1970 455 cams,first buick build help

Thanks, yeah that car does sound nice. I already have a stock bellhousing.

 

I'm also considering this cam kit http://www.compcams.com/Company/CC/cam-specs/Details.aspx?csid=1460&sb=2. I know I'm going to get flamed for overcamming but keep in mind this is the high compression motor and a stick shift.

 

I don't want to destroy your vision of how you want this car be/sound. I know you have you heart set on a thumpin' idle, but in my humble opinion this will only make your car SLOWER. BBB are great at making torque and not high rpm horsepower. Sure, you can force some more upper rpm horsepower out of it with a big cam, but you will kill torque doing so, and torque is where it is at for a great performing street car. This is especially true with stock heads. And since hp is a function of torque (hp=tq x rpm / 5252) if you increase torque, you automatically increase hp. High torque=high efficiency. If you want your car to actually perform and not just sound fast, stay with the milder cams already recommended. Your actual compression ratio is around 9.5:1. Also, the stock short block will not like rpms exceeding 5500 and will not survive for long. What you want is a combination that will create the most average torque below 5500 rpm. Besides, it is great fun to blow somebody's doors off, then pop your hood and show them your stock appearing motor. So, I am not flaming you, just showing you another viewpoint.

 

thanks Steve I appreciate the advice. That's why I bring my questions here you all have a lot more knowledge than I do on these.by the way I'm driving through Rapid City this morning with the donor car on the trailer.

 

Actually the intake valve on the Thumpr cam closes 1 degree sooner than the TA212 so it is not really an overcam situation.

The Thumpr cam was designed to give the old "Hot Rod" nasty rough idle sound by using a lot of overlap without having the long duration cam lobes.
It has 20 degrees of overlap and needs at least 20 degrees of initial advance for idle.
Power doesn't hit until 2500 rpms and then it comes on suddenly like someone turned on a switch.

Because it doesn't have a long duration intake profile the power drops off early.
The result is a very short power band, 10 mpg or less and if you start the engine in the garage the exhaust fumes will burn your eyes.
Very low intake manifold vacuum for power brakes.

Initially you asked for a rough idle and reasonable street manners.
Also wanted to optimize for a 10.25:1 compression ratio
The recommendation was to keep the overlap around 10 degrees.

A 230/240 on a 112 LSA would meet the conditions.

Paul

 

Yes you guys are def right about a cam like that. The priorities are to make the best usable power with the combination of parts I have so I'll forget about the sound and be realistic. So would you agree that the ta113 would be a good choice Paul?

 

Ah, dang! Sorry I missed ya, sodak65. That's a great project you have going there, and it will be a blast to drive. Thanks, Paul, for the concise explanation on the thumper cam. That really cleared up what that cam is designed to do and why and how it works and what you get out of it.

 

Yea Steve my family is in sturgis area now I grew up in spearfish, I'm out here for a long weekend and to work on the buick. I see you have a c/10 we are building a 69 for my dad right now and I sold my 68 to fund this gran sport project.

 

The TA 113 shows a 276 degree intake duration. The dynamic compression ratio will be right at 8:1 which is high for an iron head on pump gas.

The Crower 52241 would be a good off the shelf cam for your application.

http://www.crower.com/camshafts/bui...-400-455-compu-pro-hydraulic-cam-284-hdp.html

You would have 9 degrees of overlap for a lopey idle.

The dynamic compression ratio will be 7.8:1 if the static compression ratio is 10.25.
If the actual compression ratio was 10:1 it would give more margin on gas octane.

It will make plenty of power and with those duration specs it will respond very well if you decide to do port work later.

Paul

 

Thanks paul, as I'm told these motors come in well under 10:1 so I think I should be ok.

 

Your the man Larry

 

Would stock rockers and stage 1 springs work with that crower cam?

 

The valve lift is .505" intake and .506" exhaust.

The cam card calls for 95# closed and 255# open.
The Stage 1 spring is 100# closed and 315# open so it will work but I would use something just a little lighter for the sake of the stock rockers.

 

Would the stock springs be ok then?