Visit our Twitter feed for more great content
TRExp

Spitfire & GT6 Forum

Camshaft lift question

Moss Motors
AutoShrine Sponsor
AutoShrine Sponsor
AutoShrine Sponsor
AutoShrine Sponsor

Camshaft lift question
#1
  This topic is about my 1980 Triumph Spitfire 1500
MarcLoranger Avatar
MarcLoranger Silver Member Marc Loranger
Auburn, CA, USA   USA
I have 2 camshafts to chose from for my rebuild of a +0.030 flat top piston engine.
On is a 312188 camshaft that is marked "RC Cal Cams" on the back.
The lobe has a base diameter of 1,1064 inches and the peak of the lobe of 1.3154 inches that yields a lift of 0.3135 using a rocker ratio of 1.5:1
the second is either a 612188 or a 312188 (the 3 really does look like a 6) and there is a space where the 1 should be but it looks like it may just be lightly stamped.
This camshaft has a lobe base diameter of 1.1235 inches and the peak of the lobe at 1.3648 inches for a lift of 0.3620 inches using the same 1.5:1 ratio.
The first seems quite low,
Should I use the 1st of the second as both are in good condition.

. Hide banner ads & support this website by becoming a > Gold Supporting Member <
Notti Avatar
Notti Eric N
San Dimas, CA, USA   USA
What are you putting it in?

MarcLoranger Avatar
MarcLoranger Silver Member Marc Loranger
Auburn, CA, USA   USA
I am putting it into a Spitfire 1500 engine that has been rebuilt at least once now I am doing it again. It has +0.030 flat top pistons with a standard rocker shaft and rockers. No other special additions.

. Hide banner ads & support this website by becoming a > Gold Supporting Member <
tapkaJohnD Avatar
tapkaJohnD John Davies
Lancaster, Lancashire, UK   GBR
Your second camshaft has a cam lift of 240 thou, spot on for a standard 1500 'shaft.
The first has only 209 thou, which is less than any OE 'shaft. Has it been reground? If so, has it been rehardened? I fear that this one is best used for poking your bonfire.

John

65or66 Jim B
Lake village, IN, USA   USA
1965 Triumph Spitfire MkII
1971 Triumph Stag
1973 Triumph Spitfire 1500 "Jusanudda Munny Pit"
John, if he leaves it in the bonfire for a while, then quickly dip it in oil, it will be re-hardened… maybe. But it will still be lower lift, and probably bent too.

MarcLoranger Avatar
MarcLoranger Silver Member Marc Loranger
Auburn, CA, USA   USA
I agree the first camshaft is of no use in an engine. Since I live in wildfire region I will not have a bonfire so I will need to think of another use for this 7 lbs of iron.

I will use the 2nd one as I believe it is a standard cam for the 1500. I will then be able to confirm the spec once in the engine.

I have been looking into a possible alternative cam that may have a bit more lift and had considered the BPNW BP270 with 50 degrees of overlap.
My issue is that this is going into a 1979 spit that will need to be smoged, so I asked BPNW if they believe I could pass smog with this cam and they said it is "a bit dirty at idle" and may not pass smog.
So in the end I will make a decision later on a better cam after I have finished the rebuild and have the engine in a car with the SZ carb and a Catalytic converter.

Such is life in California.

Notti Avatar
Notti Eric N
San Dimas, CA, USA   USA
Yeah, they really should have the '79 series smog exempt at this point. I had to pass on picking up a '78 FIAT 128, like I owned in High School, because it was a 49 state car. We live in a state of fools in the legislature.

79bluespit Avatar
79bluespit Rick Lazio
Burlington, ON, Canada   CAN
Marc you might want to try this gentleman in your neck of the woods. joe. he has some regrind spitfire cams in stock ready to ship $129 no core required and free shipping. here is the spec of cam i bought. just a tad more aggressive than the factory 25 65 cam. im sure joe can talk to you about smog as he lives in CA as well.


Attachments:
timing card.jpg    37.2 KB
timing card.jpg

MarcLoranger Avatar
MarcLoranger Silver Member Marc Loranger
Auburn, CA, USA   USA
Rick,
Thanks for the reference though I did not find a link to reach him, would you send me his coordinates.
Also the overlap - in the case of the one you showed - is 56 degrees, That is what causes the smog issue.

