big base circle cam in stock elem.

I've never done it, but pontiac has problems with cam bearings. If you spin one and do excessive damage to the journal how would you repair it? They don't make an oversize cam bearing for my deal. I think the 50mm would be logical for a repair.

Originally Posted by SSDiv6

Now that is funny! There is a difference between repairing a block and machining the camshaft tunnel to use a bigger diameter cam.

[Paul Precht]

Originally Posted by Todd Hoven

I've never done it, but pontiac has problems with cam bearings. If you spin one and do excessive damage to the journal how would you repair it? They don't make an oversize cam bearing for my deal. I think the 50mm would be logical for a repair.

A decent machinist could make a sleeve and the machining process would be similar to sleeving a cylinder.

[SHANE R]

Originally Posted by Paul Precht

A decent machinist could make a sleeve and the machining process would be similar to sleeving a cylinder.

NEXT THING YOU KNOW, FUEL INJECTION WILL BE ILLEGAL ON 69 CAMARO'S ?????????

[SStockDart]

Originally Posted by Paul Precht

A decent machinist could make a sleeve and the machining process would be similar to sleeving a cylinder.

Paul, you are assuming that you use a standard cam bearing and not a roller bearing, right? I believe that is the issue.

[Paul Precht]

Originally Posted by SStockDart

Paul, you are assuming that you use a standard cam bearing and not a roller bearing, right? I believe that is the issue.

Just talkin about a repair for a stock Pontiac block with standard cam bearings, that's what I thought Todd was referring to.

[SStockDart]

I guess I don't really understand the issue here....What is the advantage to a large bearing cam shaft, as opposed to a standard bearing...????? I understand how a roller bearing camshaft bearing might make a half a horsepower.....plus add to the longevity of the engine. but a standard cam bearing versus a larger one??????? then why do Mopar guys use smaller rod bearings (chevy)...??? I'm just saying

[Billy Nees]

Originally Posted by SStockDart

I guess I don't really understand the issue here....What is the advantage to a large bearing cam shaft, as opposed to a standard bearing...?????

The issue here isn't the larger cam bearing, it's the larger base circle LOBE that the larger bearing register allows you to fit in.

[Pedigo Perf]

Originally Posted by Billy Nees

The issue here isn't the larger cam bearing, it's the larger base circle LOBE that the larger bearing register allows you to fit in.

I found the reply letter from Pat Cvengros regarding the cam journal size, of course this does NOT address the base circle of the lobes directly (as is the topic of this thread) , but if someone is getting a large base circle lobe on a stock core size camshaft in a vintage BBC I would sure like to know.

Here is the letter:


Pat Cvengros
6/9/10
to Tracy

Tracy,

The camshaft may be of the large journal design; the bearings however must be a Babbitt type, non-roller design.

Pat Cvengros

Technical Services Representative

(626) 250-2295

[TILBURG]

The first post was about "BIG BASE CIRCLE" cams. When someone has a minute could you please forward me a spread sheet w/ what the stock base circles are for everything amc,ford,chry.chevy,hudson (you never know) What if you have big power adder like a 4/7 swap cam? And it ends up being the same as a ford would something like that be considered as crossbreeding?How do you tell the car (driver) in say B stock auto that just got his 440,396,427 etc A#S drug down the track by a 2014 302 you have to go home because your base circle is to big.

Exactly!! Great post.

Originally Posted by TILBURG

The first post was about "BIG BASE CIRCLE" cams. When someone has a minute could you please forward me a spread sheet w/ what the stock base circles are for everything amc,ford,chry.chevy,hudson (you never know) What if you have big power adder like a 4/7 swap cam? And it ends up being the same as a ford would something like that be considered as crossbreeding?How do you tell the car (driver) in say B stock auto that just got his 440,396,427 etc A#S drug down the track by a 2014 302 you have to go home because your base circle is to big.