Engine and Transmission Tech

QUESTION: (esp to Nick)

What have you done to the Heads to improve flow?

The airflow of rover heads needs to be improved before ANY high lift cam makes a difference. This is why the "stock" cam works so well... it's matched to the head ports. Bolting a higher lift, longer duration cam into "stock" heads has been shown on the dyno to make little, if any, difference!

I'd make sure the heads can flow for those larger valves. You'd want something better than 160 cfm (intake) and 130 cfm (exh) for those size valves at that lift. (Those are 28" merc. readings.)

Just bolting a lot of "bigger" parts on isn't going to make any difference if you haven't changed the flow characteristics of those heads. They have always been the limiting factor to performance of that motor....

$.02

> What have you done to the Heads to improve flow?
> I'd make sure the heads can flow for those larger valves. You'd want
> something better than 160 cfm (intake) and 130 cfm (exh) for those
> size valves at that lift. (Those are 28" merc. readings.)

Switched to 1964 Buick 300 heads, ported with larger seats and valves.
CFM is just under 200 on the intake and a little over 150 on the exhaust.

> The airflow of rover heads needs to be improved before ANY high lift cam
> makes a difference. Bolting a higher lift, longer duration cam into
> "stock" heads has been shown on the dyno to make little, if any, difference!

Some dyno results below which do show HP increases. As with any
engine it's the incremental contributions of the combination that
make power.

> This is why the "stock" cam works so well... it's matched to the head
> ports.

I never found the stock cam to be particularly good. HP is directly
proportional to RPM. Cam duration drives RPM. The stock cam has too
little duration to support much in the way of RPM.

> Just bolting a lot of "bigger" parts on isn't going to make any
> difference if you haven't changed the flow characteristics of those
> heads. They have always been the limiting factor to performance of
> that motor....

Way back in 1961, Hot Rod Magazine presented the results of dyno
testing on both the Olds and Buick 215's. Starting with a 2 barrel
Buick that dyno'd at 136 HP, they ended up with a high compression
2 x 2 bbl engine that made 233 HP. Changing from the stock cam to
an Isky E2 cam, it went from 177 to 215 HP (Hedman headers and larger
carbs were installed at the same time). In the testing sequence
of the Olds, they went from a stock cam to an Isky E-4 and went from
172 to 194 HP. Head porting on the Buick picked up 7 HP.

More recently, Ted at T.S. Imports provided the results of a dyno test
on a Rover 3.5L and the results were published in a 1995 British Car
article "Improving the TR8 & Buying a TR8", Dave Destler, 1995 British
Car, pp 35, 47-48. The "V8 on the Dyno" sidebar gives the relevent
information:

conducted by Ted Schumaker of TS Imported
rebuilt 3.5L Rover V8
stock bore and stroke
unmodified cylinder heads
22 lbs steel flywheel (stock is 32)
Tri-Y TR8 headers
10.5:1 compresson cast aluminum pistons
Isky 264 hydraulic flat tappet camshaft

Run 1:
Holley 390 carb, vacuum secondaries, #51 primaries, #58 secondaries, Offy
JWR dual port manifold, 22 degrees advance, vacuum advance disconnected

RPM Torque HP
4000 211 161
4500 210 180
5000 205 195
5500 189 198
5700 189 205
5900 181 204
Run 2:
Holley double pumper 390 carb, mechanical secondaries, #62 secondary jets,
Offy/JWR dual port manifold, 28 degrees advance, vacuum advance disconnected

RPM Torque HP
4000 --- ---
4500 219 187
5000 210 200
5500 197 206
5700 191 207
5900 182 204

A later test was run with an Edelbrock Performer Rover intake and and the
results published in the MGB V-8 Newsletter, Issue III, Vol. I:

Run 3:
Edelbrock Performer Rover dual plane manifold, 30 degrees advance

RPM Torque HP
4000 232 177
4500 230 197
5000 222 212
5500 215 226
5700 217 235
5900 207 232

Dan Jones

> Head porting on the Buick picked up 7 HP.

I was surprised the head porting didn't pick up more.
I suspect the dual plane intake manifold was at fault.
If the intake manifold is more restictive than the
cylinder, which is usually the case with dual plane
intake manifolds, then you won't realize the cylinder
head's potential.

Dan Jones

Thanks for picking up the ball on this one, Dan. The answer is yes 300 heads larger valves and porting. Right now I have my heads back in the shop again to have beehive springs from CompCams installed. I'm also considering taking the heads to the next level from a port standpoint. My engine machine shop has a porter with a good machine but it couldn't hurt to toss in a couple pointers on specifics for the porting.

Do you have diagrams for where the most flow yield is to be had from the 300 heads, Dan? Where should I tell my guy to focus?

BTW here's a link to my head mod page:

[www.cardomain.com]

I think the 300 heads have 52 cc chambers as well so a different piston might be needed. Olds 4 bbl and Jetfire heads should be the same as the Buick and Rover, while I think the 300's are close to the same as the 2bbl Olds.