79bluespit Avatar
79bluespit Rick Lazio
Burlington, ON, Canada   CAN
I hate when I do that.

IMO there's 2 ways around smog. Put in a 10-50 cam which came in later half of 1968 to 71 spits.... Or 18-58 which are in 72-80 spits. I guess triumph was being super cautious early on.

Not recomending this and may get flamed by some, but I did this when we had smog in the early 90's to mid 90's when I was piss poor. Worked every 2 years for me... Went so clean once an inspector canceled test and tried me on another bay.

Keep your gas tank 1/4 full on super. Add 15% volume of methyl hydrate to tank. Drive around a bit to mix and get to carbs. Make sure engine is hot when test begins. In my experience back then, you will pass with flying colors.

When test is over put 2 stroke non synthetic oil in tank and drive around till empty. Refill tank again with preferably pure gasoline - no blends. In Canada that would be shell premium.

Methyl hydrate can cause erosion of gaskets, hence the 2 stroke dyno oil after test and drive it till near empty. You want to get rid of that gas when test is over.

79bluespit Avatar
79bluespit Rick Lazio
Burlington, ON, Canada   CAN
MarcLoranger Avatar
MarcLoranger Silver Member Marc Loranger
Auburn, CA, USA   USA
Rick
So you need to smog your car?
How would you describe the performance of this cam?
Mild, fast, high torque, racing?
It is the one Joe recommended with an increase in lash for The smog test.

Marc

GeorgeOhr Nonya Business
Yes, confused, USA   USA
What about a simple vacuum leak? How about just advancing the BP270 cam or maybe running the rockers just a bit looser? Seems you could fudge around it but I’ve never had that problemz.

79bluespit Avatar
79bluespit Rick Lazio
Burlington, ON, Canada   CAN
marc - i bought the camshaft... didn't install it yet. up here its' very cold and the car is away in storage. in summer i actually use the car as we're busy with summer sports with kids... wife takes minivan i take spitfire. so i won't install the things i'm accumulating, probably until september. joe at american says it gives torque from just above idle and keeps revving to 5500. i remember him saying many spitfire / midget ppl love this for the street. he has other cam profiles as well - this is not his only one. i just chose the one that closely matched the best factory camshaft as i want longevity with a more sporting cam.

i will buy APT lifters soon too. you should get those yourself if you use another cam. i've read too many stories here about crappy lifters from vendors.

the story i mention above i did when i was fresh in my first years of working life. was an 88 suzuki forza turbo. we had to emission test every two years car never passed on it's own - bad catalytic i suspected. it's why i got it cheap. catalytics were expensive back then and who knows if that would have fixed the test problem.... so that method saved me a lot of grief / $ back then.

ironically this new year 2019 all emission testing is now eliminated in ontario canada.

you can't go crazy with methyl hydrate either.. there comes a point where it can backfire on you.

as george says there are minor tweaks you can do depending on what is measuring high. retarding ignition timing is another 'trick'.

for your situation if you are really wanting a more sporty 25 65 range camshaft.... install one.... use methyl hydrate, retard ign timing a bit - see what happens. if it passes....great.... if you fail miserably put the emission cam back in and be done with it. at least you gave it a shot.



Edited 1 time(s). Last edit at 2019-02-07 11:04 PM by 79bluespit.

MarcLoranger Avatar
MarcLoranger Silver Member Marc Loranger
Auburn, CA, USA   USA
Rick,
Thanks for the insight on your past with the Methanol (methyl hydrate), I may try a bit of that when I go to smog.
I can not retard the timing as that is one of the things they can check on a spitfire.
I will relax the valve lash by 0.005-0.006 for the test.
I have new heavy duty tappets from BP Northwest, they are tuftrided and have a small hole on the side to get more oil to the camshaft.

. Hide banner ads & support this website by becoming a > Gold Supporting Member <

To add your reply, or post your own questions




Registration is FREE and takes less than a minute!


Having trouble posting or changing forum settings?
Read the Forum Help (FAQ) or contact the webmaster