So I have a plan but now im Second guessing myself.

48kenworth

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So as of right now my 78 f100, np435, 2.75 rear end, and powered by a .030 over 300 has an offy DP, 500cfm edelbrock with annualar boosters,
Chevy rockers, EFI manifolds, 2.5" exhaust, and 12degrees base timing rolling smoothly up to 38 degrees at 3000rpm.

I scored a 240 head that I'm am planning on having worked over, bigger valves, porting, gasket matching, screw in studs, all the normal stuff...

At the same time I swap the head I intend to throw an isky 256 supercam and proper springs at it.

This is still a work pickup though that does get labored fairly hard at times and I'm really concerned that I may have issues running 87 octane once I swap in the head and cam. Truth is I'm really not intelligent enough to determine if this set up will work on regular unleaded?

I have also no yet determined if the high ratio rockers will work with that cam or not..
 

THE FRENCHTOWN FLYER

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I would knock back the total timing to 33 - 34 degrees.
Sure, the 1.76 rockers will work with your combo. Be sure to check for coil bind and sufficient clearances in all the usual places.
 

pmuller9

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Assuming the current static compression ratio is around 8.4
The Isky 256 cam has 12 degrees less .006" duration than the stock cam and closes the intake valve 10 degrees sooner than the stock cam if it is installed straight up.
That will raise the Dynamic Compression Ratio by 0.5

The 240 head will raise the DCR another 0.5 putting the final DCR around the 7.6

Way too high for 87 to 89 octane pump gas.
 

48kenworth

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I was under the impression that the smaller chambers would affect static compression by 0.5 and would have a lesser effect on dynamic compression. We are having a conversation that's on the fringes of my mathematical abilities.
 

pmuller9

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Let's say that the static compression ratio is 8.4
That's with a 76cc chamber and 22cc pistons .025" in the hole.
The Dynamic compression ratio is 6.6 with the stock cam 4 degrees retarded.

If you change to the 240 head with a 68cc chamber the static compression ratio goes to 9.0 and the dynamic goes to 7.0 which is still good for 87 octane gas.

If you change cams to the Isky 256 and install it straight up with no advance the static compression ratio stays at 9.0 but the dynamic compression ratio moves up to 7.6 which is too high for 87 or 89 octane gas.

You would need a larger cam which is what we have been recommending for all applications.
The Crower 284HDP (19205) or the Schneider 140H (13912) would take care of the problem and give you a very wide power band with plenty of low end torque.
 

48kenworth

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pmuller9":2r93meh0 said:
Let's say that the static compression ratio is 8.4
That's with a 76cc chamber and 22cc pistons .025" in the hole.
The Dynamic compression ratio is 6.6 with the stock cam 4 degrees retarded.

If you change to the 240 head with a 68cc chamber the static compression ratio goes to 9.0 and the dynamic goes to 7.0 which is still good for 87 octane gas.

If you change cams to the Isky 256 and install it straight up with no advance the static compression ratio stays at 9.0 but the dynamic compression ratio moves up to 7.6 which is too high for 87 or 89 octane gas.

You would need a larger cam which is what we have been recommending for all applications.
The Crower 284HDP (19205) or the Schneider 140H (13912) would take care of the problem and give you a very wide power band with plenty of low end torque.

Thanks a bunch! I considered a longer duration cam to begin with but was concerned that my tall gears would really make crawling though a pasture with a load very difficult. Although I am well aware that I do not have math on my side I am having a difficult time visualizing good performance from 1000-3000rpm with a cam who's manufacturer states it's power range begins at 2500rpm. I trust you and the French town flyer as you have both been good to me but somebody will have to assure me that snheider cam won't be lumpy and gutless at 800rpm.
 

BigBlue94

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I can actually add to a thread haha!

I'm running 9.75 static CR with a dynamic CR of 7.47. It runs great on 91 octane. It ran okay on a 50/50 mix of 91 and 85 octane (at a much higher altitude than I live).

I am running the Schneider 140H cam and I can tell you it is NOT a gutless wonder off idle. It has PLENTY of grunt from idle to 4500+. Very pleased with it. It's also not overly lopey, and I get about 17-18" hg of vacuum at idle. It will idle all the way down to about 550 rpm, but I have it set at 800.

