FE Power Forums
FE Power Forums => Non-FE Discussion Forum => Topic started by: hotrodford on February 04, 2024, 08:33:34 PM
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Working with a set of 351C 4V closed chamber heads for my vintage road race car. The intake seat has/is a "venturi ring". The 60 degree cut just barely catches the seat. The throat diameter at the ring is 2.05 and narrows to 1.85" as approaching the turn.
As a"mid pack racer" am I just as well off to stay with a 2.19 valve and preserve the "venturi ring" or go to a 2.25" valve and do a 30-45-60-75 to a 1.9" throat"?
The exhaust has a ring also but I can do 30-45-60-75 to blend into the port and eliminate the ring without going to a larger valve. Good idea or bad idea?
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1.900 throat is a bit small, 89% would be 1.940, 90% would be 1.971, 91% would be 1.993". If those seats were cut properly you should be able to work with that. Going to a larger valve there would get you some shrouding of the chamber and cylinder wall and lose flow. If you need to buy new valves anyway, try to get 2.200" or 2.225" to help with unshrouding and gain your multi-angle valve job. Looking at the picture, it looks like someone cut your venturi out directly under the seat. Hopefully you can make it work. Joe-JDC
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Thanks Joe,
This might be a better picture.
The venturi rings are intact and the seats are untouched (from the factory) other than the one I lightly touched with a 30 and 60 just to highlight it. The 45 has the dye on it. The 60 is narrow and ends at the inside edge of the venturi ring. That inside edge of the venturi ring is 2.05". Right above that 2.05 diameter the venturi widens out a little before coming back in to 1.85" before the turn. I didn't know which was the better way to go. I didn't know if it was better to stay with the 2.19 valve and preserve the venturi, by using a light touch on the 60 or to go ahead and go to a larger valve to get more modern type of "radius".
Dennis
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Vintage road race you say. Typically, a larger valve may work to cut low end torque if not hp. Depending on the tracks you run at, if they do not have tight, slow corners where low end power is king, then the larger valve would not hurt cornering power.
Btw, tell us about the car and post some pics. We really don't often get road race engine questions here.
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With the 351C "Big-Port" 4V cylinder heads it is the modifications of the area below the seat and particularly the short-turn radius that will provide the greatest effect for the effort but forth; you can in all but the case of the greatest efforts pretty much ignore the rest of the port. Simply stated, all of your efforts would be to aid in the reduction of interference in the process of the atmosphere traversing through the passage, the inlet port runners though arguably are not the most efficient are of substantial area, and since the actual seating surfaces between the opening and closing flow control valving imparts the greatest restriction, the closer to this that efforts are extended the greater the gains.
Specifically, the O.E.M.'s 90-degree cut below the 45-degree seating angle (note that the original O.E.M. machining did not incorporate a 60-degree angle) creates too great of a change of direction within in the distance, this causing the laminar flow in close proximity to these surfaces to be lost, this first increasing the boundary layer and then inducing turbulence, thus an effective reduction in functional area, particularly at the higher velocity rates. Therefore generally it is accepted that in these instances, a larger valve head diameter will provide one the opportunity to correct this.
But then yes, in the case of the 351C 4V heads (those w/ 2.19" valves), they already present generous dimension, thus creating other possible concerns, so some conservatism is generally needed here as compared to that of for example the typical in-line valve head examples. Therefore, as stated by another, if your needing to purchase valves anyway, and if the job were in our shop, I would advise bumping the diameter up a bit; just that which would prove necessary to provide the area required for a better resultant effect from the valve job, particularly if bowl porting/blending is not to be incorporated in the effort, but this sum specifically would need to be established by the one executing the work on those castings.
And while on the topic of attempting to better the flow in the port, and with the thought of "transitions" and their possible negative effects, note that the greatest offender on that port tract is the 'short-turn' radius, which actually suffers from even qualifying as such, rather there is presented an absolute 'shear', which presents the worst possible effect on attempting to avoid inducing a turbulent result; so if porting is permitted, effort here will aid tremendously even if one doesn't do much of anything else in the way of porting.
Scott.
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Thank you for the replies.
The car is a 69 M code with a D1ZE B302 block and heads (no mods to the heads). This is my first and only race car build. I estimated 4 years to build and it took 9 years (curse of being a teenager in the 60's kept me going on it)!! It is a vintage correct car built to the 1969 GCR.
