Brian Crower 7M cams and ignition timing issue
- Thread starter amichie
- Start date
update? how's the car running? I'm very interested since the cams I plan to install in my 7mge will be very similar.
Tire Shredder said:
Hi Shredder
I have just advanced the exhaust cam to +4.5 cam degrees or +9 crank degrees. The car started instantly and idled perfectly. I will go for a test run later and let you know how it goes.
I think these cams have a little too much duration for a fairly stock 7mge and when I reduce the over lap by advancing the exhaust cam the idle and starting improve. They also seem to need a fair bit of advance on the intake to produce power low enough in the low rpm range to be useful.
I think if you had a manual and low gearing you would get very good performance out of these cams with a stock ecu etc.
Andrew
I really wonder how much research & development went into getting the cam timing right?
I know all engines are different to a degree but it should not take a lot of fiddling with both the intake & exhaust timing, unless you have done a lot of modification & machining.
The BC timing tag shows the overlap as being eight degrees negative.
Maybe thats why the idle & low speed performance is lousy until you advance the exhaust timing to reduce the gap.
Will really be interesting to see how the cams perform, over a wide rpm range, when they are tuned properly.
Cannot believe no one has dynoed their car with these cams.
I know all engines are different to a degree but it should not take a lot of fiddling with both the intake & exhaust timing, unless you have done a lot of modification & machining.
The BC timing tag shows the overlap as being eight degrees negative.
Maybe thats why the idle & low speed performance is lousy until you advance the exhaust timing to reduce the gap.
Will really be interesting to see how the cams perform, over a wide rpm range, when they are tuned properly.
Cannot believe no one has dynoed their car with these cams.
^^I agree, You wouldn't think that it would take that much fooling around with the cam timing just to get it running, let alone tuning it. And judging by the responce that the others have got from BC I surely would think twice about buying a set of cams from them.
Ha ha... Mine are sitting in my tool box awaiting valve springs so the head can go to the shop(I get them next week). I was seriously thinking about getting different cams, to. Meh, we'll see what happens...
Getting the Comp. BBC inner valve springs. Have a local Comp dealer here that I can get them through cheaper than Summit, but he had to order them. Don't have the money for the full Ferrea set-up, and I'm getting tight on time on this one.
Hello All
I have done a bit of road testing today and this is what I have ended up with.
Exhaust cam advanced +4.5 cam deg.
Inlet cam advanced + 4.5 cam deg.
Results.
Acceptable idle with air con off. Good idle with air con on.
Performance
Excellent performance from low rpm until the ecu changes the gear at 5500 rpm. :biglaugh: :icon_bigg It's a a shame it wont let it run out a little further because it is pulling very strongly at 5500rpm.
If you are considering BC cams and dont want too much stuffing around then I think these BC264 cams are about the limit you can use on a stock ECU etc.
Manualising the gear changes or fitting these to a manual car would make more sense.
Also you will make your life so much easier if you have two adjustable cam gears.
Now I just need to find some 4.3 gears for my LSD and I will be scaring a few of the GTE boys.
I have done a bit of road testing today and this is what I have ended up with.
Exhaust cam advanced +4.5 cam deg.
Inlet cam advanced + 4.5 cam deg.
Results.
Acceptable idle with air con off. Good idle with air con on.
Performance
Excellent performance from low rpm until the ecu changes the gear at 5500 rpm. :biglaugh: :icon_bigg It's a a shame it wont let it run out a little further because it is pulling very strongly at 5500rpm.
If you are considering BC cams and dont want too much stuffing around then I think these BC264 cams are about the limit you can use on a stock ECU etc.
Manualising the gear changes or fitting these to a manual car would make more sense.
Also you will make your life so much easier if you have two adjustable cam gears.
Now I just need to find some 4.3 gears for my LSD and I will be scaring a few of the GTE boys.
amichie said:
There are 2 ways to run past the 5500 shift point on the Cressida auto.
Without any ECU changes, hold the car in first.
The trans will not go to second,
if you have the lever all the way down in first (Low).
But because of the time delay built into the ECU, if you wait till 6500 to click the car into second,
you will over rev, and bounce off the rev limiter.
Using a shift light, try to shift at about 5700.
The delay will let the engine rev all the way to 6500-6700 if you hit it just right.
Takes some practice, and not all of them will have the exact same delay.
But it will hit second so hard, it will break the tires loose (or the right motor mount....).
This is why I now have Kazama mounts in my car, got tired of popping that damn expensive mount!!
Second way,
Send your ECU off to Kieth Goldin in Florida, and he will change the 3 clock crystals in it.
He had me take a high res picture of the board before accepting mine.
(he had never done a Cressida ECU before)
Once he looked it over, he said 'No Problem'.
He asked me where I wanted the rev limiter, and I asked for 7500.
Sent it off with $110, and had it back in a week.
Plugged it in, and with the car in nuetral, slowly brought the RPM up.
6500, 7000, 7500, 8000, and beyond......
Evidentally, his figures were a bit off.
But this didn't bother me, I going with a Crane Hi-6, that has it's own dial-in rev limiter.
But (here is the good part),
The tranny no longer shifts at such a low RPM, in ALL the gears !
In fact, I had to slack off the kick down cable to get it to shift to 3rd without going over 8500 !
Who says a 7M won't rev !!
(not that stock cams made much power up that high, they fell a little short past 7000.)
But with HKS 256 cams, the 12.5: Cosworth pistons, headers, and a 70mm throttle, that sucker reved cleanly to 8500.
