TRExp

TR7 & TR8 Forum

Offenhauser VS Edelbrock for 4 barrel conversion.

Moss Motors
AutoShrine Sponsor
AutoShrine Sponsor
AutoShrine Sponsor
AutoShrine Sponsor

Bergie Bob Berg
Powell, OH, USA   USA
For the plumbing on the new intake the edelbrock is set up to handle coolant flow same as original TR8 set up...5/8 fitting on manifold thermostat housing feeds with a short hose to back of water pump-coolant bypass and prevents coolant temp run up before thermostat opens and maintains constant coolant flow....5/8 nipple on back side of manifold(need fitting for this) plumbs to the heater core bottom fitting and the heater core top fitting plumbs back via heater hose under intake manifold to fitting on water pump return hose connection from radiator on the top...you need to drilll and tap a hole on the top of the edelbrock manifold behind the thermostat housing-triangle fitting(also used for sensors) for the bleed nipple and that connects back to the expansion tank on the firewall....dashboard temp gauge sender screws in on front of intake manifold next to thermostat housing and the brake servo takeoff screws into the provision on top of #2 cylinder feed.....see pics of my old intake-missing the bleed nipple....for the throttle cable I bought an original tr8 carbed car version and cut it down to shorter length and reconnected a new ferrel end (bicycle fitting) with shrink hose for a clean look....I have a fitting that attaches to the intake manifold bolt but you can also attach to carb bolts with lokar and/or other aftermarket options. Lokar is a high quality piece...

. Hide banner ads & support this website by becoming a > Gold Supporting Member <

Attachments:
edelbrock 3.jpg    42.4 KB
edelbrock 3.jpg

edelbrock 2.jpg    42.7 KB
Sign In or Register to view this photo
edelbrock 1.jpg    41.9 KB
Sign In or Register to view this photo
TeeR8 Avatar
TeeR8 Gold Member Henri Lefebvre
Calgary, AB, Canada   CAN
Peter:

At the pedal end, the cable has a small ball that fits perfectly in the TR8 pedal.
Both the braided exterior cable and inner cable need to be cut to the correct length. For the braided cable I measured then wrapped the cable tightly with a few wraps of masking tape to prevent 'shredding' and used a metal cut-off disc in my Dremel. I used the same procedure when I installed a similar Lokar cable throttle for the triple Webers on my TR6.
Once I installed the bracket and outer cable, I inserted the inner cable, measured, removed and also wrapped it with tape and used the cut-off wheel to trim. I made sure there were no sharp edges at the cut end of the cable then re-inserted and installed it at the pedal then at the carb end.
The Lokar kit came with excellent instructions, a first class supplier.

Ross:

Yes, the bracket installs at the base of the carb where it mounts on the manifold.


My next project is to replace the triangular filter with a conventional style, hopefully with a K&N air cleaner. I have an alloy oval filter box that is a bit too high as is, but I will look at modifying it to see if it can fit under the hood.



Henri
1980 TR8, Platinum
1971 MGB GT, Midnight Blue

Darth V8R Avatar
Darth V8R Vance Navarrette
Beaverton, OR, USA   USA
1980 Triumph TR8 "Wedgie"
In reply to # 1504874 by RossL I have decided to install a Holley 390 on my (stock) 1980 TR8. I don't really care for the ZS carbs, more specifically the choke design..... I purchased a "slightly used Holley 390" with electric choke on eBay. Which I will rebuild and rejet as necessary,

What is the preferred manifold? Offenhauser or Edelbrock. Performance and hood clearance are my concerns. I assume both manifolds clear the stock TR8 hood with the proper air cleaner. I am leaning towards the Edlebrock triangular air cleaner with the foam,.

The Edelbrock manifold is the preferred one for street, unless you do not have enough hood clearance, as others have stated. Honestly, there are only a few companies left doing development on the old school carbureted over head valve stuff. Technology has moved on, and like the side valve engine the motors are simply obsolete and are a shrinking market. Edelbrock still does development for the older stuff. Their air-gap technology has been around for a while, but is the best thing going for street driven engines. For our engine, the air gap is built in, but the superior runner design on the Edelbrock will perform better than the older Offy design.

For cams, there are only 2 companies of which I am aware that are offering modern designs. Kent Cams offers a couple of designs that are up to date. Crower is the go to company at the moment with modern profiles on their cams, and all of their offerings are good designs. Chose the cam that fits your intended purpose and you will have the best possible flat tappet design. Short of converting to roller tappets I don't think you will find any better. Most companies have stopped producing the Rover cams altogether, Comp Cams and Crane be two notable grinders that have stopped making Rover V8 cams altogether. BTW, I am not saying that any particular cam is bad, I am simply saying that a more modern design makes fewer sacrifices for a given power level.

Forget about the foam air filter. They clog easily and do not flow well. You want an oiled cotton gauze design. They flow well, filter well, and can be cleaned and reused. K&N's patents expired years ago, and several companies offer the technology, so choose your preferred brand. They do cost more than paper designs, however.