This will be my 6th year racing it and I got my first 3rd place finish this past October at HMP Topeka with HVR (Heartland Vintage Racing). To be fair though, in that race, three of the fastest cars were sidelined. Myself and the 4th place car had a great 15 minute battle for third. There are no prizes or money, it is just for the fun of it. I also take the car to the Mid America Ford Meet and run the Vintage race at Hallett. This year is the 50th, by the way, should be a great event!!
With 5 years of seat time, gaining some "tire pressure and shock adjustment" knowledge and getting 75 lbs off the car, and with the club now allowing roller cams (I have a solid flat tappet), I think I can take advantage of the improvements a roller cam and a bit of headwork might provide. I am also considering one of the smaller diameter clutches (would save another 20 lbs or so) and merge collectors. It is a "work in progress".
Link attached is short video of the cars at Topeka this past October.
https://www.youtube.com/watch?v=SFCDF8Irk3
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Vid shows as 'not available'.
KS
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A very nice car! Parnelli would be proud of you :)
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Try this:
https://www.youtube.com/watch?v=SFCDF8Irk3o
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Glad to the Mustangs are well represented. Your car looks great!
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I went thru the engine in my buddy's 1970 Boss302 in '79, and changed a few things. Dykes rings with spacers (old Stock class trick) that Cantrell had laying around, got rid of the tunnel ram with 600's that he had on it and put the original intake back with a 750. Heads were done at Hannan's in Oakland, and a (then) road racer's trick, installed tulip-shaped 426 Hemi valves with 5/16 stems, according to Cantrell someone had tried it to tame the big Boss ports with the tulip shape, and it worked. I know in this case it did, the car was much faster and more driveable, with a smaller ("Sullivan") cam which also works well in a B2. The car was driven on the street with 2.75 gears for 20 years with no driveability problems, was very responsive and sounded great
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I'm a drag racer and not sure what your rules are, but I grind all that under the seat smooth for transition into the port and narrow the guide. I would not put in a larger valve, in fact it's a decent supposition that the 73/74 4V heads with a 2.08 valve might make better torque. Speculation, but less shrouding and possibly more velocity. I know for sure putting a 2.19 in a 2.08 2V head is a partial fail due to the 2V port configuration.
If you really want to wake it up and the rules allow, you'd want to fill the port with some port tongues (Terry Parker, et al from AUS) and partially fill the intake to transition to the reduced port entrance. They reduce the port volume from around 260cc into the 220cc range, more or less
These are for a web site I did for Terry in relation to his Funnelweb intakes, but you get the idea.
(https://raceabilene.com/kelly/hotrod/images/funnelweb/funnelweb1.jpg)
(https://raceabilene.com/kelly/hotrod/images/funnelweb/funnelweb4.jpg)
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I have a pair of '69 Boss 302 heads that have a 2.250" intake valve seat. It is doable, but not the best for a small cubic inch engine. Since you use an 8.2 deck, what intake manifold are you using? Joe-JDC
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I have a pair of '69 Boss 302 heads that have a 2.250" intake valve seat. It is doable, but not the best for a small cubic inch engine. Since you use an 8.2 deck, what intake manifold are you using? Joe-JDC
Ford must have agreed with you, they reduced them to 2.19 for the 70's
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Yes, the '69 Boss 302 had 2.230" intake valves which was proven to be too big for the cubic inches. My heads had a bad valve job, and had to go to the 2.250" valve to get some of the angles back. Joe-JDC
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I have used the factory stock intake and out of curiosity and a recommendation from Randy Gillis, RIP, I put an Edelbrock #7129 on it (it was less than $200 when I bought it). Even though the 7129 is designed for the 2V port location with the track and competition as my dyno it has been the best $200 I have spent!!!! Dennis
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The port match isn't real good LOL but it is a good trick. I've run a 2V Funnelweb on my 4V when I didn't have anything else available and it worked well enough. I'd still encourage you to consider the port tongues if rules allow - you'd certainly pick up torque coming out of corners and that should reduce your lap times. Port work - I did mime in the shoip - is really minimal on 4V heads. The final numbers IIRC were 330~340 at .550 intake and right at 200 exhaust at same height. I run a solid roller 248/254 with .664/670 lift - custom Lykins Motorsports cam. Drag racing, so the only corner I turn it to gently exit the strip. If you update your cam, I very much encourage you to discuss your needs with Brent at Lykins - he can get you a stick that works.
A view of my filled intake ports - updating the engine after lunching an oil pump, should be back in the car shortly. Dufus here misplaced a pushrod so waiting on one stinkin' 8.250 x 3/8 pushrod to come from Summit [facepalm]
(https://raceabilene.com/misc/351cNotes/2023/2024_351C.jpg)
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I appreciate all of the input.