I run a 450 quickfuel 4bbl with a Clifford intake, headers, and 1.6 roller rockers with an HEI handling the ignition. It's in a bronco with np435 manual trans, 4.56 gears, and 37" tires. It will do 85mph down the highway all day long, although 65-70 is much more comfortable.
 

48kenworth

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I'm going to order the Schneider 140h this all makes better sense after reading the same conversation that was had with bigblue94 in the thread linked. Cam selection for a 300 is a very different thing than for a small block. It is can be hard to look at the straight 6 like a big block and harder still to look at manufacturers advertised rpm ranges and know they are not accurate for the 300.
 

pmuller9

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You will want to use a 1.6 ratio rocker with the 140H cam.
I don't remember anyone using the stock style stamped rockers but it shouldn't be a problem with a light valve spring.
Everyone to date has used roller rockers.
 

sandboxer

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Talked to Kevin at Schneider yesterday and was told that the 142F would fall on its face at 5500 because of the poor breathing of the head. That can is rated to 6500. As well, Jerry at Schneider today confirmed that they have all the requisite springs.
 

48kenworth

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That's kinda funny I talked to Jerry today and he said that he has been getting blown up with Ford inline 6 guys all week. I purchased the cam, lifters, and 110psi seat pressure springs while we were on the phone today.
 

48kenworth

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pmuller9":3btvb9aq said:
You will want to use a 1.6 ratio rocker with the 140H cam.
I don't remember anyone using the stock style stamped rockers but it shouldn't be a problem with a light valve spring.
Everyone to date has used roller rockers.

So I have to ask why you Are recommending stepping away from the 1.76 rockers? With the 140h cam that will give me .525 valve lift. Are you thinking the affect on ramp rate will affect low end torque?

I have seen stamped rockers used on some pretty wild setups here and there over the years. I don't suspect there will be any issue with my setup.
 

48kenworth

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BigBlue94":3s0iyszf said:
I can actually add to a thread haha!

I'm running 9.75 static CR with a dynamic CR of 7.47. It runs great on 91 octane. It ran okay on a 50/50 mix of 91 and 85 octane (at a much higher altitude than I live).

I am running the Schneider 140H cam and I can tell you it is NOT a gutless wonder off idle. It has PLENTY of grunt from idle to 4500+. Very pleased with it. It's also not overly lopey, and I get about 17-18" hg of vacuum at idle. It will idle all the way down to about 550 rpm, but I have it set at 800.

I run a 450 quickfuel 4bbl with a Clifford intake, headers, and 1.6 roller rockers with an HEI handling the ignition. It's in a bronco with np435 manual trans, 4.56 gears, and 37" tires. It will do 85mph down the highway all day long, although 65-70 is much more comfortable.

It would be interesting at this point to see a video of yours running. I'm excited to get mine together.
 

BigBlue94

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I too used their lifters, since they wont warranty the stick if you dont. Jerry originally recommended the 131H for me, but I wanted a bit bigger. PMuller helped me choose the 140H.

I also used their breakin additive and the ZDDP additive once the rings seated.

When I 'found' Schneider, I was amazed by the number of big six cams they offered. Be advised that they grind all cams to order, so it takes a bit longer.

The reason for 1.6 rockers is the cam was designed for them. With 1.73 rockers, the cam curve will be slightly different. The valves will be moving faster and that changes how the cam works. At least that's what I understood when I asked that question

I have a couple videos but they arent the best quality. I'll post em
 

48kenworth

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BigBlue94":et8u80hs said:
The reason for 1.6 rockers is the cam was designed for them. With 1.73 rockers, the cam curve will be slightly different. The valves will be moving faster and that changes how the cam works. At least that's what I understood when I asked that question

I have a couple videos but they arent the best quality. I'll post em

Yes changing rocker ratio alters the cam profile as far as the valves see it. I discussed the higher ratio rockers with Jerry and he didn't think they would not compliment the build but we didn't get into there affect on the power curve. Piston clearance is also a concern for me at this point.
 
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