As far as the carb design goes, the others in this forum are spot on. Bigger is not better for a street motor. You need good air velocity for snappy response, so something well under 500 CFM is a must on our 215CID motors. The stock Zeniths are good for roughly 440 CFM, but have the advantage of a variable venturi size, so they behave as if they are much smaller when you are idling and then behave like a much larger carb at wide open throttle. The downdraft four barrels cannot do this, so size selection is much more critical for good drivability.

And yes, you will need to rejet and tune your Holley. It would be a wild stroke of luck to have it be correct for your motor right out of the box. It will probably start and drive just fine with no changes, but optimum performance requires fiddling with jets and pump cams as others have mentioned.

Vance



1980 Platinum Metallic TR8, navy blue interior
Bare metal respray, Crower cam, raised compression
ported heads, modified Zenith carbs, 0.060" overbore

. Hide banner ads & support this website by becoming a > Gold Supporting Member <
POW Peter Wirth
HEBRON, NH - New Hampshire, USA   USA
In reply to # 1505274 by Bergie For the plumbing on the new intake the edelbrock is set up to handle coolant flow same as original TR8 set up...5/8 fitting on manifold thermostat housing feeds with a short hose to back of water pump-coolant bypass and prevents coolant temp run up before thermostat opens and maintains constant coolant flow
..


Yes, the manifold is set up for the thermostat by-pass, but the original TR8 thermostat housing, either Carb'd or FI, does not have the 5/8" nipple cast in as the one shown. Those things are kind of hard to find. Absolutely correct about everything else.

RossL Silver Member Ross LoMonaco
NJ, USA   USA
The Edelbrock manifold arrived, carb and intake gaskets are on the way. Is anyone using a spacer between the carb and manifold?

I am also going to install a heat shield. Leaning towards this one:

Heat Shield Spec

Bergie Bob Berg
Powell, OH, USA   USA
I use phenolic wood 4 hole spacers tallest you can fit under hood-I find wood works best as insulator...I also found the coned are better 2500 rpm++ especially on 360 degree/open intakes......also I use a thermo tech aluminized heat shield on the valley pan like a blanket cover to keep heat off manifold and carb (vs holley under carb heat aluminum shield)......

4 hole wood spacer (there is also a 1/4in 4 hole spacer) ...
https://www.summitracing.com/parts/edl-8723/overview/

I milled this down to fit leaving the inside "cone" full length on my wildcat open plenum intake....
http://jomarperformance.com/catalog/product_info.php?products_id=711

thermo tech blanket or use something similar:
https://www.thermotec.com/products/heat-shields-and-protection/aluminized-heat-barrier

RossL Silver Member Ross LoMonaco
NJ, USA   USA
In reply to # 1507121 by Bergie I use phenolic wood 4 hole spacers tallest you can fit under hood-I find wood works best as insulator...I also found the coned are better 2500 rpm++ especially on 360 degree/open intakes......also I use a thermo tech aluminized heat shield on the valley pan like a blanket cover to keep heat off manifold and carb (vs holley under carb heat aluminum shield)......


What air cleaner are you using? Is the spacer 1/4"?

. Hide banner ads & support this website by becoming a > Gold Supporting Member <
Bergie Bob Berg
Powell, OH, USA   USA
I'm using the wildcat open 4bbl intake which has limited clearance...currently using a dual 4inch feed spectre ultra low plenum..see link/pic below...with in line 4inch filters feed from the original fresh air duck locations on fender wells...I used the jomar coned penolic wood 4 hole spacer milled with a 4 degree wedge so carb sits level...
when I used the edelbrock 2198 intake I used a 4 hole 1/2 inch (transdapt) peneloic wood spacer(makes higher torque vs open) ....for air cleaner I had a 9 inch round x 2 inch high filter -with a k&N extreme air flow top (lid is an air filter)-there are cheaper paper 9inch filter options besides k&n...



dual plenum
https://www.spectreperformance.com/search/product.aspx?prod=9804

k&n extreme air top
https://www.knfilters.com/search/product.aspx?prod=66-0901
base and filter:
https://www.knfilters.com/search/product.aspx?prod=60-1070


Attachments:
air filter.jpg    6 KB
air filter.jpg

Bergie Bob Berg
Powell, OH, USA   USA
Here is what I have used...I looked at a lot of options for carb heat with spacers and also with a shield and settled on a blanket in valley pan....air filter I used......pm me if you want anything..