Are those Price Motorsports Stuffers you have there?
Since I have to get the car together and ready to race for May, for now, I will "mildly" work on the short turn and increase valve size only enough to gain a more favorable entry from the bowl area into the combustion chamber.
Thought I would use a cartridge roll on the short turn just enough to take that "high spot" off, so to speak, as shown on the pic attached.
Dennis
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My stuffers actually came from Parker in Australia. If PME makes some, those would also work. Yes, just a bit of cleanup to smooth the air flow could help. It's a big port, no need to get crazy LOL. Finally found some pics stored on my web site
(https://raceabilene.com/kelly/hotrod/images/falcon/2007351c/4vHeadChamber600.jpg)
(https://raceabilene.com/kelly/hotrod/images/falcon/2007351c/4vHeadIntake600.jpg)
(https://raceabilene.com/kelly/hotrod/images/falcon/2007351c/4vHeadExhaust600.jpg)
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....My stuffers actually came from Parker in Australia.
Chris, did you install them pretty much as is? It's been a long time, but I thought the Terry Parker stuffers also crept up the side of the port so as to bias the port toward the unshrowded side of the valve. Maybe that was just his "2V Funnel Web" stuffers? Ever try a filled floor intake or just smaller cross section intake on your C without stuffing the head port?
I ask because over the years, I've seen a number of B302 and 351C builds that have used intakes with much smaller (than 4V) ports that were not port matched and they made better power everywhere. They weren't really racing engines but fairly potent pump gas street car builds. One was a 347CI B302 headed engine with an Eddy air gap "e-Boss" dual plane on essentially stock B302 heads. Since the Eddy-made 335 series style head port windows are quite a bit smaller than the original B302, so is the Eddy intake. The ports were left unmatched on that stroker and it made ~530hp at ~7krpm and drove quite well.
I've been making custom cast intakes for a while now, and I've been making just about all of the 335 series lids with the runner floor raised 1/2" and telling the customers not to bother with the head port or trying to port match. This reduces the 4V cross section about 20%. The combination of the velocity increase and likely the port step being disruptive to low/mid reversion from healthier cams seems to get both good performance and better street manners. Some customers just ca'nt get past the idea everything needs to be perfectly gasket port matched and insist on the full 4V port......which they can have but wont run nearly as well.
It's also a popular misconception that 2V 335 series heads/intakes are just smaller cross section ports centered in the 4V pattern, but they are not, and are actually biased to the side and top of the 4V port. A quick look at a couple overlayed gaskets tells the tale. For quite a while, it was common knowledge in the Pantera crowd that the stock 351C would runner better at every rpm and especially down low just by bolting on a Weiand 2V "Excelerator" intake.
Best,
Kelly
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Sorry, didn't see the q until now!
The stuffers are as-delivered, set in place with Splash Zone Compound and a 10-24 socket head cap screw under to hold in place. I have seen pictures the ones that bias flow but have not noted that they come from Terry. As for intakes, I have both a 4V Funnelweb (real, imported from AUS) and a CHI intake and those both fit the stuffed 4V heads and match well with my AFD 3V aluminum heads. I have a 351C tunnel ram that I've had on the motor but a bit with a couple of "1850" Holleys for fun but never really worked them hard. The mis-match didn't seem to cause any kind of trouble. If I get serious with the T-ram, I would look for something to fill the bottom of the parts at least an inch or so up to mate better with any heads. Normal bracket config on the 351C is a 650DP on the Funnelweb. I will be trying methanol - again - this season on the 351C with a custom built 750DP. A long term wish is the T-Ram with dual Holley EFI units on the 427 9.2 deck Dart build running both a gas and methanol program.
I have run a 2V funnelweb on the 4V heads with the poor mis-match. Ran well enough in that condition and it was all I had because the 4V was on the wife engine. You are also correct, the 2V ports are not even the same. An intake port will land as you said and in the 2V heads the floor is way flatter and the short turn abrupt. Velocity and flow is good, to a point. I have also done the Xcelerator 2V trick LOL. When people start that "4V port just too big, terrible blah, blah" I just tell them "it's all in the parts combination and the tune up."
I'm running brackets, not Pro Stock so my attitude on port matching is
(https://raceabilene.com/misc/GoodEnough.jpg)
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....When people start that "4V port just too big, terrible blah, blah" I just tell them "it's all in the parts combination and the tune up."
Truth.....light and even no work on 4V heads can still get good performance compared to other OE stuff, but something motivated you to stuff the ports. :)
.....A long term wish is the T-Ram with dual Holley EFI units on the 427 9.2 deck Dart build running both a gas and methanol program.
