Small Block vs Gen3 cam swap differences
04-07-2010, 09:48 PM
#11
Below is sort of a standard recomendation I give to get most people headed in the right direction and to get them thinking of what is possible with the right combination of parts.
I think that I may have some ideas for you.
Comp Cams has the 252XFIHR13, specs are 202/212 .518/.513 113 w/1.5 rockers. It has a RPM range of 1000 to 5000.
If you want a little more bump and performance:
I've always liked the cams Lingenfelter has ground for the older SBC's.
Part # 74216 is a Hyd. Roller listed as: 213/219 .493/.506 112 w/1.6's.
You could run it with 1.5's and come up with a lift of .462/.470 and be safe. If you decided to actually run it with 1.6's, you would need to open the pushrod holes for clearance or at the very least check them, however they will most likely rub. Also, while you can drill the open the pushrod holes while on the motor, the prefered method would be off and if you were pulling the heads, you might as well machine down the guides for positive seals.
I'm sure you have heard all the stories of not being able to run much more than between .450" to .470" of lift depending on the individual heads on Vortec's.
Now if you use Comp 915 Beehives that are designed for LS1's at an installed height of 1.800", instead of the factory SBC height of 1.750" you can obviously run more lift without the retainer hitting the valve guide or seal.
To run LS1 style Beehives in a SBC designed with 11/32" valve stems, you will need to use a hybrid retainer. Comp makes such a retainer Part # 787-16. Also to get the installed height of 1.800" you will need a +0.50" steel lock/keeper and Crane made just a jewel: Part # 99095-1, coded Yellow. Comp now makes a +/- steel lock/keeper and now that Crane is out of business, you may have a hard time finding some of theirs unless they are setting on a shelf somewhere. The problem I see with the Comp keepers are they are offered in a 10degree version only and not 7degree as well. Maybe now that Crane is out of business, Comp may have added additional listings to their catalog since the last time I checked. Some people just install the Comp retainers with standard positioned locks and get away with it, but doing so un-necessarily increases the spring pressure and limits the amount of lift you can actually run.
Obviously you don't have to run the cam(s) I suggested, but if you carefully choose the right components you are not as limited as what everyone would have you believe. Just about everyone one will tell you that you must pull the heads and machine down the valve guides for the necessary clearance. This is really just closed mind-ness. If you run the numbers, you can see for yourself that it will work with just simple math. I used this same configuration on other trucks and have verified that I would have been able to run .530" lift before contact was made. Of course every combination is different and will have to be verified.
I think that I may have some ideas for you.
Comp Cams has the 252XFIHR13, specs are 202/212 .518/.513 113 w/1.5 rockers. It has a RPM range of 1000 to 5000.
If you want a little more bump and performance:
I've always liked the cams Lingenfelter has ground for the older SBC's.
Part # 74216 is a Hyd. Roller listed as: 213/219 .493/.506 112 w/1.6's.
You could run it with 1.5's and come up with a lift of .462/.470 and be safe. If you decided to actually run it with 1.6's, you would need to open the pushrod holes for clearance or at the very least check them, however they will most likely rub. Also, while you can drill the open the pushrod holes while on the motor, the prefered method would be off and if you were pulling the heads, you might as well machine down the guides for positive seals.
I'm sure you have heard all the stories of not being able to run much more than between .450" to .470" of lift depending on the individual heads on Vortec's.
Now if you use Comp 915 Beehives that are designed for LS1's at an installed height of 1.800", instead of the factory SBC height of 1.750" you can obviously run more lift without the retainer hitting the valve guide or seal.
To run LS1 style Beehives in a SBC designed with 11/32" valve stems, you will need to use a hybrid retainer. Comp makes such a retainer Part # 787-16. Also to get the installed height of 1.800" you will need a +0.50" steel lock/keeper and Crane made just a jewel: Part # 99095-1, coded Yellow. Comp now makes a +/- steel lock/keeper and now that Crane is out of business, you may have a hard time finding some of theirs unless they are setting on a shelf somewhere. The problem I see with the Comp keepers are they are offered in a 10degree version only and not 7degree as well. Maybe now that Crane is out of business, Comp may have added additional listings to their catalog since the last time I checked. Some people just install the Comp retainers with standard positioned locks and get away with it, but doing so un-necessarily increases the spring pressure and limits the amount of lift you can actually run.
Obviously you don't have to run the cam(s) I suggested, but if you carefully choose the right components you are not as limited as what everyone would have you believe. Just about everyone one will tell you that you must pull the heads and machine down the valve guides for the necessary clearance. This is really just closed mind-ness. If you run the numbers, you can see for yourself that it will work with just simple math. I used this same configuration on other trucks and have verified that I would have been able to run .530" lift before contact was made. Of course every combination is different and will have to be verified.
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