Safe EGT's for 670 HO????

[lloydguy]

As per title I have a 670 HO in a 98 summit X that I am installing a Digatron on
hopfully tomorrow.I was wondering about Max EGT's for WOT.and normal 6000 rpm
EGT's for on the trail.I do not know what all engine mods have been done by the
previous owner.Mains were 310/300 when I got it,I am at 370/360 now I believe.
I will do afew plug chop's after wide open run's,But I am a total novice at this.
Any help would be awsome.Thank's

 

[magnet]

Keep it bellow 1250 and your golden. But like it has been said before there is no " safe" number need plug and piston wash checks to be safe then set your numbers by that

 

[lloydguy]

Ok ,thanks.Do guys do plug chops for mid range as well as WOT?
Once the digatron is in and running,I will do like I have read and warm it up to
normal op.temp,install a new set of plugs,start it and make a Wide open run for
1/8 mile ish.Kill it,remove the plugs and go chop them.I will post pics here to get
plug reading info as needed.

 

[modz]

i agree max 1250, set your digitron alarm at that and let off when it alarms.

 

[tukernater]

i agree max 1250, set your digitron alarm at that and let off when it alarms.

It very important where your probes are placed.My 780 magic number was 1210 boom so I Ran it about 1100,but like I said probe placement is important.

 

[lloydguy]

So, Digitron is in and working well.I have some more info to post and see if I can get some help.
I am getting much higher egt.s in the 6000 to 6500rpm range than at WOT.?I know a little but not
enough to solve my problems without some help.
I did afew plug chops and am needing advice.Everyone always says to post more info,So I've got
lot's of it.
Temp -20 C , Elevation approx 2200tf. ,Pilot's 55's,needles 7ecy1 , needle position of 1'st plug chop
2'nd slot from the top , Max rpm approx 8200 , main jet's 370/360 , plug gap's .026" , Egt's at WOT
1165/1169 , probes 2.25" from edge of head , Burn ring (what ever you call it) on
PTO plug 2.6mm at the widest, 2.1mm at the narrowest.
Mag plug 2.5mm to 1.8mm
Ets's were 1210-1225 from 6000-6500 then cooled down to above mentioned temps at WOT.

 

[lloydguy]

Wide open run was less than 1/4 mileIs that enough to get enough info from the plug?
Pto plug is slightly tan on the top of the porceline Mag side is a little too,but for sure
not as much. Since my EGT's were quite high in the 6000 to 6500 rpm range,I lowered
the clips on the needles 2 positions,or raised the needles whatever is the proper way
to say it.
Any feedback would be awsome guy's,I'm in need of help.

 

[pistonbroke800]

I think something is wrong with a setting in your digitron if your getting temps that high. Your engine would be a puddle of melted aluminum if it was that high. Good thread though. I am also playing around tuning the 670 in my Rev chassis with egt's and plug checks right now when i have spare time.

 

[magnet]

Think he was meaning In the 6-65 rpm range. Judging by his suggested repair technique. Never gave us the actual egt

 

[pistonbroke800]

Oh ya haha i missed that one for sure. Ya mine runs really hot on the needle also. Im on the second last e clip position as of last ride and was hitting about 1180ish but i was super lean on my mains, just changed them up to 410/400. Hope that gets me close on the top so i can tune in the middle a little better

 

[lloydguy]

I see by your question pistonbroke that I didnt word things quite as I intended. Magnet is right.
I meant to say my egt's were hottest in the 6000 -6500 RPM range.1210-1220 were the temp's
Piston broke,you running a stock pipe?How far are your egt.probes from your head?
Here is a pic of another new set of plugs that had 2-1/8 mile 6500 prm runs,then a wide open run
for almost 1/4 mile.This set is AFTER I raised the needles 2 positions.
with a black marker I made a mark across the ground strap (whatever its called)
where the burn mark stops.I know this means something about the heat range,but
I'll have to re examine some old plug reading posts . My probes are 2.25" from the head.
Ring around the base of the proceline is approx 1.8mm mag side and 2.0mm pto side.
Almost no color is present on the second set of chopped plugs.

 

[magnet]

I think I had mine at 420s in each side looks a little lean still to me but I like running fat fat is safe IMO
Less Hp is cheaper than melted pistons IMO

 

[cdnemsguy]

All this talk about plugs, but i thought plugs were a less reliable sign and one should look closer at the domes on the pistons. Look at the color, amount of build up and the wash. Scopes are cheap at Princess Auto. Also to answer your midrange or lower temp. question, it sounds like its your timing curve which of course is not the same as WOT. Make sense?

 

[pistonbroke800]

I see by your question pistonbroke that I didnt word things quite as I intended. Magnet is right.
I meant to say my egt's were hottest in the 6000 -6500 RPM range.1210-1220 were the temp's
Piston broke,you running a stock pipe?How far are your egt.probes from your head?
Here is a pic of another new set of plugs that had 2-1/8 mile 6500 prm runs,then a wide open run
for almost 1/4 mile.This set is AFTER I raised the needles 2 positions.
with a black marker I made a mark across the ground strap (whatever its called)
where the burn mark stops.I know this means something about the heat range,but
I'll have to re examine some old plug reading posts . My probes are 2.25" from the head.
Ring around the base of the proceline is approx 1.8mm mag side and 2.0mm pto side.
Almost no color is present on the second set of chopped plugs.

I am running NPP custom built twin pipes on mine. Because its in a Rev chassis i pretty much had no choice but to get hand built pipes. I am also running pods in place of the air box. A crankshop short rotary valve cover and a 501 rotary valve. I also have the timing fully advanced and oil injection deleted so i run per mix Av gas if that makes any difference. I have the probes places about 6'' from the head. It calles for a different probe placement for twins than a single.

 

[lloydguy]

Put afew more miles on the old girl last weekend.Egt's climb fast about 6200 and stay hot untill i reach
about 73-7500.If I hold it steady at 6500rpm I hit 1220-1240,WOT both sides run consistant about 1120
By the WOT temp's I THINK I'm fat enough,but why are my mid temps so high?I can only raise the needles
1 more clip.IMO that aint goint to level things out.
Who wants to tune this thing and I'll come pick it up when your done.????????????

 

[DRD]

FWIW, my totally stock 670X (99) would see 1275 in the mid range, and it never made me walk. Probes were I think 100mm for the pistons or whatever it is they call for in the racing handbook.

 

[lloydguy]

So I thought i would bring this old thread back to life.As stated in previous post's I am
running 1200-1230 DEG. in the 6000-6500 rpm range and as i increase rpm's from there egt's
drop.If i remember correctly approx. 1050-1100 at WOT.
So.......... can or should I raise one more clip on my needle and drop the main's one or two sizes?
IMO, I am a too rich at WOT, and right where it likely should be in the mid range.
If i drop from a 370 to a 350, that is a 5% drop in max fuel flow. What i do not know is what % does
raising one clip on the needle change the mid range ?
Anyone have any info on tuning to share?
Thank's