TRExp

TR7 & TR8 Forum

Offenhauser VS Edelbrock for 4 barrel conversion.

Moss Motors
AutoShrine Sponsor
AutoShrine Sponsor
AutoShrine Sponsor
AutoShrine Sponsor

RossL Silver Member Ross LoMonaco
NJ, USA   USA
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,.

. Hide banner ads & support this website by becoming a > Gold Supporting Member <
darrellwalker Darrell Walker
Vancouver, WA, USA   USA
1966 Triumph TR4A "Christy"
1981 Triumph TR8 "Kate"
In reply to # 1504874 by RossL I am leaning towards the Edlebrock triangular air cleaner with the foam,.

I don't have any option between the Offy or Edelbrock intake. I have the Edelbrock and it does fit.

But I would read up on those air filters. I don't think they filter all that well, and the foam tends to break down and get ingested, and apparently they are also fire hazards if the engine should backfire.

I used the 10" Edelbrock air filter, you have to cut down the base to get it to fit. I used a cut off wheel in a drill press. You still need about 1/4" there to clear the top of the carb. I used JB Weld to reattach the cut off flange, but that probably isn't needed. It just gives a wider area to sit against the gasket.

But now I'm using a Spectre low profile air plenum (though I no longer have the Holley).



Darrell Walker
66 TR4A IRS-SC CTC67956L
81 TR8 SATPZ458XBA406206
Vancouver, WA, USA


Attachments:
IMG_0311.jpg    43.2 KB
IMG_0311.jpg

IMG_0313.jpg    33 KB
Sign In or Register to view this photo
POW Peter Wirth
HEBRON, NH - New Hampshire, USA   USA
Though I can not personally give a comparison. Here is a thread with some posts by someone who claims to have experience with both.

http://thebritishcar.com/showthread.php?1123-TR8-intake-manifolds


The 390 is an excellent choice for a down draft 4bbl, on our small V8's, and congratulations on not falling into a "bigger is better" in regards to CFM. The 390 keeps air velocity high through the venturies which translates to snappy response. I have a 390 and an Edlebrock Performer and am quite happy with the combo though it took a while to get jetting and some other settings right. Don't fall for the "pre jetted for our Rover V8's" BS either, as they can be very individually picky to accelerator pump settings, Power Valve choice and main jetting, all of which overlap to some degree. - Pete

. Hide banner ads & support this website by becoming a > Gold Supporting Member <
RossL Silver Member Ross LoMonaco
NJ, USA   USA
In reply to # 1504890 by POW Though I can not personally give a comparison. Here is a thread with some posts by someone who claims to have experience with both.

http://thebritishcar.com/showthread.php?1123-TR8-intake-manifolds


The 390 is an excellent choice for a down draft 4bbl, on our small V8's, and congratulations on not falling into a "bigger is better" in regards to CFM. The 390 keeps air velocity high through the venturies which translates to snappy response. I have a 390 and an Edlebrock Performer and am quite happy with the combo though it took a while to get jetting and some other settings right. Don't fall for the "pre jetted for our Rover V8's" BS either, as they can be very individually picky to accelerator pump settings, Power Valve choice and main jetting, all of which overlap to some degree. - Pete

Could you share what you ended up with regarding the jets and power valve? I am sure that would be closer than the carb out of the box.

TR8todd Avatar
TR8todd Todd Kishbach
Mass, USA   USA
1977 Triumph TR7 "Rally Fraud"
1978 Triumph TR8
1979 Triumph TR7
1980 Triumph TR8    & more
The Edelbrock is slightly better than the Offy. The Offy is preferred by the MGBV8 crowd because it sits a little lower than the Edelbrock. Best price on a new one is from Summit, plus free shipping. I have three or four used ones. I'd let one go a little cheaper than what a new one goes for. If you are looking for all out performance, there are some other much more expensive options. The Edelbrock also works pretty well with a throttle body FI system, where as the Offy does not.

POW Peter Wirth
HEBRON, NH - New Hampshire, USA   USA
In reply to # 1504901 by RossL
]

Could you share what you ended up with regarding the jets and power valve? I am sure that would be closer than the carb out of the box.

Sure, but again keep in mind my engine is more than likely different from your's. First of all, this carb's specs from Holley are: Main jet = 51. Secondary metering plate has a drilled jet size the equivalent of 56. The number is 34R9716-3 or possibly -59. Stock PV will be 6.5 and the pump squirter will be 25 using a red cam in I believe the # 2 position. If you are not familiar with Holley carbs this all seems really foreign but will become understandable with research.

