Cam question

glb1948 · 07-30-2006, 04:11 PM

Here are the vitals. I have a 87 Olds Cutlas with a 72 350 Old Rocket. There is a Comp Cams 268/268,456/456. It has an edelbrock performer rpm intake with an edelbrock 750 carb. All MSD ignition. A TH400 with shfit kit with a 2000-2200 stall convertor and a 9" ford rear with 4:11 gears. I want to use the car for street/strip. My questions is this. On hard acceleration the car will bog slighlty then run super but the valves seem to be floating around 4200 rpms. Does anybody have a suggestion for a good stout cam with a nice lope to it? Any infor is apprectiated...Thanks, Gary

Oldsguy · 07-31-2006, 06:54 AM

Going to a stouter cam will not fix your problems with bogging and valve float. They may be caused by two seperate issues. Does your bog happen at the start of the hard acceleration? If so, I would look to getting that carb fine tuned, your accelerator pump might be a little too much, or your timing could be off, are you using an MSD ignition box or just the distributor? If you are using the box then it might be able to fix you ignition problem with some adjustments. If the bog comes later in the acceleration it might be related to the valve train and your valve float problem, especially if your heads are all stock. 4200 rpm isn't too much for a small block Olds and you should look into upgrading your heads and valve train. It sounds like you have a pretty good engine/drivetrain build and you just need to massage it some.

glb1948 · 07-31-2006, 07:31 AM

Dan - Thanks for the reply. Yes, I believe the heads are pretty much stock and I was thinking on going to 455 heads. The bog does come right on acceleration but when it does grab, hang on. It does not seem to bad when I manually shift though. I do have the MSD box with a timing control also but the dist I believe is a HEI with a MSD cap on it. I was also told that maybe a 3,000 to 3,500 stall convertor may help to.

HWYSTR455 · 08-23-2006, 08:10 AM

The Edelbrock carbs are known for a transition stumble, and doubt you'll be able to get rid of it without replacing it (pick a Holley Avenger 670 or 770, or a 3311 750 Holley). As for the 'float' you mention, it may be the lifters are chinese junk. Comp had an issue with lifters for some time there, and ended up 're-valving' them with a slower relief internally. Aside from that, I would suggest using the 'Johnston' lifters which are now again available. Several manufacturers carry them now. As for the cam, are those 'advertised' numbers you posted? Seems kind of small, especially with those gears. I would suggest a split-lobe design, and shoot for the mid-220s on the intake, and low-to-mid-230s on the exhaust, like the Comp XE268, or XE274. I like the Crane grinds, like the H-284-2, or the H-272-2, which are the comparable grinds to the COMPs (they have a 112 CL, which gives better idle qualities).

07-30-2006, 04:11 PM	#1 (permalink)
glb1948 Junior Member Join Date: Jul 2006 Posts: 2	Cam question Here are the vitals. I have a 87 Olds Cutlas with a 72 350 Old Rocket. There is a Comp Cams 268/268,456/456. It has an edelbrock performer rpm intake with an edelbrock 750 carb. All MSD ignition. A TH400 with shfit kit with a 2000-2200 stall convertor and a 9" ford rear with 4:11 gears. I want to use the car for street/strip. My questions is this. On hard acceleration the car will bog slighlty then run super but the valves seem to be floating around 4200 rpms. Does anybody have a suggestion for a good stout cam with a nice lope to it? Any infor is apprectiated...Thanks, Gary

07-31-2006, 06:54 AM	#2 (permalink)
Oldsguy Administrator Join Date: May 2004 Location: Lees Summit MO Posts: 3,132	Going to a stouter cam will not fix your problems with bogging and valve float. They may be caused by two seperate issues. Does your bog happen at the start of the hard acceleration? If so, I would look to getting that carb fine tuned, your accelerator pump might be a little too much, or your timing could be off, are you using an MSD ignition box or just the distributor? If you are using the box then it might be able to fix you ignition problem with some adjustments. If the bog comes later in the acceleration it might be related to the valve train and your valve float problem, especially if your heads are all stock. 4200 rpm isn't too much for a small block Olds and you should look into upgrading your heads and valve train. It sounds like you have a pretty good engine/drivetrain build and you just need to massage it some. __________________ Dan '77 Cutlass Supreme '46 2 door

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07-31-2006, 07:31 AM	#3 (permalink)
glb1948 Junior Member Join Date: Jul 2006 Posts: 2	Dan - Thanks for the reply. Yes, I believe the heads are pretty much stock and I was thinking on going to 455 heads. The bog does come right on acceleration but when it does grab, hang on. It does not seem to bad when I manually shift though. I do have the MSD box with a timing control also but the dist I believe is a HEI with a MSD cap on it. I was also told that maybe a 3,000 to 3,500 stall convertor may help to.

08-23-2006, 08:10 AM	#4 (permalink)
HWYSTR455 Junior Member Join Date: Jul 2006 Posts: 16	The Edelbrock carbs are known for a transition stumble, and doubt you'll be able to get rid of it without replacing it (pick a Holley Avenger 670 or 770, or a 3311 750 Holley). As for the 'float' you mention, it may be the lifters are chinese junk. Comp had an issue with lifters for some time there, and ended up 're-valving' them with a slower relief internally. Aside from that, I would suggest using the 'Johnston' lifters which are now again available. Several manufacturers carry them now. As for the cam, are those 'advertised' numbers you posted? Seems kind of small, especially with those gears. I would suggest a split-lobe design, and shoot for the mid-220s on the intake, and low-to-mid-230s on the exhaust, like the Comp XE268, or XE274. I like the Crane grinds, like the H-284-2, or the H-272-2, which are the comparable grinds to the COMPs (they have a 112 CL, which gives better idle qualities).