat related. Using low compression 4.0 pistons in a 4.6 gives you a compression ratio of about 9.2:1 - about halfway between a low comp 4.6 and a hi comp 4.6 - a good compromise between increased compression ratio (power) and the need to use higher octane fuel. What do you use for the head gasket? The old steel gasket or the telflon coated one? Do you have issue with blown gasket? Quote Link to comment Share on other sites More sharing options...
garrycol Posted November 6, 2014 Share Posted November 6, 2014 I use the correct composite head gasket for the 4.0/4.6 engines - there is little chance of head gasket failure if the head is torqued up correctly - after all the compression ratio is still less than a Hi Comp 4.6. Quote Link to comment Share on other sites More sharing options...
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