69OLDSCUTCONV

Thought I would throw out my projects and get some comments and opinions. 455 in the shop will be complete later this week. C heads, large valves, new seats, new stainless valves with bronze guides, heads shaved .030" Comp cam kit for rockers, lifters and springs. Cam is comp 42-223-4 .485.490 lift with 270-280 duration. Keith black pistons +.030" 15 cc dish thinking comp. ratio will be 10.5. Not sure if im using cast iron intake or eledebrock. any suggestions? Any comments or conerns? As always thanks for your comments. should have a little more torque than the 350 thats in her now.

cutlassefi

That cam is too small for pump gas with 10.5:1 and iron heads, not enough off the seat time. Otherwise I'd go with the Performer, cut down the center divider 1/2in.

Jmo.

HurstOlds1775

The cam may be small, but it sure is a better engine than my ordeal with no compression in my 455!! What a chuckle, then read my post of "No compression in # 1 cylinder 455" I say cast intake, but the cut down Performer intake is a neat idea! That would solve the center divider issue. Sounds like you have put some thought into it and I hope you have fun when it's on the road! Good luck.

69OLDSCUTCONV

I talked with comp cams didnt want to get crazy being thats its a convertible so we talked about the 68-69 HO motor and its 380 horsepower and monster torque. I think the cam is close to the 69 H/O cam. I wanted it to still have vacuum for power brakes and decent idle and starting. What cam would you have recommended. Thanks for your info

cutlassefi

Your first area of concern is that your compression is too high for the cam you chose, and we know you chose that cam for the reasons given.

However that is not a match to an H/O cam. Those cams had much more off the seat time, lazier if you will. That coupled with the high octane of yesteryear allowed for high compression ratios with no issues.

Imo, you have a couple options. If you want to stay with that cam then I would suggest lowering the compression ratio a bit, below 10.0:1. Or getting another cam, something slower with a bit more spread in order to guarantee that you'll get what you're looking for, good idle and driveability while not having to use octane boost.
If it's the IC886 that KB piston is a good choice, just maybe shouldn't have had him cut the heads already, do you know what the actual measurements are?

I'm not saying you did but all too often guys go about this the wrong way and do their build backwards. Decide what it is you really want and what you don't want, then go from there.

What gear, tranny and converter are you going to be using? Other mods? I need to know that before I'd recommend anything else.

69OLDSCUTCONV

I stopped and talked with motor builder today, i was wrong about compression ratio, first I made a few math errors and assumed a few things that were wrong. First the heads i bought had been setting with the chambers down and had pitted/rusted so they had to be machined and we didnt plan that in the beginning. I calculated the .030" that was taken off the head surface at bore diameter but it only effects the chamber size which is much smaller than the bore. also we will use modern head gasket so that will actually decrease compression ratio more than head machine increased it because of diameter difference. Also i thought we were at near zero-.005" on deck height but that was incorrect also. We are looking at 9.8 to 10.0. he will actually measure the volumes, and he is planning to reduce it if it does go over 10. he believes we will stay under 175 psi cranking compression which should allow cam to work. I have two convertors a Hughes 2500 and a tci 2800. I planned to use the Hughes. I plan on a .342 rear gear. I only drive this car about 50 miles per month. this shop made several big block chevy race engines (402 & 489) and 2 street motors for me. Also I talked with somelocal Olds guys and they have made several for them. He told me today if i wasnt happy with the cam he will stand behind it, thats the most you can ask. If you have any more recomendations please let me know, the more you know ahead of the time the better. Thanks for all you help, if you have a recommendation on a cam with this info he said we he would be glad to look at.

cutlassefi

That's dictated by the cam and subsequent installation as well.
Finalize your other info and we'll go from there.

Thanks
Mark