. Hide banner ads & support this website by becoming a > Gold Supporting Member <

Attachments:
99EC5514-18DC-4421-A644-3DC7CB62A494.jpeg    45.3 KB
99EC5514-18DC-4421-A644-3DC7CB62A494.jpeg

7437C98B-72BF-41C3-9F84-A47B1EA29BC5.jpeg    40.9 KB
Sign In or Register to view this photo
02CCFF1F-4C0E-436D-9794-FA26596541DE.jpeg    55.1 KB
Sign In or Register to view this photo
47132D0B-4F0A-477A-897D-47CCEC27F803.jpeg    55.1 KB
Sign In or Register to view this photo
Bergie Bob Berg
Powell, OH, USA   USA
Heat blanket


Attachments:
43022454-7FB2-48E4-ABED-C2C6CAA51BA9.jpeg    48.1 KB
43022454-7FB2-48E4-ABED-C2C6CAA51BA9.jpeg

POW Peter Wirth
HEBRON, NH - New Hampshire, USA   USA
And for another choice is spacers, what I am using. Note that it comes with required longer studs and that it needs no other base gaskets. The stud holes incorporate spacers that will prevent over-tightening (to a reasonable degree) from warping the carb base. I have found the Holley carb to be more tolerant of heat sinking than my previous Edelbrock. I attribute this the the fact that the Eddy is a one casting design containing the fuel bowls whereas the Holley's bowls are hanging out in space so not directly in contact with the manifold. My particular set-up allows starts with about 1 turn of the engine when cold though it will take more cranking when shut off hot and setting a while.

https://www.summitracing.com/parts/edl-9266?seid=srese1&cm_mmc=pla-google-_-shopping-_-srese1-_-edelbrock&gclid=EAIaIQobChMI3o2hx5PU2AIVhrfACh2cmwvfEAQYBSABEgIOx_D_BwE



Edited 1 time(s). Last edit at 2018-01-12 11:14 PM by POW.

RossL Silver Member Ross LoMonaco
NJ, USA   USA
In reply to # 1507154 by Bergie I'm using the wildcat open 4bbl intake which has limited clearance...currently using a dual 4inch feed spectre ultra low plenum..see link/pic below...with in line 4inch filters feed from the original fresh air duck locations on fender wells...I used the jomar coned penolic wood 4 hole spacer milled with a 4 degree wedge so carb sits level...
when I used the edelbrock 2198 intake I used a 4 hole 1/2 inch (transdapt) peneloic wood spacer(makes higher torque vs open) ....for air cleaner I had a 9 inch round x 2 inch high filter -with a k&N extreme air flow top (lid is an air filter)-there are cheaper paper 9inch filter options besides k&n...



dual plenum
https://www.spectreperformance.com/search/product.aspx?prod=9804

I really like the Spectre 9804. What filters did you use? Did you have to modify the intake fixtures on the firewall?

Bergie Bob Berg
Powell, OH, USA   USA
see below links....for the intake mounting 4 inch plate I opened up the fender sheet metal to feed the 4 inch hole....duct mounts to fender well with small sheet metal screws. ........the air duct hose from pegasus is very close to what as on the car originally 4inch vs 3 inch... for connecting the duct & air filter I used standard 4 inch silicone turbo hose from vibrant performance and spectre and cut to fit the correct angle with a chop saw...standard turbo hose clamps..I also used 24 inch black zip ties to hold things in place....clean set up and benefit of cold air on those hot days....additional pics below...

https://www.spectreperformance.com/search/product.aspx?prod=9148
https://www.spectreperformance.com/search/product.aspx?prod=9832
https://www.spectreperformance.com/search/product.aspx?prod=9781
https://www.spectreperformance.com/cat/air-intake-components-couplers-reducers-epdm-4?pkid=5117206&rw=6
https://www.summitracing.com/parts/vpe-2759?seid=srese1&cm_mmc=pla-google-_-shopping-_-srese1-_-vibrant-performance&gclid=EAIaIQobChMI-JH0qt3V2AIVUoezCh3_9wkREAQYASABEgKi5fD_BwE
https://www.pegasusautoracing.com/productselection.asp?Product=3630


Attachments:
cold air set up.jpg    56.4 KB
cold air set up.jpg

cold air set up 2.jpg    46.9 KB
Sign In or Register to view this photo
cold air set up 3.jpg    53.1 KB
Sign In or Register to view this photo
cold air set up 4.jpg    39.9 KB
Sign In or Register to view this photo
Bergie Bob Berg
Powell, OH, USA   USA
2 more


Attachments:
cold air set up 5.jpg    35.8 KB
cold air set up 5.jpg

cold air set up 6.jpg    34.7 KB
Sign In or Register to view this photo
Bergie Bob Berg
Powell, OH, USA   USA
BTW.....the spectre in line air filter is buried in the hose close to the air duct on fender well...

. Hide banner ads & support this website by becoming a > Gold Supporting Member <

To add your reply, or post your own questions




Registration is FREE and takes less than a minute!


Having trouble posting or changing forum settings?
Read the Forum Help (FAQ) or contact the webmaster





Join The Club

Sign in to ask questions, share photos, and access all website features

Your Cars

1978 Triumph Spitfire 1500

Text Size

Larger Smaller
Reset Save

Sponsor Links