Nick, are those behives going on 300 heads? Since you are using them, could you ask if they will fit the Olds heads also? Lighter retainers should be a plus.

Jim

OH one more thing. I'm planning on going with the Harcourt single plane. It's got a pretty big plenum. The middle ports are going to have the best access to the carb. I'm also concerned about the fuel ratio imbalance between 7 and 2 because of the firing order. because 5-7 fire in order, fluid dynamic inertia will favor 7 and that has to reverse to get to 2.

What do you think? Do I need to insert dams at 7 or something? Or just let it go? I did find a dyno place that will tune on the engine dyno with wideband at each cylinder...

I'm not sure what the difference is in the pocket size for the Olds head. I've only worked on the 300 head. From what I understand the springs I used for that setup with a mildly aggressive cam were for a SBC. What is the Pocket dia for the Olds?

The Buick pocket dia. will take 1.260" dia. springs. I'm ordering CompCams #: 26915 for the LS1. It's seat pressure is 105 lbs. and 290ish lbs. open. It's dia. is 1.290" but I'm pretty sure I can have 30 thou machined open. The spring height is 1.7 for my cam choice.

The comparable standard spring would be TA_1436 from TA performance. Here's a link with details.

[www.taperformance.com]

Sorry I couldn't find any reference to the spring dia for the Olds. Post it if you can, Jim.

> Do you have diagrams for where the most flow yield is to be had from the 300 heads,
> Dan? Where should I tell my guy to focus?

No diagrams but take a look at the close-ups here:

[www.bacomatic.org]
[www.bacomatic.org]
[www.bacomatic.org]

I'm not sure if you have the option to view the full resolution like I do but try this link:

[www.bacomatic.org]

If he's ported Buick V6 heads before, the Buick 300 responds to similar work. The bowl area and short side
radius are the areas to pay the most attention. I'll compare a stock Buick 300 head to my ported heads
this weekend to see if I can come up with anything more specific.

Dan Jones

Thanks Dan. I'll pass these on to my porting guy. I'll also mention the info about the Buick v6 heads.

Nick I'm sorry to say I can't answer that question. Heads from the blower motor left today and the only other Olds heads I have have been converted to straight springs. I do know the Buick 215 and 300 can use the same springs and suspect the base of the Olds spring is the same, but I have no way of knowing for sure.

Jim



Edited 1 time(s). Last edit at 12/12/2008 07:27PM by BlownMGB-V8.

We took a good look at the cross section of the head I sawed up today.. the intake looks pretty cut and dry but the exhaust side is pretty restrictive.. we welded up the port floor and raised the roof.. man does that ever straighten it out.... we will look into claying up the floor on a full, good port ,and raising the roof to see what kind of gains we get on the bench.. the will essentially straighten out the dogleg..

> We took a good look at the cross section of the head I sawed up today..
> the intake looks pretty cut and dry but the exhaust side is pretty restrictive..
> we welded up the port floor and raised the roof.. man does that ever straighten
> it out.... we will look into claying up the floor on a full, good port, and
> raising the roof to see what kind of gains we get on the bench.. the will
> essentially straighten out the dogleg..

That should help a bunch. Vizard did something like that on a Rover head:

[www.bacomatic.org]

He also welded up the intake ports (on top of the casting as well as the port floor):

[www.bacomatic.org]

Valve sizes were increased and a chanmbers welded and re-worked:

[www.bacomatic.org]

Will you also be welding up the intakes? On my ported 1964 Buick 300 aluminum heads,
we used Buick V6 Stage 1 valves from Ferrea. The intake diameter was 1.775" and the
exhaust 1.5" (stock is 1.625" and 1.312", respectively). With those valves and no
weld work on the exhaust, the exhaust flowed around 75% of the intake flow:

Lift I E E/I
0.100 66 47 71.2
0.150 99 82 82.8
0.200 129 104 80.6
0.250 155 119 76.8
0.300 174 130 74.7
0.350 187 139 74.3
0.400 191 146 76.4
0.450 194 150 77.3
0.500 196 152 77.6
0.550 200 153 76.5
0.600 200 153 76.5

Increasing the exhaust to intake flow ratio beyond that value generally doesn't
make any additional power but may increase fuel economy somewhat. Higher
compression ratios (13:1) tend to favor a lower ratio. Given my results, it
appears that increasing the intake valve diameter at the expense of the exhaust
might be beneficial, assuming there are no shrouding problems. If you do end
up with higher exhaust ratios, you may want to consider a custom cam with
shorter duration and lift on the exhaust side.

Dan Jones

OK so I got a minor problem. The Iron Duke intake isn't long enough for the .544 lift of the cool Erson cam I got. He's looking for a valve that will be long enough to fit without boring the guide out. That way we can retain the smaller dia. 5mm stem for flow. The 231 valve head is too big at 1.8" dia. but the stem works. We could go with the standard buick v6 valve but we'd have to bore out the guide.