Back to your query of the particular specs of my 390: Main jets are 57, Power Valve is 8.5, squirter is 25 and it's cam is white in the 2nd hole, I am currently using the stock secondary metering plate with 56 jet equivalent but have a kit to be installed this spring that will essentially convert the secondary metering plate equipped 4160 model to a 4150 model carb by replacing the secondary plate with a block similar to the primary that will allow easy jet substitution. 60 will be my first try. Feel free to PM me if you wish.

acltpvd charles frink
Mass, USA   USA
Just an opinion but here goes.

I would do a nice set of hedders, a decent ignition system and a new cam and lifters along with the 4V and intake. Dependent on the cam cjhosen you might think
about increasing the carb size to somewhere near (I think) 450 cfm. I did this on an 80 TR8 and was surprised at the difference in performance. I got the cam from a company in CA. but can not think of the name. Idle was a bit "lumpy" but not so bad as to be objectionable or hard to deal with. Also sounded nice with those glasspaks.

Charles

P.S. I think it was Herbert Cams in CA

. Hide banner ads & support this website by becoming a > Gold Supporting Member <
Bergie Bob Berg
Powell, OH, USA   USA
I have used both edelbrock 2198 and the offenhauser john wolf racing dual port intake and the edelbrock is better torque wise off idle thru high rev's...offy does sit much lower .
I would also recommend the quick fuel Slayer Series Carburetor 450CFM Vacuum Secondary ..has a lot more tuning options than holley with air bleeds and a primary side metering block (IFR/PVCR bleeds) so when you end up with an off idle hesitation or rich idle & cruise air/fuel you will be glad you have this carb.....also any carb out of the box will need a new a set up and tune for your car and I recommend an air fuel reader to get it right........note the quick fuel is $299 on sale now vs the holley 390 #8007 at $450....I do not like the triangle edelbrock foam filter (doesn't filter well) and would fit the biggest round air cleaner you can get in that space -11in or 14in width x 2.5 or 3 inch height...also I have used the K&N extreme air flow tops which also allow air thru the top improving flow-sounds louder also smiling smiley ..


on sale at summit or jegs with holiday promotion (holley owns quick fuel) :
https://www.summitracing.com/parts/qft-sl-450-vs/overview/

POW Peter Wirth
HEBRON, NH - New Hampshire, USA   USA
In reply to # 1505097 by Bergie I have used both edelbrock 2198 and the offenhauser john wolf racing dual port intake and the edelbrock is better torque wise off idle thru high rev's...offy does sit much lower .
I would also recommend the quick fuel Slayer Series Carburetor 450CFM Vacuum Secondary ..has a lot more tuning options than holley with air bleeds and a primary side metering block (IFR/PVCR bleeds) so when you end up with an off idle hesitation or rich idle & cruise air/fuel you will be glad you have this carb.....also any carb out of the box will need a new a set up and tune for your car and I recommend an air fuel reader to get it right........note the quick fuel is $299 on sale now vs the holley 390 #8007 at $450....I do not like the triangle edelbrock foam filter (doesn't filter well) and would fit the biggest round air cleaner you can get in that space -11in or 14in width x 2.5 or 3 inch height...also I have used the K&N extreme air flow tops which also allow air thru the top improving flow-sounds louder also smiling smiley ..


on sale at summit or jegs with holiday promotion (holley owns quick fuel) :
https://www.summitracing.com/parts/qft-sl-450-vs/overview/

All of this makes a lot of sense. While that Slayer is technically a bit too large for our 3.5's, the amount of tunability incorporated into it's design makes it a viable option at a great price. However, I believe you said a 390 is what you've got so like Steven Stills said way back when even TR6's were young "If you can't be with the one you love, Honey, Love the one you're with". Meaning, the 390 is capable of being tuned to satisfaction even with it's limited adjustments compared to the Slayer and quite honestly, that 450 Slayer may have more capabilities than the average tuner can, or know how to use. If one really knows the Holley style of carb through and through (and the Slayer is of this style) it's one thing but if one is new to this design, infinite/multiple adjustments can also result in infinite/multiple mal-adjustments. Also keep in mind, as with any carb, the various replaceable tuning parts are extra $'s so when the first change is not quite right, spend some more and try again. - Pete

. Hide banner ads & support this website by becoming a > Gold Supporting Member <
mntr463 Avatar
mntr463 Pat Bob
Mpls, MN, USA   USA
1963 Triumph TR4
1980 Triumph TR8 "The Eight"
I did the conversion on my 1980 and the foam air filter brakes down and gets sucked in. With this style of base plate, I was able to use regular filters.