I have a 427CI (4.125b x 4s) 9.5 deck Siamese Dart block I pulled from my Pantera. Also wearing Brodix BF301 think C302B) heads. Drop me a PM if interested in more details.
Best,
Kelly
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....When people start that "4V port just too big, terrible blah, blah" I just tell them "it's all in the parts combination and the tune up."
Truth.....light and even no work on 4V heads can still get good performance compared to other OE stuff, but something motivated you to stuff the ports. :)
.....A long term wish is the T-Ram with dual Holley EFI units on the 427 9.2 deck Dart build running both a gas and methanol program.
I have a 427CI (4.125b x 4s) 9.5 deck Siamese Dart block I pulled from my Pantera. Complete very low mile engine wearing Brodix BF301 (think C302B) heads. Drop me a PM if interested in more details.
Best,
Kelly
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Are you all familiar with the D3 C head? Reason I ask is because I have a pair that have been sitting in the corner for 30 years, so to speak, that I have never given a second thought to because they are open chamber. For some reason I decided to take a closer look at them and, to my surprise, they have 2V valves but they are 4V heads. The "bowl area" is smaller as compared to the close chamber 4V head but is still an "inverted funnel" shape like other C heads.
The inverted funnel shape of the bowl area, on C heads, puts the "throat" at the base of the short turn as opposed to right above the valve seat. With the D3 head having a smaller bowl that translates into having more to work with meaning with a 2.1 valve or certainly a 2.19 the throat could be located right above the valve seat as opposed to 1/2" above the valve seat.
Would that translate into improved flow as compared to 4V heads that are 2.19 valve sizes OEM?
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I took a set of 2V D1 heads and put 2.19/1.71 valves in them. Did some porting, smoothing, etc. At about .450 lift on the flow bench, the air quit making the short turn with a BANG and flow dropped like 30 cfm. Still ended up in the 250 range at .550 on intake but it was weird. D3~D5 cast "4V" heads all came with open chambers and the 2V 2.04/1.66 valve sizes. Most of those heads are D5 castings AFAIK. If that short turn is close to the valve, IMHO as a total amateur porter I think you'd possibly aggravate an already iffy flow condition by increasing the valve size. The tongues raise the floor and give the air a better shot at the valve which would make the port work better for the larger valve area.
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If that short turn is close to the valve, IMHO as a total amateur porter I think you'd possibly aggravate an already iffy flow condition by increasing the valve size.
If 'just' increasing the valve diameter and incorporating a machine throat opening below the seat angles into the casting, then generally yes. But again generally if one is incurring the effort to increase the valve size and this is with performance in mind some sum of porting/blending is involved which mitigates the negative, with the limitation then becoming based on the effort and capability of the individual, and/or the castings' capacity. :)
The tongues raise the floor and give the air a better shot at the valve which would make the port work better for the larger valve area.
Well, maybe; and it all sounds good, but it just doesn't always work that way. Remember, the goal in port modification is to provide a greater effect of coercing vs. forcing the air to follow the path set forth by the port pathway, and sometimes this requires an influence upon the air column ahead of the the intended action so as not to grossly upset the continuity in that column in the greater ulltimate intent.
As an example, though somewhat removed, and yes there are many influences at work, but just for thought: For the most part, in time, a winding river will generally increase the arc of of it's turns, the river moving outward and exaggerating the radiuses (O.K. radii ::); and so remember one doesn't want to purchase the property "on the river" on the outside of a turn! :o); and haven't you always been taught that "water will follow in the path of least resistance"? ???
Scott.
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This is a picture of the B302 TA combustion chamber. This type of multiangle radiused valve seat isn't achievable on the production B302/Cleveland head, from what I am seeing, except maybe the D3 head.
I have found some approximately 20 year old posts (other forums) that the D3 head is the head of choice if "one knows what to do with it"!
What I am curious of is this type of radiused valve seat worth the work as compared to what can be done with the 2.19 valve heads?
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This is a picture of the B302 TA combustion chamber. This type of multiangle radiused valve seat isn't achievable on the production B302/Cleveland head, from what I am seeing,................
What I am curious of is this type of radiused valve seat worth the work as compared to what can be done with the 2.19 valve heads?
Specific seat and adjoining contour angles and widths, in seeking something of ideal in greater flow, will vary by cylinder head type example, and it can be quite enlightening as to how sensitive some types are to changes; so one blanket statement could be dangerous territory, but generally the more gradual the transition the 'more likely' one will experience better results. But there is also a limit to everything. :-\
Scott.