Another cam question
Thread Starter
Burning Brakes
Joined: Mar 2019
Posts: 1,057
Likes: 41
From: Chehalis, WA
Another cam question
Hi Knowledgeable Ones,
My 76 has FiTech EFI, dual exhaust, and a mild cam, according to the PO. Is there any way to determine what kind or type of cam is in there without tearing into it? I was thinking about better flowing heads, and I have learned that heads and cam should be closely matched for performance. If I was to invest in newer heads, would I be better served to also replace the cam, so I know exactly what is in there or perhaps have a whole new Edlebrock top end kit installed? Thanks and be gentle with this mechanically challenged one.
Tom
My 76 has FiTech EFI, dual exhaust, and a mild cam, according to the PO. Is there any way to determine what kind or type of cam is in there without tearing into it? I was thinking about better flowing heads, and I have learned that heads and cam should be closely matched for performance. If I was to invest in newer heads, would I be better served to also replace the cam, so I know exactly what is in there or perhaps have a whole new Edlebrock top end kit installed? Thanks and be gentle with this mechanically challenged one.
Tom
Le Mans Master
Joined: Apr 2011
Posts: 6,284
Likes: 1,170
From: Hermosa
Better flowing heads will make just about any cam perform better simply because more intake charge can flow in during the time the valve is open.
But as you said the cam can help optimize the heads by opening and just as important closing the valves at the right time reducing losses by valves being open too long.
some cams may have marking on them (few).
You can measure the lift of the cam by measuring how far the valve stem is depressed during it's opening as compared to closed and dividing that by 1.5 (assuming 1.5 ratio rockers which are standard in most applications). but to get more than that you are going to have to dial the cam using a degree wheel. something like this.
If you already have the heads off it's not too much more work to replace the cam but it is some work and $$ additional.
But as you said the cam can help optimize the heads by opening and just as important closing the valves at the right time reducing losses by valves being open too long.
some cams may have marking on them (few).
You can measure the lift of the cam by measuring how far the valve stem is depressed during it's opening as compared to closed and dividing that by 1.5 (assuming 1.5 ratio rockers which are standard in most applications). but to get more than that you are going to have to dial the cam using a degree wheel. something like this.
If you already have the heads off it's not too much more work to replace the cam but it is some work and $$ additional.
Team Owner
Joined: Oct 2004
Posts: 81,241
Likes: 3,062
From: altered state
St. Jude Donor '05
Agree on installing a cam that matches your rearend gear, useage and heads.
Could be a small cam, sometimes its stock and guys say it has one who knows. Step up to a roller if you can.
No need for a custom one either there are a bazillion proven grinds for the sbc. Seen too many customs...that are merely off shelf pieces. lol
Could be a small cam, sometimes its stock and guys say it has one who knows. Step up to a roller if you can.
No need for a custom one either there are a bazillion proven grinds for the sbc. Seen too many customs...that are merely off shelf pieces. lol
Last edited by cv67; Feb 1, 2021 at 10:12 AM.
Dr. Detroit
Joined: Mar 2012
Posts: 10,095
Likes: 4,023
From: New Braunfels Texas
You can pull an intake and exhaust rocker and measure lift and duration using a degree wheel and dial indicator.
As far as head....I try to find heads that flow exceptional at .200/.300 lift...then choose a cam off those numbers.
Jebby
As far as head....I try to find heads that flow exceptional at .200/.300 lift...then choose a cam off those numbers.
Jebby
Thread Starter
Burning Brakes
Joined: Mar 2019
Posts: 1,057
Likes: 41
From: Chehalis, WA
Thanks Jebby. I am not really looking for a street racer or anything wild. As you know, the 76 L-48 was a dog from the factory as the EPA insured that it could hardly get out of its own way. I've mentioned before that the PO had installed dual exhaust, FeTech EFI, improved distributor, and he said it had a mild cam, so it goes a bit better than new. I would like to get to somewhere north of 300 HP, which I think would provide plenty of giddy up compared to what the car has now. If I had some nice aluminum heads at .200/.300 lift with a comparable cam, would that set up be what I am looking for without being too wild. Thanks.
Melting Slicks
Joined: Dec 2009
Posts: 3,224
Likes: 653
From: Thunder Bay
All parts should be matched and heads/cam are no different but the most important things to match are probably the camshaft with the compression ratio. Do some research on dynamic compression ratio and I think it will become self explanatory.