The engine is down again because of a rod bearing failure while trying to get the cheap-ass rings I got off eBay to seat-in with 5w30 oil - BAD idea.
Felt the rod start locking up just past 8000.
By the time I got it slowed down, it had pushed a lot of trash through the whole engine.
But I am now going with a set of 264x272 cams, and Wiseco 10.5 pistons.
Now if I can just get valves to work with these damn TODA shim-under buckets, I'll have it back together shortly (without the cheap-ass 'ROCK' rings from eBay - Sh#, I know better than that!).
PS, there are some tricks to get the car to launch a lot harder also, but that is another story.......
I was thinking of just adjusting the speed sensor input to the ECU so the ECU thinks the car is going slower than it really is. As far as I know the shift points are based on road speed and throttle position. If I change to 4.3 gears from 3.9 then I will have to do this anyway to make the speedo correct.
The histall converter I have seems to be somehow be a combination of a histall speed 2800rpm and also more efficient than stock at high rpm. Before I installed it gear shifts occured at 6000 -6500 rpm at WOT. Or it may just be the shift kit changing the gears faster. I don't know for sure but I do like the super fast gear changes at full throttle that you get with the shift kit.
Hi 7M-Fanatic
Your engine bay looks great. Couple of questions.
1. Any advantage in moving the AFM closer?
2. What cams have you got in there?
3. Is your ACIS functioning? Mine runs off a switch light acctuator that opens it at 4200rpm.
4. Have you dynoed this car? If so what sort of results have you had.
The histall converter I have seems to be somehow be a combination of a histall speed 2800rpm and also more efficient than stock at high rpm. Before I installed it gear shifts occured at 6000 -6500 rpm at WOT. Or it may just be the shift kit changing the gears faster. I don't know for sure but I do like the super fast gear changes at full throttle that you get with the shift kit.
Hi 7M-Fanatic
Your engine bay looks great. Couple of questions.
1. Any advantage in moving the AFM closer?
2. What cams have you got in there?
3. Is your ACIS functioning? Mine runs off a switch light acctuator that opens it at 4200rpm.
4. Have you dynoed this car? If so what sort of results have you had.
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Just took my car out to clear out the cobwebs (again).:aigo:
Under wot in 2nd it changes around 5,800 in normal mode and 6,200 under power mode.
Will definately have to install new valve springs :cry: to take advantage of the extra revs the new cams will pull :biglaugh: as the old ones are shitting themselves around 6,000.
Under wot in 2nd it changes around 5,800 in normal mode and 6,200 under power mode.
Will definately have to install new valve springs :cry: to take advantage of the extra revs the new cams will pull :biglaugh: as the old ones are shitting themselves around 6,000.
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AJ'S 88NA said:
No just good pump gas.....
The throttle started to life as a BBK unit
meant for a Thunderbird Super Coupe.
But to adapt it to the Toyota sensors, linkage,
and manifold took a lot of work.
The manifold adaptor plate was the easy part.
To get to the TPS and linkage to work on the 7M took a new throttle shaft,
and cutting the TPS mount off the original throttle.
Also, the larger diameter did not clear the valve cover.
It took two things to correct this:
First, remachining the other end of the 'Y' pipe so it would angle up 5 degrees.
Second, machining the exhaust cam cover about 1mm for just a little clearance.
But this needs to be in it's own thread.
When I get time, and after the engine is back together again, I'll post the story on this build.
Anyone who wants to e-mail me, I'll be glad to send pictures, info.
Or if your in the states, call me (e-mail for phone #)
amichie said:
1. Yes, I can run a much LARGER K&N filter.
The baby filters I see on a lot of 7Ms are ridiculously small.
I used larger filters on a 100cc kart engine.
I use a 9" long tapered K&N with a 4" (100mm) connection.
This allows me to run the velocity stack inlet on the AFM.
2. When it was in the car last, it had HKS 256 in & ex.
It is going back together with 264 in & 272 ex.
3. ACIS ?? Sorry, not up on what your talking about
(maybe it is something I threw in the trash
)4. Nope, as I PMed you, that build never got too far.
Trying to force the issue of cheap-ass 'ROCK' rings from eBay not seating in.
The Cosworth 12.5 pistons took an odd-bal ring size, eBay was the quick way to get them, but that was a big mistake !!
Buddy says "try some really light oil, and get on it Hard".
I did, (mistake # 2) and had a rod bearing failure just above 8500 rpm.
So now it's going together with Wiseco pistons & rings, I know they work.....
Still about a week away on finishing this build.
Went to 1mm os valves this time.
But stock valve stem dimensions turned out not to be compatable with my TODA inner shim set.
Found ex valves that are (3SG Ferrea), that took some machine work, but done now.
3SG in valves turned out to be longer, and just could not get enough room anywhere to make them fit.
But I have found some 33.5mm 4AG in valves by REVvalve that have the right stem length. As soon as they hit the door, I can do the required work on them, and everything will be set to go.
Thanks for the reply.
I would love to see some pics sent to me at
a.michie@usyd.edu.au
BTW I don't remember seeing a PM from you. I hope its not my failing memory again.
Andrew.
I would love to see some pics sent to me at
a.michie@usyd.edu.au
BTW I don't remember seeing a PM from you. I hope its not my failing memory again.
Andrew.
amaichie, 7m-fanatic sent a pm to me, as I had some questions for him.
I won't comment on anything since this is a topic for another thread
I won't comment on anything since this is a topic for another thread
