Camshaft talk

**Jyrki** · 11-05-2008, 01:25 PM

The "anything new from STR8 hot rodders" thread is exploding with stuff, so I'd like to start a new thread concentrating on cams only.

First of all, I have a question for all you guys who have been racing your straight-eights:

1. Did you take your cam to a grinder and give your own specs, or did you just give the grinder free hands with the specs?

2. If you gave your own specs, how did you come up with those specs, or were you just shooting from he hip?

Here are the 1942 factory specs for the 320 cid, @0.04" valve lift. I assume it is at zero lash.
Opens Closes
Intake 14 BTDC 71 ABDC
Exhaust 56 BBDC 25 ATDC

I have no idea about the lift numbers.
Doing the math gives us "advertized" duration of 265 Intake / 261 Exhaust, with a 112 degree lobe separation. These may seem like decent numbers, but if we had the figures given @ .050" lobe lift, they would be mild.

Comparing them with typical SBC specs, it seems like the intake opening is rather retarded. For a mild upgrade, I'd tighten up lobe separation to 108, and advance the cam by 4 degrees. This will increase overlap, but with headers it's for good, and the overlap is marginal to start with. Advancing the intake would also close the valve earlier, increasing dynamic compression. For the last, I'd add 10 degrees more duration to both intake and exhaust. And with a contemporary fast ramp profile, please.

It appears back in the day, Howard, Isky and others had various grinds called 3/4, Full, Super, or Track grinds. Wonder if these are still available, and if anyone can dig up the actual specs?

**charley** · 11-07-2008, 05:10 PM

I have a 36 and a 40 shop manual both give the same timing specs.as you got in the 42 manual. The valve lift is shown as .347 intake and .342 exhaust. Doing a little reverse math, if the rocker ratio is 1.5 the cam lift is close to .230

**charley** · 11-24-2008, 06:55 AM

I know this is off the subject but I was reading your response to 36 century on his 6 carb manifold. Has anyone you know of ever tried to use constant velocity carbs on a buick 8? It looks like to me you could over carb a engine and the constant velocity carb would compensate some what.

**Jyrki** · 11-25-2008, 05:50 AM

What is a constant velocity carb? Do you mean those motorcycle carbs that have a variable-diameter throat? I think someone mentioned he was going to try those on a Buick-8. I think it was on the HAMB forum? Never heard of actual experience with those.

**charley** · 11-25-2008, 07:54 AM

Yes, a lot of motorcycle carbs are constant velocity. I think SU carbs may be also. I think they work by the slide only opening as engine demand increases and not only by the position of the butterfly.

**39CENT** · 11-25-2008, 10:01 PM

I took my cam to Chet Herbert years ago when he ran an 'Earl Sheib' type ad in the rod magazines, "any cam any grind $39.95". So I called him and asked "even a Buick strait 8 cam?" he said hesitently 'yep, bring it down' . When I picked it up he said 'Don,t tell anybody where you got it'! I said why,s that? He replied that dam thing cost me half a day to reset my grinder! HMMM well I offered to pay more and he said no dont worry about it. gggg then I asked what grind is it? he said don,t worry, its what you need. Old Chet smiled a little as I left, probly because I was gitting that cam outta there.. I havnt used it yet, so I guess I will find out when i run it???

**39CENT** · 11-25-2008, 10:16 PM

Well the lifters are almost 1" so you should be able to get a pretty wild grind on the cam. More lift would be pretty good too. It seems that the big 8,s can use lots of carb, I would think a Rochester quadrajet would be a good candidate as its plenty big and very adjustable. Also maybe a 1.6 ratio rocker from 'rocker arm specialists' would help. here,s somethin to read about cams an blown engines by Ken Dutweiler.

http://www.chevyhiperformance.com/te...ild/index.html

**Jyrki** · 11-26-2008, 05:48 AM

I've been a subscriber to CHP for years, as it's such a good source for tech info, which is often adaptable to any make.

I think it was someone of the Duttweiler clan to use Toyota twincam heads on a Buick-8. Don't know if the engine ever ran?

Thanks for keeping this thread alive, fellas. Hope someone would post some actual specs before this thread dies...

**39CENT** · 11-26-2008, 08:51 AM

Ken Duttweilers brother Gary [Gerry?] has beaut 38 Century coupe thats running a blown built straight 8! He,s a wealth of info on them. Mel Tull is the one who welded together 2 Toyota 22R heads which I dont think hav been run as yet. Mel has run his Buick str8 in a roadster to 170 mph at Bonneville, with a ported head and one 4barrell carb[and many other mods] Mel also has a long history with Buix.

**saltracer** · 11-27-2008, 05:28 PM

Originally Posted by 39CENT

Ken Duttweilers brother Gary [Gerry?] has beaut 38 Century coupe thats running a blown built straight 8! He,s a wealth of info on them. Mel Tull is the one who welded together 2 Toyota 22R heads which I dont think hav been run as yet. Mel has run his Buick str8 in a roadster to 170 mph at Bonneville, with a ported head and one 4barrell carb[and many other mods] Mel also has a long history with Buix.

Has any body talked to Gary lately? I have trued to call him but my number is no good. Anybody got his email ?

He and Mel both helped me on my Bonneville project great guys..............D. L.