Cam number ?

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MikeD

MikeD

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I've just pulled the timing set off my 360 and there's no cam number at the front, all the BB Cams i've used had the number stamped on the end.
Mick
 
Thanks but i don't want to pull the cam out just to get the number off it. The power's very soft and i've got very low vacuum, so i'm going to advance it 4 degrees to try and get some cyl pressure.
 
If it's THAT soft just gotta wonder if 4 degrees will get you relief,lol.It sounds more like a Low Dcr issue. Or a too-low stall.Or not enough rear gear. or a less than happy combo.
But since the cover is off, have at her.
But I just gotta say; 4* is good for about 6 psi on a 9.2 360.
yes 6psi
 
I 've done a comp test and lowest is 110 dry, 120 wet, highest is 145 dry, 150 wet, max vac is around 8", the power brakes are poor due to the low vac, car is high geared, stock converter, edelbrock dual plane, edelbrock carb, 1-5/8 headers. I was thinking more than 4 degrees, what's your opinion ? I thought the 73 360 was around 8.5.1 ?
Mick
 
MikeD said:
I 've done a comp test and lowest is 110 dry, 120 wet, highest is 145 dry, 150 wet, max vac is around 8", the power brakes are poor due to the low vac, car is high geared, stock converter, edelbrock dual plane, edelbrock carb, 1-5/8 headers. I was thinking more than 4 degrees, what's your opinion ? I thought the 73 360 was around 8.5.1 ?
Mick
Click to expand...
That's your problem right there, your engine is either done, never was, or the cam is 7 sizes too big, bleeding pressure.
Coupled with the boat-anchor hiway gears and stock TC, that poor girl is screaming in pain.
Yeah I know, I sound like an azz. But the truth is staring back at you. Measure the cam, don't waste your time re-timing it. Then do a leakdown test and find out where the pressure is going.
 
I dion't think you're an azz at all, it's just an engine, surely at it's best it wouldn't have a massive amount of cyl pressure with the low comp ? the timing set is worn anyway, so i'll order one. Incidently, i had a 383 with a .509 cam that had way lower cyl pressure than this engine, i advanced that cam and it ran high 12's
Mick
 
MikeD said:
I 've done a comp test and lowest is 110 dry, 120 wet, highest is 145 dry, 150 wet, max vac is around 8", the power brakes are poor due to the low vac, car is high geared, stock converter, edelbrock dual plane, edelbrock carb, 1-5/8 headers. I was thinking more than 4 degrees, what's your opinion ? I thought the 73 360 was around 8.5.1 ?
Mick
Click to expand...
You have one hole at 145/150, that hole probably is ok, at least ring wise
You have one hole at 110/120. That one needs a valve job.
So with the little info you provided, it looks like you have a 7 cylinder engine.
Now, 145psi was a stretch even when the engine was new, with a 252/260/112 cam. The only reason that engine was not a total dog at 8.0 was because it had 360 cubes.
But as soon as you put a performance cam into it, as a streeter with hiway gears;low-rpm performance disappears.
But you say you have 145psi in at least one hole, and I'm assuming that was the best one,lol. So, I would have to guess that the cam that is in there is pretty close to stock.
And so I think it would be safe to say;
That's your problem right there, your engine is either done, never was, or the cam is 7 sizes too big, bleeding pressure.
Coupled with the boat-anchor hiway gears and stock TC, that poor girl is screaming in pain.
Yeah I know, I sound like an azz. But the truth is staring back at you. Measure the cam, don't waste your time re-timing it. Then do a leakdown test and find out where the pressure is going.
Click to expand...

Except now we know it ain't a 7-size too big cam,lol.
 
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I agree with AJ 150 %.
You are there... either take it out, or get a degree wheel/indicator on there, and find out what it is.
Besides, you may find something out that would be a game changer..
I hate mysteries like this.. :)
 
Mike D, the 383 with 509 how much did you advance cam? Crackedback recommends 6 to 8 degrees @ the crank. Or 3 to 4 @ the cam.
 
Most cylinders were around 120 or so, i'm trying to avoid spending too much on this car as i may not keep it due to other projects.
Quickdart I think i advanced it around 8 degrees but i did check piston to valve.
Are the summit timing sets any good, they do a multiple keyway one and is a tensioner necessary ?
 
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I have been using cloyes true roller chain sets with good results. I have heard summit chains to be good quality. Just be sure to get a real true roller quality timing set. I've also heard edelbrock timing sets are good also.
 
Small or big block with lower compression, wind it forward a lot.

Never use the 114LSA POS cam, only the 108ish model. :)
 
Got the summit timing set today, dropped it on a 6 degrees advance, the circle on the top sprocket is at 6 o clock and it doesn't fall right in the centre of the two teeth on the crank sprocket it's nearer to one of the teeth. I've confirmed it's at tdc, rotor is pointing at 6, is this any cause for concern ?
 
no, it's not. you have a new timing set, the chain is tight, and you're probably going to have to turn the cam fwd some to get everything to come together. BUT, I would not run anything, until a degree wheel is put on it to confirm it's in the right place...
 
I turned it untill it was middle, slid the case back on and it was 10 degrees off on the marker, i've confirmed tdc on the balancer with a piston stop.
 
No offense, but I can't see it from here.. You really need to get a degree wheel and indicator on it..
It's really the only way to have any peace of knowing it's in the right place.
 
Pic of new timing set at TDC

IMG_0024.JPG
 
Fired the car up, it was idling a lot higher, reset it, took it for a run, it definitely pulls stronger and it idles really smooth now, i think the stock converter and highway gears are still holding the car back but i'm glad i advanced it, it hasn't transformed the car but it's definitely improved it some.
 
Camshafts don't bleed off pressure. That's incorrect terminology. Cylinder pressure is built at the beginning of the compression stroke. If a camshaft is "too big" it will simply never build the pressure to begin with. It doesn't bleed it off.
 
MikeD said:
Fired the car up, it was idling a lot higher, reset it, took it for a run, it definitely pulls stronger and it idles really smooth now, i think the stock converter and highway gears are still holding the car back but i'm glad i advanced it, it hasn't transformed the car but it's definitely improved it some.
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Yep, even 4 degrees advance is quite noticeable for off-idle and mid range performance. Helps if you are cruising around on a low compression engine.

BTW, if lack of a degree wheel is holding anyone back, and buying one seems like a lot of $$ for a 1 time use, print one off from the link below and glue it to some poster board. Take care to make the center hole very accurate and it will serve you quite well.
The Machinery Cleanery Universal Timing Disc, Degree Wheel, Downloadable - Goniometro per Messa in Fase dei Motori a 4 Tempi -
 
Hey Mike D what did you advance? Cam or crank. 4 at cam is 8 at crank. Just like crackedback suggests.
 
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