It would be ideal if we could end up with a total length of 4.730"

This is all to use beehive springs. I may have to revert to the standard springs. Thanks in advance for any input.

Well it was just a pipedream but you never know. Not all bad though I've officially converted to the larger dia. stemed late Buick V6 valves like Dan. I'm using Comp Cams beehive springs #: 26915. Sweet!

Thanks for all the support everybody. Holiday wishes to all.

OH, Tony, I'm saving all my parts: Valves, Springs, Retainers, Keys, Cam, etc.
Were you interested in using them?

Nic
Ill probably go the Stage 1 valve route as well.. Im also most likely going to need clearance for .580 lift..

I had thought about saving the cam for the Olds engine but I just laid out some money for Chevelle repairs.. Ive got to keep the "done" one running.. I didnt go racing once in 2008! and Im starting to suffer withdrawal! LOL
So if anyone else is interested.. this is all the stuff from the Dan Lagrou 300 head upgrade..it should work real well for a pump gas street bruiser!

Damn, I'm Iate for a party now!

Hi ,

I read with interest the advice given on cam selection and I wonder if anyone can assist with this one.

my current cam is 263 duration 47 overlap 108 lobe center separation and a low lift of .38 (rocker ratio 1.6) coupled to low compression pistons(fish bowls) in a 4.4 litre Leyland terrier(p76 truck engine)
with heavier crankshaft weights.
car is a triumph stag ..Green of course(reg is Fastag) and has 2.78 diff with alloy housing for lighness. has 5 speed supra box.

so reasonably light for a car but gearing is hard with a tall first I think on the supra box compared with the rover 5sp as well.

I am rebuilding with higher compression around 10:1 mayby 9.5 ish for fuel type.

This is an every day car and I'd just like to use the stage 3 head's capacity more. they have the valves from the newer discovery in them so.. 1mm larger or so.

I've been reading D. hardcastle..both books and vizard "how to build hp"

not racing obviously but how far can I go as the cam was first put before I opened up the inlet with open plenum manifold and
4 barrel 465 holley instead of stock p76 manifold with 2brl holley.

your thoughts on a cam selection guys ?

this is a great site..hope I can assist as well as getting assistance.
Rod

Dan.

I f you have time to comment I would love to hear your opinion on a new engine I have recently built and installed in my MGB GT which is probably around 2300lbs weight and runs a rover LT77 gearbox with .78/1 5 th gear and 3.08/1 final drive.

The engine spec is based on a 3.9 block which is fitted with a 3.03 stroke crank 5.85" rods and Keith Black hypereutectic chevy 305 flat top pistons for a bore size of 3.736" for a capacity of 4.35 litres approx 265 CI with a relatively short stroke

I have fitted Buick 300 heads with the faces machined 40 thou to reduce chamber volume to approx 48cc and fitted 1.63" Inlet valves and 1.4" exhaust valve both with waisted stems, the heads have been modified to open up the seats to the larger valves sizes and the bowls opened up to match with the guides bulleted to the same extent as your 300 heads. I purposely left the port runners as cast apart fron cleaning up a few rought bits of casting to maintain suspension of the fuel at lower RPM's

The decks were also machined 40 thou. to give a compression ratio in the region of 9.4/1 with composite gaskets, the pistons have not been pocket for the Buick rover valve position so erred on the safe side for as didn't wan't the valves kissing the pistons but would like a bit more static compression to offset the overlap as I'm sure that only 9.4/1 is going to cost me power, tin gaskets would get me in the region of 10/1 which would be nice.

The cam I selected bearing in mind that the use of the car will 90% road is a Crower 50232 and the induction system is currently an Edelbrock 500 on a performer manifold, I haven't as yet re-jetted the carb from the 3.5 settings but it does run reasonably apart from being a pig to start from cold.

Current primaries are 1441 rods and 1421 jets with the secondaries as stock so probably a little lean but it will run cleanly down to approx 1500 RPM in 4th gear but doesn't like it if you give a bit of throttle and you need to drop it down a gear or two if you want to accelerate but I'm obviously not using WOT at the moment. but it has had some short burst of hard acceleration to bed in the rings, and pulls very strongly and clean from around 2000 RPM and really wakes up at around 3000RPM.

I am also going to switch over to EFI in the near future and have the hardware from a Hotwire system and a Megasquirt ECU to control fuelling and ignition, the engine has a trigger wheel and sensor in place, and bungs in the primaries for Lamba sensors so only plumbing and electrical left to do after i've mdded the inlet to mastch the Buick ports.

You may not remember, but you gave me some good advice on setting up the carb for the original 3.5 engine for which i am grateful.

I think that the spec of the new engine is in the right ballpark but any commnts and advice would be gratefully recieved.

Regards,

Kevin Jackson. UK.

Dan

PS. Do you happen to know the actual valve opening and closing numbers for the Crower 50232 cam as the card that comes with the cam only gives figures for dialling in the cam.

Kevin.

[www.crower.com]