PS. I also did the headers also but left the engine stock.


Attachments:
TR8.jpg    33.5 KB
TR8.jpg

RossL Silver Member Ross LoMonaco
NJ, USA   USA
I bought the 390CFM Holley and the Edelbrock. I have the fitting Woody uses for the coolant bleed. I also have a rubber cap the previous owner gave me to cap something on the water pump.

I will buy the intake gaskets and a TR7 throttle cable. What else do I need?

I will figure out which air cleaner I will use once I start working on it.

POW Peter Wirth
HEBRON, NH - New Hampshire, USA   USA
If you look at the water pump just in front of the thermostat housing you will see a 5/8" hose coming off the pump and connecting to a pipe running under the original intake manifold. That pipe is a thermostat by-pass and it is connected to the underside of the original manifold. The Edlebrock (and the other) manifold has a provision for this at the thermostat housing but the problem is the original thermostat housing itself does not. The down and dirty easy thing to do is simply block off the return by-pass pipe at the waterpump and that is what the rubber cap is for. It's not really the right way to plumb the system but it will work ok. You will probably notice coolant temp spikes and drops as the thermostat alone try's to control the engine temp without the benefit of the by-pass. There is a solution but frankly I would not worry about it for now. I would concentrate first on getting your new carb dialed in. You may consider not using just that cap though because as I remember it is just rubber with no cord reinforcement. A better choice would be a short piece of 5/8" coolant hose with a bolt shank stuck in the end and two hose clamps. It will look a bit red-neck but won't blow out like that thin rubber cap might. You can address correct thermostat by-pass plumbing later.

You will need a bracket for the throttle cable and return spring and a means to connect the cable to the carb linkage. The brackets can by made yourself and secured with one of the manifold bolts or you can by any number of good professional looking throttle systems. And for connecting to the carb throttle arm, anything from nice ball&socket quick disconnect to a simple wire-through-a-barrel deal secured with a set screw (not the best but works OK on lawn mowers, "vroom, vroom"winking smiley.

And you have a crank case ventilation system to think about. A couple of ways to do that too. Again the easy way is to just come off your flame trap with a hose to the base of the air cleaner. The proper way is with a PCV valve in place of the flame trap and plumbed to the PCV pipe at the back of you Holley. There are variations of this in regards to location. The best thing would be to google TR8 and MGB V8 engine compartments to see what others have done to solve some of these problems. - Pete

TeeR8 Avatar
TeeR8 Gold Member Henri Lefebvre
Calgary, AB, Canada   CAN
In reply to # 1505181 by RossL I bought the 390CFM Holley and the Edelbrock. I have the fitting Woody uses for the coolant bleed. I also have a rubber cap the previous owner gave me to cap something on the water pump.

I will buy the intake gaskets and a TR7 throttle cable. What else do I need?

I will figure out which air cleaner I will use once I start working on it.

Ross,

For my Holley 390 and Edelbrock combo I used the Lokar DP-1000HT throttle cable and bracket kit. I am very pleased with the result.

Description here at Summit Racing



Henri
1980 TR8, Platinum
1971 MGB GT, Midnight Blue



Edited 1 time(s). Last edit at 2017-12-31 10:51 AM by TeeR8.


Attachments:
P1050809.JPG    66.9 KB
P1050809.JPG

POW Peter Wirth
HEBRON, NH - New Hampshire, USA   USA
Henri, that does look like a clean installation. What did you actually come up with for connection to the peddle? Length just right? - Pete

RossL Silver Member Ross LoMonaco
NJ, USA   USA
In reply to # 1505251 by TeeR8
In reply to # 1505181 by RossL I bought the 390CFM Holley and the Edelbrock. I have the fitting Woody uses for the coolant bleed. I also have a rubber cap the previous owner gave me to cap something on the water pump.

I will buy the intake gaskets and a TR7 throttle cable. What else do I need?

I will figure out which air cleaner I will use once I start working on it.

Ross,

For my Holley 390 and Edelbrock combo I used the Lokar DP-1000HT throttle cable and bracket kit. I am very pleased with the result.

Description here at Summit Racing

Thank you, I like that setup.

Does the Lokar bracket attach to one of the manifold bolts?

. 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

1972 Triumph TR6

Text Size

Larger Smaller
Reset Save

Sponsor Links