[STEELCITYFIREBIRD]

....Now I'm wondering which "60919" I have!?!
I'm on the other end of the scale with hi compression ~11.1 in a406.
Guess I'll find out when I degree it?
Hoping for the "big" one.

[chiphead]

I've used the XE274 on a 110LSA in a 8.8:1 400. It was hard on rocker trunnions. I would stay below 9.5:1 with a XE274 on pump gas. Can anybody calculate how much the intake close event moves when putting this cam on a 112LSA?

No reason to push the edge with a cam lobe that was built to work best with moderate compression. If you're going to push the compression, use a lobe with more seat timing like a Crower or a Lunati with similar duration at .050".

[Jay S]

The ICL for the XE274 out on 112 lsa is 67* assuming the ICL is running at 110.

The dcr is 7.74 with no altitude adjustment.

I think it may be doable to run a 45* intake valves and some port work it would work ok on pump gas for me in my part of the world. Stock heads with 30* degree seats the SCR is at least a half point to high for a pump gas engine. IMHO.

I will try to explain (maybe poorly lol) why this combo will have issues. A prepped stock d port Pontiac heads with 30 intakes flow a bunch of air at and below .300” valve lift. This results in high VE numbers early in the power band through the torque peak. It is probably one of the the main reasons Pontiacs ran hard through the low compression smog era and everyone else’s engine suffered. The heads flow great at low lifts and fill the cylinders well with out a lot of extra compression. When you combine a cam that is super aggressive at filling cylinders with a stock Pontiac head with a lot of compression it creates a perfect storm for preignition.

Slow bird had PORTED d port head with 45* valves. That will act different than a stock 30* head d port. I don’t know what his head flowed but every 30* seat and 45* head I have had on our flow bench the flow was much better below .3” lift than the 45* heads. If you want to run high compression on a Pontiac on pump gas either pick a cam with enough seat timing to manage the compression or use a cam big enough to manage the compression. It you want to go crazy high on pump gas then start looking a ways to put the power in later verse earlier. 45* valves are a starting place.

Again...If your following Butlers cam advice. Go to 45* intake valves.

[77 TRASHCAN]

Originally Posted by Jay S

When we tried running a ram air 4 cam (melling spc-8) against cams like a Crower 60919 and more aggressive Ultradynes cams in 455s below 9.5 scr the RA 4 cam lost power everywhere, not just below mid range. They just ran ok, more head (like a round port) than a std d port would help. In a smaller 400 with stock D ports it would only get worse. Some of these cams help the engine build compression and fill the cylinders through the entire power band.

You can use Rhoads to nurse the lower compression engine along. But it doesn’t solve the way they run at full rpm. To run rpms you need head flow and more compression. Or the same compression and a lot more head flow.

THanks, Jay.
On the other end of the spectrum. What's the highest comp ratio you have used with a RA4 cam, in a 455 ??? Results???

[Jay S]

Originally Posted by 77 TRASHCAN

THanks, Jay.
On the other end of the spectrum. What's the highest comp ratio you have used with a RA4 cam, in a 455 ??? Results???

Never have pushed the RA4 cam to the point it is finicky for fuel. Not yet anyway. We set them up with compression close to Jim Hand’s wagon back when he was running the RA4. IRC, Hand was running ran 9.8 his first engine and 10 SCR on the second. I witnessed how his car ran with that cam from lane next to him.

Pump gas street engine 455s with stock or pocket ported d port heads we have liked to be close to 9.7 SCR. When we went through the effort to do a lot of porting I have always used a custom cam. The highest pump gas 455 I have done was 10.35. No 96 heads, no porting, RA manifolds, q jet and Pontiac intake. Ported head I am closer to 11.

The highest SCR’s with that cam so far for me would be a current RA 4 engine with 4.25” stroke at 10.1 SCR and a RA 3 400 that was 9.98. It wouldn’t have hurt the 400 to be higher than that.

[77 TRASHCAN]

Jay,
So you've raced against Jim's wagon??? at Kansas City??? About when???
Just curious...

[Jay S]

Originally Posted by 77 TRASHCAN

Jay,
So you've raced against Jim's wagon??? at Kansas City??? About when???
Just curious...

Yes at KCIR, in the late 90s. I remember recognizing his car for the first time right after his car and Skip Fix’s car were featured in HPP in a Pontiac street machine feature. We race Super Pro or 10.90 index Super Street, he raced pro, I never raced him bracket racing. But we did some testing on Wednesday night test and tunes with our street cars. He did as well. He would drive his car in, you would walk by his pit stall and the car would be spread all over the place. At the end of the night he had it back together and drove it home . Lol

[slowbird]

Originally Posted by Jay S

The ICL for the XE274 out on 112 lsa is 67* assuming the ICL is running at 110.

The dcr is 7.74 with no altitude adjustment.

I think it may be doable to run a 45* intake valves and some port work it would work ok on pump gas for me in my part of the world. Stock heads with 30* degree seats the SCR is at least a half point to high for a pump gas engine. IMHO.

I will try to explain (maybe poorly lol) why this combo will have issues. A prepped stock d port Pontiac heads with 30 intakes flow a bunch of air at and below .300” valve lift. This results in high VE numbers early in the power band through the torque peak. It is probably one of the the main reasons Pontiacs ran hard through the low compression smog era and everyone else’s engine suffered. The heads flow great at low lifts and fill the cylinders well with out a lot of extra compression. When you combine a cam that is super aggressive at filling cylinders with a stock Pontiac head with a lot of compression it creates a perfect storm for preignition.

Slow bird had PORTED d port head with 45* valves. That will act different than a stock 30* head d port. I don’t know what his head flowed but every 30* seat and 45* head I have had on our flow bench the flow was much better below .3” lift than the 45* heads. If you want to run high compression on a Pontiac on pump gas either pick a cam with enough seat timing to manage the compression or use a cam big enough to manage the compression. It you want to go crazy high on pump gas then start looking a ways to put the power in later verse earlier. 45* valves are a starting place.

Again...If your following Butlers cam advice. Go to 45* intake valves.

Heads flowed 235-240ish ran 11.8s @113

Also fwiw may dad ran the 068 cam in a 400 (actually a 389 bored .060 using stock 400 pistons) in the 80's in a 4000lb car with stock 13 heads ran 12.9-13.0s. The 068 cam isnt a bad choice at all.

[77 TRASHCAN]

Originally Posted by slowbird

Heads flowed 235-240ish ran 11.8s @113

Also fwiw may dad ran the 068 cam in a 400 (actually a 389 bored .060 using stock 400 pistons) in the 80's in a 4000lb car with stock 13 heads ran 12.9-13.0s. The 068 cam isnt a bad choice at all.

Seemed like Jim Hand really liked it, may have used 1.65 rockers with it...